[clang] Use StringRef::{starts,ends}_with (NFC) (#75149)

This patch replaces uses of StringRef::{starts,ends}with with
StringRef::{starts,ends}_with for consistency with
std::{string,string_view}::{starts,ends}_with in C++20.

I'm planning to deprecate and eventually remove
StringRef::{starts,ends}with.

155 files changed, 547 insertions, 541 deletions

diff --git a/clang/include/clang/Basic/Attr.td b/clang/include/clang/Basic/Attr.td
index 0d94ea2..c8b17cb 100644
--- a/clang/include/clang/Basic/Attr.td
+++ b/clang/include/clang/Basic/Attr.td
@@ -2878,7 +2878,7 @@ def Target : InheritableAttr {
 
       for (auto &Feature : AttrFeatures) {
         Feature = Feature.trim();
-        if (Feature.startswith("arch="))
+        if (Feature.starts_with("arch="))
           return Feature.drop_front(sizeof("arch=") - 1);
       }
       return "";
@@ -2896,8 +2896,8 @@ def Target : InheritableAttr {
       for (auto &Feature : AttrFeatures) {
         Feature = Feature.trim();
 
-        if (!Feature.startswith("no-") && !Feature.startswith("arch=") &&
-            !Feature.startswith("fpmath=") && !Feature.startswith("tune="))
+        if (!Feature.starts_with("no-") && !Feature.starts_with("arch=") &&
+            !Feature.starts_with("fpmath=") && !Feature.starts_with("tune="))
           Out.push_back(Feature);
       }
     }
diff --git a/clang/include/clang/Basic/IdentifierTable.h b/clang/include/clang/Basic/IdentifierTable.h
index 0898e7d..1ac182d 100644
--- a/clang/include/clang/Basic/IdentifierTable.h
+++ b/clang/include/clang/Basic/IdentifierTable.h
@@ -511,7 +511,7 @@ public:
   ///   function(<#int x#>);
   /// \endcode
   bool isEditorPlaceholder() const {
-    return getName().startswith("<#") && getName().endswith("#>");
+    return getName().starts_with("<#") && getName().ends_with("#>");
   }
 
   /// Determine whether \p this is a name reserved for the implementation (C99
diff --git a/clang/include/clang/StaticAnalyzer/Core/AnalyzerOptions.h b/clang/include/clang/StaticAnalyzer/Core/AnalyzerOptions.h
index a947bd0..276d11e 100644
--- a/clang/include/clang/StaticAnalyzer/Core/AnalyzerOptions.h
+++ b/clang/include/clang/StaticAnalyzer/Core/AnalyzerOptions.h
@@ -409,8 +409,8 @@ AnalyzerOptions::getRegisteredCheckers(bool IncludeExperimental) {
   };
   std::vector<StringRef> Checkers;
   for (StringRef CheckerName : StaticAnalyzerCheckerNames) {
-    if (!CheckerName.startswith("debug.") &&
-        (IncludeExperimental || !CheckerName.startswith("alpha.")))
+    if (!CheckerName.starts_with("debug.") &&
+        (IncludeExperimental || !CheckerName.starts_with("alpha.")))
       Checkers.push_back(CheckerName);
   }
   return Checkers;
diff --git a/clang/lib/APINotes/APINotesManager.cpp b/clang/lib/APINotes/APINotesManager.cpp
index ec1fb3f..a921c8b 100644
--- a/clang/lib/APINotes/APINotesManager.cpp
+++ b/clang/lib/APINotes/APINotesManager.cpp
@@ -198,7 +198,7 @@ static void checkPrivateAPINotesName(DiagnosticsEngine &Diags,
   StringRef RealFileName =
       llvm::sys::path::filename(File->tryGetRealPathName());
   StringRef RealStem = llvm::sys::path::stem(RealFileName);
-  if (RealStem.endswith("_private"))
+  if (RealStem.ends_with("_private"))
     return;
 
   unsigned DiagID = diag::warn_apinotes_private_case;
diff --git a/clang/lib/APINotes/APINotesYAMLCompiler.cpp b/clang/lib/APINotes/APINotesYAMLCompiler.cpp
index 4dfd01d..57d6da7 100644
--- a/clang/lib/APINotes/APINotesYAMLCompiler.cpp
+++ b/clang/lib/APINotes/APINotesYAMLCompiler.cpp
@@ -745,7 +745,7 @@ public:
     convertCommonEntity(M, MI, M.Selector);
 
     // Check if the selector ends with ':' to determine if it takes arguments.
-    bool takesArguments = M.Selector.endswith(":");
+    bool takesArguments = M.Selector.ends_with(":");
 
     // Split the selector into pieces.
     llvm::SmallVector<StringRef, 4> Args;
diff --git a/clang/lib/ARCMigrate/ARCMT.cpp b/clang/lib/ARCMigrate/ARCMT.cpp
index 8e39897..b410d5f 100644
--- a/clang/lib/ARCMigrate/ARCMT.cpp
+++ b/clang/lib/ARCMigrate/ARCMT.cpp
@@ -201,7 +201,7 @@ createInvocationForMigration(CompilerInvocation &origCI,
   for (std::vector<std::string>::iterator
          I = CInvok->getDiagnosticOpts().Warnings.begin(),
          E = CInvok->getDiagnosticOpts().Warnings.end(); I != E; ++I) {
-    if (!StringRef(*I).startswith("error"))
+    if (!StringRef(*I).starts_with("error"))
       WarnOpts.push_back(*I);
   }
   WarnOpts.push_back("error=arc-unsafe-retained-assign");
diff --git a/clang/lib/ARCMigrate/ObjCMT.cpp b/clang/lib/ARCMigrate/ObjCMT.cpp
index 5a25c88..ed363a4 100644
--- a/clang/lib/ARCMigrate/ObjCMT.cpp
+++ b/clang/lib/ARCMigrate/ObjCMT.cpp
@@ -562,7 +562,7 @@ static void rewriteToObjCProperty(const ObjCMethodDecl *Getter,
 static bool IsCategoryNameWithDeprecatedSuffix(ObjCContainerDecl *D) {
   if (ObjCCategoryDecl *CatDecl = dyn_cast<ObjCCategoryDecl>(D)) {
     StringRef Name = CatDecl->getName();
-    return Name.endswith("Deprecated");
+    return Name.ends_with("Deprecated");
   }
   return false;
 }
@@ -1176,12 +1176,12 @@ bool ObjCMigrateASTConsumer::migrateProperty(ASTContext &Ctx,
   if (!SetterMethod) {
     // try a different naming convention for getter: isXxxxx
     StringRef getterNameString = getterName->getName();
-    bool IsPrefix = getterNameString.startswith("is");
+    bool IsPrefix = getterNameString.starts_with("is");
     // Note that we don't want to change an isXXX method of retainable object
     // type to property (readonly or otherwise).
     if (IsPrefix && GRT->isObjCRetainableType())
       return false;
-    if (IsPrefix || getterNameString.startswith("get")) {
+    if (IsPrefix || getterNameString.starts_with("get")) {
       LengthOfPrefix = (IsPrefix ? 2 : 3);
       const char *CGetterName = getterNameString.data() + LengthOfPrefix;
       // Make sure that first character after "is" or "get" prefix can
@@ -1320,11 +1320,11 @@ void ObjCMigrateASTConsumer::migrateFactoryMethod(ASTContext &Ctx,
   if (OIT_Family == OIT_Singleton || OIT_Family == OIT_ReturnsSelf) {
     StringRef STRefMethodName(MethodName);
     size_t len = 0;
-    if (STRefMethodName.startswith("standard"))
+    if (STRefMethodName.starts_with("standard"))
       len = strlen("standard");
-    else if (STRefMethodName.startswith("shared"))
+    else if (STRefMethodName.starts_with("shared"))
       len = strlen("shared");
-    else if (STRefMethodName.startswith("default"))
+    else if (STRefMethodName.starts_with("default"))
       len = strlen("default");
     else
       return;
@@ -1341,7 +1341,7 @@ void ObjCMigrateASTConsumer::migrateFactoryMethod(ASTContext &Ctx,
   StringRef LoweredMethodName(MethodName);
   std::string StringLoweredMethodName = LoweredMethodName.lower();
   LoweredMethodName = StringLoweredMethodName;
-  if (!LoweredMethodName.startswith(ClassNamePostfix))
+  if (!LoweredMethodName.starts_with(ClassNamePostfix))
     return;
   if (OIT_Family == OIT_ReturnsSelf)
     ReplaceWithClasstype(*this, OM);
diff --git a/clang/lib/ARCMigrate/TransUnbridgedCasts.cpp b/clang/lib/ARCMigrate/TransUnbridgedCasts.cpp
index 40220a2e..1e6354f 100644
--- a/clang/lib/ARCMigrate/TransUnbridgedCasts.cpp
+++ b/clang/lib/ARCMigrate/TransUnbridgedCasts.cpp
@@ -146,7 +146,7 @@ private:
             ento::cocoa::isRefType(E->getSubExpr()->getType(), "CF",
                                    FD->getIdentifier()->getName())) {
           StringRef fname = FD->getIdentifier()->getName();
-          if (fname.endswith("Retain") || fname.contains("Create") ||
+          if (fname.ends_with("Retain") || fname.contains("Create") ||
               fname.contains("Copy")) {
             // Do not migrate to couple of bridge transfer casts which
             // cancel each other out. Leave it unchanged so error gets user
diff --git a/clang/lib/ARCMigrate/TransformActions.cpp b/clang/lib/ARCMigrate/TransformActions.cpp
index bd5c793..6bc6fed 100644
--- a/clang/lib/ARCMigrate/TransformActions.cpp
+++ b/clang/lib/ARCMigrate/TransformActions.cpp
@@ -431,7 +431,7 @@ bool TransformActionsImpl::canReplaceText(SourceLocation loc, StringRef text) {
   if (invalidTemp)
     return false;
 
-  return file.substr(locInfo.second).startswith(text);
+  return file.substr(locInfo.second).starts_with(text);
 }
 
 void TransformActionsImpl::commitInsert(SourceLocation loc, StringRef text) {
diff --git a/clang/lib/ARCMigrate/Transforms.cpp b/clang/lib/ARCMigrate/Transforms.cpp
index 90b2b32b..2808e35 100644
--- a/clang/lib/ARCMigrate/Transforms.cpp
+++ b/clang/lib/ARCMigrate/Transforms.cpp
@@ -95,7 +95,7 @@ bool trans::isPlusOne(const Expr *E) {
           ento::cocoa::isRefType(callE->getType(), "CF",
                                  FD->getIdentifier()->getName())) {
         StringRef fname = FD->getIdentifier()->getName();
-        if (fname.endswith("Retain") || fname.contains("Create") ||
+        if (fname.ends_with("Retain") || fname.contains("Create") ||
             fname.contains("Copy"))
           return true;
       }
diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp
index e877f90..0395b3e 100644
--- a/clang/lib/AST/ASTContext.cpp
+++ b/clang/lib/AST/ASTContext.cpp
@@ -8223,7 +8223,7 @@ void ASTContext::getObjCEncodingForTypeImpl(QualType T, std::string &S,
       // Another legacy compatibility encoding. Some ObjC qualifier and type
       // combinations need to be rearranged.
       // Rewrite "in const" from "nr" to "rn"
-      if (StringRef(S).endswith("nr"))
+      if (StringRef(S).ends_with("nr"))
         S.replace(S.end()-2, S.end(), "rn");
     }
 
@@ -13519,7 +13519,7 @@ void ASTContext::getFunctionFeatureMap(llvm::StringMap<bool> &FeatureMap,
                       Target->getTargetOpts().FeaturesAsWritten.begin(),
                       Target->getTargetOpts().FeaturesAsWritten.end());
     } else {
-      if (VersionStr.startswith("arch="))
+      if (VersionStr.starts_with("arch="))
         TargetCPU = VersionStr.drop_front(sizeof("arch=") - 1);
       else if (VersionStr != "default")
         Features.push_back((StringRef{"+"} + VersionStr).str());
diff --git a/clang/lib/AST/DeclPrinter.cpp b/clang/lib/AST/DeclPrinter.cpp
index 30a26d5..24da6f2 100644
--- a/clang/lib/AST/DeclPrinter.cpp
+++ b/clang/lib/AST/DeclPrinter.cpp
@@ -1728,7 +1728,7 @@ void DeclPrinter::VisitObjCPropertyDecl(ObjCPropertyDecl *PDecl) {
   std::string TypeStr = PDecl->getASTContext().getUnqualifiedObjCPointerType(T).
       getAsString(Policy);
   Out << ' ' << TypeStr;
-  if (!StringRef(TypeStr).endswith("*"))
+  if (!StringRef(TypeStr).ends_with("*"))
     Out << ' ';
   Out << *PDecl;
   if (Policy.PolishForDeclaration)
diff --git a/clang/lib/AST/Mangle.cpp b/clang/lib/AST/Mangle.cpp
index 64c9719..d3a6b61 100644
--- a/clang/lib/AST/Mangle.cpp
+++ b/clang/lib/AST/Mangle.cpp
@@ -147,7 +147,7 @@ void MangleContext::mangleName(GlobalDecl GD, raw_ostream &Out) {
 
     // If the label isn't literal, or if this is an alias for an LLVM intrinsic,
     // do not add a "\01" prefix.
-    if (!ALA->getIsLiteralLabel() || ALA->getLabel().startswith("llvm.")) {
+    if (!ALA->getIsLiteralLabel() || ALA->getLabel().starts_with("llvm.")) {
       Out << ALA->getLabel();
       return;
     }
diff --git a/clang/lib/AST/MicrosoftMangle.cpp b/clang/lib/AST/MicrosoftMangle.cpp
index c59a66e..8346ad8 100644
--- a/clang/lib/AST/MicrosoftMangle.cpp
+++ b/clang/lib/AST/MicrosoftMangle.cpp
@@ -63,7 +63,7 @@ struct msvc_hashing_ostream : public llvm::raw_svector_ostream {
       : llvm::raw_svector_ostream(Buffer), OS(OS) {}
   ~msvc_hashing_ostream() override {
     StringRef MangledName = str();
-    bool StartsWithEscape = MangledName.startswith("\01");
+    bool StartsWithEscape = MangledName.starts_with("\01");
     if (StartsWithEscape)
       MangledName = MangledName.drop_front(1);
     if (MangledName.size() < 4096) {
diff --git a/clang/lib/AST/PrintfFormatString.cpp b/clang/lib/AST/PrintfFormatString.cpp
index f0b9d0e..3b09ca4 100644
--- a/clang/lib/AST/PrintfFormatString.cpp
+++ b/clang/lib/AST/PrintfFormatString.cpp
@@ -140,7 +140,7 @@ static PrintfSpecifierResult ParsePrintfSpecifier(FormatStringHandler &H,
         // Set the privacy flag if the privacy annotation in the
         // comma-delimited segment is at least as strict as the privacy
         // annotations in previous comma-delimited segments.
-        if (MatchedStr.startswith("mask")) {
+        if (MatchedStr.starts_with("mask")) {
           StringRef MaskType = MatchedStr.substr(sizeof("mask.") - 1);
           unsigned Size = MaskType.size();
           if (Warn && (Size == 0 || Size > 8))
diff --git a/clang/lib/AST/RawCommentList.cpp b/clang/lib/AST/RawCommentList.cpp
index c3beb23..dffa007 100644
--- a/clang/lib/AST/RawCommentList.cpp
+++ b/clang/lib/AST/RawCommentList.cpp
@@ -141,8 +141,8 @@ RawComment::RawComment(const SourceManager &SourceMgr, SourceRange SR,
     Kind = K.first;
     IsTrailingComment |= K.second;
 
-    IsAlmostTrailingComment = RawText.startswith("//<") ||
-                                 RawText.startswith("/*<");
+    IsAlmostTrailingComment =
+        RawText.starts_with("//<") || RawText.starts_with("/*<");
   } else {
     Kind = RCK_Merged;
     IsTrailingComment =
diff --git a/clang/lib/AST/Stmt.cpp b/clang/lib/AST/Stmt.cpp
index c31fb48..afd0588 100644
--- a/clang/lib/AST/Stmt.cpp
+++ b/clang/lib/AST/Stmt.cpp
@@ -811,11 +811,12 @@ std::string MSAsmStmt::generateAsmString(const ASTContext &C) const {
     StringRef Instruction = Pieces[I];
     // For vex/vex2/vex3/evex masm style prefix, convert it to att style
     // since we don't support masm style prefix in backend.
-    if (Instruction.startswith("vex "))
+    if (Instruction.starts_with("vex "))
       MSAsmString += '{' + Instruction.substr(0, 3).str() + '}' +
                      Instruction.substr(3).str();
-    else if (Instruction.startswith("vex2 ") ||
-             Instruction.startswith("vex3 ") || Instruction.startswith("evex "))
+    else if (Instruction.starts_with("vex2 ") ||
+             Instruction.starts_with("vex3 ") ||
+             Instruction.starts_with("evex "))
       MSAsmString += '{' + Instruction.substr(0, 4).str() + '}' +
                      Instruction.substr(4).str();
     else
diff --git a/clang/lib/ASTMatchers/ASTMatchersInternal.cpp b/clang/lib/ASTMatchers/ASTMatchersInternal.cpp
index 435bbde..8ed213c 100644
--- a/clang/lib/ASTMatchers/ASTMatchersInternal.cpp
+++ b/clang/lib/ASTMatchers/ASTMatchersInternal.cpp
@@ -480,11 +480,11 @@ HasNameMatcher::HasNameMatcher(std::vector<std::string> N)
 
 static bool consumeNameSuffix(StringRef &FullName, StringRef Suffix) {
   StringRef Name = FullName;
-  if (!Name.endswith(Suffix))
+  if (!Name.ends_with(Suffix))
     return false;
   Name = Name.drop_back(Suffix.size());
   if (!Name.empty()) {
-    if (!Name.endswith("::"))
+    if (!Name.ends_with("::"))
       return false;
     Name = Name.drop_back(2);
   }
@@ -530,7 +530,7 @@ public:
   PatternSet(ArrayRef<std::string> Names) {
     Patterns.reserve(Names.size());
     for (StringRef Name : Names)
-      Patterns.push_back({Name, Name.startswith("::")});
+      Patterns.push_back({Name, Name.starts_with("::")});
   }
 
   /// Consumes the name suffix from each pattern in the set and removes the ones
@@ -652,11 +652,11 @@ bool HasNameMatcher::matchesNodeFullSlow(const NamedDecl &Node) const {
     const StringRef FullName = OS.str();
 
     for (const StringRef Pattern : Names) {
-      if (Pattern.startswith("::")) {
+      if (Pattern.starts_with("::")) {
         if (FullName == Pattern)
           return true;
-      } else if (FullName.endswith(Pattern) &&
-                 FullName.drop_back(Pattern.size()).endswith("::")) {
+      } else if (FullName.ends_with(Pattern) &&
+                 FullName.drop_back(Pattern.size()).ends_with("::")) {
         return true;
       }
     }
diff --git a/clang/lib/ASTMatchers/Dynamic/Parser.cpp b/clang/lib/ASTMatchers/Dynamic/Parser.cpp
index 33a10fe..27096a8 100644
--- a/clang/lib/ASTMatchers/Dynamic/Parser.cpp
+++ b/clang/lib/ASTMatchers/Dynamic/Parser.cpp
@@ -187,10 +187,10 @@ private:
             break;
           ++TokenLength;
         }
-        if (TokenLength == 4 && Code.startswith("true")) {
+        if (TokenLength == 4 && Code.starts_with("true")) {
           Result.Kind = TokenInfo::TK_Literal;
           Result.Value = true;
-        } else if (TokenLength == 5 && Code.startswith("false")) {
+        } else if (TokenLength == 5 && Code.starts_with("false")) {
           Result.Kind = TokenInfo::TK_Literal;
           Result.Value = false;
         } else {
@@ -737,7 +737,7 @@ bool Parser::parseMatcherExpressionImpl(const TokenInfo &NameToken,
 // Completions minus the prefix.
 void Parser::addCompletion(const TokenInfo &CompToken,
                            const MatcherCompletion& Completion) {
-  if (StringRef(Completion.TypedText).startswith(CompToken.Text) &&
+  if (StringRef(Completion.TypedText).starts_with(CompToken.Text) &&
       Completion.Specificity > 0) {
     Completions.emplace_back(Completion.TypedText.substr(CompToken.Text.size()),
                              Completion.MatcherDecl, Completion.Specificity);
diff --git a/clang/lib/Analysis/BodyFarm.cpp b/clang/lib/Analysis/BodyFarm.cpp
index 13ec9b6..127e843 100644
--- a/clang/lib/Analysis/BodyFarm.cpp
+++ b/clang/lib/Analysis/BodyFarm.cpp
@@ -726,8 +726,8 @@ Stmt *BodyFarm::getBody(const FunctionDecl *D) {
       FF = nullptr;
       break;
     }
-  } else if (Name.startswith("OSAtomicCompareAndSwap") ||
-             Name.startswith("objc_atomicCompareAndSwap")) {
+  } else if (Name.starts_with("OSAtomicCompareAndSwap") ||
+             Name.starts_with("objc_atomicCompareAndSwap")) {
     FF = create_OSAtomicCompareAndSwap;
   } else if (Name == "call_once" && D->getDeclContext()->isStdNamespace()) {
     FF = create_call_once;
diff --git a/clang/lib/Analysis/CallGraph.cpp b/clang/lib/Analysis/CallGraph.cpp
index 59cc939..f892980 100644
--- a/clang/lib/Analysis/CallGraph.cpp
+++ b/clang/lib/Analysis/CallGraph.cpp
@@ -168,7 +168,7 @@ bool CallGraph::includeCalleeInGraph(const Decl *D) {
       return false;
 
     IdentifierInfo *II = FD->getIdentifier();
-    if (II && II->getName().startswith("__inline"))
+    if (II && II->getName().starts_with("__inline"))
       return false;
   }
 
diff --git a/clang/lib/Analysis/CalledOnceCheck.cpp b/clang/lib/Analysis/CalledOnceCheck.cpp
index 5b4fc24..04c5f6a 100644
--- a/clang/lib/Analysis/CalledOnceCheck.cpp
+++ b/clang/lib/Analysis/CalledOnceCheck.cpp
@@ -973,7 +973,7 @@ private:
   /// Return true if the given name has conventional suffixes.
   static bool hasConventionalSuffix(llvm::StringRef Name) {
     return llvm::any_of(CONVENTIONAL_SUFFIXES, [Name](llvm::StringRef Suffix) {
-      return Name.endswith(Suffix);
+      return Name.ends_with(Suffix);
     });
   }
 
diff --git a/clang/lib/Analysis/CocoaConventions.cpp b/clang/lib/Analysis/CocoaConventions.cpp
index 571d72e..836859c 100644
--- a/clang/lib/Analysis/CocoaConventions.cpp
+++ b/clang/lib/Analysis/CocoaConventions.cpp
@@ -26,10 +26,10 @@ bool cocoa::isRefType(QualType RetTy, StringRef Prefix,
   // Recursively walk the typedef stack, allowing typedefs of reference types.
   while (const TypedefType *TD = RetTy->getAs<TypedefType>()) {
     StringRef TDName = TD->getDecl()->getIdentifier()->getName();
-    if (TDName.startswith(Prefix) && TDName.endswith("Ref"))
+    if (TDName.starts_with(Prefix) && TDName.ends_with("Ref"))
       return true;
     // XPC unfortunately uses CF-style function names, but aren't CF types.
-    if (TDName.startswith("xpc_"))
+    if (TDName.starts_with("xpc_"))
       return false;
     RetTy = TD->getDecl()->getUnderlyingType();
   }
@@ -43,7 +43,7 @@ bool cocoa::isRefType(QualType RetTy, StringRef Prefix,
     return false;
 
   // Does the name start with the prefix?
-  return Name.startswith(Prefix);
+  return Name.starts_with(Prefix);
 }
 
 /// Returns true when the passed-in type is a CF-style reference-counted
@@ -127,10 +127,9 @@ bool coreFoundation::followsCreateRule(const FunctionDecl *fn) {
     // Scan for *lowercase* 'reate' or 'opy', followed by no lowercase
     // character.
     StringRef suffix = functionName.substr(it - start);
-    if (suffix.startswith("reate")) {
+    if (suffix.starts_with("reate")) {
       it += 5;
-    }
-    else if (suffix.startswith("opy")) {
+    } else if (suffix.starts_with("opy")) {
       it += 3;
     } else {
       // Keep scanning.
diff --git a/clang/lib/Analysis/FlowSensitive/Models/ChromiumCheckModel.cpp b/clang/lib/Analysis/FlowSensitive/Models/ChromiumCheckModel.cpp
index f49087a..5ac71e1 100644
--- a/clang/lib/Analysis/FlowSensitive/Models/ChromiumCheckModel.cpp
+++ b/clang/lib/Analysis/FlowSensitive/Models/ChromiumCheckModel.cpp
@@ -43,7 +43,7 @@ bool isCheckLikeMethod(llvm::SmallDenseSet<const CXXMethodDecl *> &CheckDecls,
       return false;
 
     for (const CXXMethodDecl *M : ParentClass->methods())
-      if (M->getDeclName().isIdentifier() && M->getName().endswith("Check"))
+      if (M->getDeclName().isIdentifier() && M->getName().ends_with("Check"))
         CheckDecls.insert(M);
   }
 
diff --git a/clang/lib/Analysis/RetainSummaryManager.cpp b/clang/lib/Analysis/RetainSummaryManager.cpp
index 4cbeb0c..6f50d95 100644
--- a/clang/lib/Analysis/RetainSummaryManager.cpp
+++ b/clang/lib/Analysis/RetainSummaryManager.cpp
@@ -174,7 +174,7 @@ static bool isOSObjectPtr(QualType QT) {
 }
 
 static bool isISLObjectRef(QualType Ty) {
-  return StringRef(Ty.getAsString()).startswith("isl_");
+  return StringRef(Ty.getAsString()).starts_with("isl_");
 }
 
 static bool isOSIteratorSubclass(const Decl *D) {
@@ -255,13 +255,13 @@ RetainSummaryManager::getSummaryForOSObject(const FunctionDecl *FD,
       // TODO: Add support for the slightly common *Matching(table) idiom.
       // Cf. IOService::nameMatching() etc. - these function have an unusual
       // contract of returning at +0 or +1 depending on their last argument.
-      if (FName.endswith("Matching")) {
+      if (FName.ends_with("Matching")) {
         return getPersistentStopSummary();
       }
 
       // All objects returned with functions *not* starting with 'get',
       // or iterators, are returned at +1.
-      if ((!FName.startswith("get") && !FName.startswith("Get")) ||
+      if ((!FName.starts_with("get") && !FName.starts_with("Get")) ||
           isOSIteratorSubclass(PD)) {
         return getOSSummaryCreateRule(FD);
       } else {
@@ -392,9 +392,9 @@ const RetainSummary *RetainSummaryManager::getSummaryForObjCOrCFObject(
     return getPersistentSummary(RetEffect::MakeNoRet(),
                                 ScratchArgs,
                                 ArgEffect(DoNothing), ArgEffect(DoNothing));
-  } else if (FName.startswith("NSLog")) {
+  } else if (FName.starts_with("NSLog")) {
     return getDoNothingSummary();
-  } else if (FName.startswith("NS") && FName.contains("Insert")) {
+  } else if (FName.starts_with("NS") && FName.contains("Insert")) {
     // Allowlist NSXXInsertXX, for example NSMapInsertIfAbsent, since they can
     // be deallocated by NSMapRemove.
     ScratchArgs = AF.add(ScratchArgs, 1, ArgEffect(StopTracking));
@@ -453,9 +453,9 @@ const RetainSummary *RetainSummaryManager::getSummaryForObjCOrCFObject(
 
   // Check for release functions, the only kind of functions that we care
   // about that don't return a pointer type.
-  if (FName.startswith("CG") || FName.startswith("CF")) {
+  if (FName.starts_with("CG") || FName.starts_with("CF")) {
     // Test for 'CGCF'.
-    FName = FName.substr(FName.startswith("CGCF") ? 4 : 2);
+    FName = FName.substr(FName.starts_with("CGCF") ? 4 : 2);
 
     if (isRelease(FD, FName))
       return getUnarySummary(FT, DecRef);
diff --git a/clang/lib/Basic/Attributes.cpp b/clang/lib/Basic/Attributes.cpp
index bb49521..44a4f18 100644
--- a/clang/lib/Basic/Attributes.cpp
+++ b/clang/lib/Basic/Attributes.cpp
@@ -33,7 +33,7 @@ int clang::hasAttribute(AttributeCommonInfo::Syntax Syntax,
                         const TargetInfo &Target, const LangOptions &LangOpts) {
   StringRef Name = Attr->getName();
   // Normalize the attribute name, __foo__ becomes foo.
-  if (Name.size() >= 4 && Name.startswith("__") && Name.endswith("__"))
+  if (Name.size() >= 4 && Name.starts_with("__") && Name.ends_with("__"))
     Name = Name.substr(2, Name.size() - 4);
 
   // Normalize the scope name, but only for gnu and clang attributes.
@@ -103,8 +103,8 @@ static StringRef normalizeAttrName(const IdentifierInfo *Name,
        (NormalizedScopeName.empty() || NormalizedScopeName == "gnu" ||
         NormalizedScopeName == "clang"));
   StringRef AttrName = Name->getName();
-  if (ShouldNormalize && AttrName.size() >= 4 && AttrName.startswith("__") &&
-      AttrName.endswith("__"))
+  if (ShouldNormalize && AttrName.size() >= 4 && AttrName.starts_with("__") &&
+      AttrName.ends_with("__"))
     AttrName = AttrName.slice(2, AttrName.size() - 2);
 
   return AttrName;
diff --git a/clang/lib/Basic/DiagnosticIDs.cpp b/clang/lib/Basic/DiagnosticIDs.cpp
index e5667d5..6c7bd50 100644
--- a/clang/lib/Basic/DiagnosticIDs.cpp
+++ b/clang/lib/Basic/DiagnosticIDs.cpp
@@ -853,5 +853,5 @@ bool DiagnosticIDs::isUnrecoverable(unsigned DiagID) const {
 
 bool DiagnosticIDs::isARCDiagnostic(unsigned DiagID) {
   unsigned cat = getCategoryNumberForDiag(DiagID);
-  return DiagnosticIDs::getCategoryNameFromID(cat).startswith("ARC ");
+  return DiagnosticIDs::getCategoryNameFromID(cat).starts_with("ARC ");
 }
diff --git a/clang/lib/Basic/IdentifierTable.cpp b/clang/lib/Basic/IdentifierTable.cpp
index 38150d1..5902c6d 100644
--- a/clang/lib/Basic/IdentifierTable.cpp
+++ b/clang/lib/Basic/IdentifierTable.cpp
@@ -604,7 +604,7 @@ LLVM_DUMP_METHOD void Selector::dump() const { print(llvm::errs()); }
 static bool startsWithWord(StringRef name, StringRef word) {
   if (name.size() < word.size()) return false;
   return ((name.size() == word.size() || !isLowercase(name[word.size()])) &&
-          name.startswith(word));
+          name.starts_with(word));
 }
 
 ObjCMethodFamily Selector::getMethodFamilyImpl(Selector sel) {
@@ -742,7 +742,7 @@ SelectorTable::constructSetterSelector(IdentifierTable &Idents,
 
 std::string SelectorTable::getPropertyNameFromSetterSelector(Selector Sel) {
   StringRef Name = Sel.getNameForSlot(0);
-  assert(Name.startswith("set") && "invalid setter name");
+  assert(Name.starts_with("set") && "invalid setter name");
   return (Twine(toLowercase(Name[3])) + Name.drop_front(4)).str();
 }
 
diff --git a/clang/lib/Basic/Module.cpp b/clang/lib/Basic/Module.cpp
index 7523e50..9252174 100644
--- a/clang/lib/Basic/Module.cpp
+++ b/clang/lib/Basic/Module.cpp
@@ -166,7 +166,8 @@ bool Module::isForBuilding(const LangOptions &LangOpts) const {
   // for either.
   if (!LangOpts.isCompilingModule() && getTopLevelModule()->IsFramework &&
       CurrentModule == LangOpts.ModuleName &&
-      !CurrentModule.endswith("_Private") && TopLevelName.endswith("_Private"))
+      !CurrentModule.ends_with("_Private") &&
+      TopLevelName.ends_with("_Private"))
     TopLevelName = TopLevelName.drop_back(8);
 
   return TopLevelName == CurrentModule;
diff --git a/clang/lib/Basic/Sarif.cpp b/clang/lib/Basic/Sarif.cpp
index 3476103..1cae7b9 100644
--- a/clang/lib/Basic/Sarif.cpp
+++ b/clang/lib/Basic/Sarif.cpp
@@ -74,7 +74,7 @@ static std::string fileNameToURI(StringRef Filename) {
 
   // Get the root name to see if it has a URI authority.
   StringRef Root = sys::path::root_name(Filename);
-  if (Root.startswith("//")) {
+  if (Root.starts_with("//")) {
     // There is an authority, so add it to the URI.
     Ret += Root.drop_front(2).str();
   } else if (!Root.empty()) {
diff --git a/clang/lib/Basic/TargetInfo.cpp b/clang/lib/Basic/TargetInfo.cpp
index 6cd5d61..96b3ad9 100644
--- a/clang/lib/Basic/TargetInfo.cpp
+++ b/clang/lib/Basic/TargetInfo.cpp
@@ -551,26 +551,26 @@ ParsedTargetAttr TargetInfo::parseTargetAttr(StringRef Features) const {
     // TODO: Support the fpmath option. It will require checking
     // overall feature validity for the function with the rest of the
     // attributes on the function.
-    if (Feature.startswith("fpmath="))
+    if (Feature.starts_with("fpmath="))
       continue;
 
-    if (Feature.startswith("branch-protection=")) {
+    if (Feature.starts_with("branch-protection=")) {
       Ret.BranchProtection = Feature.split('=').second.trim();
       continue;
     }
 
     // While we're here iterating check for a different target cpu.
-    if (Feature.startswith("arch=")) {
+    if (Feature.starts_with("arch=")) {
       if (!Ret.CPU.empty())
         Ret.Duplicate = "arch=";
       else
         Ret.CPU = Feature.split("=").second.trim();
-    } else if (Feature.startswith("tune=")) {
+    } else if (Feature.starts_with("tune=")) {
       if (!Ret.Tune.empty())
         Ret.Duplicate = "tune=";
       else
         Ret.Tune = Feature.split("=").second.trim();
-    } else if (Feature.startswith("no-"))
+    } else if (Feature.starts_with("no-"))
       Ret.Features.push_back("-" + Feature.split("-").second.str());
     else
       Ret.Features.push_back("+" + Feature.str());
diff --git a/clang/lib/Basic/Targets/AArch64.cpp b/clang/lib/Basic/Targets/AArch64.cpp
index e3e08b5..def16c0 100644
--- a/clang/lib/Basic/Targets/AArch64.cpp
+++ b/clang/lib/Basic/Targets/AArch64.cpp
@@ -1062,7 +1062,7 @@ ParsedTargetAttr AArch64TargetInfo::parseTargetAttr(StringRef Features) const {
       else
         // Pushing the original feature string to give a sema error later on
         // when they get checked.
-        if (Feature.startswith("no"))
+        if (Feature.starts_with("no"))
           Features.push_back("-" + Feature.drop_front(2).str());
         else
           Features.push_back("+" + Feature.str());
@@ -1071,15 +1071,15 @@ ParsedTargetAttr AArch64TargetInfo::parseTargetAttr(StringRef Features) const {
 
   for (auto &Feature : AttrFeatures) {
     Feature = Feature.trim();
-    if (Feature.startswith("fpmath="))
+    if (Feature.starts_with("fpmath="))
       continue;
 
-    if (Feature.startswith("branch-protection=")) {
+    if (Feature.starts_with("branch-protection=")) {
       Ret.BranchProtection = Feature.split('=').second.trim();
       continue;
     }
 
-    if (Feature.startswith("arch=")) {
+    if (Feature.starts_with("arch=")) {
       if (FoundArch)
         Ret.Duplicate = "arch=";
       FoundArch = true;
@@ -1095,7 +1095,7 @@ ParsedTargetAttr AArch64TargetInfo::parseTargetAttr(StringRef Features) const {
       Ret.Features.push_back(AI->ArchFeature.str());
       // Add any extra features, after the +
       SplitAndAddFeatures(Split.second, Ret.Features);
-    } else if (Feature.startswith("cpu=")) {
+    } else if (Feature.starts_with("cpu=")) {
       if (!Ret.CPU.empty())
         Ret.Duplicate = "cpu=";
       else {
@@ -1106,14 +1106,14 @@ ParsedTargetAttr AArch64TargetInfo::parseTargetAttr(StringRef Features) const {
         Ret.CPU = Split.first;
         SplitAndAddFeatures(Split.second, Ret.Features);
       }
-    } else if (Feature.startswith("tune=")) {
+    } else if (Feature.starts_with("tune=")) {
       if (!Ret.Tune.empty())
         Ret.Duplicate = "tune=";
       else
         Ret.Tune = Feature.split("=").second.trim();
-    } else if (Feature.startswith("+")) {
+    } else if (Feature.starts_with("+")) {
       SplitAndAddFeatures(Feature, Ret.Features);
-    } else if (Feature.startswith("no-")) {
+    } else if (Feature.starts_with("no-")) {
       StringRef FeatureName =
           llvm::AArch64::getArchExtFeature(Feature.split("-").second);
       if (!FeatureName.empty())
diff --git a/clang/lib/Basic/Targets/AMDGPU.cpp b/clang/lib/Basic/Targets/AMDGPU.cpp
index 719fc51..b064ec2 100644
--- a/clang/lib/Basic/Targets/AMDGPU.cpp
+++ b/clang/lib/Basic/Targets/AMDGPU.cpp
@@ -279,7 +279,7 @@ void AMDGPUTargetInfo::getTargetDefines(const LangOptions &Opts,
     Builder.defineMacro(Twine("__") + Twine(CanonName) + Twine("__"));
     // Emit macros for gfx family e.g. gfx906 -> __GFX9__, gfx1030 -> __GFX10___
     if (isAMDGCN(getTriple())) {
-      assert(CanonName.startswith("gfx") && "Invalid amdgcn canonical name");
+      assert(CanonName.starts_with("gfx") && "Invalid amdgcn canonical name");
       Builder.defineMacro(Twine("__") + Twine(CanonName.drop_back(2).upper()) +
                           Twine("__"));
     }
diff --git a/clang/lib/Basic/Targets/Mips.cpp b/clang/lib/Basic/Targets/Mips.cpp
index bc90d1b..3a65f53 100644
--- a/clang/lib/Basic/Targets/Mips.cpp
+++ b/clang/lib/Basic/Targets/Mips.cpp
@@ -196,7 +196,7 @@ void MipsTargetInfo::getTargetDefines(const LangOptions &Opts,
   else
     Builder.defineMacro("_MIPS_ARCH_" + StringRef(CPU).upper());
 
-  if (StringRef(CPU).startswith("octeon"))
+  if (StringRef(CPU).starts_with("octeon"))
     Builder.defineMacro("__OCTEON__");
 
   if (CPU != "mips1") {
diff --git a/clang/lib/Basic/Targets/NVPTX.cpp b/clang/lib/Basic/Targets/NVPTX.cpp
index 5c60181..c0b5db7 100644
--- a/clang/lib/Basic/Targets/NVPTX.cpp
+++ b/clang/lib/Basic/Targets/NVPTX.cpp
@@ -42,7 +42,7 @@ NVPTXTargetInfo::NVPTXTargetInfo(const llvm::Triple &Triple,
   PTXVersion = 32;
   for (const StringRef Feature : Opts.FeaturesAsWritten) {
     int PTXV;
-    if (!Feature.startswith("+ptx") ||
+    if (!Feature.starts_with("+ptx") ||
         Feature.drop_front(4).getAsInteger(10, PTXV))
       continue;
     PTXVersion = PTXV; // TODO: should it be max(PTXVersion, PTXV)?
diff --git a/clang/lib/Basic/Targets/RISCV.cpp b/clang/lib/Basic/Targets/RISCV.cpp
index 45d2302..60a4e0e 100644
--- a/clang/lib/Basic/Targets/RISCV.cpp
+++ b/clang/lib/Basic/Targets/RISCV.cpp
@@ -434,14 +434,14 @@ ParsedTargetAttr RISCVTargetInfo::parseTargetAttr(StringRef Features) const {
     Feature = Feature.trim();
     StringRef AttrString = Feature.split("=").second.trim();
 
-    if (Feature.startswith("arch=")) {
+    if (Feature.starts_with("arch=")) {
       // Override last features
       Ret.Features.clear();
       if (FoundArch)
         Ret.Duplicate = "arch=";
       FoundArch = true;
 
-      if (AttrString.startswith("+")) {
+      if (AttrString.starts_with("+")) {
         // EXTENSION like arch=+v,+zbb
         SmallVector<StringRef, 1> Exts;
         AttrString.split(Exts, ",");
@@ -461,7 +461,7 @@ ParsedTargetAttr RISCVTargetInfo::parseTargetAttr(StringRef Features) const {
         // full-arch-string like arch=rv64gcv
         handleFullArchString(AttrString, Ret.Features);
       }
-    } else if (Feature.startswith("cpu=")) {
+    } else if (Feature.starts_with("cpu=")) {
       if (!Ret.CPU.empty())
         Ret.Duplicate = "cpu=";
 
@@ -475,7 +475,7 @@ ParsedTargetAttr RISCVTargetInfo::parseTargetAttr(StringRef Features) const {
           handleFullArchString(MarchFromCPU, Ret.Features);
         }
       }
-    } else if (Feature.startswith("tune=")) {
+    } else if (Feature.starts_with("tune=")) {
       if (!Ret.Tune.empty())
         Ret.Duplicate = "tune=";
 
diff --git a/clang/lib/Basic/Warnings.cpp b/clang/lib/Basic/Warnings.cpp
index cc8c138..cb23d84 100644
--- a/clang/lib/Basic/Warnings.cpp
+++ b/clang/lib/Basic/Warnings.cpp
@@ -97,7 +97,7 @@ void clang::ProcessWarningOptions(DiagnosticsEngine &Diags,
       // Check to see if this warning starts with "no-", if so, this is a
       // negative form of the option.
       bool isPositive = true;
-      if (Opt.startswith("no-")) {
+      if (Opt.starts_with("no-")) {
         isPositive = false;
         Opt = Opt.substr(3);
       }
@@ -133,7 +133,7 @@ void clang::ProcessWarningOptions(DiagnosticsEngine &Diags,
       // table. It also has the "specifier" form of -Werror=foo. GCC supports
       // the deprecated -Werror-implicit-function-declaration which is used by
       // a few projects.
-      if (Opt.startswith("error")) {
+      if (Opt.starts_with("error")) {
         StringRef Specifier;
         if (Opt.size() > 5) {  // Specifier must be present.
           if (Opt[5] != '=' &&
@@ -162,7 +162,7 @@ void clang::ProcessWarningOptions(DiagnosticsEngine &Diags,
       }
 
       // -Wfatal-errors is yet another special case.
-      if (Opt.startswith("fatal-errors")) {
+      if (Opt.starts_with("fatal-errors")) {
         StringRef Specifier;
         if (Opt.size() != 12) {
           if ((Opt[12] != '=' && Opt[12] != '-') || Opt.size() == 13) {
@@ -204,7 +204,7 @@ void clang::ProcessWarningOptions(DiagnosticsEngine &Diags,
 
       // Check to see if this warning starts with "no-", if so, this is a
       // negative form of the option.
-      bool IsPositive = !Opt.startswith("no-");
+      bool IsPositive = !Opt.starts_with("no-");
       if (!IsPositive) Opt = Opt.substr(3);
 
       auto Severity = IsPositive ? diag::Severity::Remark
diff --git a/clang/lib/CodeGen/CGCall.cpp b/clang/lib/CodeGen/CGCall.cpp
index a24aeea..51a43b5 100644
--- a/clang/lib/CodeGen/CGCall.cpp
+++ b/clang/lib/CodeGen/CGCall.cpp
@@ -5609,7 +5609,7 @@ RValue CodeGenFunction::EmitCall(const CGFunctionInfo &CallInfo,
     EmitBlock(Cont);
   }
   if (CI->getCalledFunction() && CI->getCalledFunction()->hasName() &&
-      CI->getCalledFunction()->getName().startswith("_Z4sqrt")) {
+      CI->getCalledFunction()->getName().starts_with("_Z4sqrt")) {
     SetSqrtFPAccuracy(CI);
   }
   if (callOrInvoke)
diff --git a/clang/lib/CodeGen/CGDebugInfo.cpp b/clang/lib/CodeGen/CGDebugInfo.cpp
index 37d7a67..236d53b 100644
--- a/clang/lib/CodeGen/CGDebugInfo.cpp
+++ b/clang/lib/CodeGen/CGDebugInfo.cpp
@@ -637,7 +637,8 @@ void CGDebugInfo::CreateCompileUnit() {
     Sysroot = CGM.getHeaderSearchOpts().Sysroot;
     auto B = llvm::sys::path::rbegin(Sysroot);
     auto E = llvm::sys::path::rend(Sysroot);
-    auto It = std::find_if(B, E, [](auto SDK) { return SDK.endswith(".sdk"); });
+    auto It =
+        std::find_if(B, E, [](auto SDK) { return SDK.ends_with(".sdk"); });
     if (It != E)
       SDK = *It;
   }
@@ -2885,7 +2886,7 @@ llvm::DIModule *CGDebugInfo::getOrCreateModuleRef(ASTSourceDescriptor Mod,
   // clang::Module object, but it won't actually be built or imported; it will
   // be textual.
   if (CreateSkeletonCU && IsRootModule && Mod.getASTFile().empty() && M)
-    assert(StringRef(M->Name).startswith(CGM.getLangOpts().ModuleName) &&
+    assert(StringRef(M->Name).starts_with(CGM.getLangOpts().ModuleName) &&
            "clang module without ASTFile must be specified by -fmodule-name");
 
   // Return a StringRef to the remapped Path.
@@ -4249,7 +4250,7 @@ void CGDebugInfo::emitFunctionStart(GlobalDecl GD, SourceLocation Loc,
 
     Flags |= llvm::DINode::FlagPrototyped;
   }
-  if (Name.startswith("\01"))
+  if (Name.starts_with("\01"))
     Name = Name.substr(1);
 
   assert((!D || !isa<VarDecl>(D) ||
diff --git a/clang/lib/CodeGen/CGException.cpp b/clang/lib/CodeGen/CGException.cpp
index bae8bab..0d507da 100644
--- a/clang/lib/CodeGen/CGException.cpp
+++ b/clang/lib/CodeGen/CGException.cpp
@@ -277,7 +277,7 @@ static bool LandingPadHasOnlyCXXUses(llvm::LandingPadInst *LPI) {
       if (llvm::GlobalVariable *GV = dyn_cast<llvm::GlobalVariable>(Val))
         // ObjC EH selector entries are always global variables with
         // names starting like this.
-        if (GV->getName().startswith("OBJC_EHTYPE"))
+        if (GV->getName().starts_with("OBJC_EHTYPE"))
           return false;
     } else {
       // Check if any of the filter values have the ObjC prefix.
@@ -288,7 +288,7 @@ static bool LandingPadHasOnlyCXXUses(llvm::LandingPadInst *LPI) {
             cast<llvm::GlobalVariable>((*II)->stripPointerCasts()))
           // ObjC EH selector entries are always global variables with
           // names starting like this.
-          if (GV->getName().startswith("OBJC_EHTYPE"))
+          if (GV->getName().starts_with("OBJC_EHTYPE"))
             return false;
       }
     }
@@ -1917,7 +1917,7 @@ void CodeGenFunction::EmitCapturedLocals(CodeGenFunction &ParentCGF,
         const VarDecl *D = cast<VarDecl>(I.first);
         if (isa<ImplicitParamDecl>(D) &&
             D->getType() == getContext().VoidPtrTy) {
-          assert(D->getName().startswith("frame_pointer"));
+          assert(D->getName().starts_with("frame_pointer"));
           FramePtrAddrAlloca = cast<llvm::AllocaInst>(I.second.getPointer());
           break;
         }
diff --git a/clang/lib/CodeGen/CGExpr.cpp b/clang/lib/CodeGen/CGExpr.cpp
index 69cf7f76..ed9aaa2 100644
--- a/clang/lib/CodeGen/CGExpr.cpp
+++ b/clang/lib/CodeGen/CGExpr.cpp
@@ -431,7 +431,7 @@ static Address createReferenceTemporary(CodeGenFunction &CGF,
 
 /// Helper method to check if the underlying ABI is AAPCS
 static bool isAAPCS(const TargetInfo &TargetInfo) {
-  return TargetInfo.getABI().startswith("aapcs");
+  return TargetInfo.getABI().starts_with("aapcs");
 }
 
 LValue CodeGenFunction::
@@ -3156,7 +3156,7 @@ LValue CodeGenFunction::EmitPredefinedLValue(const PredefinedExpr *E) {
   auto SL = E->getFunctionName();
   assert(SL != nullptr && "No StringLiteral name in PredefinedExpr");
   StringRef FnName = CurFn->getName();
-  if (FnName.startswith("\01"))
+  if (FnName.starts_with("\01"))
     FnName = FnName.substr(1);
   StringRef NameItems[] = {
       PredefinedExpr::getIdentKindName(E->getIdentKind()), FnName};
diff --git a/clang/lib/CodeGen/CGObjCMac.cpp b/clang/lib/CodeGen/CGObjCMac.cpp
index ba52b23..517f7cd 100644
--- a/clang/lib/CodeGen/CGObjCMac.cpp
+++ b/clang/lib/CodeGen/CGObjCMac.cpp
@@ -1850,7 +1850,7 @@ static bool hasObjCExceptionAttribute(ASTContext &Context,
 static llvm::GlobalValue::LinkageTypes
 getLinkageTypeForObjCMetadata(CodeGenModule &CGM, StringRef Section) {
   if (CGM.getTriple().isOSBinFormatMachO() &&
-      (Section.empty() || Section.startswith("__DATA")))
+      (Section.empty() || Section.starts_with("__DATA")))
     return llvm::GlobalValue::InternalLinkage;
   return llvm::GlobalValue::PrivateLinkage;
 }
@@ -6162,7 +6162,7 @@ void CGObjCNonFragileABIMac::AddModuleClassList(
   // Section name is obtained by calling GetSectionName, which returns
   // sections in the __DATA segment on MachO.
   assert((!CGM.getTriple().isOSBinFormatMachO() ||
-          SectionName.startswith("__DATA")) &&
+          SectionName.starts_with("__DATA")) &&
          "SectionName expected to start with __DATA on MachO");
   llvm::GlobalVariable *GV = new llvm::GlobalVariable(
       CGM.getModule(), Init->getType(), false,
diff --git a/clang/lib/CodeGen/CGRecordLayoutBuilder.cpp b/clang/lib/CodeGen/CGRecordLayoutBuilder.cpp
index cbfa79e..868ef81 100644
--- a/clang/lib/CodeGen/CGRecordLayoutBuilder.cpp
+++ b/clang/lib/CodeGen/CGRecordLayoutBuilder.cpp
@@ -111,7 +111,7 @@ struct CGRecordLowering {
 
   /// Helper function to check if we are targeting AAPCS.
   bool isAAPCS() const {
-    return Context.getTargetInfo().getABI().startswith("aapcs");
+    return Context.getTargetInfo().getABI().starts_with("aapcs");
   }
 
   /// Helper function to check if the target machine is BigEndian.
diff --git a/clang/lib/CodeGen/CGStmt.cpp b/clang/lib/CodeGen/CGStmt.cpp
index a5cb806..0f79a2e 100644
--- a/clang/lib/CodeGen/CGStmt.cpp
+++ b/clang/lib/CodeGen/CGStmt.cpp
@@ -2548,7 +2548,7 @@ void CodeGenFunction::EmitAsmStmt(const AsmStmt &S) {
       ResultRegQualTys.push_back(QTy);
       ResultRegDests.push_back(Dest);
 
-      bool IsFlagReg = llvm::StringRef(OutputConstraint).startswith("{@cc");
+      bool IsFlagReg = llvm::StringRef(OutputConstraint).starts_with("{@cc");
       ResultRegIsFlagReg.push_back(IsFlagReg);
 
       llvm::Type *Ty = ConvertTypeForMem(QTy);
diff --git a/clang/lib/CodeGen/CodeGenAction.cpp b/clang/lib/CodeGen/CodeGenAction.cpp
index bb6b1a3..753a8fd 100644
--- a/clang/lib/CodeGen/CodeGenAction.cpp
+++ b/clang/lib/CodeGen/CodeGenAction.cpp
@@ -1139,7 +1139,7 @@ CodeGenAction::loadModule(MemoryBufferRef MBRef) {
 
   // Strip off a leading diagnostic code if there is one.
   StringRef Msg = Err.getMessage();
-  if (Msg.startswith("error: "))
+  if (Msg.starts_with("error: "))
     Msg = Msg.substr(7);
 
   unsigned DiagID =
diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index b931a81..7ad26ac 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -225,9 +225,9 @@ createTargetCodeGenInfo(CodeGenModule &CGM) {
     StringRef ABIStr = Target.getABI();
     unsigned XLen = Target.getPointerWidth(LangAS::Default);
     unsigned ABIFLen = 0;
-    if (ABIStr.endswith("f"))
+    if (ABIStr.ends_with("f"))
       ABIFLen = 32;
-    else if (ABIStr.endswith("d"))
+    else if (ABIStr.ends_with("d"))
       ABIFLen = 64;
     return createRISCVTargetCodeGenInfo(CGM, XLen, ABIFLen);
   }
@@ -308,9 +308,9 @@ createTargetCodeGenInfo(CodeGenModule &CGM) {
   case llvm::Triple::loongarch64: {
     StringRef ABIStr = Target.getABI();
     unsigned ABIFRLen = 0;
-    if (ABIStr.endswith("f"))
+    if (ABIStr.ends_with("f"))
       ABIFRLen = 32;
-    else if (ABIStr.endswith("d"))
+    else if (ABIStr.ends_with("d"))
       ABIFRLen = 64;
     return createLoongArchTargetCodeGenInfo(
         CGM, Target.getPointerWidth(LangAS::Default), ABIFRLen);
@@ -1715,7 +1715,7 @@ static void AppendTargetMangling(const CodeGenModule &CGM,
   llvm::sort(Info.Features, [&Target](StringRef LHS, StringRef RHS) {
     // Multiversioning doesn't allow "no-${feature}", so we can
     // only have "+" prefixes here.
-    assert(LHS.startswith("+") && RHS.startswith("+") &&
+    assert(LHS.starts_with("+") && RHS.starts_with("+") &&
            "Features should always have a prefix.");
     return Target.multiVersionSortPriority(LHS.substr(1)) >
            Target.multiVersionSortPriority(RHS.substr(1));
@@ -1769,7 +1769,7 @@ static void AppendTargetClonesMangling(const CodeGenModule &CGM,
   } else {
     Out << '.';
     StringRef FeatureStr = Attr->getFeatureStr(VersionIndex);
-    if (FeatureStr.startswith("arch="))
+    if (FeatureStr.starts_with("arch="))
       Out << "arch_" << FeatureStr.substr(sizeof("arch=") - 1);
     else
       Out << FeatureStr;
@@ -3828,7 +3828,7 @@ namespace {
       if (!BuiltinID || !BI.isLibFunction(BuiltinID))
         return false;
       StringRef BuiltinName = BI.getName(BuiltinID);
-      if (BuiltinName.startswith("__builtin_") &&
+      if (BuiltinName.starts_with("__builtin_") &&
           Name == BuiltinName.slice(strlen("__builtin_"), StringRef::npos)) {
         return true;
       }
@@ -4164,7 +4164,7 @@ void CodeGenModule::emitMultiVersionFunctions() {
               Feature.push_back(CurFeat.trim());
           }
         } else {
-          if (Version.startswith("arch="))
+          if (Version.starts_with("arch="))
             Architecture = Version.drop_front(sizeof("arch=") - 1);
           else if (Version != "default")
             Feature.push_back(Version);
diff --git a/clang/lib/CodeGen/Targets/SPIR.cpp b/clang/lib/CodeGen/Targets/SPIR.cpp
index 8bacba6..cf068cb 100644
--- a/clang/lib/CodeGen/Targets/SPIR.cpp
+++ b/clang/lib/CodeGen/Targets/SPIR.cpp
@@ -146,14 +146,14 @@ static llvm::Type *getSPIRVImageType(llvm::LLVMContext &Ctx, StringRef BaseType,
 
   // Choose the dimension of the image--this corresponds to the Dim enum in
   // SPIR-V (first integer parameter of OpTypeImage).
-  if (OpenCLName.startswith("image2d"))
+  if (OpenCLName.starts_with("image2d"))
     IntParams[0] = 1; // 1D
-  else if (OpenCLName.startswith("image3d"))
+  else if (OpenCLName.starts_with("image3d"))
     IntParams[0] = 2; // 2D
   else if (OpenCLName == "image1d_buffer")
     IntParams[0] = 5; // Buffer
   else
-    assert(OpenCLName.startswith("image1d") && "Unknown image type");
+    assert(OpenCLName.starts_with("image1d") && "Unknown image type");
 
   // Set the other integer parameters of OpTypeImage if necessary. Note that the
   // OpenCL image types don't provide any information for the Sampled or
diff --git a/clang/lib/Driver/Distro.cpp b/clang/lib/Driver/Distro.cpp
index 36f828f..a7e7f16 100644
--- a/clang/lib/Driver/Distro.cpp
+++ b/clang/lib/Driver/Distro.cpp
@@ -34,7 +34,7 @@ static Distro::DistroType DetectOsRelease(llvm::vfs::FileSystem &VFS) {
 
   // Obviously this can be improved a lot.
   for (StringRef Line : Lines)
-    if (Version == Distro::UnknownDistro && Line.startswith("ID="))
+    if (Version == Distro::UnknownDistro && Line.starts_with("ID="))
       Version = llvm::StringSwitch<Distro::DistroType>(Line.substr(3))
                     .Case("alpine", Distro::AlpineLinux)
                     .Case("fedora", Distro::Fedora)
@@ -60,7 +60,7 @@ static Distro::DistroType DetectLsbRelease(llvm::vfs::FileSystem &VFS) {
 
   for (StringRef Line : Lines)
     if (Version == Distro::UnknownDistro &&
-        Line.startswith("DISTRIB_CODENAME="))
+        Line.starts_with("DISTRIB_CODENAME="))
       Version = llvm::StringSwitch<Distro::DistroType>(Line.substr(17))
                     .Case("hardy", Distro::UbuntuHardy)
                     .Case("intrepid", Distro::UbuntuIntrepid)
@@ -119,10 +119,10 @@ static Distro::DistroType DetectDistro(llvm::vfs::FileSystem &VFS) {
 
   if (File) {
     StringRef Data = File.get()->getBuffer();
-    if (Data.startswith("Fedora release"))
+    if (Data.starts_with("Fedora release"))
       return Distro::Fedora;
-    if (Data.startswith("Red Hat Enterprise Linux") ||
-        Data.startswith("CentOS") || Data.startswith("Scientific Linux")) {
+    if (Data.starts_with("Red Hat Enterprise Linux") ||
+        Data.starts_with("CentOS") || Data.starts_with("Scientific Linux")) {
       if (Data.contains("release 7"))
         return Distro::RHEL7;
       else if (Data.contains("release 6"))
@@ -182,7 +182,7 @@ static Distro::DistroType DetectDistro(llvm::vfs::FileSystem &VFS) {
     SmallVector<StringRef, 8> Lines;
     Data.split(Lines, "\n");
     for (const StringRef &Line : Lines) {
-      if (!Line.trim().startswith("VERSION"))
+      if (!Line.trim().starts_with("VERSION"))
         continue;
       std::pair<StringRef, StringRef> SplitLine = Line.split('=');
       // Old versions have split VERSION and PATCHLEVEL
diff --git a/clang/lib/Driver/Driver.cpp b/clang/lib/Driver/Driver.cpp
index f392f67..ff95c89 100644
--- a/clang/lib/Driver/Driver.cpp
+++ b/clang/lib/Driver/Driver.cpp
@@ -1451,7 +1451,7 @@ Compilation *Driver::BuildCompilation(ArrayRef<const char *> ArgList) {
     case llvm::Triple::aarch64:
     case llvm::Triple::aarch64_be:
     case llvm::Triple::aarch64_32:
-      if (TC.getTriple().getEnvironmentName().startswith("eabi")) {
+      if (TC.getTriple().getEnvironmentName().starts_with("eabi")) {
         Diag(diag::warn_target_unrecognized_env)
             << TargetTriple
             << (TC.getTriple().getArchName().str() + "-none-elf");
@@ -1540,7 +1540,7 @@ bool Driver::getCrashDiagnosticFile(StringRef ReproCrashFilename,
   for (fs::directory_iterator File(CrashDiagDir, EC), FileEnd;
        File != FileEnd && !EC; File.increment(EC)) {
     StringRef FileName = path::filename(File->path());
-    if (!FileName.startswith(Name))
+    if (!FileName.starts_with(Name))
       continue;
     if (fs::status(File->path(), FileStatus))
       continue;
@@ -1551,7 +1551,7 @@ bool Driver::getCrashDiagnosticFile(StringRef ReproCrashFilename,
     // The first line should start with "Process:", otherwise this isn't a real
     // .crash file.
     StringRef Data = CrashFile.get()->getBuffer();
-    if (!Data.startswith("Process:"))
+    if (!Data.starts_with("Process:"))
       continue;
     // Parse parent process pid line, e.g: "Parent Process: clang-4.0 [79141]"
     size_t ParentProcPos = Data.find("Parent Process:");
@@ -1780,7 +1780,7 @@ void Driver::generateCompilationDiagnostics(
       ReproCrashFilename = TempFile;
       llvm::sys::path::replace_extension(ReproCrashFilename, ".crash");
     }
-    if (StringRef(TempFile).endswith(".cache")) {
+    if (StringRef(TempFile).ends_with(".cache")) {
       // In some cases (modules) we'll dump extra data to help with reproducing
       // the crash into a directory next to the output.
       VFS = llvm::sys::path::filename(TempFile);
@@ -2001,7 +2001,7 @@ void Driver::HandleAutocompletions(StringRef PassedFlags) const {
   // Distinguish "--autocomplete=-someflag" and "--autocomplete=-someflag,"
   // because the latter indicates that the user put space before pushing tab
   // which should end up in a file completion.
-  const bool HasSpace = PassedFlags.endswith(",");
+  const bool HasSpace = PassedFlags.ends_with(",");
 
   // Parse PassedFlags by "," as all the command-line flags are passed to this
   // function separated by ","
@@ -2041,7 +2041,7 @@ void Driver::HandleAutocompletions(StringRef PassedFlags) const {
 
   // When flag ends with '=' and there was no value completion, return empty
   // string and fall back to the file autocompletion.
-  if (SuggestedCompletions.empty() && !Cur.endswith("=")) {
+  if (SuggestedCompletions.empty() && !Cur.ends_with("=")) {
     // If the flag is in the form of "--autocomplete=-foo",
     // we were requested to print out all option names that start with "-foo".
     // For example, "--autocomplete=-fsyn" is expanded to "-fsyntax-only".
@@ -2053,7 +2053,7 @@ void Driver::HandleAutocompletions(StringRef PassedFlags) const {
     // TODO: Find a good way to add them to OptTable instead and them remove
     // this code.
     for (StringRef S : DiagnosticIDs::getDiagnosticFlags())
-      if (S.startswith(Cur))
+      if (S.starts_with(Cur))
         SuggestedCompletions.push_back(std::string(S));
   }
 
@@ -2535,7 +2535,7 @@ bool Driver::DiagnoseInputExistence(const DerivedArgList &Args, StringRef Value,
   // so we can't downgrade diagnostics for `/GR-` from an error to a warning
   // in cc mode. (We can in cl mode because cl.exe itself only warns on
   // unknown flags.)
-  if (IsCLMode() && Ty == types::TY_Object && !Value.startswith("/"))
+  if (IsCLMode() && Ty == types::TY_Object && !Value.starts_with("/"))
     return true;
 
   Diag(clang::diag::err_drv_no_such_file) << Value;
@@ -6565,7 +6565,7 @@ llvm::StringRef clang::driver::getDriverMode(StringRef ProgName,
       getDriverOptTable().getOption(options::OPT_driver_mode).getPrefixedName();
   llvm::StringRef Opt;
   for (StringRef Arg : Args) {
-    if (!Arg.startswith(OptName))
+    if (!Arg.starts_with(OptName))
       continue;
     Opt = Arg;
   }
@@ -6606,7 +6606,7 @@ llvm::Error driver::expandResponseFiles(SmallVectorImpl<const char *> &Args,
   else
     Tokenizer = &llvm::cl::TokenizeGNUCommandLine;
 
-  if (MarkEOLs && Args.size() > 1 && StringRef(Args[1]).startswith("-cc1"))
+  if (MarkEOLs && Args.size() > 1 && StringRef(Args[1]).starts_with("-cc1"))
     MarkEOLs = false;
 
   llvm::cl::ExpansionContext ECtx(Alloc, Tokenizer);
@@ -6620,7 +6620,7 @@ llvm::Error driver::expandResponseFiles(SmallVectorImpl<const char *> &Args,
   // If -cc1 came from a response file, remove the EOL sentinels.
   auto FirstArg = llvm::find_if(llvm::drop_begin(Args),
                                 [](const char *A) { return A != nullptr; });
-  if (FirstArg != Args.end() && StringRef(*FirstArg).startswith("-cc1")) {
+  if (FirstArg != Args.end() && StringRef(*FirstArg).starts_with("-cc1")) {
     // If -cc1 came from a response file, remove the EOL sentinels.
     if (MarkEOLs) {
       auto newEnd = std::remove(Args.begin(), Args.end(), nullptr);
diff --git a/clang/lib/Driver/Job.cpp b/clang/lib/Driver/Job.cpp
index 2034004..a6c1581 100644
--- a/clang/lib/Driver/Job.cpp
+++ b/clang/lib/Driver/Job.cpp
@@ -95,10 +95,10 @@ static bool skipArgs(const char *Flag, bool HaveCrashVFS, int &SkipNum,
 
   // These flags are treated as a single argument (e.g., -F<Dir>).
   StringRef FlagRef(Flag);
-  IsInclude = FlagRef.startswith("-F") || FlagRef.startswith("-I");
+  IsInclude = FlagRef.starts_with("-F") || FlagRef.starts_with("-I");
   if (IsInclude)
     return !HaveCrashVFS;
-  if (FlagRef.startswith("-fmodules-cache-path="))
+  if (FlagRef.starts_with("-fmodules-cache-path="))
     return true;
 
   SkipNum = 0;
@@ -185,8 +185,8 @@ rewriteIncludes(const llvm::ArrayRef<const char *> &Args, size_t Idx,
   SmallString<128> NewInc;
   if (NumArgs == 1) {
     StringRef FlagRef(Args[Idx + NumArgs - 1]);
-    assert((FlagRef.startswith("-F") || FlagRef.startswith("-I")) &&
-            "Expecting -I or -F");
+    assert((FlagRef.starts_with("-F") || FlagRef.starts_with("-I")) &&
+           "Expecting -I or -F");
     StringRef Inc = FlagRef.slice(2, StringRef::npos);
     if (getAbsPath(Inc, NewInc)) {
       SmallString<128> NewArg(FlagRef.slice(0, 2));
diff --git a/clang/lib/Driver/ToolChain.cpp b/clang/lib/Driver/ToolChain.cpp
index ab19166..96a5792 100644
--- a/clang/lib/Driver/ToolChain.cpp
+++ b/clang/lib/Driver/ToolChain.cpp
@@ -315,7 +315,7 @@ static const DriverSuffix *FindDriverSuffix(StringRef ProgName, size_t &Pos) {
 
   for (const auto &DS : DriverSuffixes) {
     StringRef Suffix(DS.Suffix);
-    if (ProgName.endswith(Suffix)) {
+    if (ProgName.ends_with(Suffix)) {
       Pos = ProgName.size() - Suffix.size();
       return &DS;
     }
@@ -345,7 +345,7 @@ static const DriverSuffix *parseDriverSuffix(StringRef ProgName, size_t &Pos) {
   // added via -target as implicit first argument.
   const DriverSuffix *DS = FindDriverSuffix(ProgName, Pos);
 
-  if (!DS && ProgName.endswith(".exe")) {
+  if (!DS && ProgName.ends_with(".exe")) {
     // Try again after stripping the executable suffix:
     // clang++.exe -> clang++
     ProgName = ProgName.drop_back(StringRef(".exe").size());
diff --git a/clang/lib/Driver/ToolChains/AIX.cpp b/clang/lib/Driver/ToolChains/AIX.cpp
index aed8734..f9670ea 100644
--- a/clang/lib/Driver/ToolChains/AIX.cpp
+++ b/clang/lib/Driver/ToolChains/AIX.cpp
@@ -88,7 +88,7 @@ static bool hasExportListLinkerOpts(const ArgStringList &CmdArgs) {
   for (size_t i = 0, Size = CmdArgs.size(); i < Size; ++i) {
     llvm::StringRef ArgString(CmdArgs[i]);
 
-    if (ArgString.startswith("-bE:") || ArgString.startswith("-bexport:") ||
+    if (ArgString.starts_with("-bE:") || ArgString.starts_with("-bexport:") ||
         ArgString == "-bexpall" || ArgString == "-bexpfull")
       return true;
 
@@ -96,8 +96,8 @@ static bool hasExportListLinkerOpts(const ArgStringList &CmdArgs) {
     if (ArgString == "-b" && i + 1 < Size) {
       ++i;
       llvm::StringRef ArgNextString(CmdArgs[i]);
-      if (ArgNextString.startswith("E:") ||
-          ArgNextString.startswith("export:") || ArgNextString == "expall" ||
+      if (ArgNextString.starts_with("E:") ||
+          ArgNextString.starts_with("export:") || ArgNextString == "expall" ||
           ArgNextString == "expfull")
         return true;
     }
diff --git a/clang/lib/Driver/ToolChains/AMDGPU.cpp b/clang/lib/Driver/ToolChains/AMDGPU.cpp
index cad206e..56f06fc 100644
--- a/clang/lib/Driver/ToolChains/AMDGPU.cpp
+++ b/clang/lib/Driver/ToolChains/AMDGPU.cpp
@@ -49,7 +49,7 @@ RocmInstallationDetector::findSPACKPackage(const Candidate &Cand,
                                      FileEnd;
        File != FileEnd && !EC; File.increment(EC)) {
     llvm::StringRef FileName = llvm::sys::path::filename(File->path());
-    if (FileName.startswith(Prefix)) {
+    if (FileName.starts_with(Prefix)) {
       SubDirs.push_back(FileName);
       if (SubDirs.size() > 1)
         break;
@@ -84,13 +84,13 @@ void RocmInstallationDetector::scanLibDevicePath(llvm::StringRef Path) {
        !EC && LI != LE; LI = LI.increment(EC)) {
     StringRef FilePath = LI->path();
     StringRef FileName = llvm::sys::path::filename(FilePath);
-    if (!FileName.endswith(Suffix))
+    if (!FileName.ends_with(Suffix))
       continue;
 
     StringRef BaseName;
-    if (FileName.endswith(Suffix2))
+    if (FileName.ends_with(Suffix2))
       BaseName = FileName.drop_back(Suffix2.size());
-    else if (FileName.endswith(Suffix))
+    else if (FileName.ends_with(Suffix))
       BaseName = FileName.drop_back(Suffix.size());
 
     const StringRef ABIVersionPrefix = "oclc_abi_version_";
@@ -124,7 +124,7 @@ void RocmInstallationDetector::scanLibDevicePath(llvm::StringRef Path) {
       WavefrontSize64.On = FilePath;
     } else if (BaseName == "oclc_wavefrontsize64_off") {
       WavefrontSize64.Off = FilePath;
-    } else if (BaseName.startswith(ABIVersionPrefix)) {
+    } else if (BaseName.starts_with(ABIVersionPrefix)) {
       unsigned ABIVersionNumber;
       if (BaseName.drop_front(ABIVersionPrefix.size())
               .getAsInteger(/*Redex=*/0, ABIVersionNumber))
@@ -134,7 +134,7 @@ void RocmInstallationDetector::scanLibDevicePath(llvm::StringRef Path) {
       // Process all bitcode filenames that look like
       // ocl_isa_version_XXX.amdgcn.bc
       const StringRef DeviceLibPrefix = "oclc_isa_version_";
-      if (!BaseName.startswith(DeviceLibPrefix))
+      if (!BaseName.starts_with(DeviceLibPrefix))
         continue;
 
       StringRef IsaVersionNumber =
@@ -230,7 +230,7 @@ RocmInstallationDetector::getInstallationPathCandidates() {
     // <rocm_root>/llvm-amdgpu-<rocm_release_string>-<hash>/bin directory.
     // We only consider the parent directory of llvm-amdgpu package as ROCm
     // installation candidate for SPACK.
-    if (ParentName.startswith("llvm-amdgpu-")) {
+    if (ParentName.starts_with("llvm-amdgpu-")) {
       auto SPACKPostfix =
           ParentName.drop_front(strlen("llvm-amdgpu-")).split('-');
       auto SPACKReleaseStr = SPACKPostfix.first;
@@ -243,7 +243,7 @@ RocmInstallationDetector::getInstallationPathCandidates() {
 
     // Some versions of the rocm llvm package install to /opt/rocm/llvm/bin
     // Some versions of the aomp package install to /opt/rocm/aomp/bin
-    if (ParentName == "llvm" || ParentName.startswith("aomp"))
+    if (ParentName == "llvm" || ParentName.starts_with("aomp"))
       ParentDir = llvm::sys::path::parent_path(ParentDir);
 
     return Candidate(ParentDir.str(), /*StrictChecking=*/true);
@@ -292,7 +292,7 @@ RocmInstallationDetector::getInstallationPathCandidates() {
            FileEnd;
        File != FileEnd && !EC; File.increment(EC)) {
     llvm::StringRef FileName = llvm::sys::path::filename(File->path());
-    if (!FileName.startswith("rocm-"))
+    if (!FileName.starts_with("rocm-"))
       continue;
     if (LatestROCm.empty()) {
       LatestROCm = FileName.str();
diff --git a/clang/lib/Driver/ToolChains/Arch/AArch64.cpp b/clang/lib/Driver/ToolChains/Arch/AArch64.cpp
index 097258b..912df79 100644
--- a/clang/lib/Driver/ToolChains/Arch/AArch64.cpp
+++ b/clang/lib/Driver/ToolChains/Arch/AArch64.cpp
@@ -228,7 +228,7 @@ getAArch64MicroArchFeaturesFromMtune(const Driver &D, StringRef Mtune,
   if (MtuneLowerCase == "native")
     MtuneLowerCase = std::string(llvm::sys::getHostCPUName());
   if (MtuneLowerCase == "cyclone" ||
-      StringRef(MtuneLowerCase).startswith("apple")) {
+      StringRef(MtuneLowerCase).starts_with("apple")) {
     Features.push_back("+zcm");
     Features.push_back("+zcz");
   }
@@ -262,7 +262,7 @@ void aarch64::getAArch64TargetFeatures(const Driver &D,
     for (const auto *A :
          Args.filtered(options::OPT_Wa_COMMA, options::OPT_Xassembler))
       for (StringRef Value : A->getValues())
-        if (Value.startswith("-march="))
+        if (Value.starts_with("-march="))
           WaMArch = Value.substr(7);
   // Call getAArch64ArchFeaturesFromMarch only if "-Wa,-march=" or
   // "-Xassembler -march" is detected. Otherwise it may return false
diff --git a/clang/lib/Driver/ToolChains/Arch/ARM.cpp b/clang/lib/Driver/ToolChains/Arch/ARM.cpp
index f1d7aeb..25470db 100644
--- a/clang/lib/Driver/ToolChains/Arch/ARM.cpp
+++ b/clang/lib/Driver/ToolChains/Arch/ARM.cpp
@@ -67,9 +67,9 @@ void arm::getARMArchCPUFromArgs(const ArgList &Args, llvm::StringRef &Arch,
     // Use getValues because -Wa can have multiple arguments
     // e.g. -Wa,-mcpu=foo,-mcpu=bar
     for (StringRef Value : A->getValues()) {
-      if (Value.startswith("-mcpu="))
+      if (Value.starts_with("-mcpu="))
         CPU = Value.substr(6);
-      if (Value.startswith("-march="))
+      if (Value.starts_with("-march="))
         Arch = Value.substr(7);
     }
   }
@@ -285,9 +285,9 @@ void arm::setArchNameInTriple(const Driver &D, const ArgList &Args,
         // There is no assembler equivalent of -mno-thumb, -marm, or -mno-arm.
         if (Value == "-mthumb")
           IsThumb = true;
-        else if (Value.startswith("-march="))
+        else if (Value.starts_with("-march="))
           WaMArch = Value.substr(7);
-        else if (Value.startswith("-mcpu="))
+        else if (Value.starts_with("-mcpu="))
           WaMCPU = Value.substr(6);
       }
     }
@@ -528,13 +528,13 @@ llvm::ARM::FPUKind arm::getARMTargetFeatures(const Driver &D,
       // We use getValues here because you can have many options per -Wa
       // We will keep the last one we find for each of these
       for (StringRef Value : A->getValues()) {
-        if (Value.startswith("-mfpu=")) {
+        if (Value.starts_with("-mfpu=")) {
           WaFPU = std::make_pair(A, Value.substr(6));
-        } else if (Value.startswith("-mcpu=")) {
+        } else if (Value.starts_with("-mcpu=")) {
           WaCPU = std::make_pair(A, Value.substr(6));
-        } else if (Value.startswith("-mhwdiv=")) {
+        } else if (Value.starts_with("-mhwdiv=")) {
           WaHDiv = std::make_pair(A, Value.substr(8));
-        } else if (Value.startswith("-march=")) {
+        } else if (Value.starts_with("-march=")) {
           WaArch = std::make_pair(A, Value.substr(7));
         }
       }
@@ -796,7 +796,7 @@ fp16_fml_fallthrough:
   // Propagate frame-chain model selection
   if (Arg *A = Args.getLastArg(options::OPT_mframe_chain)) {
     StringRef FrameChainOption = A->getValue();
-    if (FrameChainOption.startswith("aapcs"))
+    if (FrameChainOption.starts_with("aapcs"))
       Features.push_back("+aapcs-frame-chain");
     if (FrameChainOption == "aapcs+leaf")
       Features.push_back("+aapcs-frame-chain-leaf");
diff --git a/clang/lib/Driver/ToolChains/Arch/X86.cpp b/clang/lib/Driver/ToolChains/Arch/X86.cpp
index 3e51b2b..fef0522 100644
--- a/clang/lib/Driver/ToolChains/Arch/X86.cpp
+++ b/clang/lib/Driver/ToolChains/Arch/X86.cpp
@@ -234,15 +234,15 @@ void x86::getX86TargetFeatures(const Driver &D, const llvm::Triple &Triple,
     A->claim();
 
     // Skip over "-m".
-    assert(Name.startswith("m") && "Invalid feature name.");
+    assert(Name.starts_with("m") && "Invalid feature name.");
     Name = Name.substr(1);
 
-    bool IsNegative = Name.startswith("no-");
+    bool IsNegative = Name.starts_with("no-");
     if (IsNegative)
       Name = Name.substr(3);
 
 #ifndef NDEBUG
-    assert(Name.startswith("avx10.") && "Invalid AVX10 feature name.");
+    assert(Name.starts_with("avx10.") && "Invalid AVX10 feature name.");
     StringRef Version, Width;
     std::tie(Version, Width) = Name.substr(6).split('-');
     assert(Version == "1" && "Invalid AVX10 feature name.");
@@ -260,7 +260,7 @@ void x86::getX86TargetFeatures(const Driver &D, const llvm::Triple &Triple,
     A->claim();
 
     // Skip over "-m".
-    assert(Name.startswith("m") && "Invalid feature name.");
+    assert(Name.starts_with("m") && "Invalid feature name.");
     Name = Name.substr(1);
 
     // Replace -mgeneral-regs-only with -x87, -mmx, -sse
@@ -269,7 +269,7 @@ void x86::getX86TargetFeatures(const Driver &D, const llvm::Triple &Triple,
       continue;
     }
 
-    bool IsNegative = Name.startswith("no-");
+    bool IsNegative = Name.starts_with("no-");
     if (A->getOption().matches(options::OPT_mapx_features_EQ) ||
         A->getOption().matches(options::OPT_mno_apx_features_EQ)) {
 
diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index dd893c2..de9fd5e 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -223,7 +223,7 @@ static void ParseMRecip(const Driver &D, const ArgList &Args,
   for (unsigned i = 0; i != NumOptions; ++i) {
     StringRef Val = A->getValue(i);
 
-    bool IsDisabled = Val.startswith(DisabledPrefixIn);
+    bool IsDisabled = Val.starts_with(DisabledPrefixIn);
     // Ignore the disablement token for string matching.
     if (IsDisabled)
       Val = Val.substr(1);
@@ -433,7 +433,7 @@ static void addDebugObjectName(const ArgList &Args, ArgStringList &CmdArgs,
                                const char *OutputFileName) {
   // No need to generate a value for -object-file-name if it was provided.
   for (auto *Arg : Args.filtered(options::OPT_Xclang))
-    if (StringRef(Arg->getValue()).startswith("-object-file-name"))
+    if (StringRef(Arg->getValue()).starts_with("-object-file-name"))
       return;
 
   if (Args.hasArg(options::OPT_object_file_name_EQ))
@@ -940,7 +940,7 @@ static void handleAMDGPUCodeObjectVersionOptions(const Driver &D,
 static bool hasClangPchSignature(const Driver &D, StringRef Path) {
   if (llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> MemBuf =
           D.getVFS().getBufferForFile(Path))
-    return (*MemBuf)->getBuffer().startswith("CPCH");
+    return (*MemBuf)->getBuffer().starts_with("CPCH");
   return false;
 }
 
@@ -1715,7 +1715,7 @@ void Clang::AddAArch64TargetArgs(const ArgList &Args,
         Val.equals("256+") || Val.equals("512+") || Val.equals("1024+") ||
         Val.equals("2048+")) {
       unsigned Bits = 0;
-      if (Val.endswith("+"))
+      if (Val.ends_with("+"))
         Val = Val.substr(0, Val.size() - 1);
       else {
         bool Invalid = Val.getAsInteger(10, Bits); (void)Invalid;
@@ -2503,7 +2503,7 @@ static void CollectArgsForIntegratedAssembler(Compilation &C,
       case llvm::Triple::thumbeb:
       case llvm::Triple::arm:
       case llvm::Triple::armeb:
-        if (Value.startswith("-mimplicit-it=")) {
+        if (Value.starts_with("-mimplicit-it=")) {
           // Only store the value; the last value set takes effect.
           ImplicitIt = Value.split("=").second;
           if (CheckARMImplicitITArg(ImplicitIt))
@@ -2528,12 +2528,12 @@ static void CollectArgsForIntegratedAssembler(Compilation &C,
           CmdArgs.push_back("-use-tcc-in-div");
           continue;
         }
-        if (Value.startswith("-msoft-float")) {
+        if (Value.starts_with("-msoft-float")) {
           CmdArgs.push_back("-target-feature");
           CmdArgs.push_back("+soft-float");
           continue;
         }
-        if (Value.startswith("-mhard-float")) {
+        if (Value.starts_with("-mhard-float")) {
           CmdArgs.push_back("-target-feature");
           CmdArgs.push_back("-soft-float");
           continue;
@@ -2570,8 +2570,8 @@ static void CollectArgsForIntegratedAssembler(Compilation &C,
         CmdArgs.push_back("-massembler-no-warn");
       } else if (Value == "--noexecstack") {
         UseNoExecStack = true;
-      } else if (Value.startswith("-compress-debug-sections") ||
-                 Value.startswith("--compress-debug-sections") ||
+      } else if (Value.starts_with("-compress-debug-sections") ||
+                 Value.starts_with("--compress-debug-sections") ||
                  Value == "-nocompress-debug-sections" ||
                  Value == "--nocompress-debug-sections") {
         CmdArgs.push_back(Value.data());
@@ -2581,13 +2581,13 @@ static void CollectArgsForIntegratedAssembler(Compilation &C,
       } else if (Value == "-mrelax-relocations=no" ||
                  Value == "--mrelax-relocations=no") {
         UseRelaxRelocations = false;
-      } else if (Value.startswith("-I")) {
+      } else if (Value.starts_with("-I")) {
         CmdArgs.push_back(Value.data());
         // We need to consume the next argument if the current arg is a plain
         // -I. The next arg will be the include directory.
         if (Value == "-I")
           TakeNextArg = true;
-      } else if (Value.startswith("-gdwarf-")) {
+      } else if (Value.starts_with("-gdwarf-")) {
         // "-gdwarf-N" options are not cc1as options.
         unsigned DwarfVersion = DwarfVersionNum(Value);
         if (DwarfVersion == 0) { // Send it onward, and let cc1as complain.
@@ -2597,30 +2597,30 @@ static void CollectArgsForIntegratedAssembler(Compilation &C,
                                   llvm::codegenoptions::DebugInfoConstructor,
                                   DwarfVersion, llvm::DebuggerKind::Default);
         }
-      } else if (Value.startswith("-mcpu") || Value.startswith("-mfpu") ||
-                 Value.startswith("-mhwdiv") || Value.startswith("-march")) {
+      } else if (Value.starts_with("-mcpu") || Value.starts_with("-mfpu") ||
+                 Value.starts_with("-mhwdiv") || Value.starts_with("-march")) {
         // Do nothing, we'll validate it later.
       } else if (Value == "-defsym") {
-          if (A->getNumValues() != 2) {
-            D.Diag(diag::err_drv_defsym_invalid_format) << Value;
-            break;
-          }
-          const char *S = A->getValue(1);
-          auto Pair = StringRef(S).split('=');
-          auto Sym = Pair.first;
-          auto SVal = Pair.second;
-
-          if (Sym.empty() || SVal.empty()) {
-            D.Diag(diag::err_drv_defsym_invalid_format) << S;
-            break;
-          }
-          int64_t IVal;
-          if (SVal.getAsInteger(0, IVal)) {
-            D.Diag(diag::err_drv_defsym_invalid_symval) << SVal;
-            break;
-          }
-          CmdArgs.push_back(Value.data());
-          TakeNextArg = true;
+        if (A->getNumValues() != 2) {
+          D.Diag(diag::err_drv_defsym_invalid_format) << Value;
+          break;
+        }
+        const char *S = A->getValue(1);
+        auto Pair = StringRef(S).split('=');
+        auto Sym = Pair.first;
+        auto SVal = Pair.second;
+
+        if (Sym.empty() || SVal.empty()) {
+          D.Diag(diag::err_drv_defsym_invalid_format) << S;
+          break;
+        }
+        int64_t IVal;
+        if (SVal.getAsInteger(0, IVal)) {
+          D.Diag(diag::err_drv_defsym_invalid_symval) << SVal;
+          break;
+        }
+        CmdArgs.push_back(Value.data());
+        TakeNextArg = true;
       } else if (Value == "-fdebug-compilation-dir") {
         CmdArgs.push_back("-fdebug-compilation-dir");
         TakeNextArg = true;
@@ -3331,7 +3331,7 @@ static void RenderSSPOptions(const Driver &D, const ToolChain &TC,
   // --param ssp-buffer-size=
   for (const Arg *A : Args.filtered(options::OPT__param)) {
     StringRef Str(A->getValue());
-    if (Str.startswith("ssp-buffer-size=")) {
+    if (Str.starts_with("ssp-buffer-size=")) {
       if (StackProtectorLevel) {
         CmdArgs.push_back("-stack-protector-buffer-size");
         // FIXME: Verify the argument is a valid integer.
@@ -5886,7 +5886,7 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
     StringRef Val = A->getValue();
     if (Triple.isX86() && Triple.isOSBinFormatELF()) {
       if (Val != "all" && Val != "labels" && Val != "none" &&
-          !Val.startswith("list="))
+          !Val.starts_with("list="))
         D.Diag(diag::err_drv_invalid_value)
             << A->getAsString(Args) << A->getValue();
       else
@@ -8382,14 +8382,14 @@ void ClangAs::ConstructJob(Compilation &C, const JobAction &JA,
       continue;
     auto &JArgs = J.getArguments();
     for (unsigned I = 0; I < JArgs.size(); ++I) {
-      if (StringRef(JArgs[I]).startswith("-object-file-name=") &&
+      if (StringRef(JArgs[I]).starts_with("-object-file-name=") &&
           Output.isFilename()) {
-        ArgStringList NewArgs(JArgs.begin(), JArgs.begin() + I);
-        addDebugObjectName(Args, NewArgs, DebugCompilationDir,
-                           Output.getFilename());
-        NewArgs.append(JArgs.begin() + I + 1, JArgs.end());
-        J.replaceArguments(NewArgs);
-        break;
+       ArgStringList NewArgs(JArgs.begin(), JArgs.begin() + I);
+       addDebugObjectName(Args, NewArgs, DebugCompilationDir,
+                          Output.getFilename());
+       NewArgs.append(JArgs.begin() + I + 1, JArgs.end());
+       J.replaceArguments(NewArgs);
+       break;
       }
     }
   }
@@ -8653,7 +8653,7 @@ void OffloadPackager::ConstructJob(Compilation &C, const JobAction &JA,
     getTargetFeatures(TC->getDriver(), TC->getTriple(), TCArgs, Features,
                       false);
     llvm::copy_if(Features, std::back_inserter(FeatureArgs),
-                  [](StringRef Arg) { return !Arg.startswith("-target"); });
+                  [](StringRef Arg) { return !Arg.starts_with("-target"); });
 
     if (TC->getTriple().isAMDGPU()) {
       for (StringRef Feature : llvm::split(Arch.split(':').second, ':')) {
diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 31e7d68..01fb071 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -303,7 +303,7 @@ void tools::handleTargetFeaturesGroup(const Driver &D,
     A->claim();
 
     // Skip over "-m".
-    assert(Name.startswith("m") && "Invalid feature name.");
+    assert(Name.starts_with("m") && "Invalid feature name.");
     Name = Name.substr(1);
 
     auto Proc = getCPUName(D, Args, Triple);
@@ -317,7 +317,7 @@ void tools::handleTargetFeaturesGroup(const Driver &D,
       continue;
     }
 
-    bool IsNegative = Name.startswith("no-");
+    bool IsNegative = Name.starts_with("no-");
     if (IsNegative)
       Name = Name.substr(3);
 
@@ -2336,20 +2336,20 @@ static void GetSDLFromOffloadArchive(
   llvm::Triple Triple(D.getTargetTriple());
   bool IsMSVC = Triple.isWindowsMSVCEnvironment();
   auto Ext = IsMSVC ? ".lib" : ".a";
-  if (!Lib.startswith(":") && !Lib.startswith("-l")) {
+  if (!Lib.starts_with(":") && !Lib.starts_with("-l")) {
     if (llvm::sys::fs::exists(Lib)) {
       ArchiveOfBundles = Lib;
       FoundAOB = true;
     }
   } else {
-    if (Lib.startswith("-l"))
+    if (Lib.starts_with("-l"))
       Lib = Lib.drop_front(2);
     for (auto LPath : LibraryPaths) {
       ArchiveOfBundles.clear();
-      auto LibFile =
-          (Lib.startswith(":") ? Lib.drop_front()
-                               : IsMSVC ? Lib + Ext : "lib" + Lib + Ext)
-              .str();
+      auto LibFile = (Lib.starts_with(":") ? Lib.drop_front()
+                      : IsMSVC             ? Lib + Ext
+                                           : "lib" + Lib + Ext)
+                         .str();
       for (auto Prefix : {"/libdevice/", "/"}) {
         auto AOB = Twine(LPath + Prefix + LibFile).str();
         if (llvm::sys::fs::exists(AOB)) {
diff --git a/clang/lib/Driver/ToolChains/Cuda.cpp b/clang/lib/Driver/ToolChains/Cuda.cpp
index ef1e779..f7a2085 100644
--- a/clang/lib/Driver/ToolChains/Cuda.cpp
+++ b/clang/lib/Driver/ToolChains/Cuda.cpp
@@ -238,7 +238,7 @@ CudaInstallationDetector::CudaInstallationDetector(
         // Process all bitcode filenames that look like
         // libdevice.compute_XX.YY.bc
         const StringRef LibDeviceName = "libdevice.";
-        if (!(FileName.startswith(LibDeviceName) && FileName.endswith(".bc")))
+        if (!(FileName.starts_with(LibDeviceName) && FileName.ends_with(".bc")))
           continue;
         StringRef GpuArch = FileName.slice(
             LibDeviceName.size(), FileName.find('.', LibDeviceName.size()));
diff --git a/clang/lib/Driver/ToolChains/Darwin.cpp b/clang/lib/Driver/ToolChains/Darwin.cpp
index 692b3a3..65846ca 100644
--- a/clang/lib/Driver/ToolChains/Darwin.cpp
+++ b/clang/lib/Driver/ToolChains/Darwin.cpp
@@ -1010,13 +1010,13 @@ static const char *ArmMachOArchNameCPU(StringRef CPU) {
 
   // FIXME: Make sure this MachO triple mangling is really necessary.
   // ARMv5* normalises to ARMv5.
-  if (Arch.startswith("armv5"))
+  if (Arch.starts_with("armv5"))
     Arch = Arch.substr(0, 5);
   // ARMv6*, except ARMv6M, normalises to ARMv6.
-  else if (Arch.startswith("armv6") && !Arch.endswith("6m"))
+  else if (Arch.starts_with("armv6") && !Arch.ends_with("6m"))
     Arch = Arch.substr(0, 5);
   // ARMv7A normalises to ARMv7.
-  else if (Arch.endswith("v7a"))
+  else if (Arch.ends_with("v7a"))
     Arch = Arch.substr(0, 5);
   return Arch.data();
 }
@@ -1319,8 +1319,8 @@ StringRef Darwin::getSDKName(StringRef isysroot) {
   auto EndSDK = llvm::sys::path::rend(isysroot);
   for (auto IT = BeginSDK; IT != EndSDK; ++IT) {
     StringRef SDK = *IT;
-    if (SDK.endswith(".sdk"))
-      return SDK.slice(0, SDK.size() - 4);
+    if (SDK.ends_with(".sdk"))
+        return SDK.slice(0, SDK.size() - 4);
   }
   return "";
 }
@@ -1959,22 +1959,23 @@ inferDeploymentTargetFromSDK(DerivedArgList &Args,
 
   auto CreatePlatformFromSDKName =
       [&](StringRef SDK) -> std::optional<DarwinPlatform> {
-    if (SDK.startswith("iPhoneOS") || SDK.startswith("iPhoneSimulator"))
+    if (SDK.starts_with("iPhoneOS") || SDK.starts_with("iPhoneSimulator"))
       return DarwinPlatform::createFromSDK(
           Darwin::IPhoneOS, Version,
-          /*IsSimulator=*/SDK.startswith("iPhoneSimulator"));
-    else if (SDK.startswith("MacOSX"))
+          /*IsSimulator=*/SDK.starts_with("iPhoneSimulator"));
+    else if (SDK.starts_with("MacOSX"))
       return DarwinPlatform::createFromSDK(Darwin::MacOS,
                                            getSystemOrSDKMacOSVersion(Version));
-    else if (SDK.startswith("WatchOS") || SDK.startswith("WatchSimulator"))
+    else if (SDK.starts_with("WatchOS") || SDK.starts_with("WatchSimulator"))
       return DarwinPlatform::createFromSDK(
           Darwin::WatchOS, Version,
-          /*IsSimulator=*/SDK.startswith("WatchSimulator"));
-    else if (SDK.startswith("AppleTVOS") || SDK.startswith("AppleTVSimulator"))
+          /*IsSimulator=*/SDK.starts_with("WatchSimulator"));
+    else if (SDK.starts_with("AppleTVOS") ||
+             SDK.starts_with("AppleTVSimulator"))
       return DarwinPlatform::createFromSDK(
           Darwin::TvOS, Version,
-          /*IsSimulator=*/SDK.startswith("AppleTVSimulator"));
-    else if (SDK.startswith("DriverKit"))
+          /*IsSimulator=*/SDK.starts_with("AppleTVSimulator"));
+    else if (SDK.starts_with("DriverKit"))
       return DarwinPlatform::createFromSDK(Darwin::DriverKit, Version);
     return std::nullopt;
   };
@@ -2339,8 +2340,8 @@ void Darwin::AddDeploymentTarget(DerivedArgList &Args) const {
     if (SDK.size() > 0) {
       size_t StartVer = SDK.find_first_of("0123456789");
       StringRef SDKName = SDK.slice(0, StartVer);
-      if (!SDKName.startswith(getPlatformFamily()) &&
-          !dropSDKNamePrefix(SDKName).startswith(getPlatformFamily()))
+      if (!SDKName.starts_with(getPlatformFamily()) &&
+          !dropSDKNamePrefix(SDKName).starts_with(getPlatformFamily()))
         getDriver().Diag(diag::warn_incompatible_sysroot)
             << SDKName << getPlatformFamily();
     }
diff --git a/clang/lib/Driver/ToolChains/Flang.cpp b/clang/lib/Driver/ToolChains/Flang.cpp
index 502b9f1..41eaad3 100644
--- a/clang/lib/Driver/ToolChains/Flang.cpp
+++ b/clang/lib/Driver/ToolChains/Flang.cpp
@@ -182,7 +182,7 @@ void Flang::AddAArch64TargetArgs(const ArgList &Args,
         Val.equals("256+") || Val.equals("512+") || Val.equals("1024+") ||
         Val.equals("2048+")) {
       unsigned Bits = 0;
-      if (Val.endswith("+"))
+      if (Val.ends_with("+"))
         Val = Val.substr(0, Val.size() - 1);
       else {
         [[maybe_unused]] bool Invalid = Val.getAsInteger(10, Bits);
diff --git a/clang/lib/Driver/ToolChains/Gnu.cpp b/clang/lib/Driver/ToolChains/Gnu.cpp
index b875991..835215a 100644
--- a/clang/lib/Driver/ToolChains/Gnu.cpp
+++ b/clang/lib/Driver/ToolChains/Gnu.cpp
@@ -1084,7 +1084,7 @@ static bool findMipsCsMultilibs(const Multilib::flags_list &Flags,
             .FilterOut(NonExistent)
             .setIncludeDirsCallback([](const Multilib &M) {
               std::vector<std::string> Dirs({"/include"});
-              if (StringRef(M.includeSuffix()).startswith("/uclibc"))
+              if (StringRef(M.includeSuffix()).starts_with("/uclibc"))
                 Dirs.push_back(
                     "/../../../../mips-linux-gnu/libc/uclibc/usr/include");
               else
@@ -1288,7 +1288,7 @@ static bool findMipsMtiMultilibs(const Multilib::flags_list &Flags,
             .FilterOut(NonExistent)
             .setIncludeDirsCallback([](const Multilib &M) {
               std::vector<std::string> Dirs({"/include"});
-              if (StringRef(M.includeSuffix()).startswith("/uclibc"))
+              if (StringRef(M.includeSuffix()).starts_with("/uclibc"))
                 Dirs.push_back("/../../../../sysroot/uclibc/usr/include");
               else
                 Dirs.push_back("/../../../../sysroot/usr/include");
@@ -3055,7 +3055,7 @@ void Generic_GCC::AddMultilibPaths(const Driver &D,
     // the cross. Note that GCC does include some of these directories in some
     // configurations but this seems somewhere between questionable and simply
     // a bug.
-    if (StringRef(LibPath).startswith(SysRoot))
+    if (StringRef(LibPath).starts_with(SysRoot))
       addPathIfExists(D, LibPath + "/../" + OSLibDir, Paths);
   }
 }
diff --git a/clang/lib/Driver/ToolChains/Hexagon.cpp b/clang/lib/Driver/ToolChains/Hexagon.cpp
index d0ff7d0..6a2a105 100644
--- a/clang/lib/Driver/ToolChains/Hexagon.cpp
+++ b/clang/lib/Driver/ToolChains/Hexagon.cpp
@@ -54,11 +54,11 @@ static void handleHVXTargetFeatures(const Driver &D, const ArgList &Args,
   auto makeFeature = [&Args](Twine T, bool Enable) -> StringRef {
     const std::string &S = T.str();
     StringRef Opt(S);
-    if (Opt.endswith("="))
+    if (Opt.ends_with("="))
       Opt = Opt.drop_back(1);
-    if (Opt.startswith("mno-"))
+    if (Opt.starts_with("mno-"))
       Opt = Opt.drop_front(4);
-    else if (Opt.startswith("m"))
+    else if (Opt.starts_with("m"))
       Opt = Opt.drop_front(1);
     return Args.MakeArgString(Twine(Enable ? "+" : "-") + Twine(Opt));
   };
@@ -801,7 +801,7 @@ StringRef HexagonToolChain::GetTargetCPUVersion(const ArgList &Args) {
     CpuArg = A;
 
   StringRef CPU = CpuArg ? CpuArg->getValue() : GetDefaultCPU();
-  if (CPU.startswith("hexagon"))
+  if (CPU.starts_with("hexagon"))
     return CPU.substr(sizeof("hexagon") - 1);
   return CPU;
 }
diff --git a/clang/lib/Driver/ToolChains/Hurd.cpp b/clang/lib/Driver/ToolChains/Hurd.cpp
index 2dfc90e..7a4c2bb 100644
--- a/clang/lib/Driver/ToolChains/Hurd.cpp
+++ b/clang/lib/Driver/ToolChains/Hurd.cpp
@@ -92,7 +92,7 @@ Hurd::Hurd(const Driver &D, const llvm::Triple &Triple, const ArgList &Args)
   // those searched.
   // FIXME: It's not clear whether we should use the driver's installed
   // directory ('Dir' below) or the ResourceDir.
-  if (StringRef(D.Dir).startswith(SysRoot)) {
+  if (StringRef(D.Dir).starts_with(SysRoot)) {
     addPathIfExists(D, D.Dir + "/../lib/" + MultiarchTriple, Paths);
     addPathIfExists(D, D.Dir + "/../" + OSLibDir, Paths);
   }
@@ -110,7 +110,7 @@ Hurd::Hurd(const Driver &D, const llvm::Triple &Triple, const ArgList &Args)
   // searched.
   // FIXME: It's not clear whether we should use the driver's installed
   // directory ('Dir' below) or the ResourceDir.
-  if (StringRef(D.Dir).startswith(SysRoot))
+  if (StringRef(D.Dir).starts_with(SysRoot))
     addPathIfExists(D, D.Dir + "/../lib", Paths);
 
   addPathIfExists(D, SysRoot + "/lib", Paths);
diff --git a/clang/lib/Driver/ToolChains/MSP430.cpp b/clang/lib/Driver/ToolChains/MSP430.cpp
index b28d5e4..8dc2352 100644
--- a/clang/lib/Driver/ToolChains/MSP430.cpp
+++ b/clang/lib/Driver/ToolChains/MSP430.cpp
@@ -166,7 +166,7 @@ void MSP430ToolChain::addClangTargetOptions(const ArgList &DriverArgs,
     return;
 
   const StringRef MCU = MCUArg->getValue();
-  if (MCU.startswith("msp430i")) {
+  if (MCU.starts_with("msp430i")) {
     // 'i' should be in lower case as it's defined in TI MSP430-GCC headers
     CC1Args.push_back(DriverArgs.MakeArgString(
         "-D__MSP430i" + MCU.drop_front(7).upper() + "__"));
diff --git a/clang/lib/Driver/ToolChains/MSVC.cpp b/clang/lib/Driver/ToolChains/MSVC.cpp
index 6d92555..8e1e951 100644
--- a/clang/lib/Driver/ToolChains/MSVC.cpp
+++ b/clang/lib/Driver/ToolChains/MSVC.cpp
@@ -302,7 +302,7 @@ void visualstudio::Linker::ConstructJob(Compilation &C, const JobAction &JA,
     if (A.getOption().matches(options::OPT_l)) {
       StringRef Lib = A.getValue();
       const char *LinkLibArg;
-      if (Lib.endswith(".lib"))
+      if (Lib.ends_with(".lib"))
         LinkLibArg = Args.MakeArgString(Lib);
       else
         LinkLibArg = Args.MakeArgString(Lib + ".lib");
diff --git a/clang/lib/Driver/ToolChains/MinGW.cpp b/clang/lib/Driver/ToolChains/MinGW.cpp
index 5d7f867..65512f1 100644
--- a/clang/lib/Driver/ToolChains/MinGW.cpp
+++ b/clang/lib/Driver/ToolChains/MinGW.cpp
@@ -86,9 +86,9 @@ void tools::MinGW::Linker::AddLibGCC(const ArgList &Args,
   CmdArgs.push_back("-lmoldname");
   CmdArgs.push_back("-lmingwex");
   for (auto Lib : Args.getAllArgValues(options::OPT_l))
-    if (StringRef(Lib).startswith("msvcr") ||
-        StringRef(Lib).startswith("ucrt") ||
-        StringRef(Lib).startswith("crtdll"))
+    if (StringRef(Lib).starts_with("msvcr") ||
+        StringRef(Lib).starts_with("ucrt") ||
+        StringRef(Lib).starts_with("crtdll"))
       return;
   CmdArgs.push_back("-lmsvcrt");
 }
diff --git a/clang/lib/Driver/ToolChains/PPCLinux.cpp b/clang/lib/Driver/ToolChains/PPCLinux.cpp
index bdbecae..0ed0f91 100644
--- a/clang/lib/Driver/ToolChains/PPCLinux.cpp
+++ b/clang/lib/Driver/ToolChains/PPCLinux.cpp
@@ -31,10 +31,10 @@ static bool GlibcSupportsFloat128(const std::string &Linker) {
 
   // Since glibc 2.34, the installed .so file is not symlink anymore. But we can
   // still safely assume it's newer than 2.32.
-  if (LinkerName.startswith("ld64.so"))
+  if (LinkerName.starts_with("ld64.so"))
     return true;
 
-  if (!LinkerName.startswith("ld-2."))
+  if (!LinkerName.starts_with("ld-2."))
     return false;
   unsigned Minor = (LinkerName[5] - '0') * 10 + (LinkerName[6] - '0');
   if (Minor < 32)
diff --git a/clang/lib/Driver/ToolChains/Solaris.cpp b/clang/lib/Driver/ToolChains/Solaris.cpp
index 485730d..9a9792d 100644
--- a/clang/lib/Driver/ToolChains/Solaris.cpp
+++ b/clang/lib/Driver/ToolChains/Solaris.cpp
@@ -328,7 +328,7 @@ Solaris::Solaris(const Driver &D, const llvm::Triple &Triple,
 
   // If we are currently running Clang inside of the requested system root,
   // add its parent library path to those searched.
-  if (StringRef(D.Dir).startswith(D.SysRoot))
+  if (StringRef(D.Dir).starts_with(D.SysRoot))
     addPathIfExists(D, D.Dir + "/../lib", Paths);
 
   addPathIfExists(D, D.SysRoot + "/usr/lib" + LibSuffix, Paths);
diff --git a/clang/lib/Driver/ToolChains/WebAssembly.cpp b/clang/lib/Driver/ToolChains/WebAssembly.cpp
index f131b6c..57f4600 100644
--- a/clang/lib/Driver/ToolChains/WebAssembly.cpp
+++ b/clang/lib/Driver/ToolChains/WebAssembly.cpp
@@ -328,7 +328,7 @@ void WebAssembly::addClangTargetOptions(const ArgList &DriverArgs,
 
   for (const Arg *A : DriverArgs.filtered(options::OPT_mllvm)) {
     StringRef Opt = A->getValue(0);
-    if (Opt.startswith("-emscripten-cxx-exceptions-allowed")) {
+    if (Opt.starts_with("-emscripten-cxx-exceptions-allowed")) {
       // '-mllvm -emscripten-cxx-exceptions-allowed' should be used with
       // '-mllvm -enable-emscripten-cxx-exceptions'
       bool EmEHArgExists = false;
@@ -355,7 +355,7 @@ void WebAssembly::addClangTargetOptions(const ArgList &DriverArgs,
       }
     }
 
-    if (Opt.startswith("-wasm-enable-sjlj")) {
+    if (Opt.starts_with("-wasm-enable-sjlj")) {
       // '-mllvm -wasm-enable-sjlj' is not compatible with
       // '-mno-exception-handling'
       if (DriverArgs.hasFlag(options::OPT_mno_exception_handing,
diff --git a/clang/lib/Edit/Commit.cpp b/clang/lib/Edit/Commit.cpp
index 7c5aea6..6e785e8 100644
--- a/clang/lib/Edit/Commit.cpp
+++ b/clang/lib/Edit/Commit.cpp
@@ -334,7 +334,7 @@ bool Commit::canReplaceText(SourceLocation loc, StringRef text,
     return false;
 
   Len = text.size();
-  return file.substr(Offs.getOffset()).startswith(text);
+  return file.substr(Offs.getOffset()).starts_with(text);
 }
 
 bool Commit::isAtStartOfMacroExpansion(SourceLocation loc,
diff --git a/clang/lib/Edit/RewriteObjCFoundationAPI.cpp b/clang/lib/Edit/RewriteObjCFoundationAPI.cpp
index adb34eb..d5bf553 100644
--- a/clang/lib/Edit/RewriteObjCFoundationAPI.cpp
+++ b/clang/lib/Edit/RewriteObjCFoundationAPI.cpp
@@ -697,7 +697,7 @@ static bool getLiteralInfo(SourceRange literalRange,
 
   struct Suff {
     static bool has(StringRef suff, StringRef &text) {
-      if (text.endswith(suff)) {
+      if (text.ends_with(suff)) {
         text = text.substr(0, text.size()-suff.size());
         return true;
       }
@@ -739,9 +739,9 @@ static bool getLiteralInfo(SourceRange literalRange,
   Info.F = UpperF ? "F" : "f";
 
   Info.Hex = Info.Octal = false;
-  if (text.startswith("0x"))
+  if (text.starts_with("0x"))
     Info.Hex = true;
-  else if (!isFloat && !isIntZero && text.startswith("0"))
+  else if (!isFloat && !isIntZero && text.starts_with("0"))
     Info.Octal = true;
 
   SourceLocation B = literalRange.getBegin();
diff --git a/clang/lib/ExtractAPI/ExtractAPIConsumer.cpp b/clang/lib/ExtractAPI/ExtractAPIConsumer.cpp
index fe282df..fd62d84 100644
--- a/clang/lib/ExtractAPI/ExtractAPIConsumer.cpp
+++ b/clang/lib/ExtractAPI/ExtractAPIConsumer.cpp
@@ -105,10 +105,10 @@ std::optional<std::string> getRelativeIncludeName(const CompilerInstance &CI,
       // Special case Apple .sdk folders since the search path is typically a
       // symlink like `iPhoneSimulator14.5.sdk` while the file is instead
       // located in `iPhoneSimulator.sdk` (the real folder).
-      if (NI->endswith(".sdk") && DI->endswith(".sdk")) {
+      if (NI->ends_with(".sdk") && DI->ends_with(".sdk")) {
         StringRef NBasename = path::stem(*NI);
         StringRef DBasename = path::stem(*DI);
-        if (DBasename.startswith(NBasename))
+        if (DBasename.starts_with(NBasename))
           continue;
       }
 
diff --git a/clang/lib/ExtractAPI/Serialization/SymbolGraphSerializer.cpp b/clang/lib/ExtractAPI/Serialization/SymbolGraphSerializer.cpp
index d9675b0..53b2229 100644
--- a/clang/lib/ExtractAPI/Serialization/SymbolGraphSerializer.cpp
+++ b/clang/lib/ExtractAPI/Serialization/SymbolGraphSerializer.cpp
@@ -743,7 +743,7 @@ bool SymbolGraphSerializer::shouldSkip(const APIRecord &Record) const {
 
   // Filter out symbols prefixed with an underscored as they are understood to
   // be symbols clients should not use.
-  if (Record.Name.startswith("_"))
+  if (Record.Name.starts_with("_"))
     return true;
 
   return false;
diff --git a/clang/lib/Format/BreakableToken.cpp b/clang/lib/Format/BreakableToken.cpp
index 954eeb9..473908e 100644
--- a/clang/lib/Format/BreakableToken.cpp
+++ b/clang/lib/Format/BreakableToken.cpp
@@ -55,7 +55,7 @@ static StringRef getLineCommentIndentPrefix(StringRef Comment,
       }));
 
   for (StringRef KnownPrefix : KnownPrefixes) {
-    if (Comment.startswith(KnownPrefix)) {
+    if (Comment.starts_with(KnownPrefix)) {
       const auto PrefixLength =
           Comment.find_first_not_of(' ', KnownPrefix.size());
       return Comment.substr(0, PrefixLength);
@@ -220,8 +220,8 @@ bool switchesFormatting(const FormatToken &Token) {
   assert((Token.is(TT_BlockComment) || Token.is(TT_LineComment)) &&
          "formatting regions are switched by comment tokens");
   StringRef Content = Token.TokenText.substr(2).ltrim();
-  return Content.startswith("clang-format on") ||
-         Content.startswith("clang-format off");
+  return Content.starts_with("clang-format on") ||
+         Content.starts_with("clang-format off");
 }
 
 unsigned
@@ -271,7 +271,7 @@ BreakableStringLiteral::BreakableStringLiteral(
     : BreakableToken(Tok, InPPDirective, Encoding, Style),
       StartColumn(StartColumn), Prefix(Prefix), Postfix(Postfix),
       UnbreakableTailLength(UnbreakableTailLength) {
-  assert(Tok.TokenText.startswith(Prefix) && Tok.TokenText.endswith(Postfix));
+  assert(Tok.TokenText.starts_with(Prefix) && Tok.TokenText.ends_with(Postfix));
   Line = Tok.TokenText.substr(
       Prefix.size(), Tok.TokenText.size() - Prefix.size() - Postfix.size());
 }
@@ -454,7 +454,7 @@ static bool mayReflowContent(StringRef Content) {
   bool hasSpecialMeaningPrefix = false;
   for (StringRef Prefix :
        {"@", "TODO", "FIXME", "XXX", "-# ", "- ", "+ ", "* "}) {
-    if (Content.startswith(Prefix)) {
+    if (Content.starts_with(Prefix)) {
       hasSpecialMeaningPrefix = true;
       break;
     }
@@ -471,7 +471,7 @@ static bool mayReflowContent(StringRef Content) {
   // characters and either the first or second character must be
   // non-punctuation.
   return Content.size() >= 2 && !hasSpecialMeaningPrefix &&
-         !Content.endswith("\\") &&
+         !Content.ends_with("\\") &&
          // Note that this is UTF-8 safe, since if isPunctuation(Content[0]) is
          // true, then the first code point must be 1 byte long.
          (!isPunctuation(Content[0]) || !isPunctuation(Content[1]));
@@ -488,7 +488,7 @@ BreakableBlockComment::BreakableBlockComment(
          "block comment section must start with a block comment");
 
   StringRef TokenText(Tok.TokenText);
-  assert(TokenText.startswith("/*") && TokenText.endswith("*/"));
+  assert(TokenText.starts_with("/*") && TokenText.ends_with("*/"));
   TokenText.substr(2, TokenText.size() - 4)
       .split(Lines, UseCRLF ? "\r\n" : "\n");
 
@@ -511,7 +511,7 @@ BreakableBlockComment::BreakableBlockComment(
   // /*
   // ** blah blah blah
   // */
-  if (Lines.size() >= 2 && Content[1].startswith("**") &&
+  if (Lines.size() >= 2 && Content[1].starts_with("**") &&
       static_cast<unsigned>(ContentColumn[1]) == StartColumn) {
     DecorationColumn = StartColumn;
   }
@@ -531,10 +531,10 @@ BreakableBlockComment::BreakableBlockComment(
       // If the last line is empty, the closing "*/" will have a star.
       if (Text.empty())
         break;
-    } else if (!Text.empty() && Decoration.startswith(Text)) {
+    } else if (!Text.empty() && Decoration.starts_with(Text)) {
       continue;
     }
-    while (!Text.startswith(Decoration))
+    while (!Text.starts_with(Decoration))
       Decoration = Decoration.drop_back(1);
   }
 
@@ -562,13 +562,13 @@ BreakableBlockComment::BreakableBlockComment(
     // The last line excludes the star if LastLineNeedsDecoration is false.
     // For all other lines, adjust the line to exclude the star and
     // (optionally) the first whitespace.
-    unsigned DecorationSize = Decoration.startswith(Content[i])
+    unsigned DecorationSize = Decoration.starts_with(Content[i])
                                   ? Content[i].size()
                                   : Decoration.size();
     if (DecorationSize)
       ContentColumn[i] = DecorationColumn + DecorationSize;
     Content[i] = Content[i].substr(DecorationSize);
-    if (!Decoration.startswith(Content[i])) {
+    if (!Decoration.starts_with(Content[i])) {
       IndentAtLineBreak =
           std::min<int>(IndentAtLineBreak, std::max(0, ContentColumn[i]));
     }
@@ -577,10 +577,10 @@ BreakableBlockComment::BreakableBlockComment(
 
   // Detect a multiline jsdoc comment and set DelimitersOnNewline in that case.
   if (Style.isJavaScript() || Style.Language == FormatStyle::LK_Java) {
-    if ((Lines[0] == "*" || Lines[0].startswith("* ")) && Lines.size() > 1) {
+    if ((Lines[0] == "*" || Lines[0].starts_with("* ")) && Lines.size() > 1) {
       // This is a multiline jsdoc comment.
       DelimitersOnNewline = true;
-    } else if (Lines[0].startswith("* ") && Lines.size() == 1) {
+    } else if (Lines[0].starts_with("* ") && Lines.size() == 1) {
       // Detect a long single-line comment, like:
       // /** long long long */
       // Below, '2' is the width of '*/'.
@@ -612,7 +612,7 @@ BreakableToken::Split BreakableBlockComment::getSplit(
     return Split(StringRef::npos, 0);
   return getCommentSplit(Content[LineIndex].substr(TailOffset),
                          ContentStartColumn, ColumnLimit, Style.TabWidth,
-                         Encoding, Style, Decoration.endswith("*"));
+                         Encoding, Style, Decoration.ends_with("*"));
 }
 
 void BreakableBlockComment::adjustWhitespace(unsigned LineIndex,
@@ -623,7 +623,7 @@ void BreakableBlockComment::adjustWhitespace(unsigned LineIndex,
   // trimming the trailing whitespace. The backslash will be re-added later when
   // inserting a line break.
   size_t EndOfPreviousLine = Lines[LineIndex - 1].size();
-  if (InPPDirective && Lines[LineIndex - 1].endswith("\\"))
+  if (InPPDirective && Lines[LineIndex - 1].ends_with("\\"))
     --EndOfPreviousLine;
 
   // Calculate the end of the non-whitespace text in the previous line.
@@ -672,7 +672,7 @@ unsigned BreakableBlockComment::getRemainingLength(unsigned LineIndex,
     // We never need a decoration when breaking just the trailing "*/" postfix.
     bool HasRemainingText = Offset < Content[LineIndex].size();
     if (!HasRemainingText) {
-      bool HasDecoration = Lines[LineIndex].ltrim().startswith(Decoration);
+      bool HasDecoration = Lines[LineIndex].ltrim().starts_with(Decoration);
       if (HasDecoration)
         LineLength -= Decoration.size();
     }
@@ -700,7 +700,7 @@ unsigned BreakableBlockComment::getContentIndent(unsigned LineIndex) const {
   // /** line 0 */
   // is "* line 0", so we need to skip over the decoration in that case.
   StringRef ContentWithNoDecoration = Content[LineIndex];
-  if (LineIndex == 0 && ContentWithNoDecoration.startswith("*"))
+  if (LineIndex == 0 && ContentWithNoDecoration.starts_with("*"))
     ContentWithNoDecoration = ContentWithNoDecoration.substr(1).ltrim(Blanks);
   StringRef FirstWord = ContentWithNoDecoration.substr(
       0, ContentWithNoDecoration.find_first_of(Blanks));
@@ -853,7 +853,7 @@ bool BreakableBlockComment::mayReflow(
   // Content[LineIndex] may exclude the indent after the '*' decoration. In that
   // case, we compute the start of the comment pragma manually.
   StringRef IndentContent = Content[LineIndex];
-  if (Lines[LineIndex].ltrim(Blanks).startswith("*"))
+  if (Lines[LineIndex].ltrim(Blanks).starts_with("*"))
     IndentContent = Lines[LineIndex].ltrim(Blanks).substr(1);
   return LineIndex > 0 && !CommentPragmasRegex.match(IndentContent) &&
          mayReflowContent(Content[LineIndex]) && !Tok.Finalized &&
@@ -876,7 +876,7 @@ BreakableLineCommentSection::BreakableLineCommentSection(
        CurrentTok = CurrentTok->Next) {
     LastLineTok = LineTok;
     StringRef TokenText(CurrentTok->TokenText);
-    assert((TokenText.startswith("//") || TokenText.startswith("#")) &&
+    assert((TokenText.starts_with("//") || TokenText.starts_with("#")) &&
            "unsupported line comment prefix, '//' and '#' are supported");
     size_t FirstLineIndex = Lines.size();
     TokenText.split(Lines, "\n");
@@ -913,7 +913,7 @@ BreakableLineCommentSection::BreakableLineCommentSection(
         // #########
         // # section
         // #########
-        if (FirstCommentChar == '#' && !TokenText.startswith("#"))
+        if (FirstCommentChar == '#' && !TokenText.starts_with("#"))
           return false;
         return FirstCommentChar == '\\' || isPunctuation(FirstCommentChar) ||
                isHorizontalWhitespace(FirstCommentChar);
@@ -1152,7 +1152,7 @@ bool BreakableLineCommentSection::mayReflow(
   // Line comments have the indent as part of the prefix, so we need to
   // recompute the start of the line.
   StringRef IndentContent = Content[LineIndex];
-  if (Lines[LineIndex].startswith("//"))
+  if (Lines[LineIndex].starts_with("//"))
     IndentContent = Lines[LineIndex].substr(2);
   // FIXME: Decide whether we want to reflow non-regular indents:
   // Currently, we only reflow when the OriginalPrefix[LineIndex] matches the
diff --git a/clang/lib/Format/ContinuationIndenter.cpp b/clang/lib/Format/ContinuationIndenter.cpp
index 9e4e939..bd319f2 100644
--- a/clang/lib/Format/ContinuationIndenter.cpp
+++ b/clang/lib/Format/ContinuationIndenter.cpp
@@ -161,7 +161,7 @@ static bool opensProtoMessageField(const FormatToken &LessTok,
 // string.  For example, the delimiter of R"deli(cont)deli" is deli.
 static std::optional<StringRef> getRawStringDelimiter(StringRef TokenText) {
   if (TokenText.size() < 5 // The smallest raw string possible is 'R"()"'.
-      || !TokenText.startswith("R\"") || !TokenText.endswith("\"")) {
+      || !TokenText.starts_with("R\"") || !TokenText.ends_with("\"")) {
     return std::nullopt;
   }
 
@@ -177,7 +177,7 @@ static std::optional<StringRef> getRawStringDelimiter(StringRef TokenText) {
   size_t RParenPos = TokenText.size() - Delimiter.size() - 2;
   if (TokenText[RParenPos] != ')')
     return std::nullopt;
-  if (!TokenText.substr(RParenPos + 1).startswith(Delimiter))
+  if (!TokenText.substr(RParenPos + 1).starts_with(Delimiter))
     return std::nullopt;
   return Delimiter;
 }
@@ -608,7 +608,7 @@ bool ContinuationIndenter::mustBreak(const LineState &State) {
 
   if (Current.is(tok::lessless) &&
       ((Previous.is(tok::identifier) && Previous.TokenText == "endl") ||
-       (Previous.Tok.isLiteral() && (Previous.TokenText.endswith("\\n\"") ||
+       (Previous.Tok.isLiteral() && (Previous.TokenText.ends_with("\\n\"") ||
                                      Previous.TokenText == "\'\\n\'")))) {
     return true;
   }
@@ -2293,12 +2293,13 @@ ContinuationIndenter::createBreakableToken(const FormatToken &Current,
     if (Style.isVerilog() || Style.Language == FormatStyle::LK_Java ||
         Style.isJavaScript() || Style.isCSharp()) {
       BreakableStringLiteralUsingOperators::QuoteStyleType QuoteStyle;
-      if (Style.isJavaScript() && Text.startswith("'") && Text.endswith("'")) {
+      if (Style.isJavaScript() && Text.starts_with("'") &&
+          Text.ends_with("'")) {
         QuoteStyle = BreakableStringLiteralUsingOperators::SingleQuotes;
-      } else if (Style.isCSharp() && Text.startswith("@\"") &&
-                 Text.endswith("\"")) {
+      } else if (Style.isCSharp() && Text.starts_with("@\"") &&
+                 Text.ends_with("\"")) {
         QuoteStyle = BreakableStringLiteralUsingOperators::AtDoubleQuotes;
-      } else if (Text.startswith("\"") && Text.endswith("\"")) {
+      } else if (Text.starts_with("\"") && Text.ends_with("\"")) {
         QuoteStyle = BreakableStringLiteralUsingOperators::DoubleQuotes;
       } else {
         return nullptr;
@@ -2315,12 +2316,14 @@ ContinuationIndenter::createBreakableToken(const FormatToken &Current,
     // FIXME: Store Prefix and Suffix (or PrefixLength and SuffixLength to
     // reduce the overhead) for each FormatToken, which is a string, so that we
     // don't run multiple checks here on the hot path.
-    if ((Text.endswith(Postfix = "\"") &&
-         (Text.startswith(Prefix = "@\"") || Text.startswith(Prefix = "\"") ||
-          Text.startswith(Prefix = "u\"") || Text.startswith(Prefix = "U\"") ||
-          Text.startswith(Prefix = "u8\"") ||
-          Text.startswith(Prefix = "L\""))) ||
-        (Text.startswith(Prefix = "_T(\"") && Text.endswith(Postfix = "\")"))) {
+    if ((Text.ends_with(Postfix = "\"") &&
+         (Text.starts_with(Prefix = "@\"") || Text.starts_with(Prefix = "\"") ||
+          Text.starts_with(Prefix = "u\"") ||
+          Text.starts_with(Prefix = "U\"") ||
+          Text.starts_with(Prefix = "u8\"") ||
+          Text.starts_with(Prefix = "L\""))) ||
+        (Text.starts_with(Prefix = "_T(\"") &&
+         Text.ends_with(Postfix = "\")"))) {
       return std::make_unique<BreakableStringLiteral>(
           Current, StartColumn, Prefix, Postfix, UnbreakableTailLength,
           State.Line->InPPDirective, Encoding, Style);
@@ -2342,7 +2345,7 @@ ContinuationIndenter::createBreakableToken(const FormatToken &Current,
     bool RegularComments = [&]() {
       for (const FormatToken *T = &Current; T && T->is(TT_LineComment);
            T = T->Next) {
-        if (!(T->TokenText.startswith("//") || T->TokenText.startswith("#")))
+        if (!(T->TokenText.starts_with("//") || T->TokenText.starts_with("#")))
           return false;
       }
       return true;
@@ -2754,7 +2757,7 @@ bool ContinuationIndenter::nextIsMultilineString(const LineState &State) {
   // We never consider raw string literals "multiline" for the purpose of
   // AlwaysBreakBeforeMultilineStrings implementation as they are special-cased
   // (see TokenAnnotator::mustBreakBefore().
-  if (Current.TokenText.startswith("R\""))
+  if (Current.TokenText.starts_with("R\""))
     return false;
   if (Current.IsMultiline)
     return true;
diff --git a/clang/lib/Format/Format.cpp b/clang/lib/Format/Format.cpp
index 8feee74..668e959 100644
--- a/clang/lib/Format/Format.cpp
+++ b/clang/lib/Format/Format.cpp
@@ -2346,9 +2346,9 @@ private:
             // NB: testing for not starting with a double quote to avoid
             // breaking `template strings`.
             (Style.JavaScriptQuotes == FormatStyle::JSQS_Single &&
-             !Input.startswith("\"")) ||
+             !Input.starts_with("\"")) ||
             (Style.JavaScriptQuotes == FormatStyle::JSQS_Double &&
-             !Input.startswith("\'"))) {
+             !Input.starts_with("\'"))) {
           continue;
         }
 
@@ -2932,7 +2932,7 @@ private:
     };
 
     for (auto *Line : AnnotatedLines) {
-      if (Line->First && (Line->First->TokenText.startswith("#") ||
+      if (Line->First && (Line->First->TokenText.starts_with("#") ||
                           Line->First->TokenText == "__pragma" ||
                           Line->First->TokenText == "_Pragma")) {
         continue;
@@ -3217,7 +3217,7 @@ tooling::Replacements sortCppIncludes(const FormatStyle &Style, StringRef Code,
          Style.IncludeStyle.IncludeBlocks ==
              tooling::IncludeStyle::IBS_Regroup);
 
-    bool MergeWithNextLine = Trimmed.endswith("\\");
+    bool MergeWithNextLine = Trimmed.ends_with("\\");
     if (!FormattingOff && !MergeWithNextLine) {
       if (tooling::HeaderIncludes::IncludeRegex.match(Line, &Matches)) {
         StringRef IncludeName = Matches[2];
@@ -3243,7 +3243,7 @@ tooling::Replacements sortCppIncludes(const FormatStyle &Style, StringRef Code,
         sortCppIncludes(Style, IncludesInBlock, Ranges, FileName, Code,
                         Replaces, Cursor);
         IncludesInBlock.clear();
-        if (Trimmed.startswith("#pragma hdrstop")) // Precompiled headers.
+        if (Trimmed.starts_with("#pragma hdrstop")) // Precompiled headers.
           FirstIncludeBlock = true;
         else
           FirstIncludeBlock = false;
@@ -3271,7 +3271,7 @@ static unsigned findJavaImportGroup(const FormatStyle &Style,
   unsigned LongestMatchLength = 0;
   for (unsigned I = 0; I < Style.JavaImportGroups.size(); I++) {
     const std::string &GroupPrefix = Style.JavaImportGroups[I];
-    if (ImportIdentifier.startswith(GroupPrefix) &&
+    if (ImportIdentifier.starts_with(GroupPrefix) &&
         GroupPrefix.length() > LongestMatchLength) {
       LongestMatchIndex = I;
       LongestMatchLength = GroupPrefix.length();
@@ -3426,7 +3426,7 @@ bool isMpegTS(StringRef Code) {
   return Code.size() > 188 && Code[0] == 0x47 && Code[188] == 0x47;
 }
 
-bool isLikelyXml(StringRef Code) { return Code.ltrim().startswith("<"); }
+bool isLikelyXml(StringRef Code) { return Code.ltrim().starts_with("<"); }
 
 tooling::Replacements sortIncludes(const FormatStyle &Style, StringRef Code,
                                    ArrayRef<tooling::Range> Ranges,
@@ -3538,7 +3538,7 @@ fixCppIncludeInsertions(StringRef Code, const tooling::Replacements &Replaces,
 
   for (const auto &Header : HeadersToDelete) {
     tooling::Replacements Replaces =
-        Includes.remove(Header.trim("\"<>"), Header.startswith("<"));
+        Includes.remove(Header.trim("\"<>"), Header.starts_with("<"));
     for (const auto &R : Replaces) {
       auto Err = Result.add(R);
       if (Err) {
@@ -3560,7 +3560,7 @@ fixCppIncludeInsertions(StringRef Code, const tooling::Replacements &Replaces,
     (void)Matched;
     auto IncludeName = Matches[2];
     auto Replace =
-        Includes.insert(IncludeName.trim("\"<>"), IncludeName.startswith("<"),
+        Includes.insert(IncludeName.trim("\"<>"), IncludeName.starts_with("<"),
                         tooling::IncludeDirective::Include);
     if (Replace) {
       auto Err = Result.add(*Replace);
@@ -3882,14 +3882,14 @@ const char *StyleOptionHelpDescription =
     "   --style=\"{BasedOnStyle: llvm, IndentWidth: 8}\"";
 
 static FormatStyle::LanguageKind getLanguageByFileName(StringRef FileName) {
-  if (FileName.endswith(".java"))
+  if (FileName.ends_with(".java"))
     return FormatStyle::LK_Java;
   if (FileName.ends_with_insensitive(".js") ||
       FileName.ends_with_insensitive(".mjs") ||
       FileName.ends_with_insensitive(".ts")) {
     return FormatStyle::LK_JavaScript; // (module) JavaScript or TypeScript.
   }
-  if (FileName.endswith(".m") || FileName.endswith(".mm"))
+  if (FileName.ends_with(".m") || FileName.ends_with(".mm"))
     return FormatStyle::LK_ObjC;
   if (FileName.ends_with_insensitive(".proto") ||
       FileName.ends_with_insensitive(".protodevel")) {
@@ -3963,7 +3963,7 @@ llvm::Expected<FormatStyle> getStyle(StringRef StyleName, StringRef FileName,
   llvm::SmallVector<std::unique_ptr<llvm::MemoryBuffer>, 1>
       ChildFormatTextToApply;
 
-  if (StyleName.startswith("{")) {
+  if (StyleName.starts_with("{")) {
     // Parse YAML/JSON style from the command line.
     StringRef Source = "<command-line>";
     if (std::error_code ec =
@@ -4123,7 +4123,7 @@ static bool isClangFormatOnOff(StringRef Comment, bool On) {
   static const char ClangFormatOff[] = "// clang-format off";
   const unsigned Size = (On ? sizeof ClangFormatOn : sizeof ClangFormatOff) - 1;
 
-  return Comment.startswith(On ? ClangFormatOn : ClangFormatOff) &&
+  return Comment.starts_with(On ? ClangFormatOn : ClangFormatOff) &&
          (Comment.size() == Size || Comment[Size] == ':');
 }
 
diff --git a/clang/lib/Format/FormatToken.h b/clang/lib/Format/FormatToken.h
index 14a3c21..3f9664f 100644
--- a/clang/lib/Format/FormatToken.h
+++ b/clang/lib/Format/FormatToken.h
@@ -667,7 +667,7 @@ public:
   /// Returns whether \p Tok is ([{ or an opening < of a template or in
   /// protos.
   bool opensScope() const {
-    if (is(TT_TemplateString) && TokenText.endswith("${"))
+    if (is(TT_TemplateString) && TokenText.ends_with("${"))
       return true;
     if (is(TT_DictLiteral) && is(tok::less))
       return true;
@@ -677,7 +677,7 @@ public:
   /// Returns whether \p Tok is )]} or a closing > of a template or in
   /// protos.
   bool closesScope() const {
-    if (is(TT_TemplateString) && TokenText.startswith("}"))
+    if (is(TT_TemplateString) && TokenText.starts_with("}"))
       return true;
     if (is(TT_DictLiteral) && is(tok::greater))
       return true;
@@ -743,9 +743,9 @@ public:
     if (isNot(tok::string_literal))
       return false;
     StringRef Content = TokenText;
-    if (Content.startswith("\"") || Content.startswith("'"))
+    if (Content.starts_with("\"") || Content.starts_with("'"))
       Content = Content.drop_front(1);
-    if (Content.endswith("\"") || Content.endswith("'"))
+    if (Content.ends_with("\"") || Content.ends_with("'"))
       Content = Content.drop_back(1);
     Content = Content.trim();
     return Content.size() > 1 &&
@@ -1823,7 +1823,7 @@ private:
 };
 
 inline bool isLineComment(const FormatToken &FormatTok) {
-  return FormatTok.is(tok::comment) && !FormatTok.TokenText.startswith("/*");
+  return FormatTok.is(tok::comment) && !FormatTok.TokenText.starts_with("/*");
 }
 
 // Checks if \p FormatTok is a line comment that continues the line comment
diff --git a/clang/lib/Format/FormatTokenLexer.cpp b/clang/lib/Format/FormatTokenLexer.cpp
index e4e32e2..6143028 100644
--- a/clang/lib/Format/FormatTokenLexer.cpp
+++ b/clang/lib/Format/FormatTokenLexer.cpp
@@ -711,12 +711,12 @@ void FormatTokenLexer::handleCSharpVerbatimAndInterpolatedStrings() {
 
   bool Verbatim = false;
   bool Interpolated = false;
-  if (TokenText.startswith(R"($@")") || TokenText.startswith(R"(@$")")) {
+  if (TokenText.starts_with(R"($@")") || TokenText.starts_with(R"(@$")")) {
     Verbatim = true;
     Interpolated = true;
-  } else if (TokenText.startswith(R"(@")")) {
+  } else if (TokenText.starts_with(R"(@")")) {
     Verbatim = true;
-  } else if (TokenText.startswith(R"($")")) {
+  } else if (TokenText.starts_with(R"($")")) {
     Interpolated = true;
   }
 
@@ -1110,7 +1110,7 @@ FormatToken *FormatTokenLexer::getNextToken() {
   // the comment token at the backslash, and resets the lexer to restart behind
   // the backslash.
   if ((Style.isJavaScript() || Style.Language == FormatStyle::LK_Java) &&
-      FormatTok->is(tok::comment) && FormatTok->TokenText.startswith("//")) {
+      FormatTok->is(tok::comment) && FormatTok->TokenText.starts_with("//")) {
     size_t BackslashPos = FormatTok->TokenText.find('\\');
     while (BackslashPos != StringRef::npos) {
       if (BackslashPos + 1 < FormatTok->TokenText.size() &&
diff --git a/clang/lib/Format/SortJavaScriptImports.cpp b/clang/lib/Format/SortJavaScriptImports.cpp
index 8c6722e..1a6a1b1 100644
--- a/clang/lib/Format/SortJavaScriptImports.cpp
+++ b/clang/lib/Format/SortJavaScriptImports.cpp
@@ -468,10 +468,10 @@ private:
       // URL = TokenText without the quotes.
       Reference.URL =
           Current->TokenText.substr(1, Current->TokenText.size() - 2);
-      if (Reference.URL.startswith("..")) {
+      if (Reference.URL.starts_with("..")) {
         Reference.Category =
             JsModuleReference::ReferenceCategory::RELATIVE_PARENT;
-      } else if (Reference.URL.startswith(".")) {
+      } else if (Reference.URL.starts_with(".")) {
         Reference.Category = JsModuleReference::ReferenceCategory::RELATIVE;
       } else {
         Reference.Category = JsModuleReference::ReferenceCategory::ABSOLUTE;
diff --git a/clang/lib/Format/TokenAnnotator.cpp b/clang/lib/Format/TokenAnnotator.cpp
index eaccb58..febd683 100644
--- a/clang/lib/Format/TokenAnnotator.cpp
+++ b/clang/lib/Format/TokenAnnotator.cpp
@@ -1307,7 +1307,7 @@ private:
         if (Previous->isOneOf(TT_BinaryOperator, TT_UnaryOperator, tok::comma,
                               tok::star, tok::arrow, tok::amp, tok::ampamp) ||
             // User defined literal.
-            Previous->TokenText.startswith("\"\"")) {
+            Previous->TokenText.starts_with("\"\"")) {
           Previous->setType(TT_OverloadedOperator);
           if (CurrentToken->isOneOf(tok::less, tok::greater))
             break;
@@ -1466,7 +1466,7 @@ private:
         // Mark tokens up to the trailing line comments as implicit string
         // literals.
         if (CurrentToken->isNot(tok::comment) &&
-            !CurrentToken->TokenText.startswith("//")) {
+            !CurrentToken->TokenText.starts_with("//")) {
           CurrentToken->setType(TT_ImplicitStringLiteral);
         }
         next();
@@ -2077,8 +2077,8 @@ private:
       }
       Current.setType(TT_BinaryOperator);
     } else if (Current.is(tok::comment)) {
-      if (Current.TokenText.startswith("/*")) {
-        if (Current.TokenText.endswith("*/")) {
+      if (Current.TokenText.starts_with("/*")) {
+        if (Current.TokenText.ends_with("*/")) {
           Current.setType(TT_BlockComment);
         } else {
           // The lexer has for some reason determined a comment here. But we
@@ -3724,8 +3724,8 @@ unsigned TokenAnnotator::splitPenalty(const AnnotatedLine &Line,
       return 100;
     if (Left.is(TT_JsTypeColon))
       return 35;
-    if ((Left.is(TT_TemplateString) && Left.TokenText.endswith("${")) ||
-        (Right.is(TT_TemplateString) && Right.TokenText.startswith("}"))) {
+    if ((Left.is(TT_TemplateString) && Left.TokenText.ends_with("${")) ||
+        (Right.is(TT_TemplateString) && Right.TokenText.starts_with("}"))) {
       return 100;
     }
     // Prefer breaking call chains (".foo") over empty "{}", "[]" or "()".
@@ -4224,7 +4224,7 @@ bool TokenAnnotator::spaceRequiredBetween(const AnnotatedLine &Line,
   }
   if (Left.is(TT_BlockComment)) {
     // No whitespace in x(/*foo=*/1), except for JavaScript.
-    return Style.isJavaScript() || !Left.TokenText.endswith("=*/");
+    return Style.isJavaScript() || !Left.TokenText.ends_with("=*/");
   }
 
   // Space between template and attribute.
@@ -4572,8 +4572,8 @@ bool TokenAnnotator::spaceRequiredBefore(const AnnotatedLine &Line,
       if (Next && Next->is(TT_FatArrow))
         return true;
     }
-    if ((Left.is(TT_TemplateString) && Left.TokenText.endswith("${")) ||
-        (Right.is(TT_TemplateString) && Right.TokenText.startswith("}"))) {
+    if ((Left.is(TT_TemplateString) && Left.TokenText.ends_with("${")) ||
+        (Right.is(TT_TemplateString) && Right.TokenText.starts_with("}"))) {
       return false;
     }
     // In tagged template literals ("html`bar baz`"), there is no space between
@@ -5212,7 +5212,7 @@ bool TokenAnnotator::mustBreakBefore(const AnnotatedLine &Line,
       Left.is(TT_InheritanceComma)) {
     return true;
   }
-  if (Right.is(tok::string_literal) && Right.TokenText.startswith("R\"")) {
+  if (Right.is(tok::string_literal) && Right.TokenText.starts_with("R\"")) {
     // Multiline raw string literals are special wrt. line breaks. The author
     // has made a deliberate choice and might have aligned the contents of the
     // string literal accordingly. Thus, we try keep existing line breaks.
diff --git a/clang/lib/Format/UnwrappedLineParser.cpp b/clang/lib/Format/UnwrappedLineParser.cpp
index 57126b8..c38b4c8 100644
--- a/clang/lib/Format/UnwrappedLineParser.cpp
+++ b/clang/lib/Format/UnwrappedLineParser.cpp
@@ -1333,7 +1333,7 @@ bool UnwrappedLineParser::parseModuleImport() {
         // Mark tokens up to the trailing line comments as implicit string
         // literals.
         if (FormatTok->isNot(tok::comment) &&
-            !FormatTok->TokenText.startswith("//")) {
+            !FormatTok->TokenText.starts_with("//")) {
           FormatTok->setFinalizedType(TT_ImplicitStringLiteral);
         }
         nextToken();
@@ -1371,7 +1371,7 @@ void UnwrappedLineParser::readTokenWithJavaScriptASI() {
 
   bool PreviousMustBeValue = mustBeJSIdentOrValue(Keywords, Previous);
   bool PreviousStartsTemplateExpr =
-      Previous->is(TT_TemplateString) && Previous->TokenText.endswith("${");
+      Previous->is(TT_TemplateString) && Previous->TokenText.ends_with("${");
   if (PreviousMustBeValue || Previous->is(tok::r_paren)) {
     // If the line contains an '@' sign, the previous token might be an
     // annotation, which can precede another identifier/value.
@@ -1385,7 +1385,7 @@ void UnwrappedLineParser::readTokenWithJavaScriptASI() {
     return addUnwrappedLine();
   bool NextMustBeValue = mustBeJSIdentOrValue(Keywords, Next);
   bool NextEndsTemplateExpr =
-      Next->is(TT_TemplateString) && Next->TokenText.startswith("}");
+      Next->is(TT_TemplateString) && Next->TokenText.starts_with("}");
   if (NextMustBeValue && !NextEndsTemplateExpr && !PreviousStartsTemplateExpr &&
       (PreviousMustBeValue ||
        Previous->isOneOf(tok::r_square, tok::r_paren, tok::plusplus,
@@ -4459,8 +4459,8 @@ continuesLineCommentSection(const FormatToken &FormatTok,
     return false;
 
   StringRef IndentContent = FormatTok.TokenText;
-  if (FormatTok.TokenText.startswith("//") ||
-      FormatTok.TokenText.startswith("/*")) {
+  if (FormatTok.TokenText.starts_with("//") ||
+      FormatTok.TokenText.starts_with("/*")) {
     IndentContent = FormatTok.TokenText.substr(2);
   }
   if (CommentPragmasRegex.match(IndentContent))
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index b33bdad..11f3f2c 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -2829,7 +2829,7 @@ static bool ParseFrontendArgs(FrontendOptions &Opts, ArgList &Args,
                "-interface-stub-version=ifs-v1"
             << ErrorMessage;
         ProgramAction = frontend::ParseSyntaxOnly;
-      } else if (!ArgStr.startswith("ifs-")) {
+      } else if (!ArgStr.starts_with("ifs-")) {
         std::string ErrorMessage =
             "Invalid interface stub format: " + ArgStr.str() + ".";
         Diags.Report(diag::err_drv_invalid_value)
@@ -4106,13 +4106,13 @@ bool CompilerInvocation::ParseLangArgs(LangOptions &Opts, ArgList &Args,
 
     // Check the version number is valid: either 3.x (0 <= x <= 9) or
     // y or y.0 (4 <= y <= current version).
-    if (!VerParts.first.startswith("0") &&
-        !VerParts.first.getAsInteger(10, Major) &&
-        3 <= Major && Major <= CLANG_VERSION_MAJOR &&
-        (Major == 3 ? VerParts.second.size() == 1 &&
-                      !VerParts.second.getAsInteger(10, Minor)
-                    : VerParts.first.size() == Ver.size() ||
-                      VerParts.second == "0")) {
+    if (!VerParts.first.starts_with("0") &&
+        !VerParts.first.getAsInteger(10, Major) && 3 <= Major &&
+        Major <= CLANG_VERSION_MAJOR &&
+        (Major == 3
+             ? VerParts.second.size() == 1 &&
+                   !VerParts.second.getAsInteger(10, Minor)
+             : VerParts.first.size() == Ver.size() || VerParts.second == "0")) {
       // Got a valid version number.
       if (Major == 3 && Minor <= 8)
         Opts.setClangABICompat(LangOptions::ClangABI::Ver3_8);
diff --git a/clang/lib/Frontend/DependencyGraph.cpp b/clang/lib/Frontend/DependencyGraph.cpp
index 6aad043..e96669f 100644
--- a/clang/lib/Frontend/DependencyGraph.cpp
+++ b/clang/lib/Frontend/DependencyGraph.cpp
@@ -110,7 +110,7 @@ void DependencyGraphCallback::OutputGraphFile() {
     writeNodeReference(OS, AllFiles[I]);
     OS << " [ shape=\"box\", label=\"";
     StringRef FileName = AllFiles[I].getName();
-    if (FileName.startswith(SysRoot))
+    if (FileName.starts_with(SysRoot))
       FileName = FileName.substr(SysRoot.size());
 
     OS << DOT::EscapeString(std::string(FileName)) << "\"];\n";
diff --git a/clang/lib/Frontend/Rewrite/InclusionRewriter.cpp b/clang/lib/Frontend/Rewrite/InclusionRewriter.cpp
index 2c3a253..b6b3746 100644
--- a/clang/lib/Frontend/Rewrite/InclusionRewriter.cpp
+++ b/clang/lib/Frontend/Rewrite/InclusionRewriter.cpp
@@ -307,7 +307,7 @@ void InclusionRewriter::OutputContentUpTo(const MemoryBufferRef &FromFile,
       Rest = Rest.substr(Idx);
     }
   }
-  if (EnsureNewline && !TextToWrite.endswith(LocalEOL))
+  if (EnsureNewline && !TextToWrite.ends_with(LocalEOL))
     OS << MainEOL;
 
   WriteFrom = WriteTo;
diff --git a/clang/lib/Frontend/VerifyDiagnosticConsumer.cpp b/clang/lib/Frontend/VerifyDiagnosticConsumer.cpp
index ab8174f..09c1460 100644
--- a/clang/lib/Frontend/VerifyDiagnosticConsumer.cpp
+++ b/clang/lib/Frontend/VerifyDiagnosticConsumer.cpp
@@ -226,10 +226,10 @@ public:
     P = C;
     while (P < End) {
       StringRef S(P, End - P);
-      if (S.startswith(OpenBrace)) {
+      if (S.starts_with(OpenBrace)) {
         ++Depth;
         P += OpenBrace.size();
-      } else if (S.startswith(CloseBrace)) {
+      } else if (S.starts_with(CloseBrace)) {
         --Depth;
         if (Depth == 0) {
           PEnd = P + CloseBrace.size();
@@ -445,7 +445,7 @@ static bool ParseDirective(StringRef S, ExpectedData *ED, SourceManager &SM,
     // others.
 
     // Regex in initial directive token: -re
-    if (DToken.endswith("-re")) {
+    if (DToken.ends_with("-re")) {
       D.RegexKind = true;
       KindStr = "regex";
       DToken = DToken.substr(0, DToken.size()-3);
@@ -454,20 +454,19 @@ static bool ParseDirective(StringRef S, ExpectedData *ED, SourceManager &SM,
     // Type in initial directive token: -{error|warning|note|no-diagnostics}
     bool NoDiag = false;
     StringRef DType;
-    if (DToken.endswith(DType="-error"))
+    if (DToken.ends_with(DType = "-error"))
       D.DL = ED ? &ED->Errors : nullptr;
-    else if (DToken.endswith(DType="-warning"))
+    else if (DToken.ends_with(DType = "-warning"))
       D.DL = ED ? &ED->Warnings : nullptr;
-    else if (DToken.endswith(DType="-remark"))
+    else if (DToken.ends_with(DType = "-remark"))
       D.DL = ED ? &ED->Remarks : nullptr;
-    else if (DToken.endswith(DType="-note"))
+    else if (DToken.ends_with(DType = "-note"))
       D.DL = ED ? &ED->Notes : nullptr;
-    else if (DToken.endswith(DType="-no-diagnostics")) {
+    else if (DToken.ends_with(DType = "-no-diagnostics")) {
       NoDiag = true;
       if (D.RegexKind)
         continue;
-    }
-    else
+    } else
       continue;
     DToken = DToken.substr(0, DToken.size()-DType.size());
 
@@ -1145,7 +1144,7 @@ std::unique_ptr<Directive> Directive::create(bool RegexKind,
   std::string RegexStr;
   StringRef S = Text;
   while (!S.empty()) {
-    if (S.startswith("{{")) {
+    if (S.starts_with("{{")) {
       S = S.drop_front(2);
       size_t RegexMatchLength = S.find("}}");
       assert(RegexMatchLength != StringRef::npos);
diff --git a/clang/lib/Index/IndexSymbol.cpp b/clang/lib/Index/IndexSymbol.cpp
index c67810a..0f79694 100644
--- a/clang/lib/Index/IndexSymbol.cpp
+++ b/clang/lib/Index/IndexSymbol.cpp
@@ -36,7 +36,7 @@ static bool isUnitTest(const ObjCMethodDecl *D) {
     return false;
   if (!D->getReturnType()->isVoidType())
     return false;
-  if (!D->getSelector().getNameForSlot(0).startswith("test"))
+  if (!D->getSelector().getNameForSlot(0).starts_with("test"))
     return false;
   return isUnitTestCase(D->getClassInterface());
 }
diff --git a/clang/lib/IndexSerialization/SerializablePathCollection.cpp b/clang/lib/IndexSerialization/SerializablePathCollection.cpp
index bd5f861..74ed18a 100644
--- a/clang/lib/IndexSerialization/SerializablePathCollection.cpp
+++ b/clang/lib/IndexSerialization/SerializablePathCollection.cpp
@@ -70,11 +70,11 @@ PathPool::DirPath SerializablePathCollection::tryStoreDirPath(StringRef Dir) {
   const std::string OrigDir = Dir.str();
 
   PathPool::RootDirKind Root = PathPool::RootDirKind::Regular;
-  if (!SysRoot.empty() && Dir.startswith(SysRoot) &&
+  if (!SysRoot.empty() && Dir.starts_with(SysRoot) &&
       llvm::sys::path::is_separator(Dir[SysRoot.size()])) {
     Root = PathPool::RootDirKind::SysRoot;
     Dir = Dir.drop_front(SysRoot.size());
-  } else if (!WorkDir.empty() && Dir.startswith(WorkDir) &&
+  } else if (!WorkDir.empty() && Dir.starts_with(WorkDir) &&
              llvm::sys::path::is_separator(Dir[WorkDir.size()])) {
     Root = PathPool::RootDirKind::CurrentWorkDir;
     Dir = Dir.drop_front(WorkDir.size());
diff --git a/clang/lib/Lex/HeaderSearch.cpp b/clang/lib/Lex/HeaderSearch.cpp
index c03cf19..f24013d 100644
--- a/clang/lib/Lex/HeaderSearch.cpp
+++ b/clang/lib/Lex/HeaderSearch.cpp
@@ -796,7 +796,7 @@ static bool isFrameworkStylePath(StringRef Path, bool &IsPrivateHeader,
     } else if (*I == "PrivateHeaders") {
       ++FoundComp;
       IsPrivateHeader = true;
-    } else if (I->endswith(".framework")) {
+    } else if (I->ends_with(".framework")) {
       StringRef Name = I->drop_back(10); // Drop .framework
       // Need to reset the strings and counter to support nested frameworks.
       FrameworkName.clear();
@@ -1085,7 +1085,7 @@ OptionalFileEntryRef HeaderSearch::LookupFile(
     // If the filename matches a known system header prefix, override
     // whether the file is a system header.
     for (unsigned j = SystemHeaderPrefixes.size(); j; --j) {
-      if (Filename.startswith(SystemHeaderPrefixes[j-1].first)) {
+      if (Filename.starts_with(SystemHeaderPrefixes[j - 1].first)) {
         HFI.DirInfo = SystemHeaderPrefixes[j-1].second ? SrcMgr::C_System
                                                        : SrcMgr::C_User;
         break;
@@ -1694,7 +1694,7 @@ bool HeaderSearch::loadModuleMapFile(FileEntryRef File, bool IsSystem,
     StringRef DirName(Dir->getName());
     if (llvm::sys::path::filename(DirName) == "Modules") {
       DirName = llvm::sys::path::parent_path(DirName);
-      if (DirName.endswith(".framework"))
+      if (DirName.ends_with(".framework"))
         if (auto MaybeDir = FileMgr.getOptionalDirectoryRef(DirName))
           Dir = *MaybeDir;
       // FIXME: This assert can fail if there's a race between the above check
@@ -1965,10 +1965,10 @@ std::string HeaderSearch::suggestPathToFileForDiagnostics(
       // Special case Apple .sdk folders since the search path is typically a
       // symlink like `iPhoneSimulator14.5.sdk` while the file is instead
       // located in `iPhoneSimulator.sdk` (the real folder).
-      if (NI->endswith(".sdk") && DI->endswith(".sdk")) {
+      if (NI->ends_with(".sdk") && DI->ends_with(".sdk")) {
         StringRef NBasename = path::stem(*NI);
         StringRef DBasename = path::stem(*DI);
-        if (DBasename.startswith(NBasename))
+        if (DBasename.starts_with(NBasename))
           continue;
       }
 
diff --git a/clang/lib/Lex/InitHeaderSearch.cpp b/clang/lib/Lex/InitHeaderSearch.cpp
index 5b1b7c8..2218db1 100644
--- a/clang/lib/Lex/InitHeaderSearch.cpp
+++ b/clang/lib/Lex/InitHeaderSearch.cpp
@@ -141,8 +141,8 @@ bool InitHeaderSearch::AddUnmappedPath(const Twine &Path, IncludeDirGroup Group,
   StringRef MappedPathStr = Path.toStringRef(MappedPathStorage);
 
   // If use system headers while cross-compiling, emit the warning.
-  if (HasSysroot && (MappedPathStr.startswith("/usr/include") ||
-                     MappedPathStr.startswith("/usr/local/include"))) {
+  if (HasSysroot && (MappedPathStr.starts_with("/usr/include") ||
+                     MappedPathStr.starts_with("/usr/local/include"))) {
     Headers.getDiags().Report(diag::warn_poison_system_directories)
         << MappedPathStr;
   }
diff --git a/clang/lib/Lex/Lexer.cpp b/clang/lib/Lex/Lexer.cpp
index f4f1daa..50b5626 100644
--- a/clang/lib/Lex/Lexer.cpp
+++ b/clang/lib/Lex/Lexer.cpp
@@ -3212,8 +3212,8 @@ bool Lexer::IsStartOfConflictMarker(const char *CurPtr) {
     return false;
 
   // Check to see if we have <<<<<<< or >>>>.
-  if (!StringRef(CurPtr, BufferEnd - CurPtr).startswith("<<<<<<<") &&
-      !StringRef(CurPtr, BufferEnd - CurPtr).startswith(">>>> "))
+  if (!StringRef(CurPtr, BufferEnd - CurPtr).starts_with("<<<<<<<") &&
+      !StringRef(CurPtr, BufferEnd - CurPtr).starts_with(">>>> "))
     return false;
 
   // If we have a situation where we don't care about conflict markers, ignore
diff --git a/clang/lib/Lex/ModuleMap.cpp b/clang/lib/Lex/ModuleMap.cpp
index d35c282..ea5d13d 100644
--- a/clang/lib/Lex/ModuleMap.cpp
+++ b/clang/lib/Lex/ModuleMap.cpp
@@ -235,7 +235,7 @@ OptionalFileEntryRef ModuleMap::findHeader(
   llvm::sys::path::append(FullPathName, RelativePathName);
   auto NormalHdrFile = GetFile(FullPathName);
 
-  if (!NormalHdrFile && Directory->getName().endswith(".framework")) {
+  if (!NormalHdrFile && Directory->getName().ends_with(".framework")) {
     // The lack of 'framework' keyword in a module declaration it's a simple
     // mistake we can diagnose when the header exists within the proper
     // framework style path.
@@ -1034,7 +1034,7 @@ Module *ModuleMap::inferFrameworkModule(DirectoryEntryRef FrameworkDir,
         if (inferred == InferredDirectories.end()) {
           // We haven't looked here before. Load a module map, if there is
           // one.
-          bool IsFrameworkDir = Parent.endswith(".framework");
+          bool IsFrameworkDir = Parent.ends_with(".framework");
           if (OptionalFileEntryRef ModMapFile =
                   HeaderInfo.lookupModuleMapFile(*ParentDir, IsFrameworkDir)) {
             parseModuleMapFile(*ModMapFile, Attrs.IsSystem, *ParentDir);
@@ -1125,7 +1125,7 @@ Module *ModuleMap::inferFrameworkModule(DirectoryEntryRef FrameworkDir,
            Dir = FS.dir_begin(SubframeworksDirName, EC),
            DirEnd;
        Dir != DirEnd && !EC; Dir.increment(EC)) {
-    if (!StringRef(Dir->path()).endswith(".framework"))
+    if (!StringRef(Dir->path()).ends_with(".framework"))
       continue;
 
     if (auto SubframeworkDir = FileMgr.getOptionalDirectoryRef(Dir->path())) {
@@ -1337,7 +1337,7 @@ ModuleMap::canonicalizeModuleMapPath(SmallVectorImpl<char> &Path) {
   // Modules/ not Versions/A/Modules.
   if (llvm::sys::path::filename(Dir) == "Modules") {
     StringRef Parent = llvm::sys::path::parent_path(Dir);
-    if (Parent.endswith(".framework"))
+    if (Parent.ends_with(".framework"))
       Dir = Parent;
   }
 
@@ -2119,8 +2119,8 @@ void ModuleMapParser::parseModuleDecl() {
   ActiveModule->Directory = Directory;
 
   StringRef MapFileName(ModuleMapFile.getName());
-  if (MapFileName.endswith("module.private.modulemap") ||
-      MapFileName.endswith("module_private.map")) {
+  if (MapFileName.ends_with("module.private.modulemap") ||
+      MapFileName.ends_with("module_private.map")) {
     ActiveModule->ModuleMapIsPrivate = true;
   }
 
diff --git a/clang/lib/Lex/PPDirectives.cpp b/clang/lib/Lex/PPDirectives.cpp
index 1400348..112bc8d 100644
--- a/clang/lib/Lex/PPDirectives.cpp
+++ b/clang/lib/Lex/PPDirectives.cpp
@@ -164,13 +164,13 @@ static bool isLanguageDefinedBuiltin(const SourceManager &SourceMgr,
     return false;
   // C defines macros starting with __STDC, and C++ defines macros starting with
   // __STDCPP
-  if (MacroName.startswith("__STDC"))
+  if (MacroName.starts_with("__STDC"))
     return true;
   // C++ defines the __cplusplus macro
   if (MacroName == "__cplusplus")
     return true;
   // C++ defines various feature-test macros starting with __cpp
-  if (MacroName.startswith("__cpp"))
+  if (MacroName.starts_with("__cpp"))
     return true;
   // Anything else isn't language-defined
   return false;
@@ -646,7 +646,7 @@ void Preprocessor::SkipExcludedConditionalBlock(SourceLocation HashTokenLoc,
       Directive = StringRef(DirectiveBuf, IdLen);
     }
 
-    if (Directive.startswith("if")) {
+    if (Directive.starts_with("if")) {
       StringRef Sub = Directive.substr(2);
       if (Sub.empty() ||   // "if"
           Sub == "def" ||   // "ifdef"
@@ -2788,14 +2788,14 @@ static bool isConfigurationPattern(Token &MacroName, MacroInfo *MI,
         return false;
       StringRef ValueText = II->getName();
       StringRef TrimmedValue = ValueText;
-      if (!ValueText.startswith("__")) {
-        if (ValueText.startswith("_"))
+      if (!ValueText.starts_with("__")) {
+        if (ValueText.starts_with("_"))
           TrimmedValue = TrimmedValue.drop_front(1);
         else
           return false;
       } else {
         TrimmedValue = TrimmedValue.drop_front(2);
-        if (TrimmedValue.endswith("__"))
+        if (TrimmedValue.ends_with("__"))
           TrimmedValue = TrimmedValue.drop_back(2);
       }
       return TrimmedValue.equals(MacroText);
diff --git a/clang/lib/Lex/PPExpressions.cpp b/clang/lib/Lex/PPExpressions.cpp
index 269984a..1feb0eb 100644
--- a/clang/lib/Lex/PPExpressions.cpp
+++ b/clang/lib/Lex/PPExpressions.cpp
@@ -267,7 +267,7 @@ static bool EvaluateValue(PPValue &Result, Token &PeekTok, DefinedTracker &DT,
             const StringRef IdentifierName = II->getName();
             if (llvm::any_of(UndefPrefixes,
                              [&IdentifierName](const std::string &Prefix) {
-                               return IdentifierName.startswith(Prefix);
+                               return IdentifierName.starts_with(Prefix);
                              }))
               PP.Diag(PeekTok, diag::warn_pp_undef_prefix)
                   << AddFlagValue{llvm::join(UndefPrefixes, ",")} << II;
diff --git a/clang/lib/Lex/PPMacroExpansion.cpp b/clang/lib/Lex/PPMacroExpansion.cpp
index 30c4abd..ad02f31 100644
--- a/clang/lib/Lex/PPMacroExpansion.cpp
+++ b/clang/lib/Lex/PPMacroExpansion.cpp
@@ -1136,7 +1136,8 @@ static bool HasFeature(const Preprocessor &PP, StringRef Feature) {
   const LangOptions &LangOpts = PP.getLangOpts();
 
   // Normalize the feature name, __foo__ becomes foo.
-  if (Feature.startswith("__") && Feature.endswith("__") && Feature.size() >= 4)
+  if (Feature.starts_with("__") && Feature.ends_with("__") &&
+      Feature.size() >= 4)
     Feature = Feature.substr(2, Feature.size() - 4);
 
 #define FEATURE(Name, Predicate) .Case(#Name, Predicate)
@@ -1162,7 +1163,7 @@ static bool HasExtension(const Preprocessor &PP, StringRef Extension) {
   const LangOptions &LangOpts = PP.getLangOpts();
 
   // Normalize the extension name, __foo__ becomes foo.
-  if (Extension.startswith("__") && Extension.endswith("__") &&
+  if (Extension.starts_with("__") && Extension.ends_with("__") &&
       Extension.size() >= 4)
     Extension = Extension.substr(2, Extension.size() - 4);
 
@@ -1691,9 +1692,9 @@ void Preprocessor::ExpandBuiltinMacro(Token &Tok) {
           // as being "builtin functions", even if the syntax isn't a valid
           // function call (for example, because the builtin takes a type
           // argument).
-          if (II->getName().startswith("__builtin_") ||
-              II->getName().startswith("__is_") ||
-              II->getName().startswith("__has_"))
+          if (II->getName().starts_with("__builtin_") ||
+              II->getName().starts_with("__is_") ||
+              II->getName().starts_with("__has_"))
             return true;
           return llvm::StringSwitch<bool>(II->getName())
               .Case("__array_rank", true)
diff --git a/clang/lib/Parse/ParseDecl.cpp b/clang/lib/Parse/ParseDecl.cpp
index ece3698..ed006f9 100644
--- a/clang/lib/Parse/ParseDecl.cpp
+++ b/clang/lib/Parse/ParseDecl.cpp
@@ -84,7 +84,7 @@ TypeResult Parser::ParseTypeName(SourceRange *Range, DeclaratorContext Context,
 
 /// Normalizes an attribute name by dropping prefixed and suffixed __.
 static StringRef normalizeAttrName(StringRef Name) {
-  if (Name.size() >= 4 && Name.startswith("__") && Name.endswith("__"))
+  if (Name.size() >= 4 && Name.starts_with("__") && Name.ends_with("__"))
     return Name.drop_front(2).drop_back(2);
   return Name;
 }
@@ -7854,7 +7854,7 @@ void Parser::ParseTypeofSpecifier(DeclSpec &DS) {
 
   bool IsUnqual = Tok.is(tok::kw_typeof_unqual);
   const IdentifierInfo *II = Tok.getIdentifierInfo();
-  if (getLangOpts().C23 && !II->getName().startswith("__"))
+  if (getLangOpts().C23 && !II->getName().starts_with("__"))
     Diag(Tok.getLocation(), diag::warn_c23_compat_keyword) << Tok.getName();
 
   Token OpTok = Tok;
diff --git a/clang/lib/Parse/Parser.cpp b/clang/lib/Parse/Parser.cpp
index ec67faf..b703c2d 100644
--- a/clang/lib/Parse/Parser.cpp
+++ b/clang/lib/Parse/Parser.cpp
@@ -2645,7 +2645,7 @@ Decl *Parser::ParseModuleImport(SourceLocation AtLoc,
     auto &SrcMgr = PP.getSourceManager();
     auto FE = SrcMgr.getFileEntryRefForID(SrcMgr.getFileID(AtLoc));
     if (FE && llvm::sys::path::parent_path(FE->getDir().getName())
-                  .endswith(".framework"))
+                  .ends_with(".framework"))
       Diags.Report(AtLoc, diag::warn_atimport_in_framework_header);
   }
 
diff --git a/clang/lib/Rewrite/Rewriter.cpp b/clang/lib/Rewrite/Rewriter.cpp
index 0896221..0e6ae36 100644
--- a/clang/lib/Rewrite/Rewriter.cpp
+++ b/clang/lib/Rewrite/Rewriter.cpp
@@ -386,7 +386,7 @@ bool Rewriter::IncreaseIndentation(CharSourceRange range,
   }
   if (parentSpace.size() >= startSpace.size())
     return true;
-  if (!startSpace.startswith(parentSpace))
+  if (!startSpace.starts_with(parentSpace))
     return true;
 
   StringRef indent = startSpace.substr(parentSpace.size());
@@ -399,7 +399,7 @@ bool Rewriter::IncreaseIndentation(CharSourceRange range,
     while (isWhitespaceExceptNL(MB[i]))
       ++i;
     StringRef origIndent = MB.substr(offs, i-offs);
-    if (origIndent.startswith(startSpace))
+    if (origIndent.starts_with(startSpace))
       RB.InsertText(offs, indent, /*InsertAfter=*/false);
   }
 
diff --git a/clang/lib/Sema/CodeCompleteConsumer.cpp b/clang/lib/Sema/CodeCompleteConsumer.cpp
index 9caa1a8..350bd78 100644
--- a/clang/lib/Sema/CodeCompleteConsumer.cpp
+++ b/clang/lib/Sema/CodeCompleteConsumer.cpp
@@ -630,15 +630,16 @@ bool PrintingCodeCompleteConsumer::isResultFilteredOut(
     StringRef Filter, CodeCompletionResult Result) {
   switch (Result.Kind) {
   case CodeCompletionResult::RK_Declaration:
-    return !(Result.Declaration->getIdentifier() &&
-             Result.Declaration->getIdentifier()->getName().startswith(Filter));
+    return !(
+        Result.Declaration->getIdentifier() &&
+        Result.Declaration->getIdentifier()->getName().starts_with(Filter));
   case CodeCompletionResult::RK_Keyword:
-    return !StringRef(Result.Keyword).startswith(Filter);
+    return !StringRef(Result.Keyword).starts_with(Filter);
   case CodeCompletionResult::RK_Macro:
-    return !Result.Macro->getName().startswith(Filter);
+    return !Result.Macro->getName().starts_with(Filter);
   case CodeCompletionResult::RK_Pattern:
     return !(Result.Pattern->getTypedText() &&
-             StringRef(Result.Pattern->getTypedText()).startswith(Filter));
+             StringRef(Result.Pattern->getTypedText()).starts_with(Filter));
   }
   llvm_unreachable("Unknown code completion result Kind.");
 }
diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index cdb6e95..254c272 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -1219,7 +1219,7 @@ void Sema::checkFortifiedBuiltinMemoryFunction(FunctionDecl *FD,
     if (IsChkVariant) {
       FunctionName = FunctionName.drop_front(std::strlen("__builtin___"));
       FunctionName = FunctionName.drop_back(std::strlen("_chk"));
-    } else if (FunctionName.startswith("__builtin_")) {
+    } else if (FunctionName.starts_with("__builtin_")) {
       FunctionName = FunctionName.drop_front(std::strlen("__builtin_"));
     }
     return FunctionName;
@@ -18270,15 +18270,14 @@ static bool isSetterLikeSelector(Selector sel) {
 
   StringRef str = sel.getNameForSlot(0);
   while (!str.empty() && str.front() == '_') str = str.substr(1);
-  if (str.startswith("set"))
+  if (str.starts_with("set"))
     str = str.substr(3);
-  else if (str.startswith("add")) {
+  else if (str.starts_with("add")) {
     // Specially allow 'addOperationWithBlock:'.
-    if (sel.getNumArgs() == 1 && str.startswith("addOperationWithBlock"))
+    if (sel.getNumArgs() == 1 && str.starts_with("addOperationWithBlock"))
       return false;
     str = str.substr(3);
-  }
-  else
+  } else
     return false;
 
   if (str.empty()) return true;
diff --git a/clang/lib/Sema/SemaCodeComplete.cpp b/clang/lib/Sema/SemaCodeComplete.cpp
index 143968b4..c44be0df 100644
--- a/clang/lib/Sema/SemaCodeComplete.cpp
+++ b/clang/lib/Sema/SemaCodeComplete.cpp
@@ -9798,7 +9798,7 @@ void Sema::CodeCompleteObjCMethodDeclSelector(
   Results.ExitScope();
 
   if (!AtParameterName && !SelIdents.empty() &&
-      SelIdents.front()->getName().startswith("init")) {
+      SelIdents.front()->getName().starts_with("init")) {
     for (const auto &M : PP.macros()) {
       if (M.first->getName() != "NS_DESIGNATED_INITIALIZER")
         continue;
@@ -10110,7 +10110,7 @@ void Sema::CodeCompleteIncludedFile(llvm::StringRef Dir, bool Angled) {
     }
 
     const StringRef &Dirname = llvm::sys::path::filename(Dir);
-    const bool isQt = Dirname.startswith("Qt") || Dirname == "ActiveQt";
+    const bool isQt = Dirname.starts_with("Qt") || Dirname == "ActiveQt";
     const bool ExtensionlessHeaders =
         IsSystem || isQt || Dir.ends_with(".framework/Headers");
     std::error_code EC;
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 6385484..be6a136 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -16005,7 +16005,7 @@ Decl *Sema::ActOnFinishFunctionBody(Decl *dcl, Stmt *Body,
 
             return StartTok.consume_front("const") &&
                    (StartTok.empty() || isWhitespace(StartTok[0]) ||
-                    StartTok.startswith("/*") || StartTok.startswith("//"));
+                    StartTok.starts_with("/*") || StartTok.starts_with("//"));
           };
 
           auto findBeginLoc = [&]() {
@@ -16359,7 +16359,7 @@ NamedDecl *Sema::ImplicitlyDefineFunction(SourceLocation Loc,
 
   // Extension in C99 (defaults to error). Legal in C89, but warn about it.
   unsigned diag_id;
-  if (II.getName().startswith("__builtin_"))
+  if (II.getName().starts_with("__builtin_"))
     diag_id = diag::warn_builtin_unknown;
   // OpenCL v2.0 s6.9.u - Implicit function declaration is not supported.
   else if (getLangOpts().C99)
diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
index 59e456f..22f291e 100644
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -1809,8 +1809,8 @@ static void handleAssumumptionAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
 /// Normalize the attribute, __foo__ becomes foo.
 /// Returns true if normalization was applied.
 static bool normalizeName(StringRef &AttrName) {
-  if (AttrName.size() > 4 && AttrName.startswith("__") &&
-      AttrName.endswith("__")) {
+  if (AttrName.size() > 4 && AttrName.starts_with("__") &&
+      AttrName.ends_with("__")) {
     AttrName = AttrName.drop_front(2).drop_back(2);
     return true;
   }
@@ -3605,7 +3605,7 @@ bool Sema::checkTargetClonesAttrString(
       }
     } else {
       // Other targets ( currently X86 )
-      if (Cur.startswith("arch=")) {
+      if (Cur.starts_with("arch=")) {
         if (!Context.getTargetInfo().isValidCPUName(
                 Cur.drop_front(sizeof("arch=") - 1)))
           return Diag(CurLoc, diag::warn_unsupported_target_attribute)
@@ -3623,7 +3623,7 @@ bool Sema::checkTargetClonesAttrString(
       StringsBuffer.push_back(Cur);
     }
   }
-  if (Str.rtrim().endswith(","))
+  if (Str.rtrim().ends_with(","))
     return Diag(LiteralLoc, diag::warn_unsupported_target_attribute)
            << Unsupported << None << "" << TargetClones;
   return false;
@@ -5819,7 +5819,7 @@ struct IntrinToName {
 static bool ArmBuiltinAliasValid(unsigned BuiltinID, StringRef AliasName,
                                  ArrayRef<IntrinToName> Map,
                                  const char *IntrinNames) {
-  if (AliasName.startswith("__arm_"))
+  if (AliasName.starts_with("__arm_"))
     AliasName = AliasName.substr(6);
   const IntrinToName *It =
       llvm::lower_bound(Map, BuiltinID, [](const IntrinToName &L, unsigned Id) {
@@ -6663,10 +6663,10 @@ validateSwiftFunctionName(Sema &S, const ParsedAttr &AL, SourceLocation Loc,
 
   // Check whether this will be mapped to a getter or setter of a property.
   bool IsGetter = false, IsSetter = false;
-  if (Name.startswith("getter:")) {
+  if (Name.starts_with("getter:")) {
     IsGetter = true;
     Name = Name.substr(7);
-  } else if (Name.startswith("setter:")) {
+  } else if (Name.starts_with("setter:")) {
     IsSetter = true;
     Name = Name.substr(7);
   }
@@ -7292,7 +7292,7 @@ static void handleHLSLResourceBindingAttr(Sema &S, Decl *D,
     }
   }
 
-  if (!Space.startswith("space")) {
+  if (!Space.starts_with("space")) {
     S.Diag(SpaceArgLoc, diag::err_hlsl_expected_space) << Space;
     return;
   }
diff --git a/clang/lib/Sema/SemaDeclObjC.cpp b/clang/lib/Sema/SemaDeclObjC.cpp
index cdfa6ad..c3b95e1 100644
--- a/clang/lib/Sema/SemaDeclObjC.cpp
+++ b/clang/lib/Sema/SemaDeclObjC.cpp
@@ -296,7 +296,7 @@ static void DiagnoseObjCImplementedDeprecations(Sema &S, const NamedDecl *ND,
         RealizedPlatform = S.Context.getTargetInfo().getPlatformName();
       // Warn about implementing unavailable methods, unless the unavailable
       // is for an app extension.
-      if (RealizedPlatform.endswith("_app_extension"))
+      if (RealizedPlatform.ends_with("_app_extension"))
         return;
       S.Diag(ImplLoc, diag::warn_unavailable_def);
       S.Diag(ND->getLocation(), diag::note_method_declared_at)
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index d629be0..c7185d5 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -13808,12 +13808,12 @@ static void diagnoseXorMisusedAsPow(Sema &S, const ExprResult &XorLHS,
   StringRef RHSStrRef = RHSStr;
   // Do not diagnose literals with digit separators, binary, hexadecimal, octal
   // literals.
-  if (LHSStrRef.startswith("0b") || LHSStrRef.startswith("0B") ||
-      RHSStrRef.startswith("0b") || RHSStrRef.startswith("0B") ||
-      LHSStrRef.startswith("0x") || LHSStrRef.startswith("0X") ||
-      RHSStrRef.startswith("0x") || RHSStrRef.startswith("0X") ||
-      (LHSStrRef.size() > 1 && LHSStrRef.startswith("0")) ||
-      (RHSStrRef.size() > 1 && RHSStrRef.startswith("0")) ||
+  if (LHSStrRef.starts_with("0b") || LHSStrRef.starts_with("0B") ||
+      RHSStrRef.starts_with("0b") || RHSStrRef.starts_with("0B") ||
+      LHSStrRef.starts_with("0x") || LHSStrRef.starts_with("0X") ||
+      RHSStrRef.starts_with("0x") || RHSStrRef.starts_with("0X") ||
+      (LHSStrRef.size() > 1 && LHSStrRef.starts_with("0")) ||
+      (RHSStrRef.size() > 1 && RHSStrRef.starts_with("0")) ||
       LHSStrRef.contains('\'') || RHSStrRef.contains('\''))
     return;
 
@@ -15508,7 +15508,7 @@ static void checkObjCPointerIntrospection(Sema &S, ExprResult &L, ExprResult &R,
     if (const ObjCMessageExpr *ME = dyn_cast<ObjCMessageExpr>(Ex)) {
       Selector S = ME->getSelector();
       StringRef SelArg0 = S.getNameForSlot(0);
-      if (SelArg0.startswith("performSelector"))
+      if (SelArg0.starts_with("performSelector"))
         Diag = diag::warn_objc_pointer_masking_performSelector;
     }
 
diff --git a/clang/lib/Sema/SemaModule.cpp b/clang/lib/Sema/SemaModule.cpp
index 9282ceb..db0cbd5 100644
--- a/clang/lib/Sema/SemaModule.cpp
+++ b/clang/lib/Sema/SemaModule.cpp
@@ -268,7 +268,7 @@ Sema::ActOnModuleDecl(SourceLocation StartLoc, SourceLocation ModuleLoc,
   StringRef FirstComponentName = Path[0].first->getName();
   if (!getSourceManager().isInSystemHeader(Path[0].second) &&
       (FirstComponentName == "std" ||
-       (FirstComponentName.startswith("std") &&
+       (FirstComponentName.starts_with("std") &&
         llvm::all_of(FirstComponentName.drop_front(3), &llvm::isDigit))))
     Diag(Path[0].second, diag::warn_reserved_module_name) << Path[0].first;
 
diff --git a/clang/lib/Sema/SemaType.cpp b/clang/lib/Sema/SemaType.cpp
index c8ad8b6..a376f20 100644
--- a/clang/lib/Sema/SemaType.cpp
+++ b/clang/lib/Sema/SemaType.cpp
@@ -5371,7 +5371,7 @@ static TypeSourceInfo *GetFullTypeForDeclarator(TypeProcessingState &state,
             !(D.getIdentifier() &&
               ((D.getIdentifier()->getName() == "printf" &&
                 LangOpts.getOpenCLCompatibleVersion() >= 120) ||
-               D.getIdentifier()->getName().startswith("__")))) {
+               D.getIdentifier()->getName().starts_with("__")))) {
           S.Diag(D.getIdentifierLoc(), diag::err_opencl_variadic_function);
           D.setInvalidType(true);
         }
diff --git a/clang/lib/StaticAnalyzer/Checkers/CheckObjCDealloc.cpp b/clang/lib/StaticAnalyzer/Checkers/CheckObjCDealloc.cpp
index bd6655c..fedc6db 100644
--- a/clang/lib/StaticAnalyzer/Checkers/CheckObjCDealloc.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/CheckObjCDealloc.cpp
@@ -1045,8 +1045,8 @@ bool ObjCDeallocChecker::isReleasedByCIFilterDealloc(
   StringRef IvarName = PropImpl->getPropertyIvarDecl()->getName();
 
   const char *ReleasePrefix = "input";
-  if (!(PropName.startswith(ReleasePrefix) ||
-        IvarName.startswith(ReleasePrefix))) {
+  if (!(PropName.starts_with(ReleasePrefix) ||
+        IvarName.starts_with(ReleasePrefix))) {
     return false;
   }
 
diff --git a/clang/lib/StaticAnalyzer/Checkers/CheckSecuritySyntaxOnly.cpp b/clang/lib/StaticAnalyzer/Checkers/CheckSecuritySyntaxOnly.cpp
index dbba12b..afc5e6b 100644
--- a/clang/lib/StaticAnalyzer/Checkers/CheckSecuritySyntaxOnly.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/CheckSecuritySyntaxOnly.cpp
@@ -140,7 +140,7 @@ void WalkAST::VisitCallExpr(CallExpr *CE) {
   if (!II)   // if no identifier, not a simple C function
     return;
   StringRef Name = II->getName();
-  if (Name.startswith("__builtin_"))
+  if (Name.starts_with("__builtin_"))
     Name = Name.substr(10);
 
   // Set the evaluation function by switching on the callee name.
@@ -763,7 +763,7 @@ void WalkAST::checkDeprecatedOrUnsafeBufferHandling(const CallExpr *CE,
   enum { DEPR_ONLY = -1, UNKNOWN_CALL = -2 };
 
   StringRef Name = FD->getIdentifier()->getName();
-  if (Name.startswith("__builtin_"))
+  if (Name.starts_with("__builtin_"))
     Name = Name.substr(10);
 
   int ArgIndex =
diff --git a/clang/lib/StaticAnalyzer/Checkers/DeadStoresChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/DeadStoresChecker.cpp
index 5f44c94..86f446f 100644
--- a/clang/lib/StaticAnalyzer/Checkers/DeadStoresChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/DeadStoresChecker.cpp
@@ -183,7 +183,7 @@ public:
 
     // Files autogenerated by DriverKit IIG contain some dead stores that
     // we don't want to report.
-    if (Data.startswith("/* iig"))
+    if (Data.starts_with("/* iig"))
       return true;
 
     return false;
diff --git a/clang/lib/StaticAnalyzer/Checkers/GCDAntipatternChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/GCDAntipatternChecker.cpp
index 8e02ef7..5637941 100644
--- a/clang/lib/StaticAnalyzer/Checkers/GCDAntipatternChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/GCDAntipatternChecker.cpp
@@ -73,7 +73,7 @@ decltype(auto) bindAssignmentToDecl(const char *DeclName) {
 static bool isTest(const Decl *D) {
   if (const auto* ND = dyn_cast<NamedDecl>(D)) {
     std::string DeclName = ND->getNameAsString();
-    if (StringRef(DeclName).startswith("test"))
+    if (StringRef(DeclName).starts_with("test"))
       return true;
   }
   if (const auto *OD = dyn_cast<ObjCMethodDecl>(D)) {
diff --git a/clang/lib/StaticAnalyzer/Checkers/LocalizationChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/LocalizationChecker.cpp
index b77e9bf..70f911f 100644
--- a/clang/lib/StaticAnalyzer/Checkers/LocalizationChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/LocalizationChecker.cpp
@@ -817,9 +817,9 @@ void NonLocalizedStringChecker::checkPreObjCMessage(const ObjCMethodCall &msg,
     // Handle the case where the receiver is an NSString
     // These special NSString methods draw to the screen
 
-    if (!(SelectorName.startswith("drawAtPoint") ||
-          SelectorName.startswith("drawInRect") ||
-          SelectorName.startswith("drawWithRect")))
+    if (!(SelectorName.starts_with("drawAtPoint") ||
+          SelectorName.starts_with("drawInRect") ||
+          SelectorName.starts_with("drawWithRect")))
       return;
 
     SVal svTitle = msg.getReceiverSVal();
diff --git a/clang/lib/StaticAnalyzer/Checkers/MallocChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/MallocChecker.cpp
index c5e4add..79ab05f 100644
--- a/clang/lib/StaticAnalyzer/Checkers/MallocChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/MallocChecker.cpp
@@ -3150,16 +3150,16 @@ bool MallocChecker::mayFreeAnyEscapedMemoryOrIsModeledExplicitly(
     // transferred. Again, though, we can't be sure that the object will use
     // free() to deallocate the memory, so we can't model it explicitly.
     StringRef FirstSlot = Msg->getSelector().getNameForSlot(0);
-    if (FirstSlot.endswith("NoCopy"))
+    if (FirstSlot.ends_with("NoCopy"))
       return true;
 
     // If the first selector starts with addPointer, insertPointer,
     // or replacePointer, assume we are dealing with NSPointerArray or similar.
     // This is similar to C++ containers (vector); we still might want to check
     // that the pointers get freed by following the container itself.
-    if (FirstSlot.startswith("addPointer") ||
-        FirstSlot.startswith("insertPointer") ||
-        FirstSlot.startswith("replacePointer") ||
+    if (FirstSlot.starts_with("addPointer") ||
+        FirstSlot.starts_with("insertPointer") ||
+        FirstSlot.starts_with("replacePointer") ||
         FirstSlot.equals("valueWithPointer")) {
       return true;
     }
@@ -3199,7 +3199,7 @@ bool MallocChecker::mayFreeAnyEscapedMemoryOrIsModeledExplicitly(
 
   // White list the 'XXXNoCopy' CoreFoundation functions.
   // We specifically check these before
-  if (FName.endswith("NoCopy")) {
+  if (FName.ends_with("NoCopy")) {
     // Look for the deallocator argument. We know that the memory ownership
     // is not transferred only if the deallocator argument is
     // 'kCFAllocatorNull'.
diff --git a/clang/lib/StaticAnalyzer/Checkers/NullabilityChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/NullabilityChecker.cpp
index 627b51a..06f1ad0 100644
--- a/clang/lib/StaticAnalyzer/Checkers/NullabilityChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/NullabilityChecker.cpp
@@ -890,7 +890,7 @@ void NullabilityChecker::checkPostCall(const CallEvent &Call,
   // of CG calls.
   const SourceManager &SM = C.getSourceManager();
   StringRef FilePath = SM.getFilename(SM.getSpellingLoc(Decl->getBeginLoc()));
-  if (llvm::sys::path::filename(FilePath).startswith("CG")) {
+  if (llvm::sys::path::filename(FilePath).starts_with("CG")) {
     State = State->set<NullabilityMap>(Region, Nullability::Contradicted);
     C.addTransition(State);
     return;
@@ -992,7 +992,7 @@ void NullabilityChecker::checkPostObjCMessage(const ObjCMethodCall &M,
   // In order to reduce the noise in the diagnostics generated by this checker,
   // some framework and programming style based heuristics are used. These
   // heuristics are for Cocoa APIs which have NS prefix.
-  if (Name.startswith("NS")) {
+  if (Name.starts_with("NS")) {
     // Developers rely on dynamic invariants such as an item should be available
     // in a collection, or a collection is not empty often. Those invariants can
     // not be inferred by any static analysis tool. To not to bother the users
diff --git a/clang/lib/StaticAnalyzer/Checkers/ObjCPropertyChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/ObjCPropertyChecker.cpp
index 4636fd1..08ad687 100644
--- a/clang/lib/StaticAnalyzer/Checkers/ObjCPropertyChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/ObjCPropertyChecker.cpp
@@ -50,7 +50,7 @@ void ObjCPropertyChecker::checkCopyMutable(const ObjCPropertyDecl *D,
   const std::string &PropTypeName(T->getPointeeType().getCanonicalType()
                                                      .getUnqualifiedType()
                                                      .getAsString());
-  if (!StringRef(PropTypeName).startswith("NSMutable"))
+  if (!StringRef(PropTypeName).starts_with("NSMutable"))
     return;
 
   const ObjCImplDecl *ImplD = nullptr;
diff --git a/clang/lib/StaticAnalyzer/Core/BugReporter.cpp b/clang/lib/StaticAnalyzer/Core/BugReporter.cpp
index 9532254..a253f2b 100644
--- a/clang/lib/StaticAnalyzer/Core/BugReporter.cpp
+++ b/clang/lib/StaticAnalyzer/Core/BugReporter.cpp
@@ -2139,15 +2139,14 @@ PathSensitiveBugReport::PathSensitiveBugReport(
          "checkers to emit warnings, because checkers should depend on "
          "*modeling*, not *diagnostics*.");
 
-  assert(
-      (bt.getCheckerName().startswith("debug") ||
-       !isHidden(ErrorNode->getState()
-                     ->getAnalysisManager()
-                     .getCheckerManager()
-                     ->getCheckerRegistryData(),
-                 bt.getCheckerName())) &&
-          "Hidden checkers musn't emit diagnostics as they are by definition "
-          "non-user facing!");
+  assert((bt.getCheckerName().starts_with("debug") ||
+          !isHidden(ErrorNode->getState()
+                        ->getAnalysisManager()
+                        .getCheckerManager()
+                        ->getCheckerRegistryData(),
+                    bt.getCheckerName())) &&
+         "Hidden checkers musn't emit diagnostics as they are by definition "
+         "non-user facing!");
 }
 
 void PathSensitiveBugReport::addVisitor(
@@ -3064,8 +3063,7 @@ void BugReporter::FlushReport(BugReportEquivClass& EQ) {
   // See whether we need to silence the checker/package.
   for (const std::string &CheckerOrPackage :
        getAnalyzerOptions().SilencedCheckersAndPackages) {
-    if (report->getBugType().getCheckerName().startswith(
-            CheckerOrPackage))
+    if (report->getBugType().getCheckerName().starts_with(CheckerOrPackage))
       return;
   }
 
diff --git a/clang/lib/StaticAnalyzer/Core/BugReporterVisitors.cpp b/clang/lib/StaticAnalyzer/Core/BugReporterVisitors.cpp
index 4a9d130..2f99650 100644
--- a/clang/lib/StaticAnalyzer/Core/BugReporterVisitors.cpp
+++ b/clang/lib/StaticAnalyzer/Core/BugReporterVisitors.cpp
@@ -3372,7 +3372,7 @@ void LikelyFalsePositiveSuppressionBRVisitor::finalizeVisitor(
   FullSourceLoc Loc = BR.getLocation().asLocation();
   while (Loc.isMacroID()) {
     Loc = Loc.getSpellingLoc();
-    if (SM.getFilename(Loc).endswith("sys/queue.h")) {
+    if (SM.getFilename(Loc).ends_with("sys/queue.h")) {
       BR.markInvalid(getTag(), nullptr);
       return;
     }
diff --git a/clang/lib/StaticAnalyzer/Core/CallEvent.cpp b/clang/lib/StaticAnalyzer/Core/CallEvent.cpp
index d004c12..0ac1d91 100644
--- a/clang/lib/StaticAnalyzer/Core/CallEvent.cpp
+++ b/clang/lib/StaticAnalyzer/Core/CallEvent.cpp
@@ -659,17 +659,17 @@ bool AnyFunctionCall::argumentsMayEscape() const {
 
   // - CoreFoundation functions that end with "NoCopy" can free a passed-in
   //   buffer even if it is const.
-  if (FName.endswith("NoCopy"))
+  if (FName.ends_with("NoCopy"))
     return true;
 
   // - NSXXInsertXX, for example NSMapInsertIfAbsent, since they can
   //   be deallocated by NSMapRemove.
-  if (FName.startswith("NS") && FName.contains("Insert"))
+  if (FName.starts_with("NS") && FName.contains("Insert"))
     return true;
 
   // - Many CF containers allow objects to escape through custom
   //   allocators/deallocators upon container construction. (PR12101)
-  if (FName.startswith("CF") || FName.startswith("CG")) {
+  if (FName.starts_with("CF") || FName.starts_with("CG")) {
     return StrInStrNoCase(FName, "InsertValue")  != StringRef::npos ||
            StrInStrNoCase(FName, "AddValue")     != StringRef::npos ||
            StrInStrNoCase(FName, "SetValue")     != StringRef::npos ||
diff --git a/clang/lib/StaticAnalyzer/Core/CheckerContext.cpp b/clang/lib/StaticAnalyzer/Core/CheckerContext.cpp
index c25165c..d6d4cec 100644
--- a/clang/lib/StaticAnalyzer/Core/CheckerContext.cpp
+++ b/clang/lib/StaticAnalyzer/Core/CheckerContext.cpp
@@ -105,10 +105,11 @@ bool CheckerContext::isCLibraryFunction(const FunctionDecl *FD,
   if (FName.equals(Name))
     return true;
 
-  if (FName.startswith("__inline") && FName.contains(Name))
+  if (FName.starts_with("__inline") && FName.contains(Name))
     return true;
 
-  if (FName.startswith("__") && FName.endswith("_chk") && FName.contains(Name))
+  if (FName.starts_with("__") && FName.ends_with("_chk") &&
+      FName.contains(Name))
     return true;
 
   return false;
diff --git a/clang/lib/StaticAnalyzer/Core/CheckerRegistryData.cpp b/clang/lib/StaticAnalyzer/Core/CheckerRegistryData.cpp
index 1b3e8b1..b9c6278 100644
--- a/clang/lib/StaticAnalyzer/Core/CheckerRegistryData.cpp
+++ b/clang/lib/StaticAnalyzer/Core/CheckerRegistryData.cpp
@@ -82,7 +82,7 @@ static constexpr char PackageSeparator = '.';
 
 static bool isInPackage(const CheckerInfo &Checker, StringRef PackageName) {
   // Does the checker's full name have the package as a prefix?
-  if (!Checker.FullName.startswith(PackageName))
+  if (!Checker.FullName.starts_with(PackageName))
     return false;
 
   // Is the package actually just the name of a specific checker?
@@ -158,7 +158,7 @@ void CheckerRegistryData::printCheckerWithDescList(
       continue;
     }
 
-    if (Checker.FullName.startswith("alpha")) {
+    if (Checker.FullName.starts_with("alpha")) {
       if (AnOpts.ShowCheckerHelpAlpha)
         Print(Out, Checker,
               ("(Enable only for development!) " + Checker.Desc).str());
@@ -228,7 +228,7 @@ void CheckerRegistryData::printCheckerOptionList(const AnalyzerOptions &AnOpts,
     }
 
     if (Option.DevelopmentStatus == "alpha" ||
-        Entry.first.startswith("alpha")) {
+        Entry.first.starts_with("alpha")) {
       if (AnOpts.ShowCheckerOptionAlphaList)
         Print(Out, FullOption,
               llvm::Twine("(Enable only for development!) " + Desc).str());
diff --git a/clang/lib/StaticAnalyzer/Frontend/AnalysisConsumer.cpp b/clang/lib/StaticAnalyzer/Frontend/AnalysisConsumer.cpp
index 142acab..b6ef405 100644
--- a/clang/lib/StaticAnalyzer/Frontend/AnalysisConsumer.cpp
+++ b/clang/lib/StaticAnalyzer/Frontend/AnalysisConsumer.cpp
@@ -308,7 +308,7 @@ public:
 
   bool VisitFunctionDecl(FunctionDecl *FD) {
     IdentifierInfo *II = FD->getIdentifier();
-    if (II && II->getName().startswith("__inline"))
+    if (II && II->getName().starts_with("__inline"))
       return true;
 
     // We skip function template definitions, as their semantics is
diff --git a/clang/lib/StaticAnalyzer/Frontend/CheckerRegistry.cpp b/clang/lib/StaticAnalyzer/Frontend/CheckerRegistry.cpp
index f0d3f43..317df90 100644
--- a/clang/lib/StaticAnalyzer/Frontend/CheckerRegistry.cpp
+++ b/clang/lib/StaticAnalyzer/Frontend/CheckerRegistry.cpp
@@ -310,8 +310,8 @@ template <bool IsWeak> void CheckerRegistry::resolveDependencies() {
            "Failed to find the dependency of a checker!");
 
     // We do allow diagnostics from unit test/example dependency checkers.
-    assert((DependencyIt->FullName.startswith("test") ||
-            DependencyIt->FullName.startswith("example") || IsWeak ||
+    assert((DependencyIt->FullName.starts_with("test") ||
+            DependencyIt->FullName.starts_with("example") || IsWeak ||
             DependencyIt->IsHidden) &&
            "Strong dependencies are modeling checkers, and as such "
            "non-user facing! Mark them hidden in Checkers.td!");
diff --git a/clang/lib/Support/RISCVVIntrinsicUtils.cpp b/clang/lib/Support/RISCVVIntrinsicUtils.cpp
index a04694e..bb9f7dc7 100644
--- a/clang/lib/Support/RISCVVIntrinsicUtils.cpp
+++ b/clang/lib/Support/RISCVVIntrinsicUtils.cpp
@@ -464,7 +464,7 @@ PrototypeDescriptor::parsePrototypeDescriptor(
   PrototypeDescriptorStr = PrototypeDescriptorStr.drop_back();
 
   // Compute the vector type transformers, it can only appear one time.
-  if (PrototypeDescriptorStr.startswith("(")) {
+  if (PrototypeDescriptorStr.starts_with("(")) {
     assert(VTM == VectorTypeModifier::NoModifier &&
            "VectorTypeModifier should only have one modifier");
     size_t Idx = PrototypeDescriptorStr.find(')');
diff --git a/clang/lib/Tooling/ASTDiff/ASTDiff.cpp b/clang/lib/Tooling/ASTDiff/ASTDiff.cpp
index 52e5797..356b4bd 100644
--- a/clang/lib/Tooling/ASTDiff/ASTDiff.cpp
+++ b/clang/lib/Tooling/ASTDiff/ASTDiff.cpp
@@ -371,7 +371,7 @@ SyntaxTree::Impl::getRelativeName(const NamedDecl *ND,
   // Strip the qualifier, if Val refers to something in the current scope.
   // But leave one leading ':' in place, so that we know that this is a
   // relative path.
-  if (!ContextPrefix.empty() && StringRef(Val).startswith(ContextPrefix))
+  if (!ContextPrefix.empty() && StringRef(Val).starts_with(ContextPrefix))
     Val = Val.substr(ContextPrefix.size() + 1);
   return Val;
 }
diff --git a/clang/lib/Tooling/ArgumentsAdjusters.cpp b/clang/lib/Tooling/ArgumentsAdjusters.cpp
index e40df62..df4c742 100644
--- a/clang/lib/Tooling/ArgumentsAdjusters.cpp
+++ b/clang/lib/Tooling/ArgumentsAdjusters.cpp
@@ -45,12 +45,12 @@ ArgumentsAdjuster getClangSyntaxOnlyAdjuster() {
       StringRef Arg = Args[i];
       // Skip output commands.
       if (llvm::any_of(OutputCommands, [&Arg](llvm::StringRef OutputCommand) {
-            return Arg.startswith(OutputCommand);
+            return Arg.starts_with(OutputCommand);
           }))
         continue;
 
-      if (!Arg.startswith("-fcolor-diagnostics") &&
-          !Arg.startswith("-fdiagnostics-color"))
+      if (!Arg.starts_with("-fcolor-diagnostics") &&
+          !Arg.starts_with("-fdiagnostics-color"))
         AdjustedArgs.push_back(Args[i]);
       // If we strip a color option, make sure we strip any preceeding `-Xclang`
       // option as well.
@@ -73,7 +73,7 @@ ArgumentsAdjuster getClangStripOutputAdjuster() {
     CommandLineArguments AdjustedArgs;
     for (size_t i = 0, e = Args.size(); i < e; ++i) {
       StringRef Arg = Args[i];
-      if (!Arg.startswith("-o"))
+      if (!Arg.starts_with("-o"))
         AdjustedArgs.push_back(Args[i]);
 
       if (Arg == "-o") {
@@ -102,11 +102,11 @@ ArgumentsAdjuster getClangStripDependencyFileAdjuster() {
       // When not using the cl driver mode, dependency file generation options
       // begin with -M. These include -MM, -MF, -MG, -MP, -MT, -MQ, -MD, and
       // -MMD.
-      if (!UsingClDriver && Arg.startswith("-M"))
+      if (!UsingClDriver && Arg.starts_with("-M"))
         continue;
       // Under MSVC's cl driver mode, dependency file generation is controlled
       // using /showIncludes
-      if (Arg.startswith("/showIncludes") || Arg.startswith("-showIncludes"))
+      if (Arg.starts_with("/showIncludes") || Arg.starts_with("-showIncludes"))
         continue;
 
       AdjustedArgs.push_back(Args[i]);
@@ -159,7 +159,7 @@ ArgumentsAdjuster getStripPluginsAdjuster() {
       // -Xclang <arbitrary-argument>
       if (I + 4 < E && Args[I] == "-Xclang" &&
           (Args[I + 1] == "-load" || Args[I + 1] == "-plugin" ||
-           llvm::StringRef(Args[I + 1]).startswith("-plugin-arg-") ||
+           llvm::StringRef(Args[I + 1]).starts_with("-plugin-arg-") ||
            Args[I + 1] == "-add-plugin") &&
           Args[I + 2] == "-Xclang") {
         I += 3;
diff --git a/clang/lib/Tooling/CompilationDatabase.cpp b/clang/lib/Tooling/CompilationDatabase.cpp
index fdf6015..87ad8f2 100644
--- a/clang/lib/Tooling/CompilationDatabase.cpp
+++ b/clang/lib/Tooling/CompilationDatabase.cpp
@@ -204,7 +204,7 @@ public:
 // which don't support these options.
 struct FilterUnusedFlags {
   bool operator() (StringRef S) {
-    return (S == "-no-integrated-as") || S.startswith("-Wa,");
+    return (S == "-no-integrated-as") || S.starts_with("-Wa,");
   }
 };
 
diff --git a/clang/lib/Tooling/DependencyScanning/DependencyScanningFilesystem.cpp b/clang/lib/Tooling/DependencyScanning/DependencyScanningFilesystem.cpp
index 3e53c8f..6f71650 100644
--- a/clang/lib/Tooling/DependencyScanning/DependencyScanningFilesystem.cpp
+++ b/clang/lib/Tooling/DependencyScanning/DependencyScanningFilesystem.cpp
@@ -290,7 +290,7 @@ DependencyScanningWorkerFilesystem::status(const Twine &Path) {
   SmallString<256> OwnedFilename;
   StringRef Filename = Path.toStringRef(OwnedFilename);
 
-  if (Filename.endswith(".pcm"))
+  if (Filename.ends_with(".pcm"))
     return getUnderlyingFS().status(Path);
 
   llvm::ErrorOr<EntryRef> Result = getOrCreateFileSystemEntry(Filename);
@@ -350,7 +350,7 @@ DependencyScanningWorkerFilesystem::openFileForRead(const Twine &Path) {
   SmallString<256> OwnedFilename;
   StringRef Filename = Path.toStringRef(OwnedFilename);
 
-  if (Filename.endswith(".pcm"))
+  if (Filename.ends_with(".pcm"))
     return getUnderlyingFS().openFileForRead(Path);
 
   llvm::ErrorOr<EntryRef> Result = getOrCreateFileSystemEntry(Filename);
diff --git a/clang/lib/Tooling/DependencyScanning/ModuleDepCollector.cpp b/clang/lib/Tooling/DependencyScanning/ModuleDepCollector.cpp
index f65da41..4a3cd05 100644
--- a/clang/lib/Tooling/DependencyScanning/ModuleDepCollector.cpp
+++ b/clang/lib/Tooling/DependencyScanning/ModuleDepCollector.cpp
@@ -530,7 +530,7 @@ ModuleDepCollectorPP::handleTopLevelModule(const Module *M) {
         // this file in the proper directory and relies on the rest of Clang to
         // handle it like normal. With explicitly built modules we don't need
         // to play VFS tricks, so replace it with the correct module map.
-        if (StringRef(IFI.Filename).endswith("__inferred_module.map")) {
+        if (StringRef(IFI.Filename).ends_with("__inferred_module.map")) {
           MDC.addFileDep(MD, ModuleMap->getName());
           return;
         }
@@ -548,7 +548,7 @@ ModuleDepCollectorPP::handleTopLevelModule(const Module *M) {
         if (!(IFI.TopLevel && IFI.ModuleMap))
           return;
         if (StringRef(IFI.FilenameAsRequested)
-                .endswith("__inferred_module.map"))
+                .ends_with("__inferred_module.map"))
           return;
         MD.ModuleMapFileDeps.emplace_back(IFI.FilenameAsRequested);
       });
diff --git a/clang/lib/Tooling/Inclusions/HeaderAnalysis.cpp b/clang/lib/Tooling/Inclusions/HeaderAnalysis.cpp
index 0b3c4de..52b634e 100644
--- a/clang/lib/Tooling/Inclusions/HeaderAnalysis.cpp
+++ b/clang/lib/Tooling/Inclusions/HeaderAnalysis.cpp
@@ -21,7 +21,7 @@ bool isIf(llvm::StringRef Line) {
   if (!Line.consume_front("#"))
     return false;
   Line = Line.ltrim();
-  return Line.startswith("if");
+  return Line.starts_with("if");
 }
 
 // Is Line an #error directive mentioning includes?
@@ -30,7 +30,7 @@ bool isErrorAboutInclude(llvm::StringRef Line) {
   if (!Line.consume_front("#"))
     return false;
   Line = Line.ltrim();
-  if (!Line.startswith("error"))
+  if (!Line.starts_with("error"))
     return false;
   return Line.contains_insensitive(
       "includ"); // Matches "include" or "including".
@@ -54,7 +54,7 @@ bool isImportLine(llvm::StringRef Line) {
   if (!Line.consume_front("#"))
     return false;
   Line = Line.ltrim();
-  return Line.startswith("import");
+  return Line.starts_with("import");
 }
 
 llvm::StringRef getFileContents(FileEntryRef FE, const SourceManager &SM) {
diff --git a/clang/lib/Tooling/Inclusions/HeaderIncludes.cpp b/clang/lib/Tooling/Inclusions/HeaderIncludes.cpp
index 15a2024..d275222 100644
--- a/clang/lib/Tooling/Inclusions/HeaderIncludes.cpp
+++ b/clang/lib/Tooling/Inclusions/HeaderIncludes.cpp
@@ -196,10 +196,10 @@ IncludeCategoryManager::IncludeCategoryManager(const IncludeStyle &Style,
                                                     ? llvm::Regex::NoFlags
                                                     : llvm::Regex::IgnoreCase);
   }
-  IsMainFile = FileName.endswith(".c") || FileName.endswith(".cc") ||
-               FileName.endswith(".cpp") || FileName.endswith(".c++") ||
-               FileName.endswith(".cxx") || FileName.endswith(".m") ||
-               FileName.endswith(".mm");
+  IsMainFile = FileName.ends_with(".c") || FileName.ends_with(".cc") ||
+               FileName.ends_with(".cpp") || FileName.ends_with(".c++") ||
+               FileName.ends_with(".cxx") || FileName.ends_with(".m") ||
+               FileName.ends_with(".mm");
   if (!Style.IncludeIsMainSourceRegex.empty()) {
     llvm::Regex MainFileRegex(Style.IncludeIsMainSourceRegex);
     IsMainFile |= MainFileRegex.match(FileName);
@@ -234,7 +234,7 @@ int IncludeCategoryManager::getSortIncludePriority(StringRef IncludeName,
   return Ret;
 }
 bool IncludeCategoryManager::isMainHeader(StringRef IncludeName) const {
-  if (!IncludeName.startswith("\""))
+  if (!IncludeName.starts_with("\""))
     return false;
 
   IncludeName =
@@ -357,8 +357,8 @@ HeaderIncludes::insert(llvm::StringRef IncludeName, bool IsAngled,
   if (It != ExistingIncludes.end()) {
     for (const auto &Inc : It->second)
       if (Inc.Directive == Directive &&
-          ((IsAngled && StringRef(Inc.Name).startswith("<")) ||
-           (!IsAngled && StringRef(Inc.Name).startswith("\""))))
+          ((IsAngled && StringRef(Inc.Name).starts_with("<")) ||
+           (!IsAngled && StringRef(Inc.Name).starts_with("\""))))
         return std::nullopt;
   }
   std::string Quoted =
@@ -400,8 +400,8 @@ tooling::Replacements HeaderIncludes::remove(llvm::StringRef IncludeName,
   if (Iter == ExistingIncludes.end())
     return Result;
   for (const auto &Inc : Iter->second) {
-    if ((IsAngled && StringRef(Inc.Name).startswith("\"")) ||
-        (!IsAngled && StringRef(Inc.Name).startswith("<")))
+    if ((IsAngled && StringRef(Inc.Name).starts_with("\"")) ||
+        (!IsAngled && StringRef(Inc.Name).starts_with("<")))
       continue;
     llvm::Error Err = Result.add(tooling::Replacement(
         FileName, Inc.R.getOffset(), Inc.R.getLength(), ""));
diff --git a/clang/lib/Tooling/Refactoring/AtomicChange.cpp b/clang/lib/Tooling/Refactoring/AtomicChange.cpp
index 7237393..3d5ae2f 100644
--- a/clang/lib/Tooling/Refactoring/AtomicChange.cpp
+++ b/clang/lib/Tooling/Refactoring/AtomicChange.cpp
@@ -150,7 +150,7 @@ createReplacementsForHeaders(llvm::StringRef FilePath, llvm::StringRef Code,
   for (const auto &Change : Changes) {
     for (llvm::StringRef Header : Change.getInsertedHeaders()) {
       std::string EscapedHeader =
-          Header.startswith("<") || Header.startswith("\"")
+          Header.starts_with("<") || Header.starts_with("\"")
               ? Header.str()
               : ("\"" + Header + "\"").str();
       std::string ReplacementText = "#include " + EscapedHeader;
diff --git a/clang/lib/Tooling/Refactoring/Lookup.cpp b/clang/lib/Tooling/Refactoring/Lookup.cpp
index 9468d4d..52799f1 100644
--- a/clang/lib/Tooling/Refactoring/Lookup.cpp
+++ b/clang/lib/Tooling/Refactoring/Lookup.cpp
@@ -98,7 +98,7 @@ static StringRef getBestNamespaceSubstr(const DeclContext *DeclA,
     // from NewName if it has an identical prefix.
     std::string NS =
         "::" + cast<NamespaceDecl>(DeclA)->getQualifiedNameAsString() + "::";
-    if (NewName.startswith(NS))
+    if (NewName.starts_with(NS))
       return NewName.substr(NS.size());
 
     // No match yet. Strip of a namespace from the end of the chain and try
@@ -128,9 +128,9 @@ static std::string disambiguateSpellingInScope(StringRef Spelling,
                                                StringRef QName,
                                                const DeclContext &UseContext,
                                                SourceLocation UseLoc) {
-  assert(QName.startswith("::"));
-  assert(QName.endswith(Spelling));
-  if (Spelling.startswith("::"))
+  assert(QName.starts_with("::"));
+  assert(QName.ends_with(Spelling));
+  if (Spelling.starts_with("::"))
     return std::string(Spelling);
 
   auto UnspelledSpecifier = QName.drop_back(Spelling.size());
@@ -146,7 +146,7 @@ static std::string disambiguateSpellingInScope(StringRef Spelling,
   UseLoc = SM.getSpellingLoc(UseLoc);
 
   auto IsAmbiguousSpelling = [&](const llvm::StringRef CurSpelling) {
-    if (CurSpelling.startswith("::"))
+    if (CurSpelling.starts_with("::"))
       return false;
     // Lookup the first component of Spelling in all enclosing namespaces
     // and check if there is any existing symbols with the same name but in
@@ -160,7 +160,7 @@ static std::string disambiguateSpellingInScope(StringRef Spelling,
           // ambiguous. For example, a reference in a header file should not be
           // affected by a potentially ambiguous name in some file that includes
           // the header.
-          if (!TrimmedQName.startswith(Res->getQualifiedNameAsString()) &&
+          if (!TrimmedQName.starts_with(Res->getQualifiedNameAsString()) &&
               SM.isBeforeInTranslationUnit(
                   SM.getSpellingLoc(Res->getLocation()), UseLoc))
             return true;
@@ -187,7 +187,7 @@ std::string tooling::replaceNestedName(const NestedNameSpecifier *Use,
                                        const DeclContext *UseContext,
                                        const NamedDecl *FromDecl,
                                        StringRef ReplacementString) {
-  assert(ReplacementString.startswith("::") &&
+  assert(ReplacementString.starts_with("::") &&
          "Expected fully-qualified name!");
 
   // We can do a raw name replacement when we are not inside the namespace for
diff --git a/clang/lib/Tooling/Refactoring/Rename/USRLocFinder.cpp b/clang/lib/Tooling/Refactoring/Rename/USRLocFinder.cpp
index 9cdeeec..c18f929 100644
--- a/clang/lib/Tooling/Refactoring/Rename/USRLocFinder.cpp
+++ b/clang/lib/Tooling/Refactoring/Rename/USRLocFinder.cpp
@@ -562,8 +562,8 @@ createRenameAtomicChanges(llvm::ArrayRef<std::string> USRs,
           ReplacedName = tooling::replaceNestedName(
               RenameInfo.Specifier, RenameInfo.Begin,
               RenameInfo.Context->getDeclContext(), RenameInfo.FromDecl,
-              NewName.startswith("::") ? NewName.str()
-                                       : ("::" + NewName).str());
+              NewName.starts_with("::") ? NewName.str()
+                                        : ("::" + NewName).str());
         } else {
           // This fixes the case where type `T` is a parameter inside a function
           // type (e.g. `std::function<void(T)>`) and the DeclContext of `T`
@@ -578,13 +578,13 @@ createRenameAtomicChanges(llvm::ArrayRef<std::string> USRs,
               SM, TranslationUnitDecl->getASTContext().getLangOpts());
           // Add the leading "::" back if the name written in the code contains
           // it.
-          if (ActualName.startswith("::") && !NewName.startswith("::")) {
+          if (ActualName.starts_with("::") && !NewName.starts_with("::")) {
             ReplacedName = "::" + NewName.str();
           }
         }
       }
       // If the NewName contains leading "::", add it back.
-      if (NewName.startswith("::") && NewName.substr(2) == ReplacedName)
+      if (NewName.starts_with("::") && NewName.substr(2) == ReplacedName)
         ReplacedName = NewName.str();
     }
     Replace(RenameInfo.Begin, RenameInfo.End, ReplacedName);
diff --git a/clang/lib/Tooling/Tooling.cpp b/clang/lib/Tooling/Tooling.cpp
index e292fa7..33bfa8d 100644
--- a/clang/lib/Tooling/Tooling.cpp
+++ b/clang/lib/Tooling/Tooling.cpp
@@ -255,7 +255,7 @@ llvm::Expected<std::string> getAbsolutePath(llvm::vfs::FileSystem &FS,
                                             StringRef File) {
   StringRef RelativePath(File);
   // FIXME: Should '.\\' be accepted on Win32?
-  if (RelativePath.startswith("./")) {
+  if (RelativePath.starts_with("./")) {
     RelativePath = RelativePath.substr(strlen("./"));
   }
 
@@ -294,9 +294,9 @@ void addTargetAndModeForProgramName(std::vector<std::string> &CommandLine,
   for (auto Token = ++CommandLine.begin(); Token != CommandLine.end();
        ++Token) {
     StringRef TokenRef(*Token);
-    ShouldAddTarget = ShouldAddTarget && !TokenRef.startswith(TargetOPT) &&
+    ShouldAddTarget = ShouldAddTarget && !TokenRef.starts_with(TargetOPT) &&
                       !TokenRef.equals(TargetOPTLegacy);
-    ShouldAddMode = ShouldAddMode && !TokenRef.startswith(DriverModeOPT);
+    ShouldAddMode = ShouldAddMode && !TokenRef.starts_with(DriverModeOPT);
   }
   if (ShouldAddMode) {
     CommandLine.insert(++CommandLine.begin(), TargetMode.DriverMode);
@@ -507,7 +507,7 @@ static void injectResourceDir(CommandLineArguments &Args, const char *Argv0,
                               void *MainAddr) {
   // Allow users to override the resource dir.
   for (StringRef Arg : Args)
-    if (Arg.startswith("-resource-dir"))
+    if (Arg.starts_with("-resource-dir"))
       return;
 
   // If there's no override in place add our resource dir.
diff --git a/clang/lib/Tooling/Transformer/SourceCode.cpp b/clang/lib/Tooling/Transformer/SourceCode.cpp
index 3000953..6aae834 100644
--- a/clang/lib/Tooling/Transformer/SourceCode.cpp
+++ b/clang/lib/Tooling/Transformer/SourceCode.cpp
@@ -425,7 +425,7 @@ CharSourceRange tooling::getAssociatedRange(const Decl &Decl,
 
     for (llvm::StringRef Prefix : {"[[", "__attribute__(("}) {
       // Handle whitespace between attribute prefix and attribute value.
-      if (BeforeAttrStripped.endswith(Prefix)) {
+      if (BeforeAttrStripped.ends_with(Prefix)) {
         // Move start to start position of prefix, which is
         // length(BeforeAttr) - length(BeforeAttrStripped) + length(Prefix)
         // positions to the left.
diff --git a/clang/tools/arcmt-test/arcmt-test.cpp b/clang/tools/arcmt-test/arcmt-test.cpp
index 53229ac..b61f38e 100644
--- a/clang/tools/arcmt-test/arcmt-test.cpp
+++ b/clang/tools/arcmt-test/arcmt-test.cpp
@@ -230,7 +230,7 @@ static bool verifyTransformedFiles(ArrayRef<std::string> resultFiles) {
   for (ArrayRef<std::string>::iterator
          I = resultFiles.begin(), E = resultFiles.end(); I != E; ++I) {
     StringRef fname(*I);
-    if (!fname.endswith(".result")) {
+    if (!fname.ends_with(".result")) {
       errs() << "error: filename '" << fname
                    << "' does not have '.result' extension\n";
       return true;
diff --git a/clang/tools/clang-extdef-mapping/ClangExtDefMapGen.cpp b/clang/tools/clang-extdef-mapping/ClangExtDefMapGen.cpp
index 769727e..c048f33 100644
--- a/clang/tools/clang-extdef-mapping/ClangExtDefMapGen.cpp
+++ b/clang/tools/clang-extdef-mapping/ClangExtDefMapGen.cpp
@@ -181,7 +181,7 @@ static int HandleFiles(ArrayRef<std::string> SourceFiles,
   // process them directly in HandleAST, otherwise put them
   // on a list for ClangTool to handle.
   for (StringRef Src : SourceFiles) {
-    if (Src.endswith(".ast")) {
+    if (Src.ends_with(".ast")) {
       if (!HandleAST(Src)) {
         return 1;
       }
diff --git a/clang/tools/clang-linker-wrapper/ClangLinkerWrapper.cpp b/clang/tools/clang-linker-wrapper/ClangLinkerWrapper.cpp
index 5d2fe98..bd2fd02 100644
--- a/clang/tools/clang-linker-wrapper/ClangLinkerWrapper.cpp
+++ b/clang/tools/clang-linker-wrapper/ClangLinkerWrapper.cpp
@@ -1151,7 +1151,7 @@ linkAndWrapDeviceFiles(SmallVectorImpl<OffloadFile> &LinkerInputFiles,
 std::optional<std::string> findFile(StringRef Dir, StringRef Root,
                                     const Twine &Name) {
   SmallString<128> Path;
-  if (Dir.startswith("="))
+  if (Dir.starts_with("="))
     sys::path::append(Path, Root, Dir.substr(1), Name);
   else
     sys::path::append(Path, Dir, Name);
@@ -1188,7 +1188,7 @@ searchLibraryBaseName(StringRef Name, StringRef Root,
 /// `-lfoo` or `-l:libfoo.a`.
 std::optional<std::string> searchLibrary(StringRef Input, StringRef Root,
                                          ArrayRef<StringRef> SearchPaths) {
-  if (Input.startswith(":") || Input.ends_with(".lib"))
+  if (Input.starts_with(":") || Input.ends_with(".lib"))
     return findFromSearchPaths(Input.drop_front(), Root, SearchPaths);
   return searchLibraryBaseName(Input, Root, SearchPaths);
 }
diff --git a/clang/tools/clang-refactor/ClangRefactor.cpp b/clang/tools/clang-refactor/ClangRefactor.cpp
index d362eec..175a2b8 100644
--- a/clang/tools/clang-refactor/ClangRefactor.cpp
+++ b/clang/tools/clang-refactor/ClangRefactor.cpp
@@ -146,7 +146,7 @@ private:
 
 std::unique_ptr<SourceSelectionArgument>
 SourceSelectionArgument::fromString(StringRef Value) {
-  if (Value.startswith("test:")) {
+  if (Value.starts_with("test:")) {
     StringRef Filename = Value.drop_front(strlen("test:"));
     std::optional<TestSelectionRangesInFile> ParsedTestSelection =
         findTestSelectionRanges(Filename);
diff --git a/clang/tools/clang-repl/ClangRepl.cpp b/clang/tools/clang-repl/ClangRepl.cpp
index 5663c2c..b9b2871 100644
--- a/clang/tools/clang-repl/ClangRepl.cpp
+++ b/clang/tools/clang-repl/ClangRepl.cpp
@@ -234,7 +234,7 @@ int main(int argc, const char **argv) {
     while (std::optional<std::string> Line = LE.readLine()) {
       llvm::StringRef L = *Line;
       L = L.trim();
-      if (L.endswith("\\")) {
+      if (L.ends_with("\\")) {
         // FIXME: Support #ifdef X \ ...
         Input += L.drop_back(1);
         LE.setPrompt("clang-repl...   ");
diff --git a/clang/tools/clang-scan-deps/ClangScanDeps.cpp b/clang/tools/clang-scan-deps/ClangScanDeps.cpp
index f11c933..75aa4ae 100644
--- a/clang/tools/clang-scan-deps/ClangScanDeps.cpp
+++ b/clang/tools/clang-scan-deps/ClangScanDeps.cpp
@@ -830,9 +830,9 @@ int clang_scan_deps_main(int argc, char **argv, const llvm::ToolContext &) {
                 // Also, clang-cl adds ".obj" extension if none is found.
                 if ((Arg == "-o" || Arg == "/o") && I != R)
                   LastO = I[-1]; // Next argument (reverse iterator)
-                else if (Arg.startswith("/Fo") || Arg.startswith("-Fo"))
+                else if (Arg.starts_with("/Fo") || Arg.starts_with("-Fo"))
                   LastO = Arg.drop_front(3).str();
-                else if (Arg.startswith("/o") || Arg.startswith("-o"))
+                else if (Arg.starts_with("/o") || Arg.starts_with("-o"))
                   LastO = Arg.drop_front(2).str();
 
                 if (!LastO.empty() && !llvm::sys::path::has_extension(LastO))
diff --git a/clang/tools/diagtool/TreeView.cpp b/clang/tools/diagtool/TreeView.cpp
index 4f5d3fd..eae1624 100644
--- a/clang/tools/diagtool/TreeView.cpp
+++ b/clang/tools/diagtool/TreeView.cpp
@@ -160,7 +160,7 @@ int TreeView::run(unsigned int argc, char **argv, llvm::raw_ostream &out) {
     break;
   case 1:
     RootGroup = argv[0];
-    if (RootGroup.startswith("-W"))
+    if (RootGroup.starts_with("-W"))
       RootGroup = RootGroup.substr(2);
     if (RootGroup == "everything")
       ShowAll = true;
diff --git a/clang/tools/driver/driver.cpp b/clang/tools/driver/driver.cpp
index 531b5b4..4adc7f7 100644
--- a/clang/tools/driver/driver.cpp
+++ b/clang/tools/driver/driver.cpp
@@ -122,7 +122,7 @@ static void ApplyOneQAOverride(raw_ostream &OS,
       GetStableCStr(SavedStrings, Edit.substr(1));
     OS << "### Adding argument " << Str << " at end\n";
     Args.push_back(Str);
-  } else if (Edit[0] == 's' && Edit[1] == '/' && Edit.endswith("/") &&
+  } else if (Edit[0] == 's' && Edit[1] == '/' && Edit.ends_with("/") &&
              Edit.slice(2, Edit.size() - 1).contains('/')) {
     StringRef MatchPattern = Edit.substr(2).split('/').first;
     StringRef ReplPattern = Edit.substr(2).split('/').second;
@@ -403,7 +403,7 @@ int clang_main(int Argc, char **Argv, const llvm::ToolContext &ToolContext) {
   }
 
   // Handle -cc1 integrated tools.
-  if (Args.size() >= 2 && StringRef(Args[1]).startswith("-cc1"))
+  if (Args.size() >= 2 && StringRef(Args[1]).starts_with("-cc1"))
     return ExecuteCC1Tool(Args, ToolContext);
 
   // Handle options that need handling before the real command line parsing in
diff --git a/clang/tools/libclang/CIndexUSRs.cpp b/clang/tools/libclang/CIndexUSRs.cpp
index 75bb3b0..be7c670 100644
--- a/clang/tools/libclang/CIndexUSRs.cpp
+++ b/clang/tools/libclang/CIndexUSRs.cpp
@@ -28,7 +28,7 @@ using namespace clang::index;
 //===----------------------------------------------------------------------===//
 
 static inline StringRef extractUSRSuffix(StringRef s) {
-  return s.startswith("c:") ? s.substr(2) : "";
+  return s.starts_with("c:") ? s.substr(2) : "";
 }
 
 bool cxcursor::getDeclCursorUSR(const Decl *D, SmallVectorImpl<char> &Buf) {
diff --git a/clang/unittests/Analysis/CloneDetectionTest.cpp b/clang/unittests/Analysis/CloneDetectionTest.cpp
index fe65fab..738f6efd 100644
--- a/clang/unittests/Analysis/CloneDetectionTest.cpp
+++ b/clang/unittests/Analysis/CloneDetectionTest.cpp
@@ -42,7 +42,7 @@ public:
           for (const StmtSequence &Arg : {A, B}) {
             if (const auto *D =
                     dyn_cast<const FunctionDecl>(Arg.getContainingDecl())) {
-              if (D->getName().startswith("bar"))
+              if (D->getName().starts_with("bar"))
                 return false;
             }
           }
diff --git a/clang/unittests/Driver/ModuleCacheTest.cpp b/clang/unittests/Driver/ModuleCacheTest.cpp
index 6a0f68f..4874441 100644
--- a/clang/unittests/Driver/ModuleCacheTest.cpp
+++ b/clang/unittests/Driver/ModuleCacheTest.cpp
@@ -22,6 +22,6 @@ TEST(ModuleCacheTest, GetTargetAndMode) {
   Driver::getDefaultModuleCachePath(Buf);
   StringRef Path = Buf;
   EXPECT_TRUE(Path.find("clang") != Path.npos);
-  EXPECT_TRUE(Path.endswith("ModuleCache"));  
+  EXPECT_TRUE(Path.ends_with("ModuleCache"));
 }
 } // end anonymous namespace.
diff --git a/clang/unittests/Driver/MultilibBuilderTest.cpp b/clang/unittests/Driver/MultilibBuilderTest.cpp
index 60fe10a..e23fe7e 100644
--- a/clang/unittests/Driver/MultilibBuilderTest.cpp
+++ b/clang/unittests/Driver/MultilibBuilderTest.cpp
@@ -144,7 +144,7 @@ TEST(MultilibBuilderTest, SetFilterObject) {
       << "Size before filter was incorrect. Contents:\n"
       << MS;
   MS.FilterOut([](const Multilib &M) {
-    return StringRef(M.gccSuffix()).startswith("/p");
+    return StringRef(M.gccSuffix()).starts_with("/p");
   });
   ASSERT_EQ((int)MS.size(), 1 /* Default */ + 1 /* orange */ +
                                 1 /* orange/pear */ + 1 /* orange/plum */ +
@@ -152,7 +152,7 @@ TEST(MultilibBuilderTest, SetFilterObject) {
       << "Size after filter was incorrect. Contents:\n"
       << MS;
   for (MultilibSet::const_iterator I = MS.begin(), E = MS.end(); I != E; ++I) {
-    ASSERT_FALSE(StringRef(I->gccSuffix()).startswith("/p"))
+    ASSERT_FALSE(StringRef(I->gccSuffix()).starts_with("/p"))
         << "The filter should have removed " << *I;
   }
 }
diff --git a/clang/unittests/Driver/ToolChainTest.cpp b/clang/unittests/Driver/ToolChainTest.cpp
index acbbb87..a9b5f3c 100644
--- a/clang/unittests/Driver/ToolChainTest.cpp
+++ b/clang/unittests/Driver/ToolChainTest.cpp
@@ -531,7 +531,7 @@ TEST(ToolChainTest, CommandOutput) {
   const auto &InFile = CmdCompile->getInputInfos().front().getFilename();
   EXPECT_STREQ(InFile, "foo.cpp");
   auto ObjFile = CmdCompile->getOutputFilenames().front();
-  EXPECT_TRUE(StringRef(ObjFile).endswith(".o"));
+  EXPECT_TRUE(StringRef(ObjFile).ends_with(".o"));
 
   const auto &CmdLink = Jobs.getJobs().back();
   const auto LinkInFile = CmdLink->getInputInfos().front().getFilename();
diff --git a/clang/unittests/Frontend/OutputStreamTest.cpp b/clang/unittests/Frontend/OutputStreamTest.cpp
index 9cb101e..7d360f6 100644
--- a/clang/unittests/Frontend/OutputStreamTest.cpp
+++ b/clang/unittests/Frontend/OutputStreamTest.cpp
@@ -42,7 +42,7 @@ TEST(FrontendOutputTests, TestOutputStream) {
   bool Success = ExecuteCompilerInvocation(&Compiler);
   EXPECT_TRUE(Success);
   EXPECT_TRUE(!IRBuffer.empty());
-  EXPECT_TRUE(StringRef(IRBuffer.data()).startswith("BC"));
+  EXPECT_TRUE(StringRef(IRBuffer.data()).starts_with("BC"));
 }
 
 TEST(FrontendOutputTests, TestVerboseOutputStreamShared) {
diff --git a/clang/unittests/Interpreter/IncrementalProcessingTest.cpp b/clang/unittests/Interpreter/IncrementalProcessingTest.cpp
index f43b3dd..accdf68 100644
--- a/clang/unittests/Interpreter/IncrementalProcessingTest.cpp
+++ b/clang/unittests/Interpreter/IncrementalProcessingTest.cpp
@@ -44,7 +44,7 @@ const char TestProgram2[] = "extern \"C\" int funcForProg2() { return 42; }\n"
 
 const Function *getGlobalInit(llvm::Module *M) {
   for (const auto &Func : *M)
-    if (Func.hasName() && Func.getName().startswith("_GLOBAL__sub_I_"))
+    if (Func.hasName() && Func.getName().starts_with("_GLOBAL__sub_I_"))
       return &Func;
 
   return nullptr;
diff --git a/clang/unittests/StaticAnalyzer/AnalyzerOptionsTest.cpp b/clang/unittests/StaticAnalyzer/AnalyzerOptionsTest.cpp
index cd78014..aace4b9 100644
--- a/clang/unittests/StaticAnalyzer/AnalyzerOptionsTest.cpp
+++ b/clang/unittests/StaticAnalyzer/AnalyzerOptionsTest.cpp
@@ -15,10 +15,10 @@ namespace ento {
 
 TEST(StaticAnalyzerOptions, getRegisteredCheckers) {
   auto IsDebugChecker = [](StringRef CheckerName) {
-    return CheckerName.startswith("debug");
+    return CheckerName.starts_with("debug");
   };
   auto IsAlphaChecker = [](StringRef CheckerName) {
-    return CheckerName.startswith("alpha");
+    return CheckerName.starts_with("alpha");
   };
   const auto &AllCheckers =
       AnalyzerOptions::getRegisteredCheckers(/*IncludeExperimental=*/true);
diff --git a/clang/unittests/Tooling/HeaderIncludesTest.cpp b/clang/unittests/Tooling/HeaderIncludesTest.cpp
index 256aa82..929156a 100644
--- a/clang/unittests/Tooling/HeaderIncludesTest.cpp
+++ b/clang/unittests/Tooling/HeaderIncludesTest.cpp
@@ -23,9 +23,9 @@ protected:
   std::string insert(llvm::StringRef Code, llvm::StringRef Header,
                      IncludeDirective Directive = IncludeDirective::Include) {
     HeaderIncludes Includes(FileName, Code, Style);
-    assert(Header.startswith("\"") || Header.startswith("<"));
-    auto R =
-        Includes.insert(Header.trim("\"<>"), Header.startswith("<"), Directive);
+    assert(Header.starts_with("\"") || Header.starts_with("<"));
+    auto R = Includes.insert(Header.trim("\"<>"), Header.starts_with("<"),
+                             Directive);
     if (!R)
       return std::string(Code);
     auto Result = applyAllReplacements(Code, Replacements(*R));
@@ -35,8 +35,9 @@ protected:
 
   std::string remove(llvm::StringRef Code, llvm::StringRef Header) {
     HeaderIncludes Includes(FileName, Code, Style);
-    assert(Header.startswith("\"") || Header.startswith("<"));
-    auto Replaces = Includes.remove(Header.trim("\"<>"), Header.startswith("<"));
+    assert(Header.starts_with("\"") || Header.starts_with("<"));
+    auto Replaces =
+        Includes.remove(Header.trim("\"<>"), Header.starts_with("<"));
     auto Result = applyAllReplacements(Code, Replaces);
     EXPECT_TRUE(static_cast<bool>(Result));
     return *Result;
diff --git a/clang/unittests/libclang/LibclangTest.cpp b/clang/unittests/libclang/LibclangTest.cpp
index 60904bc..87075a4 100644
--- a/clang/unittests/libclang/LibclangTest.cpp
+++ b/clang/unittests/libclang/LibclangTest.cpp
@@ -451,8 +451,8 @@ public:
 
       const auto Filename = llvm::sys::path::filename(File->path());
       EXPECT_EQ(Filename.size(), std::strlen("preamble-%%%%%%.pch"));
-      EXPECT_TRUE(Filename.startswith("preamble-"));
-      EXPECT_TRUE(Filename.endswith(".pch"));
+      EXPECT_TRUE(Filename.starts_with("preamble-"));
+      EXPECT_TRUE(Filename.ends_with(".pch"));
 
       const auto Status = File->status();
       ASSERT_TRUE(Status);
@@ -659,7 +659,7 @@ TEST_F(LibclangReparseTest, FileName) {
   clang_disposeString(cxname);
 
   cxname = clang_File_tryGetRealPathName(cxf);
-  ASSERT_TRUE(llvm::StringRef(clang_getCString(cxname)).endswith("main.cpp"));
+  ASSERT_TRUE(llvm::StringRef(clang_getCString(cxname)).ends_with("main.cpp"));
   clang_disposeString(cxname);
 }
 
diff --git a/clang/utils/TableGen/ASTTableGen.cpp b/clang/utils/TableGen/ASTTableGen.cpp
index 60f563d..54288ff 100644
--- a/clang/utils/TableGen/ASTTableGen.cpp
+++ b/clang/utils/TableGen/ASTTableGen.cpp
@@ -33,7 +33,7 @@ llvm::StringRef clang::tblgen::HasProperties::getName() const {
 
 static StringRef removeExpectedNodeNameSuffix(Record *node, StringRef suffix) {
   StringRef nodeName = node->getName();
-  if (!nodeName.endswith(suffix)) {
+  if (!nodeName.ends_with(suffix)) {
     PrintFatalError(node->getLoc(),
                     Twine("name of node doesn't end in ") + suffix);
   }
diff --git a/clang/utils/TableGen/MveEmitter.cpp b/clang/utils/TableGen/MveEmitter.cpp
index fae889d..f0bd086 100644
--- a/clang/utils/TableGen/MveEmitter.cpp
+++ b/clang/utils/TableGen/MveEmitter.cpp
@@ -882,7 +882,7 @@ public:
       } else if (V->varnameUsed()) {
         std::string Type = V->typeName();
         OS << V->typeName();
-        if (!StringRef(Type).endswith("*"))
+        if (!StringRef(Type).ends_with("*"))
           OS << " ";
         OS << V->varname() << " = ";
       }
@@ -1680,7 +1680,7 @@ void EmitterBase::EmitBuiltinCG(raw_ostream &OS) {
       for (size_t i = 0, e = MG.ParamTypes.size(); i < e; ++i) {
         StringRef Type = MG.ParamTypes[i];
         OS << "  " << Type;
-        if (!Type.endswith("*"))
+        if (!Type.ends_with("*"))
           OS << " ";
         OS << " Param" << utostr(i) << ";\n";
       }
@@ -1833,7 +1833,7 @@ void MveEmitter::EmitHeader(raw_ostream &OS) {
         // prototype.
 
         std::string RetTypeName = Int.returnType()->cName();
-        if (!StringRef(RetTypeName).endswith("*"))
+        if (!StringRef(RetTypeName).ends_with("*"))
           RetTypeName += " ";
 
         std::vector<std::string> ArgTypeNames;
@@ -2078,7 +2078,7 @@ void CdeEmitter::EmitHeader(raw_ostream &OS) {
       // Make strings for the types involved in the function's
       // prototype.
       std::string RetTypeName = Int.returnType()->cName();
-      if (!StringRef(RetTypeName).endswith("*"))
+      if (!StringRef(RetTypeName).ends_with("*"))
         RetTypeName += " ";
 
       std::vector<std::string> ArgTypeNames;