[clang-tidy] Add new check `modernize-use-designated-initializers` (#80541)

15 files changed, 745 insertions, 166 deletions

diff --git a/clang-tools-extra/clang-tidy/modernize/CMakeLists.txt b/clang-tools-extra/clang-tidy/modernize/CMakeLists.txt
index 28ca52f..6852db6 100644
--- a/clang-tools-extra/clang-tidy/modernize/CMakeLists.txt
+++ b/clang-tools-extra/clang-tidy/modernize/CMakeLists.txt
@@ -31,6 +31,7 @@ add_clang_library(clangTidyModernizeModule
   UseBoolLiteralsCheck.cpp
   UseConstraintsCheck.cpp
   UseDefaultMemberInitCheck.cpp
+  UseDesignatedInitializersCheck.cpp
   UseEmplaceCheck.cpp
   UseEqualsDefaultCheck.cpp
   UseEqualsDeleteCheck.cpp
diff --git a/clang-tools-extra/clang-tidy/modernize/ModernizeTidyModule.cpp b/clang-tools-extra/clang-tidy/modernize/ModernizeTidyModule.cpp
index 654f4bd..e96cf27 100644
--- a/clang-tools-extra/clang-tidy/modernize/ModernizeTidyModule.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/ModernizeTidyModule.cpp
@@ -32,6 +32,7 @@
 #include "UseBoolLiteralsCheck.h"
 #include "UseConstraintsCheck.h"
 #include "UseDefaultMemberInitCheck.h"
+#include "UseDesignatedInitializersCheck.h"
 #include "UseEmplaceCheck.h"
 #include "UseEqualsDefaultCheck.h"
 #include "UseEqualsDeleteCheck.h"
@@ -68,6 +69,8 @@ public:
     CheckFactories.registerCheck<MakeSharedCheck>("modernize-make-shared");
     CheckFactories.registerCheck<MakeUniqueCheck>("modernize-make-unique");
     CheckFactories.registerCheck<PassByValueCheck>("modernize-pass-by-value");
+    CheckFactories.registerCheck<UseDesignatedInitializersCheck>(
+        "modernize-use-designated-initializers");
     CheckFactories.registerCheck<UseStartsEndsWithCheck>(
         "modernize-use-starts-ends-with");
     CheckFactories.registerCheck<UseStdNumbersCheck>(
diff --git a/clang-tools-extra/clang-tidy/modernize/UseDesignatedInitializersCheck.cpp b/clang-tools-extra/clang-tidy/modernize/UseDesignatedInitializersCheck.cpp
new file mode 100644
index 0000000..9ff6bb1
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/modernize/UseDesignatedInitializersCheck.cpp
@@ -0,0 +1,184 @@
+//===--- UseDesignatedInitializersCheck.cpp - clang-tidy ------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "UseDesignatedInitializersCheck.h"
+#include "../utils/DesignatedInitializers.h"
+#include "clang/AST/APValue.h"
+#include "clang/AST/Decl.h"
+#include "clang/AST/Expr.h"
+#include "clang/AST/Stmt.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/ASTMatchers/ASTMatchers.h"
+#include "clang/ASTMatchers/ASTMatchersMacros.h"
+#include "clang/Basic/Diagnostic.h"
+#include "clang/Lex/Lexer.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang::tidy::modernize {
+
+static constexpr char IgnoreSingleElementAggregatesName[] =
+    "IgnoreSingleElementAggregates";
+static constexpr bool IgnoreSingleElementAggregatesDefault = true;
+
+static constexpr char RestrictToPODTypesName[] = "RestrictToPODTypes";
+static constexpr bool RestrictToPODTypesDefault = false;
+
+static constexpr char IgnoreMacrosName[] = "IgnoreMacros";
+static constexpr bool IgnoreMacrosDefault = true;
+
+namespace {
+
+struct Designators {
+
+  Designators(const InitListExpr *InitList) : InitList(InitList) {
+    assert(InitList->isSyntacticForm());
+  };
+
+  unsigned size() { return getCached().size(); }
+
+  std::optional<llvm::StringRef> operator[](const SourceLocation &Location) {
+    const auto Designators = getCached();
+    const auto Result = Designators.find(Location);
+    if (Result == Designators.end())
+      return {};
+    const llvm::StringRef Designator = Result->getSecond();
+    return (Designator.front() == '.' ? Designator.substr(1) : Designator)
+        .trim("\0"); // Trim NULL characters appearing on Windows in the
+                     // name.
+  }
+
+private:
+  using LocationToNameMap = llvm::DenseMap<clang::SourceLocation, std::string>;
+
+  std::optional<LocationToNameMap> CachedDesignators;
+  const InitListExpr *InitList;
+
+  LocationToNameMap &getCached() {
+    return CachedDesignators ? *CachedDesignators
+                             : CachedDesignators.emplace(
+                                   utils::getUnwrittenDesignators(InitList));
+  }
+};
+
+unsigned getNumberOfDesignated(const InitListExpr *SyntacticInitList) {
+  return llvm::count_if(*SyntacticInitList, [](auto *InitExpr) {
+    return isa<DesignatedInitExpr>(InitExpr);
+  });
+}
+
+AST_MATCHER(CXXRecordDecl, isAggregate) { return Node.isAggregate(); }
+
+AST_MATCHER(CXXRecordDecl, isPOD) { return Node.isPOD(); }
+
+AST_MATCHER(InitListExpr, isFullyDesignated) {
+  if (const InitListExpr *SyntacticForm =
+          Node.isSyntacticForm() ? &Node : Node.getSyntacticForm())
+    return getNumberOfDesignated(SyntacticForm) == SyntacticForm->getNumInits();
+  return true;
+}
+
+AST_MATCHER(InitListExpr, hasMoreThanOneElement) {
+  return Node.getNumInits() > 1;
+}
+
+} // namespace
+
+UseDesignatedInitializersCheck::UseDesignatedInitializersCheck(
+    StringRef Name, ClangTidyContext *Context)
+    : ClangTidyCheck(Name, Context), IgnoreSingleElementAggregates(Options.get(
+                                         IgnoreSingleElementAggregatesName,
+                                         IgnoreSingleElementAggregatesDefault)),
+      RestrictToPODTypes(
+          Options.get(RestrictToPODTypesName, RestrictToPODTypesDefault)),
+      IgnoreMacros(
+          Options.getLocalOrGlobal(IgnoreMacrosName, IgnoreMacrosDefault)) {}
+
+void UseDesignatedInitializersCheck::registerMatchers(MatchFinder *Finder) {
+  const auto HasBaseWithFields =
+      hasAnyBase(hasType(cxxRecordDecl(has(fieldDecl()))));
+  Finder->addMatcher(
+      initListExpr(
+          hasType(cxxRecordDecl(RestrictToPODTypes ? isPOD() : isAggregate(),
+                                unless(HasBaseWithFields))
+                      .bind("type")),
+          IgnoreSingleElementAggregates ? hasMoreThanOneElement() : anything(),
+          unless(isFullyDesignated()))
+          .bind("init"),
+      this);
+}
+
+void UseDesignatedInitializersCheck::check(
+    const MatchFinder::MatchResult &Result) {
+  const auto *InitList = Result.Nodes.getNodeAs<InitListExpr>("init");
+  const auto *Type = Result.Nodes.getNodeAs<CXXRecordDecl>("type");
+  if (!Type || !InitList)
+    return;
+  const auto *SyntacticInitList = InitList->getSyntacticForm();
+  if (!SyntacticInitList)
+    return;
+  Designators Designators{SyntacticInitList};
+  const unsigned NumberOfDesignated = getNumberOfDesignated(SyntacticInitList);
+  if (SyntacticInitList->getNumInits() - NumberOfDesignated >
+      Designators.size())
+    return;
+
+  // If the whole initializer list is un-designated, issue only one warning and
+  // a single fix-it for the whole expression.
+  if (0 == NumberOfDesignated) {
+    if (IgnoreMacros && InitList->getBeginLoc().isMacroID())
+      return;
+    {
+      DiagnosticBuilder Diag =
+          diag(InitList->getLBraceLoc(),
+               "use designated initializer list to initialize %0");
+      Diag << Type << InitList->getSourceRange();
+      for (const Stmt *InitExpr : *SyntacticInitList) {
+        const auto Designator = Designators[InitExpr->getBeginLoc()];
+        if (Designator && !Designator->empty())
+          Diag << FixItHint::CreateInsertion(InitExpr->getBeginLoc(),
+                                             ("." + *Designator + "=").str());
+      }
+    }
+    diag(Type->getBeginLoc(), "aggregate type is defined here",
+         DiagnosticIDs::Note);
+    return;
+  }
+
+  // In case that only a few elements are un-designated (not all as before), the
+  // check offers dedicated issues and fix-its for each of them.
+  for (const auto *InitExpr : *SyntacticInitList) {
+    if (isa<DesignatedInitExpr>(InitExpr))
+      continue;
+    if (IgnoreMacros && InitExpr->getBeginLoc().isMacroID())
+      continue;
+    const auto Designator = Designators[InitExpr->getBeginLoc()];
+    if (!Designator || Designator->empty()) {
+      // There should always be a designator. If there's unexpectedly none, we
+      // at least report a generic diagnostic.
+      diag(InitExpr->getBeginLoc(), "use designated init expression")
+          << InitExpr->getSourceRange();
+    } else {
+      diag(InitExpr->getBeginLoc(),
+           "use designated init expression to initialize field '%0'")
+          << InitExpr->getSourceRange() << *Designator
+          << FixItHint::CreateInsertion(InitExpr->getBeginLoc(),
+                                        ("." + *Designator + "=").str());
+    }
+  }
+}
+
+void UseDesignatedInitializersCheck::storeOptions(
+    ClangTidyOptions::OptionMap &Opts) {
+  Options.store(Opts, IgnoreSingleElementAggregatesName,
+                IgnoreSingleElementAggregates);
+  Options.store(Opts, RestrictToPODTypesName, RestrictToPODTypes);
+  Options.store(Opts, IgnoreMacrosName, IgnoreMacros);
+}
+
+} // namespace clang::tidy::modernize
diff --git a/clang-tools-extra/clang-tidy/modernize/UseDesignatedInitializersCheck.h b/clang-tools-extra/clang-tidy/modernize/UseDesignatedInitializersCheck.h
new file mode 100644
index 0000000..0a496f5
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/modernize/UseDesignatedInitializersCheck.h
@@ -0,0 +1,40 @@
+//===--- UseDesignatedInitializersCheck.h - clang-tidy ----------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MODERNIZE_USEDESIGNATEDINITIALIZERSCHECK_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MODERNIZE_USEDESIGNATEDINITIALIZERSCHECK_H
+
+#include "../ClangTidyCheck.h"
+
+namespace clang::tidy::modernize {
+
+/// Finds initializer lists for aggregate type that could be
+/// written as designated initializers instead.
+///
+/// For the user-facing documentation see:
+/// http://clang.llvm.org/extra/clang-tidy/checks/modernize/use-designated-initializers.html
+class UseDesignatedInitializersCheck : public ClangTidyCheck {
+public:
+  UseDesignatedInitializersCheck(StringRef Name, ClangTidyContext *Context);
+  void registerMatchers(ast_matchers::MatchFinder *Finder) override;
+  void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+  void storeOptions(ClangTidyOptions::OptionMap &Opts) override;
+
+  std::optional<TraversalKind> getCheckTraversalKind() const override {
+    return TK_IgnoreUnlessSpelledInSource;
+  }
+
+private:
+  bool IgnoreSingleElementAggregates;
+  bool RestrictToPODTypes;
+  bool IgnoreMacros;
+};
+
+} // namespace clang::tidy::modernize
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MODERNIZE_USEDESIGNATEDINITIALIZERSCHECK_H
diff --git a/clang-tools-extra/clang-tidy/utils/CMakeLists.txt b/clang-tools-extra/clang-tidy/utils/CMakeLists.txt
index 88638d4..f0160fa 100644
--- a/clang-tools-extra/clang-tidy/utils/CMakeLists.txt
+++ b/clang-tools-extra/clang-tidy/utils/CMakeLists.txt
@@ -7,6 +7,7 @@ add_clang_library(clangTidyUtils
   Aliasing.cpp
   ASTUtils.cpp
   DeclRefExprUtils.cpp
+  DesignatedInitializers.cpp
   ExceptionAnalyzer.cpp
   ExceptionSpecAnalyzer.cpp
   ExprSequence.cpp
diff --git a/clang-tools-extra/clang-tidy/utils/DesignatedInitializers.cpp b/clang-tools-extra/clang-tidy/utils/DesignatedInitializers.cpp
new file mode 100644
index 0000000..6faeb7a
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/utils/DesignatedInitializers.cpp
@@ -0,0 +1,195 @@
+//===--- DesignatedInitializers.cpp - clang-tidy --------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// This file provides utilities for designated initializers.
+///
+//===----------------------------------------------------------------------===//
+
+#include "DesignatedInitializers.h"
+#include "clang/AST/DeclCXX.h"
+#include "llvm/ADT/DenseSet.h"
+#include "llvm/ADT/ScopeExit.h"
+
+namespace clang::tidy::utils {
+
+namespace {
+
+/// Returns true if Name is reserved, like _Foo or __Vector_base.
+static inline bool isReservedName(llvm::StringRef Name) {
+  // This doesn't catch all cases, but the most common.
+  return Name.size() >= 2 && Name[0] == '_' &&
+         (isUppercase(Name[1]) || Name[1] == '_');
+}
+
+// Helper class to iterate over the designator names of an aggregate type.
+//
+// For an array type, yields [0], [1], [2]...
+// For aggregate classes, yields null for each base, then .field1, .field2,
+// ...
+class AggregateDesignatorNames {
+public:
+  AggregateDesignatorNames(QualType T) {
+    if (!T.isNull()) {
+      T = T.getCanonicalType();
+      if (T->isArrayType()) {
+        IsArray = true;
+        Valid = true;
+        return;
+      }
+      if (const RecordDecl *RD = T->getAsRecordDecl()) {
+        Valid = true;
+        FieldsIt = RD->field_begin();
+        FieldsEnd = RD->field_end();
+        if (const auto *CRD = llvm::dyn_cast<CXXRecordDecl>(RD)) {
+          BasesIt = CRD->bases_begin();
+          BasesEnd = CRD->bases_end();
+          Valid = CRD->isAggregate();
+        }
+        OneField = Valid && BasesIt == BasesEnd && FieldsIt != FieldsEnd &&
+                   std::next(FieldsIt) == FieldsEnd;
+      }
+    }
+  }
+  // Returns false if the type was not an aggregate.
+  operator bool() { return Valid; }
+  // Advance to the next element in the aggregate.
+  void next() {
+    if (IsArray)
+      ++Index;
+    else if (BasesIt != BasesEnd)
+      ++BasesIt;
+    else if (FieldsIt != FieldsEnd)
+      ++FieldsIt;
+  }
+  // Print the designator to Out.
+  // Returns false if we could not produce a designator for this element.
+  bool append(std::string &Out, bool ForSubobject) {
+    if (IsArray) {
+      Out.push_back('[');
+      Out.append(std::to_string(Index));
+      Out.push_back(']');
+      return true;
+    }
+    if (BasesIt != BasesEnd)
+      return false; // Bases can't be designated. Should we make one up?
+    if (FieldsIt != FieldsEnd) {
+      llvm::StringRef FieldName;
+      if (const IdentifierInfo *II = FieldsIt->getIdentifier())
+        FieldName = II->getName();
+
+      // For certain objects, their subobjects may be named directly.
+      if (ForSubobject &&
+          (FieldsIt->isAnonymousStructOrUnion() ||
+           // std::array<int,3> x = {1,2,3}. Designators not strictly valid!
+           (OneField && isReservedName(FieldName))))
+        return true;
+
+      if (!FieldName.empty() && !isReservedName(FieldName)) {
+        Out.push_back('.');
+        Out.append(FieldName.begin(), FieldName.end());
+        return true;
+      }
+      return false;
+    }
+    return false;
+  }
+
+private:
+  bool Valid = false;
+  bool IsArray = false;
+  bool OneField = false; // e.g. std::array { T __elements[N]; }
+  unsigned Index = 0;
+  CXXRecordDecl::base_class_const_iterator BasesIt;
+  CXXRecordDecl::base_class_const_iterator BasesEnd;
+  RecordDecl::field_iterator FieldsIt;
+  RecordDecl::field_iterator FieldsEnd;
+};
+
+// Collect designator labels describing the elements of an init list.
+//
+// This function contributes the designators of some (sub)object, which is
+// represented by the semantic InitListExpr Sem.
+// This includes any nested subobjects, but *only* if they are part of the
+// same original syntactic init list (due to brace elision). In other words,
+// it may descend into subobjects but not written init-lists.
+//
+// For example: struct Outer { Inner a,b; }; struct Inner { int x, y; }
+//              Outer o{{1, 2}, 3};
+// This function will be called with Sem = { {1, 2}, {3, ImplicitValue} }
+// It should generate designators '.a:' and '.b.x:'.
+// '.a:' is produced directly without recursing into the written sublist.
+// (The written sublist will have a separate collectDesignators() call later).
+// Recursion with Prefix='.b' and Sem = {3, ImplicitValue} produces '.b.x:'.
+void collectDesignators(const InitListExpr *Sem,
+                        llvm::DenseMap<SourceLocation, std::string> &Out,
+                        const llvm::DenseSet<SourceLocation> &NestedBraces,
+                        std::string &Prefix) {
+  if (!Sem || Sem->isTransparent())
+    return;
+  assert(Sem->isSemanticForm());
+
+  // The elements of the semantic form all correspond to direct subobjects of
+  // the aggregate type. `Fields` iterates over these subobject names.
+  AggregateDesignatorNames Fields(Sem->getType());
+  if (!Fields)
+    return;
+  for (const Expr *Init : Sem->inits()) {
+    auto Next = llvm::make_scope_exit([&, Size(Prefix.size())] {
+      Fields.next();       // Always advance to the next subobject name.
+      Prefix.resize(Size); // Erase any designator we appended.
+    });
+    // Skip for a broken initializer or if it is a "hole" in a subobject that
+    // was not explicitly initialized.
+    if (!Init || llvm::isa<ImplicitValueInitExpr>(Init))
+      continue;
+
+    const auto *BraceElidedSubobject = llvm::dyn_cast<InitListExpr>(Init);
+    if (BraceElidedSubobject &&
+        NestedBraces.contains(BraceElidedSubobject->getLBraceLoc()))
+      BraceElidedSubobject = nullptr; // there were braces!
+
+    if (!Fields.append(Prefix, BraceElidedSubobject != nullptr))
+      continue; // no designator available for this subobject
+    if (BraceElidedSubobject) {
+      // If the braces were elided, this aggregate subobject is initialized
+      // inline in the same syntactic list.
+      // Descend into the semantic list describing the subobject.
+      // (NestedBraces are still correct, they're from the same syntactic
+      // list).
+      collectDesignators(BraceElidedSubobject, Out, NestedBraces, Prefix);
+      continue;
+    }
+    Out.try_emplace(Init->getBeginLoc(), Prefix);
+  }
+}
+
+} // namespace
+
+llvm::DenseMap<SourceLocation, std::string>
+getUnwrittenDesignators(const InitListExpr *Syn) {
+  assert(Syn->isSyntacticForm());
+
+  // collectDesignators needs to know which InitListExprs in the semantic tree
+  // were actually written, but InitListExpr::isExplicit() lies.
+  // Instead, record where braces of sub-init-lists occur in the syntactic form.
+  llvm::DenseSet<SourceLocation> NestedBraces;
+  for (const Expr *Init : Syn->inits())
+    if (auto *Nested = llvm::dyn_cast<InitListExpr>(Init))
+      NestedBraces.insert(Nested->getLBraceLoc());
+
+  // Traverse the semantic form to find the designators.
+  // We use their SourceLocation to correlate with the syntactic form later.
+  llvm::DenseMap<SourceLocation, std::string> Designators;
+  std::string EmptyPrefix;
+  collectDesignators(Syn->isSemanticForm() ? Syn : Syn->getSemanticForm(),
+                     Designators, NestedBraces, EmptyPrefix);
+  return Designators;
+}
+
+} // namespace clang::tidy::utils
diff --git a/clang-tools-extra/clang-tidy/utils/DesignatedInitializers.h b/clang-tools-extra/clang-tidy/utils/DesignatedInitializers.h
new file mode 100644
index 0000000..a6cb296
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/utils/DesignatedInitializers.h
@@ -0,0 +1,42 @@
+//===--- DesignatedInitializers.h - clang-tidy ------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// This file provides utilities for designated initializers.
+///
+//===----------------------------------------------------------------------===//
+
+#include "clang/AST/Expr.h"
+#include "clang/Basic/SourceLocation.h"
+#include "llvm/ADT/DenseMap.h"
+
+namespace clang::tidy::utils {
+
+/// Get designators describing the elements of a (syntactic) init list.
+///
+/// Given for example the type
+/// \code
+/// struct S { int i, j; };
+/// \endcode
+/// and the definition
+/// \code
+///  S s{1, 2};
+/// \endcode
+/// calling `getUnwrittenDesignators` for the initializer list expression
+/// `{1, 2}` would produce the map `{loc(1): ".i", loc(2): ".j"}`.
+///
+/// It does not produce designators for any explicitly-written nested lists,
+/// e.g. `{1, .j=2}` would only return `{loc(1): ".i"}`.
+///
+/// It also considers structs with fields of record types like
+/// `struct T { S s; };`. In this case, there would be designators of the
+/// form `.s.i` and `.s.j` in the returned map.
+llvm::DenseMap<clang::SourceLocation, std::string>
+getUnwrittenDesignators(const clang::InitListExpr *Syn);
+
+} // namespace clang::tidy::utils
diff --git a/clang-tools-extra/clangd/CMakeLists.txt b/clang-tools-extra/clangd/CMakeLists.txt
index 3911fb6..f497041 100644
--- a/clang-tools-extra/clangd/CMakeLists.txt
+++ b/clang-tools-extra/clangd/CMakeLists.txt
@@ -182,6 +182,7 @@ target_link_libraries(clangDaemon
   clangIncludeCleaner
   clangPseudo
   clangTidy
+  clangTidyUtils
 
   clangdSupport
   )
diff --git a/clang-tools-extra/clangd/InlayHints.cpp b/clang-tools-extra/clangd/InlayHints.cpp
index 671a9c3..a0ebc63 100644
--- a/clang-tools-extra/clangd/InlayHints.cpp
+++ b/clang-tools-extra/clangd/InlayHints.cpp
@@ -6,6 +6,7 @@
 //
 //===----------------------------------------------------------------------===//
 #include "InlayHints.h"
+#include "../clang-tidy/utils/DesignatedInitializers.h"
 #include "AST.h"
 #include "Config.h"
 #include "HeuristicResolver.h"
@@ -24,7 +25,6 @@
 #include "clang/Basic/OperatorKinds.h"
 #include "clang/Basic/SourceManager.h"
 #include "llvm/ADT/DenseSet.h"
-#include "llvm/ADT/ScopeExit.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/Twine.h"
@@ -42,169 +42,6 @@ namespace {
 // For now, inlay hints are always anchored at the left or right of their range.
 enum class HintSide { Left, Right };
 
-// Helper class to iterate over the designator names of an aggregate type.
-//
-// For an array type, yields [0], [1], [2]...
-// For aggregate classes, yields null for each base, then .field1, .field2, ...
-class AggregateDesignatorNames {
-public:
-  AggregateDesignatorNames(QualType T) {
-    if (!T.isNull()) {
-      T = T.getCanonicalType();
-      if (T->isArrayType()) {
-        IsArray = true;
-        Valid = true;
-        return;
-      }
-      if (const RecordDecl *RD = T->getAsRecordDecl()) {
-        Valid = true;
-        FieldsIt = RD->field_begin();
-        FieldsEnd = RD->field_end();
-        if (const auto *CRD = llvm::dyn_cast<CXXRecordDecl>(RD)) {
-          BasesIt = CRD->bases_begin();
-          BasesEnd = CRD->bases_end();
-          Valid = CRD->isAggregate();
-        }
-        OneField = Valid && BasesIt == BasesEnd && FieldsIt != FieldsEnd &&
-                   std::next(FieldsIt) == FieldsEnd;
-      }
-    }
-  }
-  // Returns false if the type was not an aggregate.
-  operator bool() { return Valid; }
-  // Advance to the next element in the aggregate.
-  void next() {
-    if (IsArray)
-      ++Index;
-    else if (BasesIt != BasesEnd)
-      ++BasesIt;
-    else if (FieldsIt != FieldsEnd)
-      ++FieldsIt;
-  }
-  // Print the designator to Out.
-  // Returns false if we could not produce a designator for this element.
-  bool append(std::string &Out, bool ForSubobject) {
-    if (IsArray) {
-      Out.push_back('[');
-      Out.append(std::to_string(Index));
-      Out.push_back(']');
-      return true;
-    }
-    if (BasesIt != BasesEnd)
-      return false; // Bases can't be designated. Should we make one up?
-    if (FieldsIt != FieldsEnd) {
-      llvm::StringRef FieldName;
-      if (const IdentifierInfo *II = FieldsIt->getIdentifier())
-        FieldName = II->getName();
-
-      // For certain objects, their subobjects may be named directly.
-      if (ForSubobject &&
-          (FieldsIt->isAnonymousStructOrUnion() ||
-           // std::array<int,3> x = {1,2,3}. Designators not strictly valid!
-           (OneField && isReservedName(FieldName))))
-        return true;
-
-      if (!FieldName.empty() && !isReservedName(FieldName)) {
-        Out.push_back('.');
-        Out.append(FieldName.begin(), FieldName.end());
-        return true;
-      }
-      return false;
-    }
-    return false;
-  }
-
-private:
-  bool Valid = false;
-  bool IsArray = false;
-  bool OneField = false; // e.g. std::array { T __elements[N]; }
-  unsigned Index = 0;
-  CXXRecordDecl::base_class_const_iterator BasesIt;
-  CXXRecordDecl::base_class_const_iterator BasesEnd;
-  RecordDecl::field_iterator FieldsIt;
-  RecordDecl::field_iterator FieldsEnd;
-};
-
-// Collect designator labels describing the elements of an init list.
-//
-// This function contributes the designators of some (sub)object, which is
-// represented by the semantic InitListExpr Sem.
-// This includes any nested subobjects, but *only* if they are part of the same
-// original syntactic init list (due to brace elision).
-// In other words, it may descend into subobjects but not written init-lists.
-//
-// For example: struct Outer { Inner a,b; }; struct Inner { int x, y; }
-//              Outer o{{1, 2}, 3};
-// This function will be called with Sem = { {1, 2}, {3, ImplicitValue} }
-// It should generate designators '.a:' and '.b.x:'.
-// '.a:' is produced directly without recursing into the written sublist.
-// (The written sublist will have a separate collectDesignators() call later).
-// Recursion with Prefix='.b' and Sem = {3, ImplicitValue} produces '.b.x:'.
-void collectDesignators(const InitListExpr *Sem,
-                        llvm::DenseMap<SourceLocation, std::string> &Out,
-                        const llvm::DenseSet<SourceLocation> &NestedBraces,
-                        std::string &Prefix) {
-  if (!Sem || Sem->isTransparent())
-    return;
-  assert(Sem->isSemanticForm());
-
-  // The elements of the semantic form all correspond to direct subobjects of
-  // the aggregate type. `Fields` iterates over these subobject names.
-  AggregateDesignatorNames Fields(Sem->getType());
-  if (!Fields)
-    return;
-  for (const Expr *Init : Sem->inits()) {
-    auto Next = llvm::make_scope_exit([&, Size(Prefix.size())] {
-      Fields.next();       // Always advance to the next subobject name.
-      Prefix.resize(Size); // Erase any designator we appended.
-    });
-    // Skip for a broken initializer or if it is a "hole" in a subobject that
-    // was not explicitly initialized.
-    if (!Init || llvm::isa<ImplicitValueInitExpr>(Init))
-      continue;
-
-    const auto *BraceElidedSubobject = llvm::dyn_cast<InitListExpr>(Init);
-    if (BraceElidedSubobject &&
-        NestedBraces.contains(BraceElidedSubobject->getLBraceLoc()))
-      BraceElidedSubobject = nullptr; // there were braces!
-
-    if (!Fields.append(Prefix, BraceElidedSubobject != nullptr))
-      continue; // no designator available for this subobject
-    if (BraceElidedSubobject) {
-      // If the braces were elided, this aggregate subobject is initialized
-      // inline in the same syntactic list.
-      // Descend into the semantic list describing the subobject.
-      // (NestedBraces are still correct, they're from the same syntactic list).
-      collectDesignators(BraceElidedSubobject, Out, NestedBraces, Prefix);
-      continue;
-    }
-    Out.try_emplace(Init->getBeginLoc(), Prefix);
-  }
-}
-
-// Get designators describing the elements of a (syntactic) init list.
-// This does not produce designators for any explicitly-written nested lists.
-llvm::DenseMap<SourceLocation, std::string>
-getDesignators(const InitListExpr *Syn) {
-  assert(Syn->isSyntacticForm());
-
-  // collectDesignators needs to know which InitListExprs in the semantic tree
-  // were actually written, but InitListExpr::isExplicit() lies.
-  // Instead, record where braces of sub-init-lists occur in the syntactic form.
-  llvm::DenseSet<SourceLocation> NestedBraces;
-  for (const Expr *Init : Syn->inits())
-    if (auto *Nested = llvm::dyn_cast<InitListExpr>(Init))
-      NestedBraces.insert(Nested->getLBraceLoc());
-
-  // Traverse the semantic form to find the designators.
-  // We use their SourceLocation to correlate with the syntactic form later.
-  llvm::DenseMap<SourceLocation, std::string> Designators;
-  std::string EmptyPrefix;
-  collectDesignators(Syn->isSemanticForm() ? Syn : Syn->getSemanticForm(),
-                     Designators, NestedBraces, EmptyPrefix);
-  return Designators;
-}
-
 void stripLeadingUnderscores(StringRef &Name) { Name = Name.ltrim('_'); }
 
 // getDeclForType() returns the decl responsible for Type's spelling.
@@ -847,14 +684,15 @@ public:
     // This is the one we will ultimately attach designators to.
     // It may have subobject initializers inlined without braces. The *semantic*
     // form of the init-list has nested init-lists for these.
-    // getDesignators will look at the semantic form to determine the labels.
+    // getUnwrittenDesignators will look at the semantic form to determine the
+    // labels.
     assert(Syn->isSyntacticForm() && "RAV should not visit implicit code!");
     if (!Cfg.InlayHints.Designators)
       return true;
     if (Syn->isIdiomaticZeroInitializer(AST.getLangOpts()))
       return true;
     llvm::DenseMap<SourceLocation, std::string> Designators =
-        getDesignators(Syn);
+        tidy::utils::getUnwrittenDesignators(Syn);
     for (const Expr *Init : Syn->inits()) {
       if (llvm::isa<DesignatedInitExpr>(Init))
         continue;
diff --git a/clang-tools-extra/clangd/tool/CMakeLists.txt b/clang-tools-extra/clangd/tool/CMakeLists.txt
index 6c21175..4012b64 100644
--- a/clang-tools-extra/clangd/tool/CMakeLists.txt
+++ b/clang-tools-extra/clangd/tool/CMakeLists.txt
@@ -33,6 +33,7 @@ clang_target_link_libraries(clangdMain
 target_link_libraries(clangdMain
   PRIVATE
   clangTidy
+  clangTidyUtils
 
   clangDaemon
   clangdRemoteIndex
diff --git a/clang-tools-extra/clangd/unittests/CMakeLists.txt b/clang-tools-extra/clangd/unittests/CMakeLists.txt
index 9cd195e..e432db8 100644
--- a/clang-tools-extra/clangd/unittests/CMakeLists.txt
+++ b/clang-tools-extra/clangd/unittests/CMakeLists.txt
@@ -175,6 +175,7 @@ target_link_libraries(ClangdTests
   clangIncludeCleaner
   clangTesting
   clangTidy
+  clangTidyUtils
   clangdSupport
   )
 
diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
index 3f90e7d..5bae530 100644
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -104,6 +104,12 @@ Improvements to clang-tidy
 New checks
 ^^^^^^^^^^
 
+- New :doc:`modernize-use-designated-initializers
+  <clang-tidy/checks/modernize/use-designated-initializers>` check.
+
+  Finds initializer lists for aggregate types that could be
+  written as designated initializers instead.
+
 - New :doc:`readability-use-std-min-max
   <clang-tidy/checks/readability/use-std-min-max>` check.
 
diff --git a/clang-tools-extra/docs/clang-tidy/checks/list.rst b/clang-tools-extra/docs/clang-tidy/checks/list.rst
index 59ef69f..5e57bc0 100644
--- a/clang-tools-extra/docs/clang-tidy/checks/list.rst
+++ b/clang-tools-extra/docs/clang-tidy/checks/list.rst
@@ -287,6 +287,7 @@ Clang-Tidy Checks
    :doc:`modernize-use-bool-literals <modernize/use-bool-literals>`, "Yes"
    :doc:`modernize-use-constraints <modernize/use-constraints>`, "Yes"
    :doc:`modernize-use-default-member-init <modernize/use-default-member-init>`, "Yes"
+   :doc:`modernize-use-designated-initializers <modernize/use-designated-initializers>`, "Yes"
    :doc:`modernize-use-emplace <modernize/use-emplace>`, "Yes"
    :doc:`modernize-use-equals-default <modernize/use-equals-default>`, "Yes"
    :doc:`modernize-use-equals-delete <modernize/use-equals-delete>`, "Yes"
diff --git a/clang-tools-extra/docs/clang-tidy/checks/modernize/use-designated-initializers.rst b/clang-tools-extra/docs/clang-tidy/checks/modernize/use-designated-initializers.rst
new file mode 100644
index 0000000..22f5098
--- /dev/null
+++ b/clang-tools-extra/docs/clang-tidy/checks/modernize/use-designated-initializers.rst
@@ -0,0 +1,62 @@
+.. title:: clang-tidy - modernize-use-designated-initializers
+
+modernize-use-designated-initializers
+=====================================
+
+Finds initializer lists for aggregate types which could be written as designated
+initializers instead.
+
+With plain initializer lists, it is very easy to introduce bugs when adding new
+fields in the middle of a struct or class type. The same confusion might arise
+when changing the order of fields.
+
+C++20 supports the designated initializer syntax for aggregate types. By
+applying it, we can always be sure that aggregates are constructed correctly,
+because every variable being initialized is referenced by its name.
+
+Example:
+
+.. code-block::
+
+    struct S { int i, j; };
+
+is an aggregate type that should be initialized as
+
+.. code-block::
+
+    S s{.i = 1, .j = 2};
+
+instead of
+
+.. code-block::
+
+    S s{1, 2};
+
+which could easily become an issue when ``i`` and ``j`` are swapped in the
+declaration of ``S``.
+
+Even when compiling in a language version older than C++20, depending on your
+compiler, designated initializers are potentially supported. Therefore, the
+check is not restricted to C++20 and newer versions. Check out the options
+``-Wc99-designator`` to get support for mixed designators in initializer list in
+C and ``-Wc++20-designator`` for support of designated initializers in older C++
+language modes.
+
+Options
+-------
+
+.. option::  IgnoreMacros
+
+  The value `false` specifies that components of initializer lists expanded from
+  macros are not checked. The default value is `true`.
+
+.. option:: IgnoreSingleElementAggregates
+
+    The value `false` specifies that even initializers for aggregate types with
+    only a single element should be checked. The default value is `true`.
+
+.. option:: RestrictToPODTypes
+
+    The value `true` specifies that only Plain Old Data (POD) types shall be
+    checked. This makes the check applicable to even older C++ standards. The
+    default value is `false`.
diff --git a/clang-tools-extra/test/clang-tidy/checkers/modernize/use-designated-initializers.cpp b/clang-tools-extra/test/clang-tidy/checkers/modernize/use-designated-initializers.cpp
new file mode 100644
index 0000000..7e5c26e3
--- /dev/null
+++ b/clang-tools-extra/test/clang-tidy/checkers/modernize/use-designated-initializers.cpp
@@ -0,0 +1,203 @@
+// RUN: %check_clang_tidy -std=c++17 %s modernize-use-designated-initializers %t \
+// RUN:     -- \
+// RUN:     -- -fno-delayed-template-parsing
+// RUN: %check_clang_tidy -check-suffixes=,SINGLE-ELEMENT -std=c++17 %s modernize-use-designated-initializers %t \
+// RUN:     -- -config="{CheckOptions: {modernize-use-designated-initializers.IgnoreSingleElementAggregates: false}}" \
+// RUN:     -- -fno-delayed-template-parsing
+// RUN: %check_clang_tidy -check-suffixes=POD -std=c++17 %s modernize-use-designated-initializers %t \
+// RUN:     -- -config="{CheckOptions: {modernize-use-designated-initializers.RestrictToPODTypes: true}}" \
+// RUN:     -- -fno-delayed-template-parsing
+// RUN: %check_clang_tidy -check-suffixes=,MACROS -std=c++17 %s modernize-use-designated-initializers %t \
+// RUN:     -- -config="{CheckOptions: {modernize-use-designated-initializers.IgnoreMacros: false}}" \
+// RUN:     -- -fno-delayed-template-parsing
+
+struct S1 {};
+
+S1 s11{};
+S1 s12 = {};
+S1 s13();
+S1 s14;
+
+struct S2 { int i, j; };
+
+S2 s21{.i=1, .j =2};
+
+S2 s22 = {1, 2};
+// CHECK-MESSAGES: :[[@LINE-1]]:10: warning: use designated initializer list to initialize 'S2' [modernize-use-designated-initializers]
+// CHECK-MESSAGES: :[[@LINE-6]]:1: note: aggregate type is defined here
+// CHECK-MESSAGES-POD: :[[@LINE-3]]:10: warning: use designated initializer list to initialize 'S2' [modernize-use-designated-initializers]
+// CHECK-MESSAGES-POD: :[[@LINE-8]]:1: note: aggregate type is defined here
+// CHECK-FIXES: S2 s22 = {.i=1, .j=2};
+
+S2 s23{1};
+// CHECK-MESSAGES: :[[@LINE-1]]:7: warning: use designated initializer list to initialize 'S2' [modernize-use-designated-initializers]
+// CHECK-MESSAGES: :[[@LINE-13]]:1: note: aggregate type is defined here
+// CHECK-MESSAGES-POD: :[[@LINE-3]]:7: warning: use designated initializer list to initialize 'S2' [modernize-use-designated-initializers]
+// CHECK-MESSAGES-POD: :[[@LINE-15]]:1: note: aggregate type is defined here
+// CHECK-FIXES: S2 s23{.i=1};
+
+S2 s24{.i = 1};
+
+S2 s25 = {.i=1, 2};
+// CHECK-MESSAGES: :[[@LINE-1]]:17: warning: use designated init expression to initialize field 'j' [modernize-use-designated-initializers]
+// CHECK-MESSAGES-POD: :[[@LINE-2]]:17: warning: use designated init expression to initialize field 'j' [modernize-use-designated-initializers]
+// CHECK-FIXES: S2 s25 = {.i=1, .j=2};
+
+class S3 {
+  public:
+    S2 s2;
+    double d;
+};
+
+S3 s31 = {.s2 = 1, 2, 3.1};
+// CHECK-MESSAGES: :[[@LINE-1]]:20: warning: use designated init expression to initialize field 's2.j' [modernize-use-designated-initializers]
+// CHECK-MESSAGES: :[[@LINE-2]]:23: warning: use designated init expression to initialize field 'd' [modernize-use-designated-initializers]
+// CHECK-MESSAGES-POD: :[[@LINE-3]]:20: warning: use designated init expression to initialize field 's2.j' [modernize-use-designated-initializers]
+// CHECK-MESSAGES-POD: :[[@LINE-4]]:23: warning: use designated init expression to initialize field 'd' [modernize-use-designated-initializers]
+// CHECK-FIXES: S3 s31 = {.s2 = 1, .s2.j=2, .d=3.1};
+
+S3 s32 = {{.i = 1, 2}};
+// CHECK-MESSAGES: :[[@LINE-1]]:10: warning: use designated initializer list to initialize 'S3' [modernize-use-designated-initializers]
+// CHECK-MESSAGES: :[[@LINE-15]]:1: note: aggregate type is defined here
+// CHECK-MESSAGES: :[[@LINE-3]]:20: warning: use designated init expression to initialize field 'j' [modernize-use-designated-initializers]
+// CHECK-MESSAGES-POD: :[[@LINE-4]]:10: warning: use designated initializer list to initialize 'S3' [modernize-use-designated-initializers]
+// CHECK-MESSAGES-POD: :[[@LINE-18]]:1: note: aggregate type is defined here
+// CHECK-MESSAGES-POD: :[[@LINE-6]]:20: warning: use designated init expression to initialize field 'j' [modernize-use-designated-initializers]
+// CHECK-FIXES: S3 s32 = {.s2={.i = 1, .j=2}};
+
+S3 s33 = {{2}, .d=3.1};
+// CHECK-MESSAGES: :[[@LINE-1]]:11: warning: use designated init expression to initialize field 's2' [modernize-use-designated-initializers]
+// CHECK-MESSAGES: :[[@LINE-2]]:11: warning: use designated initializer list to initialize 'S2' [modernize-use-designated-initializers]
+// CHECK-MESSAGES: :[[@LINE-50]]:1: note: aggregate type is defined here
+// CHECK-MESSAGES-POD: :[[@LINE-4]]:11: warning: use designated init expression to initialize field 's2' [modernize-use-designated-initializers]
+// CHECK-MESSAGES-POD: :[[@LINE-5]]:11: warning: use designated initializer list to initialize 'S2' [modernize-use-designated-initializers]
+// CHECK-MESSAGES-POD: :[[@LINE-53]]:1: note: aggregate type is defined here
+// CHECK-FIXES: S3 s33 = {.s2={.i=2}, .d=3.1};
+
+struct S4 {
+    double d;
+    private: static int i;
+};
+
+S4 s41 {2.2};
+// CHECK-MESSAGES-SINGLE-ELEMENT: :[[@LINE-1]]:8: warning: use designated initializer list to initialize 'S4' [modernize-use-designated-initializers]
+// CHECK-MESSAGES-SINGLE-ELEMENT: :[[@LINE-7]]:1: note: aggregate type is defined here
+// CHECK-FIXES-SINGLE-ELEMENT: S4 s41 {.d=2.2};
+
+S4 s42 = {{}};
+// CHECK-MESSAGES-SINGLE-ELEMENT: :[[@LINE-1]]:10: warning: use designated initializer list to initialize 'S4' [modernize-use-designated-initializers]
+// CHECK-MESSAGES-SINGLE-ELEMENT: :[[@LINE-12]]:1: note: aggregate type is defined here
+// CHECK-FIXES-SINGLE-ELEMENT: S4 s42 = {.d={}};
+
+template<typename S> S template1() { return {10, 11}; }
+
+S2 s26 = template1<S2>();
+
+template<typename S> S template2() { return {}; }
+
+S2 s27 = template2<S2>();
+
+struct S5: S2 { int x, y; };
+
+S5 s51 {1, 2, .x = 3, .y = 4};
+
+struct S6 {
+    int i;
+    struct { int j; } s;
+};
+
+S6 s61 {1, 2};
+// CHECK-MESSAGES: :[[@LINE-1]]:8: warning: use designated initializer list to initialize 'S6' [modernize-use-designated-initializers]
+// CHECK-MESSAGES: :[[@LINE-7]]:1: note: aggregate type is defined here
+// CHECK-MESSAGES-POD: :[[@LINE-3]]:8: warning: use designated initializer list to initialize 'S6' [modernize-use-designated-initializers]
+// CHECK-MESSAGES-POD: :[[@LINE-9]]:1: note: aggregate type is defined here
+// CHECK-FIXES: S6 s61 {.i=1, .s.j=2};
+
+struct S7 {
+    union {
+        int k;
+        double d;
+    } u;
+};
+
+S7 s71 {1};
+// CHECK-MESSAGES-SINGLE-ELEMENT: :[[@LINE-1]]:8: warning: use designated initializer list to initialize 'S7' [modernize-use-designated-initializers]
+// CHECK-MESSAGES-SINGLE-ELEMENT: :[[@LINE-9]]:1: note: aggregate type is defined here
+// CHECK-FIXES-SINGLE-ELEMENT: S7 s71 {.u.k=1};
+
+struct S8: S7 { int i; };
+
+S8 s81{1, 2};
+
+struct S9 {
+    int i, j;
+    S9 &operator=(S9);
+};
+
+S9 s91{1, 2};
+// CHECK-MESSAGES: :[[@LINE-1]]:7: warning: use designated initializer list to initialize 'S9' [modernize-use-designated-initializers]
+// CHECK-MESSAGES: :[[@LINE-7]]:1: note: aggregate type is defined here
+// CHECK-FIXES: S9 s91{.i=1, .j=2};
+
+struct S10 { int i = 1, j = 2; };
+
+S10 s101 {1, .j=2};
+// CHECK-MESSAGES: :[[@LINE-1]]:11: warning: use designated init expression to initialize field 'i' [modernize-use-designated-initializers]
+// CHECK-FIXES: S10 s101 {.i=1, .j=2};
+
+struct S11 { int i; S10 s10; };
+
+S11 s111 { .i = 1 };
+S11 s112 { 1 };
+// CHECK-MESSAGES: :[[@LINE-1]]:10: warning: use designated initializer list to initialize 'S11' [modernize-use-designated-initializers]
+// CHECK-MESSAGES: :[[@LINE-5]]:1: note: aggregate type is defined here
+// CHECK-FIXES: S11 s112 { .i=1 };
+
+S11 s113 { .i=1, {}};
+// CHECK-MESSAGES: :[[@LINE-1]]:18: warning: use designated init expression to initialize field 's10' [modernize-use-designated-initializers]
+// CHECK-FIXES: S11 s113 { .i=1, .s10={}};
+
+S11 s114 { .i=1, .s10={1, .j=2}};
+// CHECK-MESSAGES: :[[@LINE-1]]:24: warning: use designated init expression to initialize field 'i' [modernize-use-designated-initializers]
+// CHECK-FIXES: S11 s114 { .i=1, .s10={.i=1, .j=2}};
+
+struct S12 {
+    int i;
+    struct { int j; };
+};
+
+S12 s121 {1, 2};
+// CHECK-MESSAGES: :[[@LINE-1]]:10: warning: use designated initializer list to initialize 'S12' [modernize-use-designated-initializers]
+// CHECK-MESSAGES: :[[@LINE-7]]:1: note: aggregate type is defined here
+// CHECK-MESSAGES-POD: :[[@LINE-3]]:10: warning: use designated initializer list to initialize 'S12' [modernize-use-designated-initializers]
+// CHECK-MESSAGES-POD: :[[@LINE-9]]:1: note: aggregate type is defined here
+// CHECK-FIXES: S12 s121 {.i=1, .j=2};
+
+struct S13 {
+    union {
+        int k;
+        double d;
+    };
+    int i;
+};
+
+S13 s131 {1, 2};
+// CHECK-MESSAGES: :[[@LINE-1]]:10: warning: use designated initializer list to initialize 'S13' [modernize-use-designated-initializers]
+// CHECK-MESSAGES: :[[@LINE-10]]:1: note: aggregate type is defined here
+// CHECK-MESSAGES-POD: :[[@LINE-3]]:10: warning: use designated initializer list to initialize 'S13' [modernize-use-designated-initializers]
+// CHECK-MESSAGES-POD: :[[@LINE-12]]:1: note: aggregate type is defined here
+// CHECK-FIXES: S13 s131 {.k=1, .i=2};
+
+#define A (3+2)
+#define B .j=1
+
+S9 s92 {A, B};
+// CHECK-MESSAGES-MACROS: :[[@LINE-1]]:9: warning: use designated init expression to initialize field 'i' [modernize-use-designated-initializers]
+// CHECK-MESSAGES-MACROS: :[[@LINE-5]]:11: note: expanded from macro 'A'
+
+#define DECLARE_S93 S9 s93 {1, 2}
+
+DECLARE_S93;
+// CHECK-MESSAGES-MACROS: :[[@LINE-1]]:1: warning: use designated initializer list to initialize 'S9' [modernize-use-designated-initializers]
+// CHECK-MESSAGES-MACROS: :[[@LINE-4]]:28: note: expanded from macro 'DECLARE_S93'
+// CHECK-MESSAGES-MACROS: :[[@LINE-71]]:1: note: aggregate type is defined here