Reapply "[Clang] Implement resolution for CWG1835 (#92957)" (#98547)

Reapplies #92957, fixing an instance where the `template` keyword was
missing prior to a dependent name in `llvm/ADT/ArrayRef.h`. An
_alias-declaration_ is used to work around a bug affecting GCC releases
before 11.1 (see https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94799) which
rejects the use of the `template` keyword prior to the
_nested-name-specifier_ in the class member access.

1 files changed, 25 insertions, 18 deletions

diff --git a/clang/lib/Serialization/ASTWriterStmt.cpp b/clang/lib/Serialization/ASTWriterStmt.cpp
index ea49901..30c5b1b 100644
--- a/clang/lib/Serialization/ASTWriterStmt.cpp
+++ b/clang/lib/Serialization/ASTWriterStmt.cpp
@@ -1988,34 +1988,41 @@ void ASTStmtWriter::VisitCXXDependentScopeMemberExpr(
     CXXDependentScopeMemberExpr *E) {
   VisitExpr(E);
 
-  // Don't emit anything here (or if you do you will have to update
-  // the corresponding deserialization function).
-  Record.push_back(E->getNumTemplateArgs());
-  CurrentPackingBits.updateBits();
-  CurrentPackingBits.addBit(E->hasTemplateKWAndArgsInfo());
-  CurrentPackingBits.addBit(E->hasFirstQualifierFoundInScope());
-
-  if (E->hasTemplateKWAndArgsInfo()) {
-    const ASTTemplateKWAndArgsInfo &ArgInfo =
-        *E->getTrailingObjects<ASTTemplateKWAndArgsInfo>();
-    AddTemplateKWAndArgsInfo(ArgInfo,
-                             E->getTrailingObjects<TemplateArgumentLoc>());
-  }
+  bool HasQualifier = E->hasQualifier();
+  unsigned NumUnqualifiedLookups = E->getNumUnqualifiedLookups();
+  bool HasTemplateInfo = E->hasTemplateKWAndArgsInfo();
+  unsigned NumTemplateArgs = E->getNumTemplateArgs();
 
-  CurrentPackingBits.addBit(E->isArrow());
+  // Write these first for easy access when deserializing, as they affect the
+  // size of the CXXDependentScopeMemberExpr.
+  CurrentPackingBits.updateBits();
+  CurrentPackingBits.addBit(HasQualifier);
+  CurrentPackingBits.addBit(HasTemplateInfo);
+  Record.push_back(NumUnqualifiedLookups);
+  Record.push_back(NumTemplateArgs);
 
   Record.AddTypeRef(E->getBaseType());
-  Record.AddNestedNameSpecifierLoc(E->getQualifierLoc());
+  CurrentPackingBits.addBit(E->isArrow());
   CurrentPackingBits.addBit(!E->isImplicitAccess());
   if (!E->isImplicitAccess())
     Record.AddStmt(E->getBase());
 
   Record.AddSourceLocation(E->getOperatorLoc());
 
-  if (E->hasFirstQualifierFoundInScope())
-    Record.AddDeclRef(E->getFirstQualifierFoundInScope());
-
   Record.AddDeclarationNameInfo(E->MemberNameInfo);
+
+  if (HasQualifier)
+    Record.AddNestedNameSpecifierLoc(E->getQualifierLoc());
+
+  for (DeclAccessPair D : E->unqualified_lookups()) {
+    Record.AddDeclRef(D.getDecl());
+    Record.push_back(D.getAccess());
+  }
+
+  if (HasTemplateInfo)
+    AddTemplateKWAndArgsInfo(*E->getTrailingObjects<ASTTemplateKWAndArgsInfo>(),
+                             E->getTrailingObjects<TemplateArgumentLoc>());
+
   Code = serialization::EXPR_CXX_DEPENDENT_SCOPE_MEMBER;
 }