[Clang] Fix pack indexing profiling (#139276)

When profiling a pack indexing that has been partially substituted, we
should profile the expansions, rather than the pattern itseld

This is a better approach to #139057

This mirrors the fix done for SizeOfPackExpr in #124533

Fixes #138255

Author: cor3ntin

clang/docs/ReleaseNotes.rst

@@ -679,6 +679,7 @@ Bug Fixes to C++ Support
   whose type depends on itself. (#GH51347), (#GH55872)
 - Improved parser recovery of invalid requirement expressions. In turn, this
   fixes crashes from follow-on processing of the invalid requirement. (#GH138820)
+- Fixed the handling of pack indexing types in the constraints of a member function redeclaration. (#GH138255)
 
 Bug Fixes to AST Handling
 ^^^^^^^^^^^^^^^^^^^^^^^^^

clang/include/clang/AST/ASTContext.h

@@ -221,7 +221,8 @@ class ASTContext : public RefCountedBase<ASTContext> {
   mutable llvm::ContextualFoldingSet<DependentDecltypeType, ASTContext &>
       DependentDecltypeTypes;
 
-  mutable llvm::FoldingSet<PackIndexingType> DependentPackIndexingTypes;
+  mutable llvm::ContextualFoldingSet<PackIndexingType, ASTContext &>
+      DependentPackIndexingTypes;
 
   mutable llvm::FoldingSet<TemplateTypeParmType> TemplateTypeParmTypes;
   mutable llvm::FoldingSet<ObjCTypeParamType> ObjCTypeParamTypes;

clang/include/clang/AST/ExprCXX.h

@@ -4547,6 +4547,7 @@ class PackIndexingExpr final
   static PackIndexingExpr *CreateDeserialized(ASTContext &Context,
                                               unsigned NumTransformedExprs);
 
+  // The index expression and all elements of the pack have been substituted.
   bool isFullySubstituted() const { return FullySubstituted; }
 
   /// Determine if the expression was expanded to empty.

clang/include/clang/AST/Type.h

@@ -5976,7 +5976,6 @@ class PackIndexingType final
       private llvm::TrailingObjects<PackIndexingType, QualType> {
   friend TrailingObjects;
 
-  const ASTContext &Context;
   QualType Pattern;
   Expr *IndexExpr;
 
@@ -5987,9 +5986,8 @@ class PackIndexingType final
 
 protected:
   friend class ASTContext; // ASTContext creates these.
-  PackIndexingType(const ASTContext &Context, QualType Canonical,
-                   QualType Pattern, Expr *IndexExpr, bool FullySubstituted,
-                   ArrayRef<QualType> Expansions = {});
+  PackIndexingType(QualType Canonical, QualType Pattern, Expr *IndexExpr,
+                   bool FullySubstituted, ArrayRef<QualType> Expansions = {});
 
 public:
   Expr *getIndexExpr() const { return IndexExpr; }
@@ -6024,14 +6022,10 @@ class PackIndexingType final
     return T->getTypeClass() == PackIndexing;
   }
 
-  void Profile(llvm::FoldingSetNodeID &ID) {
-    if (hasSelectedType())
-      getSelectedType().Profile(ID);
-    else
-      Profile(ID, Context, getPattern(), getIndexExpr(), isFullySubstituted());
-  }
+  void Profile(llvm::FoldingSetNodeID &ID, const ASTContext &Context);
   static void Profile(llvm::FoldingSetNodeID &ID, const ASTContext &Context,
-                      QualType Pattern, Expr *E, bool FullySubstituted);
+                      QualType Pattern, Expr *E, bool FullySubstituted,
+                      ArrayRef<QualType> Expansions);
 
 private:
   const QualType *getExpansionsPtr() const {

clang/lib/AST/ASTContext.cpp

@@ -940,7 +940,7 @@ ASTContext::ASTContext(LangOptions &LOpts, SourceManager &SM,
       DependentSizedMatrixTypes(this_()),
       FunctionProtoTypes(this_(), FunctionProtoTypesLog2InitSize),
       DependentTypeOfExprTypes(this_()), DependentDecltypeTypes(this_()),
-      TemplateSpecializationTypes(this_()),
+      DependentPackIndexingTypes(this_()), TemplateSpecializationTypes(this_()),
       DependentTemplateSpecializationTypes(this_()),
       DependentBitIntTypes(this_()), SubstTemplateTemplateParmPacks(this_()),
       DeducedTemplates(this_()), ArrayParameterTypes(this_()),
@@ -6438,17 +6438,17 @@ QualType ASTContext::getPackIndexingType(QualType Pattern, Expr *IndexExpr,
   } else {
     llvm::FoldingSetNodeID ID;
     PackIndexingType::Profile(ID, *this, Pattern.getCanonicalType(), IndexExpr,
-                              FullySubstituted);
+                              FullySubstituted, Expansions);
     void *InsertPos = nullptr;
     PackIndexingType *Canon =
         DependentPackIndexingTypes.FindNodeOrInsertPos(ID, InsertPos);
     if (!Canon) {
       void *Mem = Allocate(
           PackIndexingType::totalSizeToAlloc<QualType>(Expansions.size()),
           TypeAlignment);
-      Canon = new (Mem)
-          PackIndexingType(*this, QualType(), Pattern.getCanonicalType(),
-                           IndexExpr, FullySubstituted, Expansions);
+      Canon =
+          new (Mem) PackIndexingType(QualType(), Pattern.getCanonicalType(),
+                                     IndexExpr, FullySubstituted, Expansions);
       DependentPackIndexingTypes.InsertNode(Canon, InsertPos);
     }
     Canonical = QualType(Canon, 0);
@@ -6457,7 +6457,7 @@ QualType ASTContext::getPackIndexingType(QualType Pattern, Expr *IndexExpr,
   void *Mem =
       Allocate(PackIndexingType::totalSizeToAlloc<QualType>(Expansions.size()),
                TypeAlignment);
-  auto *T = new (Mem) PackIndexingType(*this, Canonical, Pattern, IndexExpr,
+  auto *T = new (Mem) PackIndexingType(Canonical, Pattern, IndexExpr,
                                        FullySubstituted, Expansions);
   Types.push_back(T);
   return QualType(T, 0);

clang/lib/AST/StmtProfile.cpp

@@ -2291,9 +2291,15 @@ void StmtProfiler::VisitSizeOfPackExpr(const SizeOfPackExpr *S) {
 }
 
 void StmtProfiler::VisitPackIndexingExpr(const PackIndexingExpr *E) {
-  VisitExpr(E);
-  VisitExpr(E->getPackIdExpression());
   VisitExpr(E->getIndexExpr());
+
+  if (E->expandsToEmptyPack() || E->getExpressions().size() != 0) {
+    ID.AddInteger(E->getExpressions().size());
+    for (const Expr *Sub : E->getExpressions())
+      Visit(Sub);
+  } else {
+    VisitExpr(E->getPackIdExpression());
+  }
 }
 
 void StmtProfiler::VisitSubstNonTypeTemplateParmPackExpr(

clang/lib/AST/Type.cpp

@@ -4125,14 +4125,14 @@ void DependentDecltypeType::Profile(llvm::FoldingSetNodeID &ID,
   E->Profile(ID, Context, true);
 }
 
-PackIndexingType::PackIndexingType(const ASTContext &Context,
-                                   QualType Canonical, QualType Pattern,
+PackIndexingType::PackIndexingType(QualType Canonical, QualType Pattern,
                                    Expr *IndexExpr, bool FullySubstituted,
                                    ArrayRef<QualType> Expansions)
     : Type(PackIndexing, Canonical,
            computeDependence(Pattern, IndexExpr, Expansions)),
-      Context(Context), Pattern(Pattern), IndexExpr(IndexExpr),
-      Size(Expansions.size()), FullySubstituted(FullySubstituted) {
+      Pattern(Pattern), IndexExpr(IndexExpr), Size(Expansions.size()),
+      FullySubstituted(FullySubstituted) {
+
   llvm::uninitialized_copy(Expansions, getTrailingObjects<QualType>());
 }
 
@@ -4173,12 +4173,26 @@ PackIndexingType::computeDependence(QualType Pattern, Expr *IndexExpr,
   return TD;
 }
 
+void PackIndexingType::Profile(llvm::FoldingSetNodeID &ID,
+                               const ASTContext &Context) {
+  Profile(ID, Context, getPattern(), getIndexExpr(), isFullySubstituted(),
+          getExpansions());
+}
+
 void PackIndexingType::Profile(llvm::FoldingSetNodeID &ID,
                                const ASTContext &Context, QualType Pattern,
-                               Expr *E, bool FullySubstituted) {
-  Pattern.Profile(ID);
+                               Expr *E, bool FullySubstituted,
+                               ArrayRef<QualType> Expansions) {
+
   E->Profile(ID, Context, true);
   ID.AddBoolean(FullySubstituted);
+  if (!Expansions.empty()) {
+    ID.AddInteger(Expansions.size());
+    for (QualType T : Expansions)
+      T.getCanonicalType().Profile(ID);
+  } else {
+    Pattern.Profile(ID);
+  }
 }
 
 UnaryTransformType::UnaryTransformType(QualType BaseType,

clang/test/SemaTemplate/concepts-out-of-line-def.cpp

@@ -1,4 +1,6 @@
-// RUN: %clang_cc1 -std=c++20 -verify %s
+// RUN: %clang_cc1 -std=c++20 -Wno-c++26-extensions -verify %s
+// RUN: %clang_cc1 -std=c++2c -Wno-c++26-extensions -verify %s
+
 
 static constexpr int PRIMARY = 0;
 static constexpr int SPECIALIZATION_CONCEPT = 1;
@@ -779,3 +781,75 @@ template <typename T>
 consteval void S::mfn() requires (bool(&fn)) {}
 
 }
+
+
+namespace GH138255 {
+
+template <typename... T>
+concept C = true;
+
+struct Func {
+  template<typename... Ts>
+  requires C<Ts...[0]>
+  static auto buggy() -> void;
+
+  template<typename... Ts>
+  requires C<Ts...[0]>
+  friend auto fr() -> void;
+
+  template<typename... Ts>
+  requires C<Ts...[0]>
+  friend auto fr2() -> void{}; // expected-note{{previous definition is here}}
+};
+
+template<typename... Ts>
+requires C<Ts...[0]>
+auto Func::buggy() -> void {}
+
+template<typename... Ts>
+requires C<Ts...[0]>
+auto fr() -> void {}
+
+template<typename... Ts>
+requires C<Ts...[0]>
+auto fr2() -> void {} // expected-error{{redefinition of 'fr2'}}
+
+
+template <typename... Ts>
+requires C<Ts...[0]>
+struct Class;
+
+template <typename... Ts>
+requires C<Ts...[0]>
+struct Class;
+
+
+template <typename...>
+struct TplClass {
+  template<typename... Ts>
+  requires C<Ts...[0]>
+  static auto buggy() -> void;
+};
+
+template<>
+template<typename... Ts>
+requires C<Ts...[0]>
+auto TplClass<int>::buggy() -> void {}
+
+}
+
+namespace PackIndexExpr {
+template <int... T>
+concept C = true;
+
+template <typename...> struct TplClass {
+  template <int... Ts>
+  requires C<Ts...[0]>
+  static auto buggy() -> void;
+};
+
+template <>
+template <int... Ts>
+requires C<Ts...[0]>
+auto TplClass<int>::buggy() -> void {}
+}