[clang][NFC] Remove const-qualification from FunctionTemplateSpecializationInfo::TemplateArguments

[Endilll]

This patch remove const-qualification from pointee type of FunctionTemplateSpecializationInfo::TemplateArguments, because it's (eventually) used to initialize MultiLevelTemplateArgumentList, which can actually mutate the arguments via

llvm-project/clang/include/clang/Sema/Template.h

Lines 197 to 204 in f42f57b

	void setArgument(unsigned Depth, unsigned Index,
	TemplateArgument Arg) {
	assert(NumRetainedOuterLevels <= Depth && Depth < getNumLevels());
	assert(Index <
	TemplateArgumentLists[getNumLevels() - Depth - 1].Args.size());
	const_cast<TemplateArgument &>(
	TemplateArgumentLists[getNumLevels() - Depth - 1].Args[Index]) = Arg;
	}

Mutation seems to be required to correctly handle packs:

llvm-project/clang/lib/Sema/SemaTemplateInstantiate.cpp

Lines 1440 to 1469 in 9144553

	TemplateArgument ForgetPartiallySubstitutedPack() {
	TemplateArgument Result;
	if (NamedDecl *PartialPack
	= SemaRef.CurrentInstantiationScope->getPartiallySubstitutedPack()){
	MultiLevelTemplateArgumentList &TemplateArgs
	= const_cast<MultiLevelTemplateArgumentList &>(this->TemplateArgs);
	unsigned Depth, Index;
	std::tie(Depth, Index) = getDepthAndIndex(PartialPack);
	if (TemplateArgs.hasTemplateArgument(Depth, Index)) {
	Result = TemplateArgs(Depth, Index);
	TemplateArgs.setArgument(Depth, Index, TemplateArgument());
	}
	}
	return Result;
	}
	void RememberPartiallySubstitutedPack(TemplateArgument Arg) {
	if (Arg.isNull())
	return;
	if (NamedDecl *PartialPack
	= SemaRef.CurrentInstantiationScope->getPartiallySubstitutedPack()){
	MultiLevelTemplateArgumentList &TemplateArgs
	= const_cast<MultiLevelTemplateArgumentList &>(this->TemplateArgs);
	unsigned Depth, Index;
	std::tie(Depth, Index) = getDepthAndIndex(PartialPack);
	TemplateArgs.setArgument(Depth, Index, Arg);
	}
	}

[llvmbot]

@llvm/pr-subscribers-clang

Author: Vlad Serebrennikov (Endilll)

Changes

This patch remove const-qualification from pointee type of FunctionTemplateSpecializationInfo::TemplateArguments, because it's (eventually) used to initialize MultiLevelTemplateArgumentList, which can actually mutate the arguments via

llvm-project/clang/include/clang/Sema/Template.h

Lines 197 to 204 in f42f57b

	void setArgument(unsigned Depth, unsigned Index,
	TemplateArgument Arg) {
	assert(NumRetainedOuterLevels <= Depth && Depth < getNumLevels());
	assert(Index <
	TemplateArgumentLists[getNumLevels() - Depth - 1].Args.size());
	const_cast<TemplateArgument &>(
	TemplateArgumentLists[getNumLevels() - Depth - 1].Args[Index]) = Arg;
	}

Mutation seems to be required to correctly handle packs:

llvm-project/clang/lib/Sema/SemaTemplateInstantiate.cpp

Lines 1440 to 1469 in 9144553

	TemplateArgument ForgetPartiallySubstitutedPack() {
	TemplateArgument Result;
	if (NamedDecl *PartialPack
	= SemaRef.CurrentInstantiationScope->getPartiallySubstitutedPack()){
	MultiLevelTemplateArgumentList &TemplateArgs
	= const_cast<MultiLevelTemplateArgumentList &>(this->TemplateArgs);
	unsigned Depth, Index;
	std::tie(Depth, Index) = getDepthAndIndex(PartialPack);
	if (TemplateArgs.hasTemplateArgument(Depth, Index)) {
	Result = TemplateArgs(Depth, Index);
	TemplateArgs.setArgument(Depth, Index, TemplateArgument());
	}
	}
	return Result;
	}
	void RememberPartiallySubstitutedPack(TemplateArgument Arg) {
	if (Arg.isNull())
	return;
	if (NamedDecl *PartialPack
	= SemaRef.CurrentInstantiationScope->getPartiallySubstitutedPack()){
	MultiLevelTemplateArgumentList &TemplateArgs
	= const_cast<MultiLevelTemplateArgumentList &>(this->TemplateArgs);
	unsigned Depth, Index;
	std::tie(Depth, Index) = getDepthAndIndex(PartialPack);
	TemplateArgs.setArgument(Depth, Index, Arg);
	}
	}

---

Full diff: https://github.com/llvm/llvm-project/pull/92500.diff

5 Files Affected:

• (modified) clang/include/clang/AST/Decl.h (+12-13)
• (modified) clang/include/clang/AST/DeclTemplate.h (+3-4)
• (modified) clang/lib/AST/Decl.cpp (+6-8)
• (modified) clang/lib/AST/DeclTemplate.cpp (+1-1)
• (modified) clang/lib/Sema/SemaTemplate.cpp (+1-1)

diff --git a/clang/include/clang/AST/Decl.h b/clang/include/clang/AST/Decl.h
index de8b923645f8d..5e485ccb85a13 100644
--- a/clang/include/clang/AST/Decl.h
+++ b/clang/include/clang/AST/Decl.h
@@ -2096,13 +2096,12 @@ class FunctionDecl : public DeclaratorDecl,
   ///
   /// \param PointOfInstantiation point at which the function template
   /// specialization was first instantiated.
-  void setFunctionTemplateSpecialization(ASTContext &C,
-                                         FunctionTemplateDecl *Template,
-                                       const TemplateArgumentList *TemplateArgs,
-                                         void *InsertPos,
-                                         TemplateSpecializationKind TSK,
-                          const TemplateArgumentListInfo *TemplateArgsAsWritten,
-                                         SourceLocation PointOfInstantiation);
+  void setFunctionTemplateSpecialization(
+      ASTContext &C, FunctionTemplateDecl *Template,
+      TemplateArgumentList *TemplateArgs, void *InsertPos,
+      TemplateSpecializationKind TSK,
+      const TemplateArgumentListInfo *TemplateArgsAsWritten,
+      SourceLocation PointOfInstantiation);
 
   /// Specify that this record is an instantiation of the
   /// member function FD.
@@ -2981,12 +2980,12 @@ class FunctionDecl : public DeclaratorDecl,
   ///
   /// \param PointOfInstantiation point at which the function template
   /// specialization was first instantiated.
-  void setFunctionTemplateSpecialization(FunctionTemplateDecl *Template,
-                const TemplateArgumentList *TemplateArgs,
-                void *InsertPos,
-                TemplateSpecializationKind TSK = TSK_ImplicitInstantiation,
-                const TemplateArgumentListInfo *TemplateArgsAsWritten = nullptr,
-                SourceLocation PointOfInstantiation = SourceLocation()) {
+  void setFunctionTemplateSpecialization(
+      FunctionTemplateDecl *Template, TemplateArgumentList *TemplateArgs,
+      void *InsertPos,
+      TemplateSpecializationKind TSK = TSK_ImplicitInstantiation,
+      TemplateArgumentListInfo *TemplateArgsAsWritten = nullptr,
+      SourceLocation PointOfInstantiation = SourceLocation()) {
     setFunctionTemplateSpecialization(getASTContext(), Template, TemplateArgs,
                                       InsertPos, TSK, TemplateArgsAsWritten,
                                       PointOfInstantiation);
diff --git a/clang/include/clang/AST/DeclTemplate.h b/clang/include/clang/AST/DeclTemplate.h
index 268aeacf2f20f..f3d6a321ecf10 100644
--- a/clang/include/clang/AST/DeclTemplate.h
+++ b/clang/include/clang/AST/DeclTemplate.h
@@ -478,7 +478,7 @@ class FunctionTemplateSpecializationInfo final
 public:
   /// The template arguments used to produce the function template
   /// specialization from the function template.
-  const TemplateArgumentList *TemplateArguments;
+  TemplateArgumentList *TemplateArguments;
 
   /// The template arguments as written in the sources, if provided.
   /// FIXME: Normally null; tail-allocate this.
@@ -491,7 +491,7 @@ class FunctionTemplateSpecializationInfo final
 private:
   FunctionTemplateSpecializationInfo(
       FunctionDecl *FD, FunctionTemplateDecl *Template,
-      TemplateSpecializationKind TSK, const TemplateArgumentList *TemplateArgs,
+      TemplateSpecializationKind TSK, TemplateArgumentList *TemplateArgs,
       const ASTTemplateArgumentListInfo *TemplateArgsAsWritten,
       SourceLocation POI, MemberSpecializationInfo *MSInfo)
       : Function(FD, MSInfo ? true : false), Template(Template, TSK - 1),
@@ -511,8 +511,7 @@ class FunctionTemplateSpecializationInfo final
 
   static FunctionTemplateSpecializationInfo *
   Create(ASTContext &C, FunctionDecl *FD, FunctionTemplateDecl *Template,
-         TemplateSpecializationKind TSK,
-         const TemplateArgumentList *TemplateArgs,
+         TemplateSpecializationKind TSK, TemplateArgumentList *TemplateArgs,
          const TemplateArgumentListInfo *TemplateArgsAsWritten,
          SourceLocation POI, MemberSpecializationInfo *MSInfo);
 
diff --git a/clang/lib/AST/Decl.cpp b/clang/lib/AST/Decl.cpp
index ec851c9371e10..41fbfe281ef65 100644
--- a/clang/lib/AST/Decl.cpp
+++ b/clang/lib/AST/Decl.cpp
@@ -4199,14 +4199,12 @@ FunctionDecl::getTemplateSpecializationArgsAsWritten() const {
   return nullptr;
 }
 
-void
-FunctionDecl::setFunctionTemplateSpecialization(ASTContext &C,
-                                                FunctionTemplateDecl *Template,
-                                     const TemplateArgumentList *TemplateArgs,
-                                                void *InsertPos,
-                                                TemplateSpecializationKind TSK,
-                        const TemplateArgumentListInfo *TemplateArgsAsWritten,
-                                          SourceLocation PointOfInstantiation) {
+void FunctionDecl::setFunctionTemplateSpecialization(
+    ASTContext &C, FunctionTemplateDecl *Template,
+    TemplateArgumentList *TemplateArgs, void *InsertPos,
+    TemplateSpecializationKind TSK,
+    const TemplateArgumentListInfo *TemplateArgsAsWritten,
+    SourceLocation PointOfInstantiation) {
   assert((TemplateOrSpecialization.isNull() ||
           TemplateOrSpecialization.is<MemberSpecializationInfo *>()) &&
          "Member function is already a specialization");
diff --git a/clang/lib/AST/DeclTemplate.cpp b/clang/lib/AST/DeclTemplate.cpp
index d22ecc3c032e7..26765a5da1dc6 100644
--- a/clang/lib/AST/DeclTemplate.cpp
+++ b/clang/lib/AST/DeclTemplate.cpp
@@ -884,7 +884,7 @@ TemplateArgumentList::CreateCopy(ASTContext &Context,
 
 FunctionTemplateSpecializationInfo *FunctionTemplateSpecializationInfo::Create(
     ASTContext &C, FunctionDecl *FD, FunctionTemplateDecl *Template,
-    TemplateSpecializationKind TSK, const TemplateArgumentList *TemplateArgs,
+    TemplateSpecializationKind TSK, TemplateArgumentList *TemplateArgs,
     const TemplateArgumentListInfo *TemplateArgsAsWritten, SourceLocation POI,
     MemberSpecializationInfo *MSInfo) {
   const ASTTemplateArgumentListInfo *ArgsAsWritten = nullptr;
diff --git a/clang/lib/Sema/SemaTemplate.cpp b/clang/lib/Sema/SemaTemplate.cpp
index 1b3f1e8bf80f4..ce09193721239 100644
--- a/clang/lib/Sema/SemaTemplate.cpp
+++ b/clang/lib/Sema/SemaTemplate.cpp
@@ -10494,7 +10494,7 @@ bool Sema::CheckFunctionTemplateSpecialization(
   // specialization, with the template arguments from the previous
   // specialization.
   // Take copies of (semantic and syntactic) template argument lists.
-  const TemplateArgumentList *TemplArgs = TemplateArgumentList::CreateCopy(
+  TemplateArgumentList *TemplArgs = TemplateArgumentList::CreateCopy(
       Context, Specialization->getTemplateSpecializationArgs()->asArray());
   FD->setFunctionTemplateSpecialization(
       Specialization->getPrimaryTemplate(), TemplArgs, /*InsertPos=*/nullptr,