[clang] [clang][AST] Pass ProfileArguments by value in findSpecialization{Impl,Locally} (PR #139489)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: Nathan Ridge (HighCommander4)

<details>
<summary>Changes</summary>

The arguments passed are lightweight (an ArrayRef and a pointer), and findSpecializationImpl passes them to multiple functions, making it a potential hazard to pass them by rvalue reference (even though no one was in fact moving them).

---
Full diff: https://github.com/llvm/llvm-project/pull/139489.diff


2 Files Affected:

- (modified) clang/include/clang/AST/DeclTemplate.h (+4-5) 
- (modified) clang/lib/AST/DeclTemplate.cpp (+6-10) 


``````````diff
diff --git a/clang/include/clang/AST/DeclTemplate.h b/clang/include/clang/AST/DeclTemplate.h
index a8100b642e04c..80c97681d9163 100644
--- a/clang/include/clang/AST/DeclTemplate.h
+++ b/clang/include/clang/AST/DeclTemplate.h
@@ -781,16 +781,15 @@ class RedeclarableTemplateDecl : public TemplateDecl,
   bool loadLazySpecializationsImpl(llvm::ArrayRef<TemplateArgument> Args,
                                    TemplateParameterList *TPL = nullptr) const;
 
-  template <class EntryType, typename ...ProfileArguments>
-  typename SpecEntryTraits<EntryType>::DeclType*
+  template <class EntryType, typename... ProfileArguments>
+  typename SpecEntryTraits<EntryType>::DeclType *
   findSpecializationImpl(llvm::FoldingSetVector<EntryType> &Specs,
-                         void *&InsertPos, ProfileArguments &&...ProfileArgs);
+                         void *&InsertPos, ProfileArguments... ProfileArgs);
 
   template <class EntryType, typename... ProfileArguments>
   typename SpecEntryTraits<EntryType>::DeclType *
   findSpecializationLocally(llvm::FoldingSetVector<EntryType> &Specs,
-                            void *&InsertPos,
-                            ProfileArguments &&...ProfileArgs);
+                            void *&InsertPos, ProfileArguments... ProfileArgs);
 
   template <class Derived, class EntryType>
   void addSpecializationImpl(llvm::FoldingSetVector<EntryType> &Specs,
diff --git a/clang/lib/AST/DeclTemplate.cpp b/clang/lib/AST/DeclTemplate.cpp
index d058831b9f6bf..6857eef87de38 100644
--- a/clang/lib/AST/DeclTemplate.cpp
+++ b/clang/lib/AST/DeclTemplate.cpp
@@ -382,12 +382,11 @@ template <class EntryType, typename... ProfileArguments>
 typename RedeclarableTemplateDecl::SpecEntryTraits<EntryType>::DeclType *
 RedeclarableTemplateDecl::findSpecializationLocally(
     llvm::FoldingSetVector<EntryType> &Specs, void *&InsertPos,
-    ProfileArguments &&...ProfileArgs) {
+    ProfileArguments... ProfileArgs) {
   using SETraits = RedeclarableTemplateDecl::SpecEntryTraits<EntryType>;
 
   llvm::FoldingSetNodeID ID;
-  EntryType::Profile(ID, std::forward<ProfileArguments>(ProfileArgs)...,
-                     getASTContext());
+  EntryType::Profile(ID, ProfileArgs..., getASTContext());
   EntryType *Entry = Specs.FindNodeOrInsertPos(ID, InsertPos);
   return Entry ? SETraits::getDecl(Entry)->getMostRecentDecl() : nullptr;
 }
@@ -396,18 +395,15 @@ template <class EntryType, typename... ProfileArguments>
 typename RedeclarableTemplateDecl::SpecEntryTraits<EntryType>::DeclType *
 RedeclarableTemplateDecl::findSpecializationImpl(
     llvm::FoldingSetVector<EntryType> &Specs, void *&InsertPos,
-    ProfileArguments &&...ProfileArgs) {
+    ProfileArguments... ProfileArgs) {
 
-  if (auto *Found = findSpecializationLocally(
-          Specs, InsertPos, std::forward<ProfileArguments>(ProfileArgs)...))
+  if (auto *Found = findSpecializationLocally(Specs, InsertPos, ProfileArgs...))
     return Found;
 
-  if (!loadLazySpecializationsImpl(
-          std::forward<ProfileArguments>(ProfileArgs)...))
+  if (!loadLazySpecializationsImpl(ProfileArgs...))
     return nullptr;
 
-  return findSpecializationLocally(
-      Specs, InsertPos, std::forward<ProfileArguments>(ProfileArgs)...);
+  return findSpecializationLocally(Specs, InsertPos, ProfileArgs...);
 }
 
 template<class Derived, class EntryType>

``````````

</details>


https://github.com/llvm/llvm-project/pull/139489