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

[Nathan Ridge via cfe-commits]

https://github.com/HighCommander4 created https://github.com/llvm/llvm-project/pull/139489

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).

>From 069edae907f41f127ac1f4010a7e01acbc494b40 Mon Sep 17 00:00:00 2001
From: Nathan Ridge <zeratul976 at hotmail.com>
Date: Sun, 11 May 2025 22:02:21 -0500
Subject: [PATCH] [clang][AST] Pass ProfileArguments by value in
 findSpecialization{Impl,Locally}

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).
---
 clang/include/clang/AST/DeclTemplate.h |  9 ++++-----
 clang/lib/AST/DeclTemplate.cpp         | 16 ++++++----------
 2 files changed, 10 insertions(+), 15 deletions(-)

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>