[clang] [clang] Preserve found-decl when constructing VarTemplateIds (PR #82265)

[kadir çetinkaya via cfe-commits]

https://github.com/kadircet created https://github.com/llvm/llvm-project/pull/82265

None

>From 05e1d91361b4ce4226d21b00a312eb7642057c8f Mon Sep 17 00:00:00 2001
From: Kadir Cetinkaya <kadircet at google.com>
Date: Mon, 19 Feb 2024 17:42:34 +0100
Subject: [PATCH] [clang] Preserve found-decl when constructing VarTemplateIds

---
 clang/include/clang/Sema/Sema.h   |  2 +-
 clang/lib/Sema/SemaTemplate.cpp   | 18 ++++++++----------
 clang/test/AST/ast-dump-using.cpp |  7 +++++++
 3 files changed, 16 insertions(+), 11 deletions(-)

diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index 1f1cbd11ff7358..6c0c8945d7de25 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -8416,7 +8416,7 @@ class Sema final {
   /// if the arguments are dependent.
   ExprResult CheckVarTemplateId(const CXXScopeSpec &SS,
                                 const DeclarationNameInfo &NameInfo,
-                                VarTemplateDecl *Template,
+                                VarTemplateDecl *Template, NamedDecl *FoundD,
                                 SourceLocation TemplateLoc,
                                 const TemplateArgumentListInfo *TemplateArgs);
 
diff --git a/clang/lib/Sema/SemaTemplate.cpp b/clang/lib/Sema/SemaTemplate.cpp
index 9bfa71dc8bcf1d..ee00b1e119e042 100644
--- a/clang/lib/Sema/SemaTemplate.cpp
+++ b/clang/lib/Sema/SemaTemplate.cpp
@@ -4960,11 +4960,10 @@ Sema::CheckVarTemplateId(VarTemplateDecl *Template, SourceLocation TemplateLoc,
   return Decl;
 }
 
-ExprResult
-Sema::CheckVarTemplateId(const CXXScopeSpec &SS,
-                         const DeclarationNameInfo &NameInfo,
-                         VarTemplateDecl *Template, SourceLocation TemplateLoc,
-                         const TemplateArgumentListInfo *TemplateArgs) {
+ExprResult Sema::CheckVarTemplateId(
+    const CXXScopeSpec &SS, const DeclarationNameInfo &NameInfo,
+    VarTemplateDecl *Template, NamedDecl *FoundD, SourceLocation TemplateLoc,
+    const TemplateArgumentListInfo *TemplateArgs) {
 
   DeclResult Decl = CheckVarTemplateId(Template, TemplateLoc, NameInfo.getLoc(),
                                        *TemplateArgs);
@@ -4980,8 +4979,7 @@ Sema::CheckVarTemplateId(const CXXScopeSpec &SS,
                                        NameInfo.getLoc());
 
   // Build an ordinary singleton decl ref.
-  return BuildDeclarationNameExpr(SS, NameInfo, Var,
-                                  /*FoundD=*/nullptr, TemplateArgs);
+  return BuildDeclarationNameExpr(SS, NameInfo, Var, FoundD, TemplateArgs);
 }
 
 void Sema::diagnoseMissingTemplateArguments(TemplateName Name,
@@ -5068,9 +5066,9 @@ ExprResult Sema::BuildTemplateIdExpr(const CXXScopeSpec &SS,
   bool KnownDependent = false;
   // In C++1y, check variable template ids.
   if (R.getAsSingle<VarTemplateDecl>()) {
-    ExprResult Res = CheckVarTemplateId(SS, R.getLookupNameInfo(),
-                                        R.getAsSingle<VarTemplateDecl>(),
-                                        TemplateKWLoc, TemplateArgs);
+    ExprResult Res = CheckVarTemplateId(
+        SS, R.getLookupNameInfo(), R.getAsSingle<VarTemplateDecl>(),
+        R.getRepresentativeDecl(), TemplateKWLoc, TemplateArgs);
     if (Res.isInvalid() || Res.isUsable())
       return Res;
     // Result is dependent. Carry on to build an UnresolvedLookupEpxr.
diff --git a/clang/test/AST/ast-dump-using.cpp b/clang/test/AST/ast-dump-using.cpp
index c007ecd8bda583..32826bb95676f3 100644
--- a/clang/test/AST/ast-dump-using.cpp
+++ b/clang/test/AST/ast-dump-using.cpp
@@ -2,6 +2,7 @@
 
 namespace a {
 struct S;
+template <typename T> T x = {};
 }
 namespace b {
 using a::S;
@@ -15,4 +16,10 @@ typedef S f; // to dump the introduced type
 // CHECK-NEXT:   `-UsingType {{.*}} 'a::S' sugar
 // CHECK-NEXT:     |-UsingShadow {{.*}} 'S'
 // CHECK-NEXT:     `-RecordType {{.*}} 'a::S'
+using a::x;
+
+void foo() {
+  x<int> = 3;
+  // CHECK: DeclRefExpr {{.*}} 'x' {{.*}} (UsingShadow {{.*}} 'x')
+}
 }