[clang] [WIP] fix gh163837 (PR #165098)

[Zhikai Zeng via cfe-commits]

https://github.com/Backl1ght created https://github.com/llvm/llvm-project/pull/165098

fix https://github.com/llvm/llvm-project/issues/163837

>From c55a21e42d56b35f343c728fc35fa5d089d50154 Mon Sep 17 00:00:00 2001
From: Backl1ght <backlight.zzk at gmail.com>
Date: Sat, 25 Oct 2025 14:25:55 +0000
Subject: [PATCH] fix

---
 clang/lib/Sema/SemaTemplateInstantiateDecl.cpp | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
index 28925cca8f956..9c1bbb405ad22 100644
--- a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -7061,8 +7061,15 @@ NamedDecl *Sema::FindInstantiatedDecl(SourceLocation Loc, NamedDecl *D,
     // anonymous unions in class templates).
   }
 
-  if (!ParentDependsOnArgs)
+  if (!ParentDependsOnArgs) {
+    if (auto Found =
+            CurrentInstantiationScope
+                ? CurrentInstantiationScope->getInstantiationOfIfExists(D)
+                : nullptr) {
+        return cast<NamedDecl>(Found->dyn_cast<Decl *>());
+    }
     return D;
+  }
 
   ParentDC = FindInstantiatedContext(Loc, ParentDC, TemplateArgs);
   if (!ParentDC)