[clang] [Clang] Fix a wrong diagnostic about a local variable inside a lambda in unevaluated context need capture (PR #165098)

[Oliver Hunt via cfe-commits]

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@@ -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 *>());
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ojhunt wrote:

`cast_or_null` would be appropriate

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