[clang] [Clang] Refactor instantiation of declarations within concepts (PR #221707)

[Younan Zhang via cfe-commits]

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@@ -1996,11 +1989,41 @@ Decl *TemplateInstantiator::TransformDecl(SourceLocation Loc, Decl *D) {
   return SemaRef.FindInstantiatedDecl(Loc, cast<NamedDecl>(D), TemplateArgs);
 }
 
-bool TemplateInstantiator::maybeInstantiateFunctionParameterToScope(
-    ParmVarDecl *OldParm) {
-  if (SemaRef.CurrentInstantiationScope->getInstantiationOfIfExists(OldParm))
+bool TemplateInstantiator::instantiateMissingDeclsToScopeForConcepts(Decl *PD) {
+  if (!(PD && (SemaRef.inConstraintSubstitution() ||
+               SemaRef.inParameterMappingSubstitution())))
+    return false;
+
+  auto *Current = SemaRef.CurrentInstantiationScope;
+  if (!Current)
+    return false;
----------------
zyn0217 wrote:

Hmm actually in parameter mapping we cannot have one: we want to leave them unsubstituted, and a null Scope instructs FindInstantiatedDecl for that.

And we check if (SemaRef.CurrentInstantiationScope) in previous, so I think this is harmless.

https://github.com/llvm/llvm-project/pull/221707