[Clang] Consider outer instantiation scopes for constraint normalization

We need to compare constraint expressions when instantiating a friend
declaration that is lexically defined within a class template. Since the
evaluation is deferred, the expression might refer to untransformed function
parameters such that the substitution needs the mapping of instantiation.

These mappings are maintained by the function declaration instantiation,
so we need to establish a "transparent" LocalInstantiationScope before
substituting into the constraint.

Author: zyn0217

clang/lib/Sema/SemaConcept.cpp

@@ -975,7 +975,7 @@ static const Expr *SubstituteConstraintExpressionWithoutSatisfaction(
   std::optional<LocalInstantiationScope> ScopeForParameters;
   if (const NamedDecl *ND = DeclInfo.getDecl();
       ND && ND->isFunctionOrFunctionTemplate()) {
-    ScopeForParameters.emplace(S);
+    ScopeForParameters.emplace(S, /*CombineWithOuterScope=*/true);
     const FunctionDecl *FD = ND->getAsFunction();
     for (auto *PVD : FD->parameters()) {
       if (!PVD->isParameterPack()) {

clang/test/SemaTemplate/concepts-out-of-line-def.cpp

@@ -702,3 +702,19 @@ class TTP;
 C v;
 
 } // namespace GH93099
+
+namespace GH114685 {
+
+template <typename T> struct ptr {
+  template <typename U>
+  friend ptr<U> make_item(auto &&args)
+    requires(sizeof(args) > 1);
+};
+
+template <typename U>
+ptr<U> make_item(auto &&args)
+  requires(sizeof(args) > 1) {}
+
+ptr<char> p;
+
+} // namespace GH114685