[Clang] Consider outer instantiation scopes for constraint normalization (llvm#114749)

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.

No release note as this fixes a regression in 19.

Fixes llvm#114685

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