[Clang] Ensure correct parameters are in the scope for constraint equivalence checking (#149264)

This is another case where untransformed constraint expressions led to
inconsistent transforms.

We did fix some of those issues by looking at parent scopes, however the
parent instantiation scope is not always available because we could also
reach here after the parents get instantiated.

Fixes #146614

3 files changed, 27 insertions, 0 deletions

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index fcd3887..6f55d14 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -808,6 +808,7 @@ Bug Fixes in This Version
   nested scopes. (#GH147495)
 - Fixed a failed assertion with an operator call expression which comes from a
   macro expansion when performing analysis for nullability attributes. (#GH138371)
+- Fixed a concept equivalent checking crash due to untransformed constraint expressions. (#GH146614)
 
 Bug Fixes to Compiler Builtins
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/clang/lib/Sema/SemaConcept.cpp b/clang/lib/Sema/SemaConcept.cpp
index 834417f..5205ca0b 100644
--- a/clang/lib/Sema/SemaConcept.cpp
+++ b/clang/lib/Sema/SemaConcept.cpp
@@ -925,7 +925,12 @@ static const Expr *SubstituteConstraintExpressionWithoutSatisfaction(
       ND && ND->isFunctionOrFunctionTemplate()) {
     ScopeForParameters.emplace(S, /*CombineWithOuterScope=*/true);
     const FunctionDecl *FD = ND->getAsFunction();
+    if (FunctionTemplateDecl *Template = FD->getDescribedFunctionTemplate();
+        Template && Template->getInstantiatedFromMemberTemplate())
+      FD = Template->getInstantiatedFromMemberTemplate()->getTemplatedDecl();
     for (auto *PVD : FD->parameters()) {
+      if (ScopeForParameters->getInstantiationOfIfExists(PVD))
+        continue;
       if (!PVD->isParameterPack()) {
         ScopeForParameters->InstantiatedLocal(PVD, PVD);
         continue;
diff --git a/clang/test/SemaTemplate/concepts-using-decl.cpp b/clang/test/SemaTemplate/concepts-using-decl.cpp
index fca69de..41f7b6d 100644
--- a/clang/test/SemaTemplate/concepts-using-decl.cpp
+++ b/clang/test/SemaTemplate/concepts-using-decl.cpp
@@ -176,3 +176,24 @@ void func() {
   f.foo<10, 10>(); // expected-error {{no matching member function for call to 'foo'}}
 }
 } // namespace heads_without_concepts.
+
+namespace GH146614 {
+
+template <typename T>
+struct base {
+    template <typename A>
+    void foo(A x)
+        requires (requires{x;})
+    {}
+};
+
+
+struct child : base<int> {
+  using base<int>::foo;
+  template <typename A>
+  void foo(A x)
+      requires (false)
+  {}
+};
+
+}