[clang] concepts: perform parameter mapping substitution in correct context

clang/docs/ReleaseNotes.rst

@@ -179,6 +179,9 @@ Bug Fixes to C++ Support
   with a string literal. (#GH82167)
 - Fix a crash when matching template template parameters with templates which have
   parameters of different class type. (#GH101394)
+- Clang now correctly recognizes the correct context for parameter
+  substitutions in concepts, so it doesn't incorrectly complain of missing
+  module imports in those situations. (#GH60336)
 
 Bug Fixes to AST Handling
 ^^^^^^^^^^^^^^^^^^^^^^^^^

clang/include/clang/Sema/SemaConcept.h

@@ -30,10 +30,11 @@ enum { ConstraintAlignment = 8 };
 
 struct alignas(ConstraintAlignment) AtomicConstraint {
   const Expr *ConstraintExpr;
+  NamedDecl *ConstraintDecl;
   std::optional<ArrayRef<TemplateArgumentLoc>> ParameterMapping;
 
-  AtomicConstraint(Sema &S, const Expr *ConstraintExpr) :
-      ConstraintExpr(ConstraintExpr) { };
+  AtomicConstraint(const Expr *ConstraintExpr, NamedDecl *ConstraintDecl)
+      : ConstraintExpr(ConstraintExpr), ConstraintDecl(ConstraintDecl) {};
 
   bool hasMatchingParameterMapping(ASTContext &C,
                                    const AtomicConstraint &Other) const {

clang/lib/Sema/SemaConcept.cpp

@@ -1457,8 +1457,8 @@ substituteParameterMappings(Sema &S, NormalizedConstraint &N,
           : ArgsAsWritten->arguments().front().getSourceRange().getEnd();
   Sema::InstantiatingTemplate Inst(
       S, InstLocBegin,
-      Sema::InstantiatingTemplate::ParameterMappingSubstitution{}, Concept,
-      {InstLocBegin, InstLocEnd});
+      Sema::InstantiatingTemplate::ParameterMappingSubstitution{},
+      Atomic.ConstraintDecl, {InstLocBegin, InstLocEnd});
   if (Inst.isInvalid())
     return true;
   if (S.SubstTemplateArguments(*Atomic.ParameterMapping, MLTAL, SubstArgs))
@@ -1632,7 +1632,7 @@ NormalizedConstraint::fromConstraintExpr(Sema &S, NamedDecl *D, const Expr *E) {
         Kind, std::move(*Sub), FE->getPattern()}};
   }
 
-  return NormalizedConstraint{new (S.Context) AtomicConstraint(S, E)};
+  return NormalizedConstraint{new (S.Context) AtomicConstraint(E, D)};
 }
 
 bool FoldExpandedConstraint::AreCompatibleForSubsumption(

clang/test/Modules/GH60336-2.cpp

@@ -0,0 +1,44 @@
+// RUN: rm -rf %t
+// RUN: %clang_cc1 -x c++ -std=c++20 %s -verify -fmodules -fmodules-cache-path=%t
+// expected-no-diagnostics
+
+#pragma clang module build std
+module std {
+  module concepts {}
+  module functional {}
+}
+#pragma clang module contents
+#pragma clang module begin std
+
+template <class _Tp> struct common_reference {
+  using type = _Tp;
+};
+
+#pragma clang module end
+#pragma clang module begin std.concepts
+#pragma clang module import std
+
+template <class _Tp>
+concept same_as = __is_same(_Tp, _Tp);
+
+template <class _Tp>
+concept common_reference_with =
+    same_as<typename common_reference<_Tp>::type>;
+
+#pragma clang module end
+#pragma clang module begin std.functional
+#pragma clang module import std.concepts
+
+template <class, class _Ip>
+concept sentinel_for = common_reference_with<_Ip>;
+
+constexpr bool ntsf_subsumes_sf(sentinel_for<char *> auto)
+  requires true
+{
+  return true;
+}
+bool ntsf_subsumes_sf(sentinel_for<char *> auto);
+static_assert(ntsf_subsumes_sf(""));
+
+#pragma clang module end
+#pragma clang module endbuild

clang/test/Modules/GH60336.cpp

@@ -1,5 +1,7 @@
 // RUN: rm -rf %t
 // RUN: %clang_cc1 -x c++ -std=c++20 %s -verify -fmodules -fmodules-cache-path=%t
+// expected-no-diagnostics
+
 #pragma clang module build std
 module std   [system] {
   module concepts     [system] {
@@ -65,14 +67,3 @@ constexpr bool ntsf_subsumes_sf(std::nothrow_sentinel_for<char*> auto) requires
 }
 constexpr bool ntsf_subsumes_sf(std::sentinel_for<char*> auto);
 static_assert(ntsf_subsumes_sf("foo"));
-
-// Note: Doing diagnostics verify lines in the individual modules isn't
-// permitted, and using 'bookmarks' in a module also doesn't work, so we're 
-// forced to diagnose this by line-number.
-//
-// Check to ensure that this error happens, prior to a revert of a concepts
-// sugaring patch, this diagnostic didn't happen correctly.
-
-// expected-error@* {{partial specialization of 'common_reference<_Tp, _Up>' must be imported from module 'std.type_traits' before it is required}}
-// expected-note@63 {{while substituting into concept arguments here}}
-// expected-note@*{{partial specialization declared here is not reachable}}