[clang] 9e9d98a - [clang] concepts: perform parameter mapping substitution in correct context (#101745)

[via cfe-commits]

Author: Matheus Izvekov
Date: 2024-08-04T19:00:54-03:00
New Revision: 9e9d98aaf503171e2cb229e89966ec1c0adf3804

URL: https://github.com/llvm/llvm-project/commit/9e9d98aaf503171e2cb229e89966ec1c0adf3804
DIFF: https://github.com/llvm/llvm-project/commit/9e9d98aaf503171e2cb229e89966ec1c0adf3804.diff

LOG: [clang] concepts: perform parameter mapping substitution in correct context (#101745)

Prior to this patch, during constraint normalization we could forget
from which declaration an atomic constraint was normalized from.

Subsequently when performing parameter mapping substitution for that
atomic constraint with an incorrect context, we couldn't correctly
recognize which declarations are supposed to be visible.

Fixes #60336

Added: 
    clang/test/Modules/GH60336-2.cpp

Modified: 
    clang/docs/ReleaseNotes.rst
    clang/include/clang/Sema/SemaConcept.h
    clang/lib/Sema/SemaConcept.cpp
    clang/test/Modules/GH60336.cpp

Removed: 
    


################################################################################
diff  --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 3d76bd3ae272f..5bd5dbfce7778 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/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 
diff erent 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
 ^^^^^^^^^^^^^^^^^^^^^^^^^

diff  --git a/clang/include/clang/Sema/SemaConcept.h b/clang/include/clang/Sema/SemaConcept.h
index 03791962b2dc0..4b1abccb7741a 100644
--- a/clang/include/clang/Sema/SemaConcept.h
+++ b/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 {

diff  --git a/clang/lib/Sema/SemaConcept.cpp b/clang/lib/Sema/SemaConcept.cpp
index 9e16b67284be4..7d7a94e9fd637 100644
--- a/clang/lib/Sema/SemaConcept.cpp
+++ b/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(

diff  --git a/clang/test/Modules/GH60336-2.cpp b/clang/test/Modules/GH60336-2.cpp
new file mode 100644
index 0000000000000..9740c744b7b7b
--- /dev/null
+++ b/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

diff  --git a/clang/test/Modules/GH60336.cpp b/clang/test/Modules/GH60336.cpp
index fefbd37b7926c..e181c24904217 100644
--- a/clang/test/Modules/GH60336.cpp
+++ b/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 at 63 {{while substituting into concept arguments here}}
-// expected-note@*{{partial specialization declared here is not reachable}}