[Clang] Fix crash on malformed std::partial_ordering static members

clang/docs/ReleaseNotes.rst

@@ -602,6 +602,7 @@ Bug Fixes to C++ Support
 - Fixed an issue where templates prevented nested anonymous records from checking the deletion of special members. (#GH167217)
 - Fixed spurious diagnoses of certain nested lambda expressions. (#GH149121) (#GH156579)
 - Fix the result of ``__is_pointer_interconvertible_base_of`` when arguments are qualified and passed via template parameters. (#GH135273)
+- Fixed a crash when standard comparison categories (e.g. ``std::partial_ordering``) are defined with incorrect static member types. (#GH170015)
 
 Bug Fixes to AST Handling
 ^^^^^^^^^^^^^^^^^^^^^^^^^

clang/lib/AST/ComparisonCategories.cpp

@@ -49,7 +49,7 @@ bool ComparisonCategoryInfo::ValueInfo::hasValidIntValue() const {
  // Before we attempt to get the value of the first field, ensure that we
  // actually have one (and only one) field.
  const auto *Record = VD->getType()->getAsCXXRecordDecl();
- if (Record->getNumFields() != 1 ||
+ if (!Record || Record->getNumFields() != 1 ||
  !Record->field_begin()->getType()->isIntegralOrEnumerationType())
  return false;
 
@@ -83,7 +83,14 @@ ComparisonCategoryInfo::ValueInfo *ComparisonCategoryInfo::lookupValueInfo(
  &Ctx.Idents.get(ComparisonCategories::getResultString(ValueKind)));
  if (Lookup.empty() || !isa<VarDecl>(Lookup.front()))
  return nullptr;
- Objects.emplace_back(ValueKind, cast<VarDecl>(Lookup.front()));
+ // The static member must have the same type as the comparison category class
+ // itself (e.g., std::partial_ordering::less must be of type partial_ordering).
+ VarDecl *ValueDecl = cast<VarDecl>(Lookup.front());
+ const CXXRecordDecl *ValueDeclRecord = ValueDecl->getType()->getAsCXXRecordDecl();
+ if (!ValueDeclRecord || ValueDeclRecord->getCanonicalDecl() != Record->getCanonicalDecl())
+ return nullptr;
+
+ Objects.emplace_back(ValueKind, ValueDecl);
  return &Objects.back();
 }
 

clang/test/SemaCXX/cxx2a-three-way-comparison.cpp

@@ -67,3 +67,28 @@ struct comparable_t {
  expected-note {{defaulted 'operator<=>' is implicitly deleted because defaulted comparison of vector types is not supported}}
 };
 } // namespace GH137452
+
+namespace GH170015 {
+// This test ensures that the compiler enforces strict type checking on the 
+// static members of comparison category types.
+// Previously, a mismatch (e.g., equivalent being an int) could crash the compiler.
+}
+
+namespace std {
+ struct partial_ordering {
+ // Malformed: 'equivalent' should be of type 'partial_ordering', not 'int'.
+ static constexpr int equivalent = 0; 
+ static constexpr int less = -1;
+ static constexpr int greater = 1;
+ static constexpr int unordered = 2;
+ };
+}
+
+namespace GH170015 {
+ void f() {
+ float a = 0.0f, b = 0.0f;
+ // We expect the compiler to complain that the type form is wrong 
+ // (because the static members are ints, not objects).
+ auto res = a <=> b; // expected-error {{standard library implementation of 'std::partial_ordering' is not supported; the type does not have the expected form}}
+ }
+}