[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 +83,17 @@ 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/PR172001.cpp

@@ -0,0 +1,41 @@
+// RUN: %clang_cc1 -std=c++20 -verify=test1 -DTEST1 %s
+// RUN: %clang_cc1 -std=c++20 -verify=test2 -DTEST2 %s
+// RUN: %clang_cc1 -std=c++20 -verify=test3 -DTEST3 %s
+// RUN: %clang_cc1 -std=c++20 -verify=test4 -DTEST4 %s
+
+namespace std {
+#ifdef TEST1
+ // Case 1: Malformed struct (static members are wrong type)
+ // This triggered the original crash (GH170015).
+ struct partial_ordering {
+ static constexpr int equivalent = 0;
+ static constexpr int less = -1;
+ static constexpr int greater = 1;
+ static constexpr int unordered = 2;
+ };
+#elif defined(TEST2)
+ // Case 2: partial_ordering is a typedef to int
+ using partial_ordering = int;
+#elif defined(TEST3)
+ // Case 3: partial_ordering is a forward declaration
+ struct partial_ordering; // test3-note {{forward declaration of 'std::partial_ordering'}}
+#elif defined(TEST4)
+ // Case 4: partial_ordering is a template (Paranoia check)
+ template <class> struct partial_ordering {
+ static const partial_ordering less;
+ static const partial_ordering equivalent;
+ static const partial_ordering greater;
+ static const partial_ordering unordered;
+ };
+#endif
+}
+
+void f() {
+ float a = 0.0f, b = 0.0f;
+ auto res = a <=> b; 
+ // test1-error@-1 {{standard library implementation of 'std::partial_ordering' is not supported; the type does not have the expected form}}
+ // test2-error@-2 {{cannot use builtin operator '<=>' because type 'std::partial_ordering' was not found; include <compare>}}
+ // test3-error@-3 {{incomplete type 'std::partial_ordering' where a complete type is required}}
+ // test4-error@-4 {{cannot use builtin operator '<=>' because type 'std::partial_ordering' was not found; include <compare>}}
+}
+