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

[code-pankaj]

This fixes a crash (segmentation fault) when the standard library implementation of comparison categories (like std::partial_ordering) is malformed.

Specifically, if the static members (like equivalent) are defined as a primitive type (e.g., int) instead of the comparison category type itself, the compiler previously attempted to process them incorrectly, leading to a crash.

This adds strict type checking in ComparisonCategoryInfo::lookupValueInfo. If the found static member does not match the record type, it is rejected safely, triggering a diagnostic error instead of a crash.

Fixes #170015

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[llvmbot]

@llvm/pr-subscribers-clang

Author: Pankaj (code-pankaj)

Changes

Add a null check for Record in
ComparisonCategoryInfo::ValueInfo::hasValidIntValue to avoid dereferencing a null CXXRecordDecl when the comparison category types (such as std::partial_ordering) are missing, incomplete, or malformed.

Previously, this caused a crash in both freestanding (-nostdinc++) and normal configurations when <compare> is unavailable or inconsistent.

---

Full diff: https://github.com/llvm/llvm-project/pull/172001.diff

1 Files Affected:

• (modified) clang/lib/AST/ComparisonCategories.cpp (+1-1)

diff --git a/clang/lib/AST/ComparisonCategories.cpp b/clang/lib/AST/ComparisonCategories.cpp index 1b9c938e2ace3..431d6f77bc0a0 100644 --- a/clang/lib/AST/ComparisonCategories.cpp +++ b/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; 

[tbaederr]

1. Add "Fixes <link to issue>" to your PR description
2. You need to add a test as well.

[zwuis]

If AI was used to create PR, please disclose it. And to what extent it was used.

Please mention the issue fixed by this patch in PR description.

Please add tests.

Please add a release note entry.

[code-pankaj]

Yes, GitHub Copilot was used to suggest code changes and commit messages.
But not to create PR (I was just testing it for the first time ever and didn't knew till what extent it go)
I added the issues fixes in the PR description

Will let you guys know after writing the test case.

[code-pankaj]

@tbaederr @zwuis Thanks for the Review!

I have updated the PR based on the feedback. I moved the fix to ComparisonCategoryInfo::lookupValueInfo to enforce strict type checking on the static members. This ensures we reject malformed types (like int) immediately with a proper "member missing" error.

I have also added the test and the Release Note entry.

Please let me know if anything else is needed!