[PATCH] D126864: [clang] Introduce -fstrict-flex-arrays=<n> for stricter handling of flexible arrays

[Fangrui Song via Phabricator via cfe-commits]

MaskRay added a comment.

The CPython usage is a real UB: https://github.com/python/cpython/issues/94250

In D126864#3609497 <https://reviews.llvm.org/D126864#3609497>, @efriedma wrote:

> I suspect the refactoring in the latest version of the patch accidentally made UBSan a bit more strict by default.

Yes, the patch accidentally dropped a -fsanitize=array-bounds workaround for size-1 array as the last member of a structure. I added it back in 572b08790a69f955ae0cbb1b4a7d4a215f15dad9 <https://reviews.llvm.org/rG572b08790a69f955ae0cbb1b4a7d4a215f15dad9>


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