Don't set subobject bounds on hand-rolled offsetof idioms #608
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…seExpr It's possible we could do without the QualType out param, but I'm not sure if edge cases where references are involved would be otherwise ambiguous.
Technically this is UB, but it exists in real-world code and it's unnecessarily hostile to break such idioms.
bsdjhb
approved these changes
Feb 9, 2022
arichardson
approved these changes
Feb 9, 2022
| E->getDereferencedBaseExpr(getContext())->IgnoreParenCasts(); | ||
| if (BaseDeref->isNullPointerConstant(getContext(), | ||
| Expr::NPC_ValueDependentIsNotNull)) | ||
| return cannotSetBounds(*this, E, Ty, Kind, |
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I wonder if we should be emit a warning and suggest replacing it with (__builtin_)offsetof?
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The thought did occur to me but then forgot about it; probably should
Yeah, really odd failure mode |
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ping? Should we merge this as-is or are you planning to add the fixit? |
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From memory I found a bunch of problems in testing this where it didn’t work for anything non-trivial |
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