[PATCH] D96914: [ELF] Add -z start-stop-gc to let __start_/__stop_ not retain C identifier name sections

[Fangrui Song via Phabricator via llvm-commits]

MaskRay added a comment.

In D96914#3128217 <https://reviews.llvm.org/D96914#3128217>, @hvdijk wrote:

> In D96914#3128155 <https://reviews.llvm.org/D96914#3128155>, @MaskRay wrote:
>
>> (I shall note that declaring reserved identifiers `__start_` is UB in the first place. Well, the compiler has just always been just permissive.)
>
> It's UB from a C and C++ standards POV, it's not UB from an LLVM POV. It's the LLVM POV that's relevant here, C and C++ UB that falls under a supported LLVM extension needs to behave as specified by that extension. Changes to the behaviour of that extension can be made (both in spec and in code), sure, but the fact that they are outside of the scope of the C and C++ standards doesn't automatically make them okay. If I were to commit a patch to clang to issue a hard error whenever an identifier starting with `__` is used outside of a standard library header, I would expect that patch to be reverted promptly, and rightly so.

`-Wreserved-identifier` which is not in -Wall/-Wextra catches exactly this.


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https://reviews.llvm.org/D96914