[PATCH] D73852: [clang] detect switch fallthrough marked by a comment (PR43465)

[Richard Smith - zygoloid via Phabricator via cfe-commits]

rsmith added a comment.

In D73852#1901699 <https://reviews.llvm.org/D73852#1901699>, @llunak wrote:

> In D73852#1901186 <https://reviews.llvm.org/D73852#1901186>, @rsmith wrote:
>
> > We shouldn't enable the warning under -Wextra in language modes where there's no standard way to suppress it.
>
>
> That may be true, but that is not what the bugreport is about, it explicitly mentions flex. There are codebases that explicitly use -Wimplicit-fallthrough, and flex generates the same code even for C++. So either Clang needs to handle it, or flex needs to change (which may be non-trivial if https://bugs.llvm.org/show_bug.cgi?id=43465#c24 is right), or codebases using flex will need to either special-case Clang or live with the warning.


... or turn off the warning for generated code. As noted on that bug, `-Wimplicit-fallthrough` enforces a particular coding style, so users should expect to need to not enable it in generated code that doesn't follow that style. You might need to turn off (eg) `-Windent` or `-Wparentheses` in flex-generated code too.

In any case, none of this has any bearing on whether this patch has had sufficient review. It hasn't, so it needs to be reverted for now.


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