Re: [PATCH] preprocessor: Set input_location to the most recently seen token

[Joseph Myers <joseph@codesourcery.com>]

On Mon, 11 Jul 2022, Lewis Hyatt via Gcc-patches wrote:

> Hello-
> 
> As discussed here:
> https://gcc.gnu.org/pipermail/gcc-patches/2022-July/598136.html
> 
> Here is another short patch that improves "#pragma GCC diagnostic" handling.
> Longer term, it will be desirable to make the handling of this pragma
> independent of the global input_location. But in the meantime, some glitches
> like this one can be readily addressed by making input_location point to
> something better. In this case, input_location during preprocessing (-E or
> -save-temps) is made to point to the most recently seen token rather than the
> beginning of the file. To the best of my knowledge, nothing else besides
> "#pragma GCC diagnostic" handling can observe input_location during
> token streaming, so this is expected not to have any other
> repercussions. Bootstrap + regtest does look clean on x86-64 Linux.
> 
> By the way, the new testcase fails when compiled with C++, but it's not
> because of pragma handling, it's rather because the C++ frontend changes the
> location on the warning to the wrong place. Once done_lexing has been set to
> true, it changes the location of all warnings to input_location, however
> that's not correct when the location is the cached location of a macro
> definition; the original location is preferable. I will file a separate PR
> about that, and have xfailed that testcase for now, since I am not quite there
> with grokking the reason it behaves this way, and anyway it's not related to
> this 1-line fix for gcc -E.
> 
> Please let me know how it looks? Thanks!

OK.

-- 
Joseph S. Myers
joseph@codesourcery.com