[Bug preprocessor/58687] "#line __LINE__ ..." changes subsequent line numbers

["mtewoodbury at gmail dot com" <gcc-bugzilla@gcc.gnu.org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58687

--- Comment #21 from Max TenEyck Woodbury <mtewoodbury at gmail dot com> ---
(In reply to Joseph S. Myers from comment #20)
> Suspending pending a DR since I think the present code is correct and while
> the standard is ambiguous I think the interpretation here strains the
> wording of the standard.  I'd proposed to close this if a DR (or other WG14
> document) isn't under consideration at the Parma meeting of WG14.

A 'DR' is not necessary and is unlikely to be submitted.  The ambiguity
referred 
to is in the expansion of macros, not in the processing of directives.  

The elaborate description of the different forms of the '#line' (and other) 
directives makes it clear that <pp-token> expansion is not to take place until 
after the <end-of-line> for the directive has been seen.  

Accepted usage is for '#line __LINE__' to leave the line numbering unchanged.  
Any other interpretation would require some form of expression evaluation in 
order to leave line numbering unchanged; a possibility that has been rejected.