On Thu, 28 Nov 2013, Max Woodbury wrote: > As for the sequence of comments you point to, they are discussing the > use of __LINE__ in macros, not directives. The standard is quite a bit > more explicit about token substitution in directives, making it fairly > clear that substitution is not to occur in directives until > specifically called for. The elaboration of three distinct forms for > the '#line' directive with substitution only being called for in the > third and last form, indicates that something special is intended.
I think the natural reading is that the current token is __LINE__ on the #line line, because that's what's being macro-expanded, and that the relevant number of newlines is those strictly before the #line line, so this directive is expected to make the next line's number that of the current line (i.e. one less than it would otherwise have been). I think interpreting it otherwise is what strains the language of the standard. I think it's completely irrelevant what later parts of the source file are involved in identifying the form of the directive - the relevant thing is what is being expanded rather than anything later that was involved in causing it to be expanded. So, I think this patch is a bad idea, absent direction otherwise from WG14, and you should raise a DR with WG14 if you disagree. -- Joseph S. Myers jos...@codesourcery.com
