Re: preprocessor/21250 and address of <built-in>

[Neil Booth <neil at daikokuya dot co dot uk>]

Per Bothner wrote:-

> Opinions on how to handle this bug?
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21250
> 
> This came up because we give <built-in> declarations
> line 0, but used line 1 in a different date structure.
> I fixed the code to consistently use line 0, which is
> needed for the --enable-mapped-location unification.
> 
> However, we end up with preprocessor output like this:
> 
> # 1 "any-file"
> # 0 "<built-in>"
> # 1 "<command line>"
> # 1 "any-file"
> 
> Some assemblers complain about line number 0.  This is especially
> an issue for people who use cpp to preprocessor assembler, which
> of course we don't really support.
> 
> My suggested solution: suppress the output of <built-in>, so
> we get:
> # 1 "any-file"
> # 1 "<command line>"
> # 1 "any-file"
> 
> There should never be anything following <built-in>, so it's useless

Well, there is with -d output dumping.

> as well as confusing.  Also, if we compile multiple files at once (or
> use a compile server), then logically the <built-in> declaration
> *precede* all the actual code, which suggests that if <built-in> is
> output it should be the *first* line.  

I wanted it to be the first line, but like you say it breaks too much
including GCC's own -fpreprocessed.

> But that would break too much
> code.  Simplest and cleanest solution: Just get rid of the <built-in>
> line in pre-processor output.  This might break some tools that look
> at cpp output, but it seems unlikely.

Agreed - we never guarantee the form of -E anyway.

Neil.