Re: Warning: Obscure preprocessor/configure/include file problem (with solution)

[Roland McGrath <roland@frob.com>]

> we have an obscure problem in our setup if we use
> "-W,-rpath=/usr/i386-gnu/lib" in our i386-gnu-gcc wrapper script:

I don't think you ever want to do that.  That sets the DT_RPATH encoded in
the binaries.  You want -rpath-link, which affects only ld's behavior at
link time.  (And I assume that's "-Wl,..." not "-W,..." in actuality.)

> ./configure will test for the preprocessor, first it tries "i386-gnu-gcc -E".  
> But because this has output on stderr, namely:
> 
> gcc: -rpath=/usr/i386-gnu/lib: linker input file unused since linking not done

I have never seen a problem like this.  My specs file has the -rpath-link
in the *lib section, so it's never consulted when not linking.

> The solution is, if we can't suppress the output, to either specify an
> environment variable CPP before calling configure, or to check this special
> case in the wrapper, or to move the rpath from the wrapper to the specs
> file.

The only downside of having it in the specs file is the need for specific
cross-compile directory names to be substituted into the specs file.