Clang '-g' unused warnings in FreeBSD (linking)

[Konstantin Belousov]

On Sun, Jul 15, 2012 at 07:32:35PM +0200, Dimitry Andric wrote:
> On 2012-07-15 15:39, Jakub Lach wrote:
> > While this is old "bug" upstream:
> > 
> > http://llvm.org/bugs/show_bug.cgi?id=8611
> > 
> > http://llvm.org/bugs/show_bug.cgi?id=8630
> > 
> > Here, 
> > 
> > (FreeBSD clang version 3.1 (branches/release_31 156863) 20120523
> > Target: x86_64-unknown-freebsd9.0)
> > 
> > Passing -g during linking (which lot's of projects do by 
> > including CFLAGS in linking) I still get 
> > 
> > "clang: warning: argument unused during compilation: '-g'"
> ...
> On 2012-07-15 16:04, Jakub Lach wrote:
> > Maybe I should include a question too, so I have better chance 
> > of getting answer :)
> > 
> > Is this intended behaviour? 
> 
> This is a bit typical issue for clang, which originates in the way it
> parses command line arguments: different parts of the compiler stages
> 'claim' arguments, and any that are left at the end are reported as
> unused.
> 
> Regarding the LLVM PRs you mentioned, one could argue that passing '-g'
> to the link stage is nonsensical, since ld cannot add debug information,
> it can only remove it (via the '-s' flag).  But since it is apparently
> common to do this, it may be a bit too annoying to complain about it.
> 
> In any case, upstream fixed it for Linux, but not for any other
> operating system.  I will make a similar fix for FreeBSD, and send it
> upstream too.

Note that historical ld(1) did emited debugging information into
resulting binary only if -g was specified, so the linker flag is not
always 'meaningless'. I suspect that Solaris ld still behaves this way.
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