Re: [PATCH] musl-gcc.spec: honour $LIBRARY_PATH / $LPATH

[Rich Felker <dalias@libc.org>]

On Wed, Feb 22, 2017 at 10:54:24PM +0100, Mathias Krause wrote:
> On Wed, Feb 22, 2017 at 04:11:58PM -0500, Rich Felker wrote:
> > On Wed, Feb 22, 2017 at 09:57:05PM +0100, Mathias Krause wrote:
> > > To support additional library search paths via $LIBRARY_PATH / $LPATH
> > > extend the link_libgcc variable instead of replacing it. The original
> > > one will contain the required "%D" to support this.
> > > 
> > > musl's library path is still the first in the list, so its object files
> > > will be found before other paths are taken into account.
> > > 
> > > Signed-off-by: Mathias Krause <minipli@googlemail.com>
> > > ---
> > >  tools/musl-gcc.specs.sh |    4 +++-
> > >  1 file changed, 3 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/tools/musl-gcc.specs.sh b/tools/musl-gcc.specs.sh
> > > index 294e24f75503..819799a6d5a7 100644
> > > --- a/tools/musl-gcc.specs.sh
> > > +++ b/tools/musl-gcc.specs.sh
> > > @@ -10,8 +10,10 @@ cat <<EOF
> > >  *cc1:
> > >  %(cc1_cpu) -nostdinc -isystem $incdir -isystem include%s
> > >  
> > > +%rename link_libgcc old_link_libgcc
> > > +
> > >  *link_libgcc:
> > > --L$libdir -L .%s
> > > +-L$libdir %(old_link_libgcc)
> > 
> > I'm pretty sure this is wrong. What are you trying to achieve?
> 
> I'm trying to make musl-gcc not break gcc's ability to search for
> additional library paths via the LIBRARY_PATH environment variable.
> 
> Let me past the relevant section of gcc's manpage:
> 
>    LIBRARY_PATH
>        The value of LIBRARY_PATH is a colon-separated list of
>        directories, much like PATH.  When configured as a native
>        compiler, GCC tries the directories thus specified when
>        searching for special linker files, if it can't find them
>        using GCC_EXEC_PREFIX.  Linking using GCC also uses these
>        directories when searching for ordinary libraries for the
>        -l option (but directories specified with -L come first).
> 
> I'm trying to make use of the "…when searching for ordinary libraries
> for the -l option" part.
> 
> > The whole point of musl-gcc is to _remove_ any existing library paths
> > since, if present, they will cause configure scripts to detect and
> > link to incompatible libraries (linked against glibc).
> 
> Can you elaborate on this? How would including $LIBRARY_PATH provided
> paths break configure scripts? In fact, the way the specs file is now
> breaks my use case but I don't want to break yours. :/

It's not that $LIBRARY_PATH breaks it, but rather that the defaults
copied from the original link_libgcc might break it. If you think this
is wrong, please check; it's been a long time since I looked at this.

Rich