Re: make needs to know about multiarch for expansion of -l target dependencies

[Jonathan Nieder]

Hi Paul,

FYI:

Steve Langasek wrote[1]:

> As part of the initial deployment of multiarch support in Ubuntu, we've
> discovered that some packages rely on make dependencies on "-lpthread" and
> the like, which GNU make resolves internally to a library file.  Since
> multiarch means changing the paths at which libraries are installed on the
> system, this means an update to make is required to know about the extended
> system path on Debian systems.
>
> The attached patch implements this.
[...]
> (Note, this currently doesn't include /usr/local/lib/$triplet.  The reason
> for this is that the gcc and eglibc patches for multiarch do not mention
> /usr/local/lib/$triplet, so I'm following suit here; but we may want to
> revisit this issue down the line, I'm not sure this is very FHS upstreamable
> without the /usr/local/lib analogue.)
>
> Changelog entry used for the upload to Ubuntu was:
>
>   * remake.c, configure.in: prepend multiarch paths to the library path in 
>     library_search() when we have a target dependency of '-lfoo', so that
>     this still works when all our libraries are moving to multiarch library
>     directories.  LP: #737641.

This all suggests to me that we need a

        getconf LIBRARY_PATH

command so the same system-specific rules do not have to be reimplemented
in every program that cares.

Potential Debian-specific patch to just deal with this in "make" in the
short term follows.  Thoughts?

Thanks,
Jonathan

[1] http://bugs.debian.org/618840

> --- Makefile.am       2006-05-03 21:49:55 +0000
> +++ Makefile.am       2011-03-18 20:34:06 +0000
> @@ -57,7 +57,7 @@
>  
>  man_MANS =   make.1
>  
> -DEFS =               -DLOCALEDIR=\"$(localedir)\" -DLIBDIR=\"$(libdir)\" 
> -DINCLUDEDIR=\"$(includedir)\" @DEFS@
> +DEFS =               -DLOCALEDIR=\"$(localedir)\" -DLIBDIR=\"$(libdir)\" 
> -DINCLUDEDIR=\"$(includedir)\" -DMULTIARCH_DIRS="$(MULTIARCH_DIRS)" @DEFS@
>  
>  AM_CPPFLAGS =        $(GLOBINC)
>  # Only process if target is MS-Windows
> 
> === modified file 'configure.in'
> --- configure.in      2006-05-03 21:49:55 +0000
> +++ configure.in      2011-03-18 20:41:16 +0000
> @@ -374,6 +374,24 @@
>  MAKE_HOST="$host"
>  AC_SUBST(MAKE_HOST)
>  
> +AC_PATH_TOOL([DPKG_ARCH], [dpkg-architecture])
> +AC_MSG_CHECKING([for multiarch paths])
> +multiarch_triplet=""
> +if test -n "$DPKG_ARCH"; then
> +     multiarch_triplet=$($DPKG_ARCH -qDEB_HOST_MULTIARCH)
> +     if test -z "$multiarch_triplet"; then
> +             multiarch_triplet=$($DPKG_ARCH -qDEB_HOST_GNU_TYPE)
> +     fi
> +fi
> +if test -n "$multiarch_triplet"; then
> +     MULTIARCH_DIRS="\\\"/lib/$multiarch_triplet\\\", 
> \\\"/usr/lib/$multiarch_triplet\\\","
> +     AC_MSG_RESULT([$MULTIARCH_DIRS])
> +else
> +     AC_MSG_RESULT([not found])
> +fi
> +
> +AC_SUBST(MULTIARCH_DIRS)
> +
>  w32_target_env=no
>  AM_CONDITIONAL([WINDOWSENV], false)
>  
> 
> === modified file 'remake.c'
> --- remake.c  2008-04-03 02:04:02 +0000
> +++ remake.c  2011-03-18 20:17:13 +0000
> @@ -1451,6 +1451,9 @@
>  {
>    static char *dirs[] =
>      {
> +#ifdef MULTIARCH_DIRS
> +      MULTIARCH_DIRS
> +#endif
>  #ifndef _AMIGA
>        "/lib",
>  #endif
>