Bug#768265: gcc-4.9: Please support i386 compilation on amd64 through multiarch

[Ralf Jung <post@ralfj.de>]

Package: gcc-4.9
Version: 4.9.1-19
Severity: wishlist

Dear Maintainer,

I tried to compile a simple "Hello world" C program to a 32bit binary on
my amd64 system, using:

$ gcc -m32 test.c -o test

But this does not work:

/usr/bin/ld: skipping incompatible /usr/lib/gcc/x86_64-linux-gnu/4.9/libgcc.a when searching for -lgcc
/usr/bin/ld: cannot find -lgcc
/usr/bin/ld: skipping incompatible /usr/lib/gcc/x86_64-linux-gnu/4.9/libgcc_s.so when searching for -lgcc_s
/usr/bin/ld: cannot find -lgcc_s
collect2: error: ld returned 1 exit status

I do have libgcc-4.9-dev:i386 installed, so both libgcc.a and libgcc_s.so are available as 32bit binaries.
It just doesn't find them. I tried guiding it with "-L", but that did not help.

Of course I could install gcc-multilib, but that will pull in libc6-dev-i386:amd64, duplicating what
I already have from libc6-dev:i386. That seems like a useless waste.

Kind regards
Ralf

-- System Information:
Debian Release: jessie/sid
  APT prefers testing
  APT policy: (990, 'testing'), (100, 'unstable')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 3.17.0+ (SMP w/4 CPU cores)
Locale: LANG=en_GB.UTF-8, LC_CTYPE=en_GB.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash

Versions of packages gcc-4.9 depends on:
ii  binutils        2.24.90.20141023-1
ii  cpp-4.9         4.9.1-19
ii  gcc-4.9-base    4.9.1-19
ii  libc6           2.19-12
ii  libcloog-isl4   0.18.2-1
ii  libgcc-4.9-dev  4.9.1-19
ii  libgmp10        2:6.0.0+dfsg-6
ii  libisl10        0.12.2-2
ii  libmpc3         1.0.2-1
ii  libmpfr4        3.1.2-1
ii  zlib1g          1:1.2.8.dfsg-2

Versions of packages gcc-4.9 recommends:
ii  libc6-dev  2.19-12

Versions of packages gcc-4.9 suggests:
ii  gcc-4.9-doc       4.9.1-3
pn  gcc-4.9-locales   <none>
pn  gcc-4.9-multilib  <none>
pn  libasan1-dbg      <none>
pn  libatomic1-dbg    <none>
pn  libcilkrts5-dbg   <none>
pn  libgcc1-dbg       <none>
pn  libgomp1-dbg      <none>
pn  libitm1-dbg       <none>
pn  liblsan0-dbg      <none>
pn  libquadmath0-dbg  <none>
pn  libtsan0-dbg      <none>
pn  libubsan0-dbg     <none>

-- no debconf information