Re: [Tinycc-devel] Add support of musl-libc to tinycc

[Michael Matz]

Hi,

On Sat, 6 May 2017, Larry Doolittle wrote:

> Micheal, Marc, and tinycc lurkers -
>
> On Sun, May 07, 2017 at 04:54:38AM +0200, Michael Matz wrote:
> > On Thu, 20 Apr 2017, Marc Vertes wrote:
> > > I just committed the patch to support musl-libc in the tcc
> > > compiler development branch: http://repo.or.cz/w/tinycc.git
> > > [...]
> > > Dear tinycc developers, let me know if this feature can be added
> > > to the upcoming 0.9.27 version, and also how to fix the DLL
> > > bootstrap problem.
> > Fixed in mob.  The problem is the stricter dynamic loader of musl,
> > which ignores all STB_LOCAL symbols for symbol resolution [...]
> > With that the tests also run on musl.  [...]
>
> On Debian Jessie amd64 with musl-dev installed, tinycc (commit 5732a188)
> detects that musl exists (CONFIG_musl=yes in config.mak), builds OK, but
> fails on make test at dlltest:
>
> ./tcc2 -B.. -I/home/larry/git/tinycc/include -I/home/larry/git/tinycc -I.. 
> -DCONFIG_TRIPLET="\"x86_64-linux-gnu\"" -DTCC_TARGET_X86_64 -DTCC_MUSL 
> -DONE_SOURCE -run /home/larry/git/tinycc/tcc.c -B.. -I/home/larry/git/tinycc/include 
> -I/home/larry/git/tinycc -I.. -run /home/larry/git/tinycc/examples/ex1.c
> /usr/lib/x86_64-linux-gnu/libc.so:2: error: unrecognized file type
> tcc: error: Unknown relocation type: 23

On debain, if you have libc6-dev and musl-dev installed you get a strange 
mix of glibc and musl objects and shared libraries linked into the exe. 
E.g. in the above it picks up /usr/lib/x86_64-linux-gnu/libc.a (from 
glibc), which has TPOFF32 relocs and those aren't handled by TCC.

Removing libc6-dev, installing musl-tools, and using musl-gcc for 
compilation ensures that there's no mixture at least.  But that then fails 
because TCC itself isn't prepared to look into e.g. 
/usr/include/x86_64-linux-musl for standard headers like e.g. stdio.h, 
neither does it look into /usr/lib/x86_64-linux-musl/ for startup files 
like crt1.o.  So, yeah, the detection/support of musl is early and doesn't 
work with the split-mind approach that debian is using.

It does work for the setup of musl as the main libc, like with alpine 
linux; so I'm not sure the detection should be disabled or rather be 
improved (or there should perhaps be a configure option to override the 
detection by users).

> I just made a quick attempt to build gcc-4.7.4 with current git tcc.
> It made it through about 337 compiles before failing on
> ../.././gcc/c-family/c-opts.c:141: error: ';' expected (got "=")

Yeah, thanks for finding the cause downthread.  extern file-scope 
declarations with initializer are questionable style but indeed allowed by 
the standard, i.e. the above rejection is a bug in TCC.  Fixed in mob.


Ciao,
Michael.