Re: Link tests after GCC_NO_EXECUTABLES

[Bernd Schmidt <bernds_cb1@t-online.de>]

Mark Mitchell wrote:
> Bernd Schmidt wrote:
> 
>> "libstdc++-v3/configure.ac" AM_PROG_LIBTOOL -> "libtool.m4" LT_INIT ->
>> _LT_SETUP -> _LT_LANG_C_CONFIG -> LT_SYS_DLOPEN_SELF
>>
>> which leads to
>> checking for shl_load... configure: error: Link tests are not allowed
>> after GCC_NO_EXECUTABLES.
>> make[1]: *** [configure-target-libstdc++-v3] Error 1
> 
> Thanks.  Perhaps the difference here is that <dlfcn.h> isn't available
> for MIPS/Power ELF, but is available in your configuration because
> you're building with uClibc as your C library?

We're talking bfin-elf here, so that'd be newlib.  I have no great
desire to meddle in the affairs of libtool, and I'd like to again make
the point that this isn't the first time I've seen the "Link tests are
not allowed after GCC_NO_EXECUTABLES" message; if there is a rule that
libstdc++ configure shouldn't try to link anything, it doesn't appear to
be well enforced.

There's another reason why the patch is helpful: the uClibc build system
tries to guess an OUTPUT_FORMAT for the linker from the output of
  bfin-elf-gcc -mfdpic -Wl,--verbose
which currently fails because without -msim, the linker is trying to
pull in the wrong objects.  I suppose that could be changed too, or I
could try to investigate other ways of building up all the toolchains
that don't require -mfdpic multilibs for bfin-elf.

> In any case, I think this is something that ought to be decided as a
> global policy for GCC and its run-time libraries, not something that
> differs between ports.  In particular, if run-time libraries are allowed
> to depend on linking in their configure tests, that's something everyone
> should know.

If you wish to approve Jie's original patch, I'm not stopping you.  I'll
then revert my patch if I can get some fix into the uClibc repository,
but I reserve the right to reapply it in the future if libstdc++ breaks
my build again.

What I'm trying to do here is to ensure that gcc-4.3 will work out of
the box as a compiler for our uClinux distribution.


Bernd
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