Re: PATCH: fix breakage from "[PATCH] Fix genmatch linking"

[Richard Biener <rguenther at suse dot de>]

On Fri, 24 Oct 2014, Hans-Peter Nilsson wrote:

> > From: Richard Biener <rguenther@suse.de>
> > Date: Thu, 23 Oct 2014 10:47:43 +0200
> 
> > This adds a libcpp host module without NLS and ICONV support
> > and properly links genmatch against the build libcpp instead of
> > the host one.
> > 
> > Bootstrap running on x86_64-unknown-linux-gnu (stage1 all-gcc
> > finished fine).
> > 
> > Ok for trunk?
> > 
> > Thanks,
> > Richard.
> > 
> > 2014-10-23  Richard Biener  <rguenther@suse.de>
> > 
> > 	* Makefile.def: Add libcpp build module and dependencies.
> > 	* configure.ac: Add libcpp build module.
> > 	* Makefile.in: Regenerate.
> > 	* configure: Likewise.
> 
> You only exposed a dormant issue, but ever since this commit
> (nominally, some commit in "(216573:216588]" but I only see this
> one matching) I see, for cross-builds (to cris-elf):
> 
> make[2]: Entering directory `/tmp/hpautotest-gcc1/cris-elf/gccobj/build-x86_64-unknown-linux-gnu/libcpp'
> g++  -I/tmp/hpautotest-gcc1/gcc/libcpp -I. -I/tmp/hpautotest-gcc1/gcc/libcpp/../include -I/tmp/hpautotest-gcc1/gcc/libcpp/include  -g -O2 -W -Wall -Wwrite-strings -Wmissing-format-attribute -pedantic -Wno-long-long  -fno-exceptions -fno-rtti -I/tmp/hpautotest-gcc1/gcc/libcpp -I. -I/tmp/hpautotest-gcc1/gcc/libcpp/../include -I/tmp/hpautotest-gcc1/gcc/libcpp/include   -c -o charset.o -MT charset.o -MMD -MP -MF .deps/charset.Tpo /tmp/hpautotest-gcc1/gcc/libcpp/charset.c
> In file included from /tmp/hpautotest-gcc1/gcc/libcpp/system.h:370,
>                  from /tmp/hpautotest-gcc1/gcc/libcpp/charset.c:21:
> /tmp/hpautotest-gcc1/gcc/libcpp/../include/libiberty.h:113: error: new declaration 'char* basename(const char*)'
> /usr/include/string.h:601: error: ambiguates old declaration 'const char* basename(const char*)'
> make[2]: *** [charset.o] Error 1
> make[2]: Leaving directory `/tmp/hpautotest-gcc1/cris-elf/gccobj/build-x86_64-unknown-linux-gnu/libcpp'
> make[1]: *** [all-build-libcpp] Error 2
> make[1]: Leaving directory `/tmp/hpautotest-gcc1/cris-elf/gccobj'
> make: *** [all] Error 2
> 
> Above that, we have:
> checking whether basename is declared... (cached) no
> 
> and above that, we have:
> make[2]: Leaving directory `/tmp/hpautotest-gcc1/cris-elf/gccobj/build-x86_64-unknown-linux-gnu/fixincludes'
> mkdir -p -- build-x86_64-unknown-linux-gnu/libcpp
> Configuring in build-x86_64-unknown-linux-gnu/libcpp
> configure: loading cache ../config.cache
> 
> which is apparently set due to (above that, first non-cached):
> mkdir -p -- build-x86_64-unknown-linux-gnu/libiberty
> Configuring in build-x86_64-unknown-linux-gnu/libiberty
> configure: creating cache ../config.cache
> ...
> checking whether basename is declared... no
> 
> Your commit introduces build-subdirectories for cross-builds.
> Build-subdirs share a config.cache (in build-<host>/config.cache),
> with subdirs in build-<host> being fixincludes, libcpp and
> libiberty.
> 
> But, libiberty and fixincludes are configure-tested and compiled
> using gcc, while libcpp is compiled with g++, which causes a
> different set of declarations to be exposed, so the shared
> config.cache is invalid and its use is bogus.  Not sure how this
> works for native builds.
> 
> The libcpp configure checks are actually run with gcc which is
> bogus by itself, but apparently working.  I guess the C vs. C++
> declaration etc. differences for libcpp are mostly hidden by
> using _GNU_SOURCE (through AC_USE_SYSTEM_EXTENSIONS), and I'm a
> bit surprised that's not used for libiberty and fixincludes.
> Still, a red herring.  Aligning those options *may* cause the
> build to succeed, but I think that'd be too much of sweeping the
> issue under the carpet.
> 
> It seems "more correct" to just disable the config.cache sharing
> between the differently-configured build-subdirectories, as is
> already is done for host-libraries and target-libraries, even if
> that may slow down the builds.  (Erroring out is infinitely
> slower. :)  Still, I don't understand exactly how your patch
> introduces build-subdirectories where there were none before.
> Maybe that "+all-gcc: maybe-all-build-libcpp" was wrong and
> should be different?

No, we do need a build-libcpp to build gcc/build/genmatch.
Not sure how you got around without a build-libiberty as other
gen* programs surely require that.

> Anyway, with this, a cris-elf cross build passes the point of
> failure; compilers and libraries built, progressing into
> testing.
> 
> Ok to commit?

Ok.

Thanks,
Richard.

> toplev:
> 	* configure.ac (build_configargs): Don't share
> 	config.cache between build subdirs.
> 
> Index: configure.ac
> ===================================================================
> --- configure.ac	(revision 216610)
> +++ configure.ac	(working copy)
> @@ -2922,8 +2922,10 @@ AC_ARG_VAR([target_configargs],
>  
>  # For the build-side libraries, we just need to pretend we're native,
>  # and not use the same cache file.  Multilibs are neither needed nor
> -# desired.
> -build_configargs="$build_configargs --cache-file=../config.cache ${baseargs}"
> +# desired.  We can't even use the same cache file for all build-side
> +# libraries, as they're compiled differently; some with C, some with
> +# C++ or with different feature-enabling options.
> +build_configargs="$build_configargs --cache-file=./config.cache ${baseargs}"
>  
>  # For host modules, accept cache file option, or specification as blank.
>  case "${cache_file}" in
> Index: configure
> ===================================================================
> --- configure	(revision 216610)
> +++ configure	(working copy)
> @@ -7386,8 +7386,10 @@ tbaseargs="$tbaseargs --disable-option-c
>  
>  # For the build-side libraries, we just need to pretend we're native,
>  # and not use the same cache file.  Multilibs are neither needed nor
> -# desired.
> -build_configargs="$build_configargs --cache-file=../config.cache ${baseargs}"
> +# desired.  We can't even use the same cache file for all build-side
> +# libraries, as they're compiled differently; some with C, some with
> +# C++ or with different feature-enabling options.
> +build_configargs="$build_configargs --cache-file=./config.cache ${baseargs}"
>  
>  # For host modules, accept cache file option, or specification as blank.
>  case "${cache_file}" in
> 
> brgds, H-P
> 
> 

-- 
Richard Biener <rguenther@suse.de>
SUSE / SUSE Labs
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