Re: ☠ Buildbot (GNU Toolchain): elfutils-try-debian-armhf - failed compile (failure) (users/marxin/try-zstd-support-v2)

[Mark Wielaard <aegon@wildebeest.org>]

Hi,

On Wed, 2022-12-21 at 15:42 +0100, Mark Wielaard wrote:
> 
> Unfortunately buildbot itself doesn't show the config.log.
> Trying to get that...
> 
> configure:6961: checking for library containing ZSTD_compressStream2
> configure:6992: gcc -o conftest -D_FORTIFY_SOURCE=3 -g -O2
> -fsanitize=undefined 
> -fno-sanitize-recover -fsanitize=address -fno-sanitize-
> recover   conftest.c -llz
> ma -lbz2  >&5
> /usr/bin/ld: /tmp/ccKZnuYA.o: in function `main':
> /var/lib/buildbot/workers/wildebeest/elfutils-try-debian-
> armhf/build/conftest.c:
> 30: undefined reference to `ZSTD_compressStream2'
> collect2: error: ld returned 1 exit status
> configure:6992: $? = 1
> configure: failed program was:
> > /* confdefs.h */
> > #define PACKAGE_NAME "elfutils"
> > #define PACKAGE_TARNAME "elfutils"
> > #define PACKAGE_VERSION "0.188"
> > #define PACKAGE_STRING "elfutils 0.188"
> > #define PACKAGE_BUGREPORT "https://sourceware.org/bugzilla"
> > #define PACKAGE_URL "http://elfutils.org/"
> > #define PACKAGE "elfutils"
> > #define VERSION "0.188"
> > #define DEFAULT_AR_DETERMINISTIC false
> > #define HAVE_VISIBILITY 1
> > #define HAVE_STDATOMIC_H 1
> > #define _FILE_OFFSET_BITS 64
> > #define CHECK_UNDEFINED 1
> > #define USE_ZLIB 1
> > #define USE_BZLIB 1
> > #define USE_LZMA 1
> > /* end confdefs.h.  */
> > 
> > /* Override any GCC internal prototype to avoid an error.
> >    Use char because int might match the return type of a GCC
> >    builtin and then its argument prototype would still apply.  */
> > #ifdef __cplusplus
> > extern "C"
> > #endif
> > char ZSTD_compressStream2 ();
> > int
> > main ()
> > {
> > return ZSTD_compressStream2 ();
> >   ;
> >   return 0;
> > }
> 
> configure:6992: gcc -o conftest -D_FORTIFY_SOURCE=3 -g -O2
> -fsanitize=undefined 
> -fno-sanitize-recover -fsanitize=address -fno-sanitize-
> recover   conftest.c -lzs
> td  -llzma -lbz2  >&5
> configure:6992: $? = 0
> configure:7009: result: -lzstd
> 
> ehe? So it fails and then succeeds anyway?
> 
> Strangely the same happens for the other compression library
> checks...
> lzma_auto_decoder and BZ2_bzdopen
> 
> I don't fully understand this. Oddly the same seems to happen locally
> on my x86_64 box. So maybe the configure macros we have been using
> have
> always been bad/broken?

No, this is "normal". It first tries without the -l library (which is
the failing case) and then with the -l library (which succeeds).

What goes wrong is that this debian old stable arm setup has libzstd
containing a ZSTD_compressStream2 symbol...

    40: 0000d349   264 FUNC    GLOBAL DEFAULT   11 ZSTD_compressStream2

But the zstd.h header doesn't expose it...

/*******************************************************************************
*********
 *   ADVANCED AND EXPERIMENTAL FUNCTIONS
 *******************************************************************************
*********
 * The definitions in the following section are considered experimental.
 * They are provided for advanced scenarios.
 * They should never be used with a dynamic library, as prototypes may change in
 the future.
 * Use them only in association with static linking.
 * *****************************************************************************
**********/

#if defined(ZSTD_STATIC_LINKING_ONLY) && !defined(ZSTD_H_ZSTD_STATIC_LINKING_ONLY)

...

grmbl.

This is somewhat unfortunate. We need a smarter configure check for this...

Cheers,

Mark