Yang Tse wrote:
2009/6/9, Gregor Jasny wrote:
Yang Tse wrote:
The -export-symbols-regex libtool option was introduced in libtool in
1999, now ten years later it certainly still misbehaves on solaris
systems using the solaris linker creating unusable shared libraries.
Do you have some pointers to e.g. bug reports?
Nope. i've not bothered to do any bug report archeology related with
this. But if I wanted to search for something i would look for libtool
problems related with -export-symbols-regex and/or libtool erroneously
assuming that the gnu linker is the one being used when actually its
another one.
The problem has been verified using libcurl autobuilds. When using
-export-symbols-regex with a sparc-sun-solaris2.10 host building
shared and static versions of c-ares library, the libraries seemed to
build successfully but as soon as the shared c-ares library was linked
with libcurl and curl the result was the following output:
Undefined -- first referenced
symbol ----- in file
ares_gethostbyname ../lib/.libs/libcurl.so
ares_strerror ../lib/.libs/libcurl.so
ares_process_fd ../lib/.libs/libcurl.so
ares_cancel ../lib/.libs/libcurl.so
ares_library_cleanup ../lib/.libs/libcurl.so
ares_version ../lib/.libs/libcurl.so
ares_getsock ../lib/.libs/libcurl.so
ares_destroy ../lib/.libs/libcurl.so
ares_timeout ../lib/.libs/libcurl.so
ares_init ../lib/.libs/libcurl.so
ares_library_init ../lib/.libs/libcurl.so
ld: fatal: Symbol referencing errors. No output written to .libs/curl
As soon as -export-symbols-regex was commented out from Makefile.am
the build suceeded without above errors and all curl test suite pass
ok.
I have no access to this box, so it would be plain wrong for me
attempting to report this bug, for which I can give no further details
nor make further tests, to the libtool team.
My opinion is to remove now the -export-symbols-regex libtool option
introduced in Makefile.am nearly one month ago and never released.
And if someone wants to reduce the number of exported sysmbols provide
a patch based on the 'visibility' attribute for GNUC and __global for
Sun compilers, taking in account also Windows DLLs.
How about enabling it conditionally for gnu systems until a visibility patch
is available?
Or even better, introduce now a configure script option which enabled
building with 'hidden-symbols'. When given, this option would now use
the -export-symbols-regex libtool option if using a gnu linker, and in
the future would use the 'visibility patch'.
What we can not do is force the -export-symbols-regex libtool option
on all systems as the default setting.
As I suck at doing m4/autoconf I'll prepare a visibility patch within
the next days for the GCC compiler.
Gregor
