Re: [PATCH] Use correct export_dynamic_flag_spec for PE-COFF $hosts

[Bob Friesenhahn]

On Sun, 29 Mar 2009, Charles Wilson wrote:

> * libltdl/m4/libtool.m4 (_LT_LINKER_SHLIBS) [cygwin*|mingw*|pw32*|cegcc*]:
> Define export_dynamic_flag_spec as -Wl,--export-all-symbols, as required
> by GNU ld for PE-COFF.
>
> Original patch by Yaakov Selkowitz. As he explained:
>
> On Cygwin, the --export-all-symbols linker flag is required;
> --export-dynamic has no effect
> (see http://sourceware.org/bugzilla/show_bug.cgi?id=6744).
>
> This patch fixes two problems:
>
> (1) LT_SYS_DLOPEN_SELF returns a false negative;
> (2) Using the -export-dynamic libtool flag does not affect the
>   resulting binary.
>
> Tested in combination with several other cygwin patches, as part of the
> recent cygwin "official" 2.2.7a-N libtool release(s):
> http://cygwin.com/ml/cygwin-announce/2009-03/msg00080.html
> http://cygwin.com/ml/cygwin-announce/2009-03/msg00081.html
>
> No regressions.  Okay to push?

If you are sure that --export-all-symbols will work with older (within 
reason) Cygwin and MinGW installs, then this seems ok to push.  I do 
see support for --export-all-symbols in my archaic MinGW install so 
the risk of problems seems low.

Bob

> libltdl/m4/libtool.m4 |    1 +
> 1 files changed, 1 insertions(+), 0 deletions(-)
>
> diff --git a/libltdl/m4/libtool.m4 b/libltdl/m4/libtool.m4
> index 477f6e3..15612c0 100644
> --- a/libltdl/m4/libtool.m4
> +++ b/libltdl/m4/libtool.m4
> @@ -4275,6 +4275,7 @@ _LT_EOF
>       # _LT_TAGVAR(hardcode_libdir_flag_spec, $1) is actually meaningless,
>       # as there is no search path for DLLs.
>       _LT_TAGVAR(hardcode_libdir_flag_spec, $1)='-L$libdir'
> +      _LT_TAGVAR(export_dynamic_flag_spec, $1)='${wl}--export-all-symbols'
>       _LT_TAGVAR(allow_undefined_flag, $1)=unsupported
>       _LT_TAGVAR(always_export_symbols, $1)=no
>       _LT_TAGVAR(enable_shared_with_static_runtimes, $1)=yes
> --
> 1.6.1.2

--
Bob Friesenhahn
address@hidden, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/