Re: Let --enable-shared on MSYS2 generate .dll and .dll.a files

[Reini Urban]

On Sun, Dec 13, 2020 at 4:27 PM Håkon Hægland <hakon.hagland@gmail.com>
wrote:

> I am trying to generate Perl wrappers for GSL on Windows 10, MSYS2. These
> wrappers are produced by SWIG which produces .dll libraries that are loaded
> by Perl at run time. Since configure.ac currently ignores --enable-shared
> for MSYS2 and generates only a static libgsl.a library, the the .dll
> libraries generated by Perl will each include copies of the global
> variables in libgsl.a. For example, the variable gsl_error_handler in
> error.c. This makes the usage of the function gsl_set_error_handler_off()
> in error.c unpredictable, since its result will depend on which of the Perl
> generated .dll modules are called.
>
> I believe configure.ac needs to be updated here. See line 167:
>
> case $host in
>   *-*-cygwin* | *-*-mingw* )
>   if test "$enable_shared" = yes; then
>     GSLCBLAS_LDFLAGS="$GSLCBLAS_LDFLAGS -no-undefined"
>     GSL_LDFLAGS="$GSL_LDFLAGS -no-undefined"
>     GSL_LIBADD="cblas/libgslcblas.la"
>   fi
>   ;;
> esac
>
>
> by adding "msys" at line 168, it is possible to create a
> libgsl.dll.a import library that will refer to a .dll shared library. If I
> change line 168 to:
>
>   *-*-cygwin* | *-*-mingw*  | *-*-msys* )  # <-- add msys here
>
> and rerun ./autogen.sh and then run
>
>   ./configure --enable-shared --prefix=/opt/gsl/gsl-2.6; make; make install
>
> it now produces an import libarary in /opt/gsl/gsl-2.6/lib/libgsl.dll.a and
> a shared library in /opt/gsl/gsl-2.6/bin/msys-gsl-25.dll
>

Can confirm, that's the right thing to do.

-- 
Reini Urban