Re: Cross-compiling with mingw

[Sylvain Beucler <beuc@beuc.net>]

On Mon, May 26, 2008 at 10:43:44PM +0200, Sylvain Beucler wrote:
> Hi,
> 
> I'm tring to cross-compile Guile from GNU/Linux with mingw (so I can
> statically build guile in a .exe without having to use that other OS).
> 
> I cross-compiled gmp and libltdl (dependencies).
> Now I have a few troubles with guile:
> 
> 
> Act I) Configuration
> 
> $ CPPFLAGS="-I/usr/local/cross-tools/i386-mingw32msvc/include" \
>   LDFLAGS="-L/usr/local/cross-tools/i386-mingw32msvc/lib" \
>   ./configure --host=i586-mingw32msvc --build=i686-pc-linux-gnu
> [...]
> checking for restartable system calls... configure: error: cannot run test program while cross compiling
> 
> The problem apparently lies in configure.in, macro AC_SYS_RESTARTABLE_SYSCALLS
> 
> Note that the autoconf documentation deprecates this macro:
> "These days portable programs [...] should not rely on
> `HAVE_RESTARTABLE_SYSCALLS', since nowadays whether a system call is
> restartable is a dynamic issue, not a configuration-time issue."
> 
> I commented it out for a start.
> 
> 
> Act II) Compilation
> 
> $ make
> [...]
> DLL_EXPORT -DPIC -o .libs/libguile_la-stime.o
> cc1: warnings being treated as errors
> stime.c:85: warning: ‘tzname’ redeclared without dllimport attribute: previous dllimport ignored
> 
> I found 2 references to this issue:
> - http://cygwin.com/ml/cygwin/2008-01/msg00491.html
> => removed tzname
> - http://www.nabble.com/getdate-on-mingw:-tzname-problems-td14855896.html
> => use HAVE_DECL_TZNAME instead
> 
> I used the 2nd option:
> # if !HAVE_DECL_TZNAME /* For SGI.  */
> extern char *tzname[]; /* RS6000 and others reject char **tzname.  */
> #endif
> #if defined (__MINGW32__)
> # define tzname _tzname
> #endif
> 
> 
> Act III) Linking
> 
> i586-mingw32msvc-gcc -I/usr/local/cross-tools/i386-mingw32msvc/include -g -O2 -Wall -Wmissing-prototypes -Werror .libs/guile.exeS.o -I/usr/local/cross-tools/i386-mingw32msvc/include -o guile.exe guile-guile.o -Wl,--export-dynamic  -L/usr/local/cross-tools/i386-mingw32msvc/lib ./.libs/libguile.a /usr/local/cross-tools/i386-mingw32msvc/lib/libgmp.a -lws2_32 /usr/local/cross-tools/i386-mingw32msvc/lib/libltdl.dll.a   -L/usr/local/cross-tools/i386-mingw32msvc/lib -L/usr/local/cross-tools/i386-mingw32msvc/lib
> guile-guile.o: In function `main':
> /usr/src/guile-1.8.5/libguile/guile.c:74: undefined reference to `__imp__scm_boot_guile'
> guile-guile.o: In function `inner_main':
> /usr/src/guile-1.8.5/libguile/guile.c:55: undefined reference to `__imp__gdb_options'
> /usr/src/guile-1.8.5/libguile/guile.c:55: undefined reference to `__imp__gdb_language'
> /usr/src/guile-1.8.5/libguile/guile.c:55: undefined reference to `__imp__gdb_result'
> /usr/src/guile-1.8.5/libguile/guile.c:55: undefined reference to `__imp__gdb_output'
> /usr/src/guile-1.8.5/libguile/guile.c:55: undefined reference to `__imp__gdb_output_length'
> /usr/src/guile-1.8.5/libguile/guile.c:55: undefined reference to `__imp__gdb_maybe_valid_type_p'
> /usr/src/guile-1.8.5/libguile/guile.c:55: undefined reference to `__imp__gdb_read'
> /usr/src/guile-1.8.5/libguile/guile.c:55: undefined reference to `__imp__gdb_eval'
> /usr/src/guile-1.8.5/libguile/guile.c:55: undefined reference to `__imp__gdb_print'
> /usr/src/guile-1.8.5/libguile/guile.c:55: undefined reference to `__imp__gdb_binding'
> /usr/src/guile-1.8.5/libguile/guile.c:59: undefined reference to `__imp__scm_shell'
> collect2: ld returned 1 exit status
> rm -f .libs/guile.exeS.o
> make[3]: *** [guile.exe] Erreur 1
> 
> Duh!
> I'm out of ideas. Help? :)

This one is apparently due to guile.c:

#ifdef __MINGW32__
# define SCM_IMPORT 1
#endif


When the error occured, the build system was apparently using
libguile.la statically. In this case, __declspec (dllimport) need not
be used, and so SCM_IMPORT need not be defined, so the linker won't
use the '__imp__' symbols.


(

The goat book uses a slightly more complex technique to detect the use
of DLL imports:
http://sources.redhat.com/autobook/autobook/autobook_255.html

# ----------------------------------------------------------------------
# Win32 objects need to tell the header whether they will be linking
# with a dll or static archive in order that everything is imported
# to the object in the same way that it was exported from the
# archive (extern for static, __declspec(dllimport) for dlls)
# ----------------------------------------------------------------------
LIBHELLO_DLL_IMPORT=
case "$host" in
*-*-cygwin* | *-*-mingw* )
  if test X"$enable_shared" = Xyes; then
    AC_TRY_LINK_FUNC([libhello_is_dll],
                     [LIBHELLO_DLL_IMPORT=-DLIBHELLO_DLL_IMPORT])
  fi
  ;;
esac
AC_SUBST(LIBHELLO_DLL_IMPORT)

and then:
#ifdef _WIN32
#  ifdef DLL_EXPORT
#    define HELLO_SCOPE         __declspec(dllexport)
#  else
#    ifdef LIBHELLO_DLL_IMPORT
#      define HELLO_SCOPE       extern __declspec(dllimport)
#    endif
#  endif
#endif
#ifndef HELLO_SCOPE
#  define HELLO_SCOPE           extern
#endif

)


With the ./configure line I mentioned, I then ran in to problems
linking with gmp.  GMP can't be built statically and as a DLL at once
("gmp.h is different for each", it says), so it was only built
statically in my environment, and thus guile didn't link.

So I added "--disable-shared" to ./configure, added an '#undefine
SCM_IMPORT' in guile.c, and it eventually (cross-)compiled entirely.


Now, how to properly fix it? :)

-- 
Sylvain