[FFmpeg-devel] [PATCH] Shared library support for MSVC build.

[Ronald S. Bultje]

Hi,

On Wed, Oct 3, 2012 at 2:01 PM, jamal <jamrial at gmail.com> wrote:
> On 03/10/12 2:35 AM, Ronald S. Bultje wrote:> Hi,
>>
>> On Tue, Oct 2, 2012 at 8:59 PM, jamal <jamrial at gmail.com> wrote:
>>> You're doing what you mentioned you wanted to avoid the other day: Create a header for essentially a single purpose/platform and include it in those files that would require it.
>>> __declspec() is an attribute, so you could instead add it to libavutil/attributes.h to more or less avoid that, since it's a widely used header.
>>
>> Can do, but then I'd need to create a libavcodec/attributes.h also,
>> which I thought was kind of weird, i.e. you'd have
>> libavutil/attributes.h with all general attributes, and then
>> libavcodec/attributes.h with the symbol-stuff specific to libavcodec.
>> But sure if you prefer, I can do that too...
>>
>> Ronald
>
> Can't you use libavutil/attributes.h for both cases instead of creating a new header in libavcodec?

That puts libavcodec stuff in libavutil, which is silly.

>
> That aside:
>
>> @@ -3078,11 +3079,13 @@ case $target_os in
>>          shlibdir_default="$bindir_default"
>>          SLIBPREF=""
>>          SLIBSUF=".dll"
>> +        LIBPREF=""
>> +        LIBSUF=".lib"
>>          SLIBNAME_WITH_VERSION='$(SLIBPREF)$(FULLNAME)-$(LIBVERSION)$(SLIBSUF)'
>>          SLIBNAME_WITH_MAJOR='$(SLIBPREF)$(FULLNAME)-$(LIBMAJOR)$(SLIBSUF)'
>>          dlltool="${cross_prefix}dlltool"
>>          if check_cmd lib.exe -list; then
>> -            SLIB_EXTRA_CMD='-lib.exe /machine:$(LIBTARGET) /def:$$(@:$(SLIBSUF)=.def) /out:$(SUBDIR)$(SLIBNAME:$(SLIBSUF)=.lib)'
>> +            SLIB_EXTRA_CMD='-lib.exe -machine:$(LIBTARGET) -def:$$(@:$(SLIBSUF)=.def) -out:$(SUBDIR)$(SLIBNAME:$(SLIBSUF)=.lib)'
>>              if enabled x86_64; then
>>                  LIBTARGET=x64
>>              fi
>> @@ -3092,8 +3095,8 @@ case $target_os in
>>          SLIB_INSTALL_NAME='$(SLIBNAME_WITH_MAJOR)'
>>          SLIB_INSTALL_LINKS=
>>          SLIB_INSTALL_EXTRA_SHLIB='$(SLIBNAME:$(SLIBSUF)=.lib)'
>> -        SLIB_INSTALL_EXTRA_LIB='lib$(SLIBNAME:$(SLIBSUF)=.dll.a) $(SLIBNAME_WITH_MAJOR:$(SLIBSUF)=.def)'
>> -        SHFLAGS='-shared -Wl,--output-def,$$(@:$(SLIBSUF)=.def) -Wl,--out-implib,$(SUBDIR)lib$(SLIBNAME:$(SLIBSUF)=.dll.a) -Wl,--enable-runtime-pseudo-reloc -Wl,--enable-auto-image-base'
>> +        SLIB_INSTALL_EXTRA_LIB='lib$(SLIBNAME:$(SLIBSUF)=.dll) $(SLIBNAME_WITH_MAJOR:$(SLIBSUF)=.def)'
>> +        SHFLAGS='-dll -def:$$(@:$(SLIBSUF)=.def) -implib:$(SUBDIR)lib$(SLIBNAME:$(SLIBSUF)=.dll.a)'
>>          objformat="win32"
>>          ranlib=:
>>          enable dos_paths
>
> This breaks compilation with Mingw. The change to SHFLAGS generates this error:
>
> LD      libavutil/avutil-51.dll
> i686-w64-mingw32-gcc.exe: error: unrecognized command line option '-implib:libavutil/libavutil.dll.a'
> make: *** [libavutil/avutil-51.dll] Error 1
>
> And the change to SLIB_INSTALL_EXTRA_LIB generates this error during install (After undoing the change to SHFLAGS so the libraries actually compile):
>
> $ make install
> INSTALL libavdevice/avdevice.lib
> INSTALL libavdevice/avdevice.dll
> STRIP   install-libavdevice-shared
> INSTALL libavdevice/avdevice.dll
> INSTALL libavdevice/avdevice.dll
> install: cannot stat `libavdevice/libavdevice.dll': No such file or directory
> make: *** [install-libavdevice-shared] Error 1
>
> Also, by changing LIBSUF to ".lib" you're making the build system overwrite the static libraries created with gnu ar with the shared ones created with lib.exe/dlltool (Or skipping the creation of static libraries altogether if lib.exe/dlltool was run first, since a .lib file would already exist)

Someone else should probably fix that up to work with mingw again, I
can't test every single config right away unfortunately. If not, I'll
try to fix that later.

Ronald