[FFmpeg-devel] [PATCH] Proper support for building MSVC import libraries

[Måns Rullgård]

Ramiro Polla <ramiro at lisha.ufsc.br> writes:

> Hello,
>
> Currently, MSVC import libraries are created for dlls if the lib
> program exists on MinGW's PATH (with the wrong name, since BUILDSUF is
> not respected).
> IMO, Makefile commands don't belong in configure (such as
> SLIB_INSTALL_EXTRA_CMD).
>
> Attached patch adds an option to configure and puts Makefile commands
> in common.mak.
>
> Ramiro Polla
> Index: configure
> ===================================================================
> --- configure	(revision 9765)
> +++ configure	(working copy)
> @@ -65,6 +65,7 @@
>    echo "  --enable-static          build static libraries [default=yes]"
>    echo "  --disable-static         do not build static libraries [default=no]"
>    echo "  --enable-shared          build shared libraries [default=no]"
> +  echo "  --enable-msvc-implib     build MSVC import libs for dlls [default=no]"

Why this option?

> @@ -1157,9 +1159,10 @@
>      EXESUF=".exe"
>      SLIBNAME_WITH_VERSION='$(SLIBPREF)$(NAME)-$(LIBVERSION)$(SLIBSUF)'
>      SLIBNAME_WITH_MAJOR='$(SLIBPREF)$(NAME)-$(LIBMAJOR)$(SLIBSUF)'
> -    SLIB_EXTRA_CMD="-lib /machine:i386 /def:\$(@:${SLIBSUF}=.def)"
> -    SLIB_INSTALL_EXTRA_CMD="-install -m 644 \$(SLIBNAME_WITH_MAJOR:\$(SLIBSUF)=.lib) \"\$(shlibdir)/\$(SLIBNAME_WITH_MAJOR:\$(SLIBSUF)=.lib)\""
> -    SHFLAGS="-shared -Wl,--output-def,\$(@:${SLIBSUF}=.def),--out-implib,lib\$(SLIBNAME:\$(SLIBSUF)=.dll.a) -Wl,--enable-runtime-pseudo-reloc -Wl,--enable-auto-image-base"
> +    MSVC_IMPLIB='$(SLIBNAME_WITH_MAJOR:.dll=.lib)'
> +    enabled msvc_implib &&
> +        MSVC_IMPLIB_SHFLAGS='-Wl,--output-def,$(MSVC_IMPLIB:.lib=.def)'
> +    SHFLAGS='-shared $(MSVC_IMPLIB_SHFLAGS) -Wl,--out-implib,lib$(SLIBNAME:$(SLIBSUF)=.dll.a) -Wl,--enable-runtime-pseudo-reloc -Wl,--enable-auto-image-base'

Is this really correct?  That unconditional --out-imlib option looks a
little fishy to my untrained eye.

BTW, am I the only one who thinks that chunk is really ugly to look at?

>      enabled network && add_extralibs -lws2_32
>      ;;
>    cygwin*)
> @@ -1930,8 +1933,10 @@
>    echo "SLIBNAME=${SLIBNAME}" >> config.mak
>    echo "SLIBNAME_WITH_VERSION=${SLIBNAME_WITH_VERSION}" >> config.mak
>    echo "SLIBNAME_WITH_MAJOR=${SLIBNAME_WITH_MAJOR}" >> config.mak
> -  echo "SLIB_EXTRA_CMD=${SLIB_EXTRA_CMD}" >> config.mak
> -  echo "SLIB_INSTALL_EXTRA_CMD=${SLIB_INSTALL_EXTRA_CMD}" >> config.mak
> +  enabled msvc_implib &&
> +    echo "BUILD_MSVC_IMPLIB=yes" >> config.mak

Settings like this one should be done the generic way.

> +  echo "MSVC_IMPLIB=${MSVC_IMPLIB}" >> config.mak
> +  echo "MSVC_IMPLIB_SHFLAGS=${MSVC_IMPLIB_SHFLAGS}" >> config.mak
>  fi
>  echo "LIB_INSTALL_EXTRA_CMD=${LIB_INSTALL_EXTRA_CMD}" >> config.mak
>  echo "EXTRALIBS=$extralibs" >> config.mak
> Index: common.mak
> ===================================================================
> --- common.mak	(revision 9765)
> +++ common.mak	(working copy)
> @@ -19,7 +19,7 @@
>  STATIC_OBJS := $(OBJS) $(STATIC_OBJS)
>  SHARED_OBJS := $(OBJS) $(SHARED_OBJS)
>
> -all: $(EXTRADEPS) $(LIB) $(SLIBNAME)
> +all: $(EXTRADEPS) $(LIB) $(SLIBNAME) $(MSVC_IMPLIB)
>
>  $(LIB): $(STATIC_OBJS)
>  	rm -f $@
> @@ -31,8 +31,10 @@
>
>  $(SLIBNAME_WITH_MAJOR): $(SHARED_OBJS)
>  	$(CC) $(SHFLAGS) $(LDFLAGS) -o $@ $^ $(EXTRALIBS) $(EXTRAOBJS)
> -	$(SLIB_EXTRA_CMD)
>
> +$(MSVC_IMPLIB): $(SLIBNAME_WITH_MAJOR)
> +	lib /machine:i386 /def:$(@:.lib=.def)
> +
>  %.o: %.c
>  	$(CC) $(CFLAGS) $(LIBOBJFLAGS) -c -o $@ $<
>
> @@ -64,6 +66,9 @@
>  ifeq ($(BUILD_STATIC),yes)
>  INSTLIBTARGETS += install-lib-static
>  endif
> +ifeq ($(BUILD_MSVC_IMPLIB),yes)
> +INSTLIBTARGETS += install-lib-msvc-implib
> +endif
>
>  install: install-libs install-headers
>
> @@ -77,13 +82,15 @@
>  		ln -sf $(SLIBNAME_WITH_VERSION) $(SLIBNAME_WITH_MAJOR)
>  	cd "$(shlibdir)" && \
>  		ln -sf $(SLIBNAME_WITH_VERSION) $(SLIBNAME)
> -	$(SLIB_INSTALL_EXTRA_CMD)
>
>  install-lib-static: $(LIB)
>  	install -d "$(libdir)"
>  	install -m 644 $(LIB) "$(libdir)"
> -	$(LIB_INSTALL_EXTRA_CMD)
>
> +install-lib-msvc-implib: $(MSVC_IMPLIB)
> +	install -d "$(libdir)"
> +	install -m 644 $(MSVC_IMPLIB) "$(libdir)"

install-lib-static: $(LIB) $(MSVC_IMPLIB)
	...

Or some variation thereof.  I don't recall the exact semantics of
these targets.

-- 
M?ns Rullg?rd
mans at mansr.com