Edit
kc3-lang/gnulib/doc/ld-output-def.texi
Neil Jerram
- doc/ld-output-def.texi
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@node Visual Studio Compatibility @section Visual Studio Compatibility @cindex DEF files @cindex LD DEF files The @code{lib-msvc-compat} module detects whether the linker supports @code{--output-def} when building a library. That parameter is used to generate a DEF file for a shared library (DLL). DEF files are useful for developers that use Visual Studio to develop programs that links to your library. See the GNU LD manual for more information. There are other ways to create a DEF file, but we believe they are all sub-optimal to using @code{--output-def} during the build process. The variants we have considered include: @itemize @bullet @item Use DUMPBIN /EXPORTS. This is explained in @url{http://support.microsoft.com/kb/131313/en-us}. The tool does not generate DEF files directly, so its output needs to be post processed manually: @smallexample $ @{ echo EXPORTS; \ dumpbin /EXPORTS libfoo-0.dll | tail -n+20 | awk '@{ print $4 @}'; \ @} > libfoo-0.def $ lib /def:libfoo-0.def @end smallexample @item Use IMPDEF. There is a tool called IMPDEF (@url{http://sei.pku.edu.cn/~caodg/course/c/reference/win32/tools/dlltool.html}) that can generate DEF files. However, it is not part of a standard Visual Studio installation. Further, it is documented as being an unreliable process. @item Use DLLTOOL. The dlltool is part of the MinGW suite, and thus not part of a standard Visual Studio installation. The documentation for the IMPDEF tool claims that DLLTOOL is the wrong tool for this job. Finally, DLLTOOL does not generate DEF files directly, so it requires post-processing of the output. @end itemize If you are using libtool to build your shared library, here is how to use this module. Import @code{lib-msvc-compat} to your project, and then add the following lines to the @code{Makefile.am} that builds the library: @smallexample if HAVE_LD_OUTPUT_DEF libfoo_la_LDFLAGS += -Wl,--output-def,libfoo-$(DLL_VERSION).def defexecdir = $(bindir) defexec_DATA = libfoo-$(DLL_VERSION).def DISTCLEANFILES += $(defexec_DATA) endif @end smallexample The @code{DLL_VERSION} variable needs to be defined. It should be the shared library version number used in the DLL filename. For Windows targets you compute this value from the values you pass to Libtool's @code{-version-info}. Assuming you have variables @code{LT_CURRENT} and @code{LT_AGE} defined for the @code{CURRENT} and @code{AGE} libtool version integers, you compute @code{DLL_VERSION} as follows: @smallexample DLL_VERSION=`expr $@{LT_CURRENT@} - $@{LT_AGE@}` AC_SUBST(DLL_VERSION) @end smallexample