kc3-lang/gnulib/doc/ld-output-def.texi

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  Date : 2021-01-13T14:38:20
  

  lib-msvc-compat: Update libtool usage recommendation.
  
  * doc/ld-output-def.texi (Visual Studio Compatibility): Install
  .def files into libdir, not bindir.  Have libfoo-*.def file depend
  on libfoo.la to fix parallell builds.
  

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• doc/ld-output-def.texi

• @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{https://docs.microsoft.com/en-us/cpp/build/reference/dash-exports}.
  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
  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-$(DLL_VERSION).def
  libfoo-$(DLL_VERSION).def: libfoo.la
  defexecdir = $(libdir)
  defexec_DATA = libfoo-$(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
  

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