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Diffstat (limited to 'm4/lib-ignore.m4')
| -rw-r--r-- | m4/lib-ignore.m4 | 115 |
1 files changed, 115 insertions, 0 deletions
diff --git a/m4/lib-ignore.m4 b/m4/lib-ignore.m4 new file mode 100644 index 0000000..c4d0217 --- /dev/null +++ b/m4/lib-ignore.m4 @@ -0,0 +1,115 @@ +# If possible, ignore libraries that are not depended on. + +dnl Copyright (C) 2006, 2009-2023 Free Software Foundation, Inc. +dnl This file is free software; the Free Software Foundation +dnl gives unlimited permission to copy and/or distribute it, +dnl with or without modifications, as long as this notice is preserved. + +dnl Written by Paul Eggert. + +# gl_IGNORE_UNUSED_LIBRARIES +# -------------------------- +# Determines the option to be passed to the C/C++/Fortran compiler, so that it +# omits unused libraries. +# Example (on Solaris): +# $ cc foo.c -lnsl; ldd ./a.out +# libnsl.so.1 => /lib/libnsl.so.1 +# libc.so.1 => /lib/libc.so.1 +# libmp.so.2 => /lib/libmp.so.2 +# libmd.so.1 => /lib/libmd.so.1 +# libscf.so.1 => /lib/libscf.so.1 +# libdoor.so.1 => /lib/libdoor.so.1 +# libuutil.so.1 => /lib/libuutil.so.1 +# libgen.so.1 => /lib/libgen.so.1 +# libm.so.2 => /lib/libm.so.2 +# $ cc foo.c -lnsl -Wl,-z,ignore; ldd ./a.out +# libc.so.1 => /lib/libc.so.1 +# libm.so.2 => /lib/libm.so.2 +# +# Note that the option works only for the C compiler, not for the C++ +# compiler: +# - Sun C likes '-Wl,-z,ignore'. +# '-Qoption ld -z,ignore' is not accepted. +# '-z ignore' is accepted but has no effect. +# - Sun C++ and Sun Fortran like '-Qoption ld -z,ignore'. +# '-Wl,-z,ignore' is not accepted. +# '-z ignore' is accepted but has no effect. +# +# Sets and substitutes a variable that depends on the current language: +# - IGNORE_UNUSED_LIBRARIES_CFLAGS for C +# - IGNORE_UNUSED_LIBRARIES_CXXFLAGS for C++ +# - IGNORE_UNUSED_LIBRARIES_FFLAGS for Fortran +# +# Note that the option works only for direct invocation of the compiler, not +# through libtool: When libtool is used to create a shared library, it will +# honor and translate '-Wl,-z,ignore' to '-Qoption ld -z -Qoption ld ignore' +# if needed, but it will drop a '-Qoption ld -z,ignore' on the command line. +# +AC_DEFUN([gl_IGNORE_UNUSED_LIBRARIES], +[ + AC_CACHE_CHECK([for []_AC_LANG[] compiler flag to ignore unused libraries], + [gl_cv_prog_[]_AC_LANG_ABBREV[]_ignore_unused_libraries], + [gl_cv_prog_[]_AC_LANG_ABBREV[]_ignore_unused_libraries=none + gl_saved_ldflags=$LDFLAGS + gl_saved_libs=$LIBS + # Link with -lm to detect binutils 2.16 bug with --as-needed; see + # <https://lists.gnu.org/r/bug-gnulib/2006-06/msg00131.html>. + LIBS="$LIBS -lm" + # Use long option sequences like '-z ignore' to test for the feature, + # to forestall problems with linkers that have -z, -i, -g, -n, etc. flags. + # GCC + binutils likes '-Wl,--as-needed'. + # GCC + Solaris ld likes '-Wl,-z,ignore'. + # Sun C likes '-Wl,-z,ignore'. '-z ignore' is accepted but has no effect. + # Don't try bare '--as-needed'; nothing likes it and the HP-UX 11.11 + # native cc issues annoying warnings and then ignores it, + # which would cause us to incorrectly conclude that it worked. + for gl_flags in _gl_IGNORE_UNUSED_LIBRARIES_OPTIONS + do + LDFLAGS="$gl_flags $LDFLAGS" + AC_LINK_IFELSE([AC_LANG_PROGRAM()], + [gl_cv_prog_[]_AC_LANG_ABBREV[]_ignore_unused_libraries=$gl_flags]) + LDFLAGS=$gl_saved_ldflags + test "$gl_cv_prog_[]_AC_LANG_ABBREV[]_ignore_unused_libraries" != none && + break + done + LIBS=$gl_saved_libs + ]) + IGNORE_UNUSED_LIBRARIES_[]_AC_LANG_PREFIX[]FLAGS= + if test "$gl_cv_prog_[]_AC_LANG_ABBREV[]_ignore_unused_libraries" != none; then + IGNORE_UNUSED_LIBRARIES_[]_AC_LANG_PREFIX[]FLAGS="$gl_cv_prog_[]_AC_LANG_ABBREV[]_ignore_unused_libraries" + fi + AC_SUBST([IGNORE_UNUSED_LIBRARIES_]_AC_LANG_PREFIX[FLAGS]) +]) + +# _gl_IGNORE_UNUSED_LIBRARIES_OPTIONS +# ----------------------------------- +# Expands to the language dependent options to be tried. +AC_DEFUN([_gl_IGNORE_UNUSED_LIBRARIES_OPTIONS], +[_AC_LANG_DISPATCH([$0], _AC_LANG, $@)]) + +# _gl_IGNORE_UNUSED_LIBRARIES_OPTIONS(C) +# -------------------------------------- +m4_define([_gl_IGNORE_UNUSED_LIBRARIES_OPTIONS(C)], +[ '-Wl,--as-needed' \ + '-Wl,-z,ignore' \ + '-z ignore' +]) + +# _gl_IGNORE_UNUSED_LIBRARIES_OPTIONS(C++) +# ---------------------------------------- +m4_define([_gl_IGNORE_UNUSED_LIBRARIES_OPTIONS(C++)], +[ '-Wl,--as-needed' \ + '-Qoption ld -z,ignore' \ + '-Wl,-z,ignore' \ + '-z ignore' +]) + +# _gl_IGNORE_UNUSED_LIBRARIES_OPTIONS(Fortran 77) +# ----------------------------------------------- +m4_copy([_gl_IGNORE_UNUSED_LIBRARIES_OPTIONS(C++)], + [_gl_IGNORE_UNUSED_LIBRARIES_OPTIONS(Fortran 77)]) + +# _gl_IGNORE_UNUSED_LIBRARIES_OPTIONS(Fortran) +# -------------------------------------------- +m4_copy([_gl_IGNORE_UNUSED_LIBRARIES_OPTIONS(Fortran 77)], + [_gl_IGNORE_UNUSED_LIBRARIES_OPTIONS(Fortran)]) |