Mercurial > hg > CbC > CbC_gcc
view config/weakref.m4 @ 158:494b0b89df80 default tip
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author | Shinji KONO <kono@ie.u-ryukyu.ac.jp> |
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date | Mon, 25 May 2020 18:13:55 +0900 |
parents | 04ced10e8804 |
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dnl Check if the target supports weak. AC_DEFUN([GCC_CHECK_ATTRIBUTE_WEAK], [ AC_CACHE_CHECK([whether the target supports weak], ac_cv_have_attribute_weak, [ weakref_m4_saved_CFLAGS="$CFLAGS" CFLAGS="$CFLAGS -Werror" AC_TRY_COMPILE([void __attribute__((weak)) foo(void) { }], [], ac_cv_have_attribute_weak=yes, ac_cv_have_attribute_weak=no) CFLAGS="$weakref_m4_saved_CFLAGS"]) if test x"$ac_cv_have_attribute_weak" = xyes; then AC_DEFINE(HAVE_ATTRIBUTE_WEAK, 1, [Define to 1 if the target supports __attribute__((weak)).]) fi]) dnl Check whether weak refs work like the ELF ones. dnl This means that the weak reference works without having to satify dnl linkage for the item. dnl There are targets (at least Darwin) where we have fully functional dnl weakrefs at runtime, but must supply the referenced item at link time. AC_DEFUN([GCC_CHECK_ELF_STYLE_WEAKREF], [ AC_CACHE_CHECK([whether weak refs work like ELF], ac_cv_have_elf_style_weakref, [ weakref_m4_saved_CFLAGS="$CFLAGS" case "${host}" in *-apple-darwin*) CFLAGS="$CFLAGS -Wl,-undefined,dynamic_lookup" ;; *) ;; esac AC_RUN_IFELSE([AC_LANG_SOURCE([[ extern void fNotToBeFound(void) __attribute__((weak)); int main () { if (fNotToBeFound) return 1; else return 0; } ]])], ac_cv_have_elf_style_weakref=yes, ac_cv_have_elf_style_weakref=no, [ case "${host}" in *-apple-darwin[[89]]*) ac_cv_have_elf_style_weakref=no ;; *) ac_cv_have_elf_style_weakref=yes;; esac])CFLAGS="$weakref_m4_saved_CFLAGS"]) if test x"$ac_cv_have_elf_style_weakref" = xyes; then AC_DEFINE(HAVE_ELF_STYLE_WEAKREF, 1, [Define to 1 if target has a weakref that works like the ELF one.]) fi])