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48 lines
1.7 KiB
Plaintext
48 lines
1.7 KiB
Plaintext
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dnl Check if the target supports weak.
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AC_DEFUN([GCC_CHECK_ATTRIBUTE_WEAK], [
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AC_CACHE_CHECK([whether the target supports weak],
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ac_cv_have_attribute_weak, [
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weakref_m4_saved_CFLAGS="$CFLAGS"
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CFLAGS="$CFLAGS -Werror"
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AC_TRY_COMPILE([void __attribute__((weak)) foo(void) { }],
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[], ac_cv_have_attribute_weak=yes,
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ac_cv_have_attribute_weak=no)
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CFLAGS="$weakref_m4_saved_CFLAGS"])
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if test x"$ac_cv_have_attribute_weak" = xyes; then
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AC_DEFINE(HAVE_ATTRIBUTE_WEAK, 1,
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[Define to 1 if the target supports __attribute__((weak)).])
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fi])
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dnl Check whether weak refs work like the ELF ones.
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dnl This means that the weak reference works without having to satify
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dnl linkage for the item.
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dnl There are targets (at least Darwin) where we have fully functional
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dnl weakrefs at runtime, but must supply the referenced item at link time.
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AC_DEFUN([GCC_CHECK_ELF_STYLE_WEAKREF], [
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AC_CACHE_CHECK([whether weak refs work like ELF],
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ac_cv_have_elf_style_weakref, [
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weakref_m4_saved_CFLAGS="$CFLAGS"
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case "${host}" in
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*-apple-darwin*) CFLAGS="$CFLAGS -Wl,-undefined,dynamic_lookup" ;;
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*) ;;
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esac
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AC_RUN_IFELSE([AC_LANG_SOURCE([[
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extern void fNotToBeFound(void) __attribute__((weak));
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int main ()
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{
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if (fNotToBeFound)
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return 1;
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else
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return 0;
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}
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]])], ac_cv_have_elf_style_weakref=yes, ac_cv_have_elf_style_weakref=no, [
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case "${host}" in
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*-apple-darwin[[89]]*) ac_cv_have_elf_style_weakref=no ;;
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*) ac_cv_have_elf_style_weakref=yes;;
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esac])CFLAGS="$weakref_m4_saved_CFLAGS"])
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if test x"$ac_cv_have_elf_style_weakref" = xyes; then
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AC_DEFINE(HAVE_ELF_STYLE_WEAKREF, 1, [Define to 1 if target has a weakref that works like the ELF one.])
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fi])
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