mirror of https://github.com/aria2/aria2
53 lines
2.1 KiB
Plaintext
53 lines
2.1 KiB
Plaintext
# visibility.m4 serial 1 (gettext-0.15)
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dnl Copyright (C) 2005 Free Software Foundation, Inc.
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dnl This file is free software; the Free Software Foundation
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dnl gives unlimited permission to copy and/or distribute it,
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dnl with or without modifications, as long as this notice is preserved.
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dnl From Bruno Haible.
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dnl Tests whether the compiler supports the command-line option
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dnl -fvisibility=hidden and the function and variable attributes
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dnl __attribute__((__visibility__("hidden"))) and
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dnl __attribute__((__visibility__("default"))).
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dnl Does *not* test for __visibility__("protected") - which has tricky
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dnl semantics (see the 'vismain' test in glibc) and does not exist e.g. on
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dnl MacOS X.
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dnl Does *not* test for __visibility__("internal") - which has processor
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dnl dependent semantics.
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dnl Does *not* test for #pragma GCC visibility push(hidden) - which is
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dnl "really only recommended for legacy code".
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dnl Set the variable CFLAG_VISIBILITY.
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dnl Defines and sets the variable HAVE_VISIBILITY.
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AC_DEFUN([gl_VISIBILITY],
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[
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AC_REQUIRE([AC_PROG_CC])
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CFLAG_VISIBILITY=
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HAVE_VISIBILITY=0
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if test -n "$GCC"; then
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AC_MSG_CHECKING([for simple visibility declarations])
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AC_CACHE_VAL(gl_cv_cc_visibility, [
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gl_save_CFLAGS="$CFLAGS"
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CFLAGS="$CFLAGS -fvisibility=hidden"
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AC_TRY_COMPILE(
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[extern __attribute__((__visibility__("hidden"))) int hiddenvar;
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extern __attribute__((__visibility__("default"))) int exportedvar;
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extern __attribute__((__visibility__("hidden"))) int hiddenfunc (void);
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extern __attribute__((__visibility__("default"))) int exportedfunc (void);],
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[],
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gl_cv_cc_visibility=yes,
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gl_cv_cc_visibility=no)
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CFLAGS="$gl_save_CFLAGS"])
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AC_MSG_RESULT([$gl_cv_cc_visibility])
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if test $gl_cv_cc_visibility = yes; then
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CFLAG_VISIBILITY="-fvisibility=hidden"
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HAVE_VISIBILITY=1
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fi
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fi
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AC_SUBST([CFLAG_VISIBILITY])
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AC_SUBST([HAVE_VISIBILITY])
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AC_DEFINE_UNQUOTED([HAVE_VISIBILITY], [$HAVE_VISIBILITY],
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[Define to 1 or 0, depending whether the compiler supports simple visibility declarations.])
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])
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