From 1484e50a2818b2f207688765cef6cd2f5cc71520 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Cristian=20Rodr=C3=ADguez?= <crrodriguez@opensuse.org>
Date: Mon, 22 Oct 2012 22:38:34 +0200
Subject: [PATCH] build: Use GCC visibility to hide private symbols

http://bugs.exim.org/show_bug.cgi?id=1173
--
diff --git a/m4/visibility.m4 b/m4/visibility.m4
new file mode 100644
index 0000000..07fccee
--- /dev/null
+++ b/m4/visibility.m4
@@ -0,0 +1,89 @@
+# visibility.m4 serial 4 (gettext-0.18.2)
+dnl Copyright (C) 2005, 2008, 2010-2011 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 From Bruno Haible.
+
+dnl Tests whether the compiler supports the command-line option
+dnl -fvisibility=hidden and the function and variable attributes
+dnl __attribute__((__visibility__("hidden"))) and
+dnl __attribute__((__visibility__("default"))).
+dnl Does *not* test for __visibility__("protected") - which has tricky
+dnl semantics (see the 'vismain' test in glibc) and does not exist e.g. on
+dnl MacOS X.
+dnl Does *not* test for __visibility__("internal") - which has processor
+dnl dependent semantics.
+dnl Does *not* test for #pragma GCC visibility push(hidden) - which is
+dnl "really only recommended for legacy code".
+dnl Set the variable CFLAG_VISIBILITY.
+dnl Defines and sets the variable HAVE_VISIBILITY.
+
+dnl Modified to fit with PCRE build environment by Cristian Rodríguez.
+
+AC_DEFUN([PCRE_VISIBILITY],
+[
+  AC_REQUIRE([AC_PROG_CC])
+  CFLAG_VISIBILITY=
+  CXXFLAG_INLINES_HIDDEN=
+  HAVE_VISIBILITY=0
+  if test -n "$GCC"; then
+    dnl First, check whether -Werror can be added to the command line, or
+    dnl whether it leads to an error because of some other option that the
+    dnl user has put into $CC $CFLAGS $CPPFLAGS.
+    AC_MSG_CHECKING([whether the -Werror option is usable])
+    AC_CACHE_VAL([gl_cv_cc_vis_werror], [
+      gl_save_CFLAGS="$CFLAGS"
+      CFLAGS="$CFLAGS -Werror"
+      AC_COMPILE_IFELSE(
+        [AC_LANG_PROGRAM([[]], [[]])],
+        [gl_cv_cc_vis_werror=yes],
+        [gl_cv_cc_vis_werror=no])
+      CFLAGS="$gl_save_CFLAGS"])
+    AC_MSG_RESULT([$gl_cv_cc_vis_werror])
+    dnl Now check whether visibility declarations are supported.
+    AC_MSG_CHECKING([for simple visibility declarations])
+    AC_CACHE_VAL([gl_cv_cc_visibility], [
+      gl_save_CFLAGS="$CFLAGS"
+      CFLAGS="$CFLAGS -fvisibility=hidden"
+      dnl We use the option -Werror and a function dummyfunc, because on some
+      dnl platforms (Cygwin 1.7) the use of -fvisibility triggers a warning
+      dnl "visibility attribute not supported in this configuration; ignored"
+      dnl at the first function definition in every compilation unit, and we
+      dnl don't want to use the option in this case.
+      if test $pcre_cv_cc_vis_werror = yes; then
+        CFLAGS="$CFLAGS -Werror"
+      fi
+      AC_COMPILE_IFELSE(
+        [AC_LANG_PROGRAM(
+           [[extern __attribute__((__visibility__("hidden"))) int hiddenvar;
+             extern __attribute__((__visibility__("default"))) int exportedvar;
+             extern __attribute__((__visibility__("hidden"))) int hiddenfunc (void);
+             extern __attribute__((__visibility__("default"))) int exportedfunc (void);
+             void dummyfunc (void) {}
+           ]],
+           [[]])],
+        [pcre_cv_cc_visibility=yes],
+        [pcre_cv_cc_visibility=no])
+      CFLAGS="$gl_save_CFLAGS"])
+    AC_MSG_RESULT([$pcre_cv_cc_visibility])
+    if test $pcre_cv_cc_visibility = yes; then
+      VISIBILITY_CFLAGS="-fvisibility=hidden"
+      VISIBILITY_CXXFLAGS="-fvisibility=hidden -fvisibility-inlines-hidden"
+      HAVE_VISIBILITY=1
+      AC_DEFINE(PCRE_EXP_DECL, [extern __attribute__ ((visibility ("default")))], [to make a symbol visible])
+      AC_DEFINE(PCRE_EXP_DEFN, [__attribute__ ((visibility ("default")))], [to make a symbol visible])
+      AC_DEFINE(PCRE_EXP_DATA_DEFN, [__attribute__ ((visibility ("default")))], [to make a symbol visible])
+      AC_DEFINE(PCREPOSIX_EXP_DECL, [extern __attribute__ ((visibility ("default")))], [to make a symbol visible])
+      AC_DEFINE(PCREPOSIX_EXP_DEFN, [extern __attribute__ ((visibility ("default")))], [to make a symbol visible])
+      AC_DEFINE(PCRECPP_EXP_DECL, [extern __attribute__ ((visibility ("default")))], [to make a symbol visible])
+      AC_DEFINE(PCRECPP_EXP_DEFN, [__attribute__ ((visibility ("default")))], [to make a symbol visible])
+    fi
+  fi
+  AC_SUBST([VISIBILITY_CFLAGS])
+  AC_SUBST([VISIBILITY_CXXFLAGS])
+  AC_SUBST([HAVE_VISIBILITY])
+  AC_DEFINE_UNQUOTED([HAVE_VISIBILITY], [$HAVE_VISIBILITY],
+    [Define to 1 or 0, depending whether the compiler supports simple visibility declarations.])
+])
-- 
1.7.12.503.g5976753.dirty