[telepathy-qt4/master] Add an autoconf macro to detect gcc's -fvisibility=hidden option

[Simon McVittie]

---
 configure.ac               |    1 +
 m4/Makefile.am             |    1 +
 m4/tp-visibility-hidden.m4 |   55 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 57 insertions(+), 0 deletions(-)
 create mode 100644 m4/tp-visibility-hidden.m4

diff --git a/configure.ac b/configure.ac
index 311d39b..dff3d6a 100644
--- a/configure.ac
+++ b/configure.ac
@@ -76,6 +76,7 @@ COMPILER_OPTIMISATIONS
 COMPILER_COVERAGE
 LINKER_OPTIMISATIONS
 LINKER_VERSION_SCRIPT
+TP_VISIBILITY_HIDDEN
 
 ifelse(tp_qt4_nano_version, 0,
     [ official_release=yes ],
diff --git a/m4/Makefile.am b/m4/Makefile.am
index 83b024b..facfddc 100644
--- a/m4/Makefile.am
+++ b/m4/Makefile.am
@@ -1,5 +1,6 @@
 EXTRA_DIST = \
 tp-compiler-flag.m4 \
 tp-compiler-warnings.m4 \
+tp-visibility-hidden.m4 \
 compiler.m4 \
 linker.m4
diff --git a/m4/tp-visibility-hidden.m4 b/m4/tp-visibility-hidden.m4
new file mode 100644
index 0000000..2f2dea8
--- /dev/null
+++ b/m4/tp-visibility-hidden.m4
@@ -0,0 +1,55 @@
+# tp-visibility-hidden.m4 - detect support for -fvisibility-hidden
+# Based on linker.m4 by Scott James Remnant.
+#
+# Copyright © 2005 Scott James Remnant <scott at netsplit.com>.
+# Copyright © 2009 Collabora Ltd. <http://www.collabora.co.uk/>
+# Copyright © 2009 Nokia Corporation
+#
+# Permission is hereby granted, free of charge, to any person obtaining
+# a copy of this software and associated documentation files (the
+# "Software"), to deal in the Software without restriction, including
+# without limitation the rights to use, copy, modify, merge, publish,
+# distribute, sublicense, and/or sell copies of the Software, and to
+# permit persons to whom the Software is furnished to do so, subject to
+# the following conditions:
+# 
+# The above copyright notice and this permission notice shall be
+# included in all copies or substantial portions of the Software.
+# 
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+# IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR
+# ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
+# CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+# TP_VISIBILITY_HIDDEN
+# --------------------------
+# Detect whether the (C/C++) compiler and linker both support
+# -fvisibility=hidden.
+#
+# If so, put it in $(VISIBILITY_HIDDEN_FLAGS).
+AC_DEFUN([TP_VISIBILITY_HIDDEN],
+[AC_MSG_CHECKING([for compiler/linker symbol-hiding argument])
+tp_old_ldflags="$LDFLAGS"
+tp_old_cflags="$CFLAGS"
+tp_old_cxxflags="$CXXFLAGS"
+for tp_try_arg in "-fvisibility=hidden"; do
+	LDFLAGS="$tp_old_ldflags $tp_try_arg"
+	CFLAGS="$tp_old_cflags $tp_try_arg"
+	CXXFLAGS="$tp_old_cxxflags $tp_try_arg"
+	AC_TRY_LINK([], [], [
+		AC_MSG_RESULT([$tp_try_arg])
+		AC_SUBST([VISIBILITY_HIDDEN_FLAGS], [$tp_try_arg])
+		break
+	])
+done
+LDFLAGS="$tp_old_ldflags"
+CFLAGS="$tp_old_cflags"
+CXXFLAGS="$tp_old_cxxflags"
+AM_CONDITIONAL(HAVE_VISIBILITY_HIDDEN_FLAGS, [test -n "$VISIBILITY_HIDDEN_FLAGS"])
+if test -z "$VISIBILITY_HIDDEN_FLAGS"; then
+	AC_MSG_RESULT([not supported])
+fi
+])dnl
-- 
1.5.6.5