From bd35d903a04c4d388adb4065b0fa271302380895 Mon Sep 17 00:00:00 2001
From: Lasse Collin <lasse.collin@tukaani.org>
Date: Sat, 28 May 2011 15:55:39 +0300
Subject: liblzma: Use symbol versioning.

Symbol versioning is enabled by default on GNU/Linux,
other GNU-based systems, and FreeBSD.

I'm not sure how stable this is, so it may need
backward-incompatible changes before the next release.

The idea is that alpha and beta symbols are considered
unstable and require recompiling the applications that
use those symbols. Once a symbol is stable, it may get
extended with new features in ways that don't break
compatibility with older ABI & API.

The mydist target runs validate_map.sh which should
catch some probable problems in liblzma.map. Otherwise
I would forget to update the map file for new releases.
---
 configure.ac | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

(limited to 'configure.ac')

diff --git a/configure.ac b/configure.ac
index bc85fdd0..106c0811 100644
--- a/configure.ac
+++ b/configure.ac
@@ -403,6 +403,27 @@ AC_ARG_ENABLE([scripts], [AC_HELP_STRING([--disable-scripts],
 AM_CONDITIONAL([COND_SCRIPTS], [test x$enable_scripts != xno])
 
 
+#####################
+# Symbol versioning #
+#####################
+
+AC_ARG_ENABLE([symbol-versions], [AC_HELP_STRING([--enable-symbol-versions],
+		[Use symbol versioning for liblzma. Enabled by default on
+		GNU/Linux, other GNU-based systems, and FreeBSD.])],
+	[], [enable_symbol_versions=auto])
+if test "x$enable_symbol_versions" = xauto; then
+	case $host_os in
+		gnu* | *-gnu* | freebsd*)
+			enable_symbol_versions=yes
+			;;
+		*)
+			enable_symbol_versions=no
+			;;
+	esac
+fi
+AM_CONDITIONAL([COND_SYMVERS], [test "x$enable_symbol_versions" = xyes])
+
+
 ###############################################################################
 # Checks for programs.
 ###############################################################################
-- 
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