From 1e211901ba9e534ff5050f4a8129e0b39a9a4a35 Mon Sep 17 00:00:00 2001
From: Moritz Bunkus <moritz@bunkus.org>
Date: Mon, 15 Mar 2010 09:29:56 +0100
Subject: [PATCH] Only use precompiled headers with gcc 4.4 or newer

See bug repoert http://gcc.gnu.org/bugzilla/show_bug.cgi?id=13675
---
 Makefile.in               |  3 +++
 ac/gcc_version.m4         |  4 ++++
 ac/precompiled_headers.m4 | 23 +++++++++++++++++++++++
 configure.in              |  2 ++
 4 files changed, 32 insertions(+)
 create mode 100644 ac/gcc_version.m4
 create mode 100644 ac/precompiled_headers.m4

diff --git a/Makefile.in b/Makefile.in
index a45a68f2a..75b906f52 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -96,6 +96,7 @@ PROFILING_CFLAGS = @PROFILING_CFLAGS@
 PROFILING_LIBS = @PROFILING_LIBS@
 QT_CFLAGS = @QT_CFLAGS@
 QT_LIBS = @QT_LIBS@
+USE_PRECOMPILED_HEADERS = @USE_PRECOMPILED_HEADERS@
 USER_CPPFLAGS = @USER_CPPFLAGS@
 USER_CXXFLAGS = @USER_CXXFLAGS@
 USER_CFLAGS = @USER_CFLAGS@
@@ -333,7 +334,9 @@ endif
 	@echo ' WINDRES ' $<
 	$(Q)$(RCCOMPILE) -o $@ $<
 
+ifeq (yes,$(USE_PRECOMPILED_HEADERS))
 $(ALL_OBJECTS): src/common/common.h.gch
+endif
 
 %.h.gch: %.h
 	@echo '     CXX ' $<
diff --git a/ac/gcc_version.m4 b/ac/gcc_version.m4
new file mode 100644
index 000000000..fc1e88146
--- /dev/null
+++ b/ac/gcc_version.m4
@@ -0,0 +1,4 @@
+AC_CACHE_CHECK(
+  [gcc version],
+  [ac_cv_gcc_version],
+  [ac_cv_gcc_version=`$ac_cv_prog_CXX -dumpversion | sed -e 's/[[^0-9\.]]//g'`])
diff --git a/ac/precompiled_headers.m4 b/ac/precompiled_headers.m4
new file mode 100644
index 000000000..1067da94f
--- /dev/null
+++ b/ac/precompiled_headers.m4
@@ -0,0 +1,23 @@
+dnl
+dnl Precompiled headers
+dnl
+
+AC_ARG_ENABLE([precompiled_headers],
+  AC_HELP_STRING([--enable-precompiled-headers],[enable the generation and use of precompiled headers (auto)]),
+  [enable_precompiled_headers=yes],
+  [enable_precompiled_headers=auto])
+
+if test x"$enable_precompiled_headers" = x"auto"; then
+  if ! check_version 4.4.0 $ac_cv_gcc_version ; then
+    enable_precompiled_headers=no
+  else
+    enable_precompiled_headers=yes
+  fi
+fi
+
+if test x"$enable_precompiled_headers" = x"yes"; then
+  AC_DEFINE(USE_PRECOMPILED_HEADERS, 1, [Define if precompiled headers are generated and used])
+  USE_PRECOMPILED_HEADERS=yes
+fi
+
+AC_SUBST(USE_PRECOMPILED_HEADERS)
diff --git a/configure.in b/configure.in
index 48177a484..be65aa59e 100644
--- a/configure.in
+++ b/configure.in
@@ -14,10 +14,12 @@ opt_features_no=""
 
 m4_include(ac/initialization.m4)
 m4_include(ac/check_version.m4)
+m4_include(ac/gcc_version.m4)
 m4_include(ac/endianess.m4)
 m4_include(ac/mingw.m4)
 m4_include(ac/extra_inc_lib.m4)
 m4_include(ac/debugging_profiling.m4)
+m4_include(ac/precompiled_headers.m4)
 m4_include(ac/build_timestamp_in_version.m4)
 m4_include(ac/inttypes.m4)
 m4_include(ac/pri64d.m4)