From 82b1728c4b03f80c56eae0f59d0e9a75e3d2bf9f Mon Sep 17 00:00:00 2001
From: Pádraig Brady <P@draigBrady.com>
Date: Wed, 19 Dec 2012 09:13:21 +0000
Subject: build: avoid --enable-gcc-warnings on GCC <= 4.5

* configure.ac: Only enable warnings automatically when
on GCC >= 4.6 (and when building from a git checkout)
as that was the first GCC version to support fine-grained
control of warnings, allowing them to be adjusted around
certain code sections.  gnulib relies on this for certain
warnings, so avoid auto enabling this option lest we trigger
build failures on now over two year old compilers.
Reported by Zartaj Majeed with GCC 4.5.3 on cygwin.
---
 configure.ac | 32 +++++++++++++++++---------------
 1 file changed, 17 insertions(+), 15 deletions(-)

diff --git a/configure.ac b/configure.ac
index 6504144ee..295802dc5 100644
--- a/configure.ac
+++ b/configure.ac
@@ -67,21 +67,6 @@ cu_have_perl=yes
 case $PERL in *"/missing "*) cu_have_perl=no;; esac
 AM_CONDITIONAL([HAVE_PERL], [test $cu_have_perl = yes])
 
-AC_ARG_ENABLE([gcc-warnings],
-  [AS_HELP_STRING([--enable-gcc-warnings],
-     [turn on many GCC warnings (for developers; best with GNU make)])],
-  [case $enableval in
-     yes|no) ;;
-     *)      AC_MSG_ERROR([bad value $enableval for gcc-warnings option]) ;;
-   esac
-   gl_gcc_warnings=$enableval],
-  [if test -d "$srcdir"/.git; then
-     gl_gcc_warnings=yes
-   else
-     gl_gcc_warnings=no
-   fi]
-)
-
 # gl_GCC_VERSION_IFELSE([major], [minor], [run-if-found], [run-if-not-found])
 # ------------------------------------------------
 # If $CPP is gcc-MAJOR.MINOR or newer, then run RUN-IF-FOUND.
@@ -100,6 +85,23 @@ AC_DEFUN([gl_GCC_VERSION_IFELSE],
   ]
 )
 
+AC_ARG_ENABLE([gcc-warnings],
+  [AS_HELP_STRING([--enable-gcc-warnings],
+     [turn on many GCC warnings (for developers; best with GNU make)])],
+  [case $enableval in
+     yes|no) ;;
+     *)      AC_MSG_ERROR([bad value $enableval for gcc-warnings option]) ;;
+   esac
+   gl_gcc_warnings=$enableval],
+  [
+   # GCC provides fine-grained control over diagnostics which
+   # is used in gnulib for example to suppress warnings from
+   # certain sections of code.  So if this is available and
+   # we're running from a git repo, then auto enable the warnings.
+   gl_gcc_warnings=no
+   gl_GCC_VERSION_IFELSE([4], [6], [test -d "$srcdir"/.git && gl_gcc_warnings=yes])]
+)
+
 if test "$gl_gcc_warnings" = yes; then
   gl_WARN_ADD([-Werror], [WERROR_CFLAGS])
   AC_SUBST([WERROR_CFLAGS])
-- 
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