Issue 2513: Build: add -fno-tree-vrp to CXXFLAGS for gcc 4.7.0

That optimization breaks min() call in simultaneous-music-iterator.cc
leading to incorrect output and bogus barcheck errors.

Generalize STEPMAKE_GXXCODEGENBUG to show bug description with the flag.

GCC bug reported:
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53239

Signed-off-by: David Kastrup <dak@gnu.org>

diff --git a/stepmake/aclocal.m4 b/stepmake/aclocal.m4
index 8be2cab11dbe82218add1190679c27782c3b57b8..42c65a58cd6d4b075f999dc17ce6fd6935d6e4b1 100644 (file)
--- a/stepmake/aclocal.m4
+++ b/stepmake/aclocal.m4
@@ -287,12 +287,16 @@ AC_DEFUN(STEPMAKE_CXXTEMPLATE, [
 ])
 
 AC_DEFUN(STEPMAKE_GXXCODEGENBUG, [
-    AC_MSG_CHECKING([options for known g++ tail call bug])
+    AC_MSG_CHECKING([options for known g++ bugs])
     case "$GXX:$CXX_VERSION" in
        yes:400600?)
-           AC_MSG_RESULT([-fno-optimize-sibling-calls])
+           AC_MSG_RESULT([-fno-optimize-sibling-calls (tail call bug)])
            CXXFLAGS="$CXXFLAGS -fno-optimize-sibling-calls"
            ;;
+       yes:400700?)
+           AC_MSG_RESULT([-fno-tree-vrp (comparison bug)])
+           CXXFLAGS="$CXXFLAGS -fno-tree-vrp"
+           ;;
        *) AC_MSG_RESULT([none])
     esac
     AC_SUBST(CXXFLAGS)