configure: Don't override user -g or -O options for debug builds

Principle of least surprise: --enable-debug should enable debugging.
Ages ago, Mesa's build system only added -g in dri-debug builds (yay for
the static Makefiles).  If you forgot to change it (or wrap the build
with custom scripts), you would often be disappointed when trying to gdb
Mesa bugs.  New developers, that may not yet have custom scripts, will
have this same issue.

I think we should enable experienced developers to do what they want,
and make things easier for new developers.  I already pass '-ggdb3 -O1'
or '-ggdb3 -Og' for CFLAGS, and I don't want configure to change them
for me.

Signed-off-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Matt Turner <mattst88@gmail.com>

diff --git a/configure.ac b/configure.ac
index 3a6fde2df6b2e35b021e7f1021984004cdac9733..6b0d43fd81997fcf40e53fdb6a4692b5b878bfb7 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -301,10 +301,20 @@ AC_ARG_ENABLE([debug],
 if test "x$enable_debug" = xyes; then
     DEFINES="$DEFINES -DDEBUG"
     if test "x$GCC" = xyes; then
-        CFLAGS="$CFLAGS -g -O0"
+        if ! echo "$CFLAGS" | grep -q -e '-g'; then
+            CFLAGS="$CFLAGS -g"
+        fi
+        if ! echo "$CFLAGS" | grep -q -e '-O'; then
+            CFLAGS="$CFLAGS -O0"
+        fi
     fi
     if test "x$GXX" = xyes; then
-        CXXFLAGS="$CXXFLAGS -g -O0"
+        if ! echo "$CXXFLAGS" | grep -q -e '-g'; then
+            CXXFLAGS="$CXXFLAGS -g"
+        fi
+        if ! echo "$CXXFLAGS" | grep -q -e '-O'; then
+            CXXFLAGS="$CXXFLAGS -O0"
+        fi
     fi
 fi