[Qemu-devel] [PATCH] configure: Enable extra compiler warnings

[Stefan Weil <sw@weilnetz.de>]

Compiler option -Wextra enables an additional set of compiler warnings.

Some of these warnings were already enabled explicitly in QEMU:
-Wold-style-declaration, -Wtype-limits, -Wignored-qualifiers and
-Wempty-body are now redundant and can be removed.

Others don't work with the current code and must be disabled to
avoid warnings: -Wno-missing-field-initializers, -Wno-override-init,
-Wno-sign-compare and -Wno-unused-parameter.

Signed-off-by: Stefan Weil <sw@weilnetz.de>
---
This is a rather old and long tested patch: I use -Wextra in my
QEMU builds for more than a year now. At least one bug was found
by using this warning level (see commit
b22dd1243f38286263d40496ce5298a8a7d96eea).

My tests include Linux and Windows hosts (gcc), but not BSD based hosts,
so maybe those hosts might need additional code fixes.
clang reports lots of -Wunused-value warnings.

Regards,
Stefan

 configure |   14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/configure b/configure
index 18fa608..252214b 100755
--- a/configure
+++ b/configure
@@ -299,7 +299,7 @@ sdl_config="${SDL_CONFIG-${cross_prefix}sdl-config}"
 
 # default flags for all hosts
 QEMU_CFLAGS="-fno-strict-aliasing $QEMU_CFLAGS"
-QEMU_CFLAGS="-Wall -Wundef -Wwrite-strings -Wmissing-prototypes $QEMU_CFLAGS"
+QEMU_CFLAGS="-Wall -Wextra -Wundef -Wwrite-strings -Wmissing-prototypes $QEMU_CFLAGS"
 QEMU_CFLAGS="-Wstrict-prototypes -Wredundant-decls $QEMU_CFLAGS"
 QEMU_CFLAGS="-D_GNU_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE $QEMU_CFLAGS"
 QEMU_INCLUDES="-I. -I\$(SRC_PATH) -I\$(SRC_PATH)/include"
@@ -1199,11 +1199,15 @@ if test -z "$werror" ; then
     fi
 fi
 
-gcc_flags="-Wold-style-declaration -Wold-style-definition -Wtype-limits"
-gcc_flags="-Wformat-security -Wformat-y2k -Winit-self -Wignored-qualifiers $gcc_flags"
-gcc_flags="-Wmissing-include-dirs -Wempty-body -Wnested-externs $gcc_flags"
-gcc_flags="-Wendif-labels $gcc_flags"
+gcc_flags="-Wold-style-definition"
+gcc_flags="-Wformat-security -Wformat-y2k -Winit-self $gcc_flags"
+gcc_flags="-Wmissing-include-dirs -Wnested-externs $gcc_flags"
+gcc_flags="-fstack-protector-all -Wendif-labels $gcc_flags"
 gcc_flags="-Wno-initializer-overrides $gcc_flags"
+gcc_flags="-Wno-missing-field-initializers $gcc_flags"
+gcc_flags="-Wno-override-init $gcc_flags"
+gcc_flags="-Wno-sign-compare $gcc_flags"
+gcc_flags="-Wno-unused-parameter $gcc_flags"
 # Note that we do not add -Werror to gcc_flags here, because that would
 # enable it for all configure tests. If a configure test failed due
 # to -Werror this would just silently disable some features,
-- 
1.7.10.4