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|
dnl
dnl Enable all known GCC compiler warnings, except for those
dnl we can't yet cope with
dnl
AC_DEFUN([LIBVIRT_COMPILE_WARNINGS],[
dnl ******************************
dnl More compiler warnings
dnl ******************************
AC_ARG_ENABLE([werror],
AS_HELP_STRING([--enable-werror], [Use -Werror (if supported)]),
[set_werror="$enableval"],
[if test -d $srcdir/.git; then
is_git_version=true
set_werror=yes
else
set_werror=no
fi])
# List of warnings that are not relevant / wanted
# Don't care about C++ compiler compat
dontwarn="$dontwarn -Wc++-compat"
dontwarn="$dontwarn -Wabi"
dontwarn="$dontwarn -Wdeprecated"
# Don't care about ancient C standard compat
dontwarn="$dontwarn -Wtraditional"
# Don't care about ancient C standard compat
dontwarn="$dontwarn -Wtraditional-conversion"
# Ignore warnings in /usr/include
dontwarn="$dontwarn -Wsystem-headers"
# Happy for compiler to add struct padding
dontwarn="$dontwarn -Wpadded"
# GCC very confused with -O2
dontwarn="$dontwarn -Wunreachable-code"
# Too many to deal with
dontwarn="$dontwarn -Wconversion"
# Too many to deal with
dontwarn="$dontwarn -Wsign-conversion"
# GNULIB gettext.h violates
dontwarn="$dontwarn -Wvla"
# Many GNULIB header violations
dontwarn="$dontwarn -Wundef"
# Need to allow bad cast for execve()
dontwarn="$dontwarn -Wcast-qual"
# We need to use long long in many places
dontwarn="$dontwarn -Wlong-long"
# We allow manual list of all enum cases without default:
dontwarn="$dontwarn -Wswitch-default"
# We allow optional default: instead of listing all enum values
dontwarn="$dontwarn -Wswitch-enum"
# Not a problem since we don't use -fstrict-overflow
dontwarn="$dontwarn -Wstrict-overflow"
# Not a problem since we don't use -funsafe-loop-optimizations
dontwarn="$dontwarn -Wunsafe-loop-optimizations"
# Things like virAsprintf mean we can't use this
dontwarn="$dontwarn -Wformat-nonliteral"
# Gnulib's stat-time.h violates this
dontwarn="$dontwarn -Waggregate-return"
# gcc 4.4.6 complains this is C++ only; gcc 4.7.0 implies this from -Wall
dontwarn="$dontwarn -Wenum-compare"
# gcc 5.1 -Wformat-signedness mishandles enums, not ready for prime time
dontwarn="$dontwarn -Wformat-signedness"
# gcc 4.2 treats attribute(format) as an implicit attribute(nonnull),
# which triggers spurious warnings for our usage
AC_CACHE_CHECK([whether the C compiler's -Wformat allows NULL strings],
[lv_cv_gcc_wformat_null_works], [
save_CFLAGS=$CFLAGS
CFLAGS='-Wunknown-pragmas -Werror -Wformat'
AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
#include <stddef.h>
static __attribute__ ((__format__ (__printf__, 1, 2))) int
foo (const char *fmt, ...) { return !fmt; }
]], [[
return foo(NULL);
]])],
[lv_cv_gcc_wformat_null_works=yes],
[lv_cv_gcc_wformat_null_works=no])
CFLAGS=$save_CFLAGS])
# Gnulib uses '#pragma GCC diagnostic push' to silence some
# warnings, but older gcc doesn't support this.
AC_CACHE_CHECK([whether pragma GCC diagnostic push works],
[lv_cv_gcc_pragma_push_works], [
save_CFLAGS=$CFLAGS
CFLAGS='-Wunknown-pragmas -Werror'
AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
#pragma GCC diagnostic push
#pragma GCC diagnostic pop
]])],
[lv_cv_gcc_pragma_push_works=yes],
[lv_cv_gcc_pragma_push_works=no])
CFLAGS=$save_CFLAGS])
if test $lv_cv_gcc_pragma_push_works = no; then
dontwarn="$dontwarn -Wmissing-prototypes"
dontwarn="$dontwarn -Wmissing-declarations"
dontwarn="$dontwarn -Wcast-align"
else
AC_DEFINE_UNQUOTED([WORKING_PRAGMA_PUSH], 1,
[Define to 1 if gcc supports pragma push/pop])
fi
dnl Check whether strchr(s, char variable) causes a bogus compile
dnl warning, which is the case with GCC < 4.6 on some glibc
AC_CACHE_CHECK([whether the C compiler's -Wlogical-op gives bogus warnings],
[lv_cv_gcc_wlogical_op_broken], [
save_CFLAGS="$CFLAGS"
CFLAGS="-O2 -Wlogical-op -Werror"
AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
#include <string.h>
]], [[
const char *haystack;
char needle;
return strchr(haystack, needle) == haystack;]])],
[lv_cv_gcc_wlogical_op_broken=no],
[lv_cv_gcc_wlogical_op_broken=yes])
CFLAGS="$save_CFLAGS"])
AC_CACHE_CHECK([whether gcc gives bogus warnings for -Wlogical-op],
[lv_cv_gcc_wlogical_op_equal_expr_broken], [
save_CFLAGS="$CFLAGS"
CFLAGS="-O2 -Wlogical-op -Werror"
AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
#define TEST1 1
#define TEST2 TEST1
]], [[
int test = 0;
return test == TEST1 || test == TEST2;]])],
[lv_cv_gcc_wlogical_op_equal_expr_broken=no],
[lv_cv_gcc_wlogical_op_equal_expr_broken=yes])
CFLAGS="$save_CFLAGS"])
# We might fundamentally need some of these disabled forever, but
# ideally we'd turn many of them on
dontwarn="$dontwarn -Wfloat-equal"
dontwarn="$dontwarn -Wdeclaration-after-statement"
dontwarn="$dontwarn -Wpacked"
dontwarn="$dontwarn -Wunused-macros"
dontwarn="$dontwarn -Woverlength-strings"
dontwarn="$dontwarn -Wstack-protector"
# Get all possible GCC warnings
gl_MANYWARN_ALL_GCC([maybewarn])
# Remove the ones we don't want, blacklisted earlier
gl_MANYWARN_COMPLEMENT([wantwarn], [$maybewarn], [$dontwarn])
# GNULIB uses '-W' (aka -Wextra) which includes a bunch of stuff.
# Unfortunately, this means you can't simply use '-Wsign-compare'
# with gl_MANYWARN_COMPLEMENT
# So we have -W enabled, and then have to explicitly turn off...
wantwarn="$wantwarn -Wno-sign-compare"
# GNULIB expects this to be part of -Wc++-compat, but we turn
# that one off, so we need to manually enable this again
wantwarn="$wantwarn -Wjump-misses-init"
# GNULIB turns on -Wformat=2 which implies -Wformat-nonliteral,
# so we need to manually re-exclude it. Also, older gcc 4.2
# added an implied ATTRIBUTE_NONNULL on any parameter marked
# ATTRIBUTE_FMT_PRINT, which causes -Wformat failure on our
# intentional use of virReportError(code, NULL).
wantwarn="$wantwarn -Wno-format-nonliteral"
if test $lv_cv_gcc_wformat_null_works = no; then
wantwarn="$wantwarn -Wno-format"
fi
# This should be < 256 really. Currently we're down to 4096,
# but using 1024 bytes sized buffers (mostly for virStrerror)
# stops us from going down further
wantwarn="$wantwarn -Wframe-larger-than=4096"
dnl wantwarn="$wantwarn -Wframe-larger-than=256"
# Extra special flags
dnl -fstack-protector stuff passes gl_WARN_ADD with gcc
dnl on Mingw32, but fails when actually used
case $host in
aarch64-*-*)
dnl "error: -fstack-protector not supported for this target [-Werror]"
;;
*-*-linux*)
dnl Prefer -fstack-protector-strong if it's available.
dnl There doesn't seem to be great overhead in adding
dnl -fstack-protector-all instead of -fstack-protector.
dnl
dnl We also don't need ssp-buffer-size with -all or -strong,
dnl since functions are protected regardless of buffer size.
dnl wantwarn="$wantwarn --param=ssp-buffer-size=4"
wantwarn="$wantwarn -fstack-protector-strong"
;;
*-*-freebsd*)
dnl FreeBSD ships old gcc 4.2.1 which doesn't handle
dnl -fstack-protector-all well
wantwarn="$wantwarn -fstack-protector"
wantwarn="$wantwarn -Wno-unused-command-line-argument"
;;
esac
wantwarn="$wantwarn -fexceptions"
wantwarn="$wantwarn -fasynchronous-unwind-tables"
# Need -fipa-pure-const in order to make -Wsuggest-attribute=pure
# fire even without -O.
wantwarn="$wantwarn -fipa-pure-const"
# We should eventually enable this, but right now there are at
# least 75 functions triggering warnings.
wantwarn="$wantwarn -Wno-suggest-attribute=pure"
wantwarn="$wantwarn -Wno-suggest-attribute=const"
if test "$set_werror" = "yes"
then
wantwarn="$wantwarn -Werror"
fi
# Check for $CC support of each warning
for w in $wantwarn; do
gl_WARN_ADD([$w])
done
case $host in
*-*-linux*)
dnl Fall back to -fstack-protector-all if -strong is not available
case $WARN_CFLAGS in
*-fstack-protector-strong*)
;;
*)
gl_WARN_ADD(["-fstack-protector-all"])
;;
esac
;;
esac
case $WARN_CFLAGS in
*-Wsuggest-attribute=format*)
AC_DEFINE([HAVE_SUGGEST_ATTRIBUTE_FORMAT], [1], [Whether -Wsuggest-attribute=format works])
;;
esac
# Silence certain warnings in gnulib, and use improved glibc headers
AC_DEFINE([lint], [1],
[Define to 1 if the compiler is checking for lint.])
AH_VERBATIM([FORTIFY_SOURCE],
[/* Enable compile-time and run-time bounds-checking, and some warnings,
without upsetting newer glibc. */
#if !defined _FORTIFY_SOURCE && defined __OPTIMIZE__ && __OPTIMIZE__
# define _FORTIFY_SOURCE 2
#endif
])
if test "$gl_cv_warn_c__Wlogical_op" = yes &&
test "$lv_cv_gcc_wlogical_op_broken" = yes; then
AC_DEFINE_UNQUOTED([BROKEN_GCC_WLOGICALOP_STRCHR], 1,
[Define to 1 if gcc -Wlogical-op reports false positives on strchr])
fi
if test "$gl_cv_warn_c__Wlogical_op" = yes &&
test "$lv_cv_gcc_wlogical_op_equal_expr_broken" = yes; then
AC_DEFINE_UNQUOTED([BROKEN_GCC_WLOGICALOP_EQUAL_EXPR], 1,
[Define to 1 if gcc -Wlogical-op reports false positive 'or' equal expr])
fi
])
|
