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 ****************************** LIBVIRT_ARG_ENABLE([WERROR], [Use -Werror (if supported)], [check]) if test "$enable_werror" = "check"; then if test -d $srcdir/.git; then is_git_version=true enable_werror=yes else enable_werror=no fi fi # List of warnings that are not relevant / wanted # Don't care about C++ compiler compat dontwarn="$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" # 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" # Several conditionals expand the same on both branches # depending on the particular platform/architecture dontwarn="$dontwarn -Wduplicated-branches" # > This warning does not generally indicate that there is anything wrong # > with your code; it merely indicates that GCC's optimizers are unable # > to handle the code effectively. # Source: https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html dontwarn="$dontwarn -Wdisabled-optimization" # Various valid glib APIs/macros trigger this warning dontwarn="$dontwarn -Wbad-function-cast" # Broken in 6.0 and later # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69602 AC_CACHE_CHECK([whether gcc gives bogus warnings for -Wlogical-op], [lv_cv_gcc_wlogical_op_equal_expr_broken], [ save_CFLAGS="$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="$save_CFLAGS"]) AC_CACHE_CHECK([whether clang gives bogus warnings for -Wdouble-promotion], [lv_cv_clang_double_promotion_broken], [ save_CFLAGS="$CFLAGS" CFLAGS="-O2 -Wdouble-promotion -Werror" AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[ #include ]], [[ float f = 0.0; return isnan(f);]])], [lv_cv_clang_double_promotion_broken=no], [lv_cv_clang_double_promotion_broken=yes]) CFLAGS="$save_CFLAGS"]) if test "$lv_cv_clang_double_promotion_broken" = "yes"; then dontwarn="$dontwarn -Wdouble-promotion" fi # We might fundamentally need some of these disabled forever, but # ideally we'd turn many of them on dontwarn="$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" # We do "bad" function casts all the time for event callbacks wantwarn="$wantwarn -Wno-cast-function-type" # CLang incorrectly complains about dup typedefs win gnu99 mode # so use this CLang-specific arg to keep it quiet wantwarn="$wantwarn -Wno-typedef-redefinition" # GNULIB expects this to be part of -Wc++-compat, but we turn # that one off, so we need to manually enable this again wantwarn="$wantwarn -Wjump-misses-init" # GNULIB explicitly filters it out, preferring -Wswitch # but that doesn't report missing enums if a default: # is present. wantwarn="$wantwarn -Wswitch-enum" # GNULIB turns on -Wformat=2 which implies -Wformat-nonliteral, # so we need to manually re-exclude it. wantwarn="$wantwarn -Wno-format-nonliteral" # -Wformat enables this by default, and we should keep it, # but need to rewrite various areas of code first wantwarn="$wantwarn -Wno-format-truncation" # 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 gl_WARN_ADD([-Wframe-larger-than=4096], [STRICT_FRAME_LIMIT_CFLAGS]) gl_WARN_ADD([-Wframe-larger-than=32768], [RELAXED_FRAME_LIMIT_CFLAGS]) # 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 "$enable_werror" = "yes" then wantwarn="$wantwarn -Werror" fi # Request the gnu99 standard which is the best choice with # gcc 4.8.0. Not a warning flag, but the probing mechanism # is convenient wantwarn="$wantwarn -std=gnu99" # 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_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 ])