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https://gitlab.com/libvirt/libvirt.git
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c579d6b3d6
OpenBSD ships with gcc 4.2.1, which annoyingly treats all format strings as though they were also attribute((nonnull)). The two concepts are orthogonal, though, as evidenced by the number of spurious warnings it generates on uses where we know that virReportError specifically handles NULL instead of a format string; worse, since we now force -Werror on git builds, it prevents development builds on OpenBSD. I hate to do this, as it disables ALL format checking on older gcc, and therefore misses out on some useful checks (code that happened to compile on Linux may still have type mismatches when compiled on other platforms, as evidenced by the number of times I have fixed formatting mismatches for uid_t as found by warnings on Cygwin), but I don't see any other way to keep -Werror alive and still compile on OpenBSD. A more invasive change would be to make virReportError() mark its format attribute as nonnull, and fix (a lot of) fallout; we may end up doing that anyways as part of danpb's error refactoring improvements, but not today. * src/internal.h (ATTRIBUTE_FMT_PRINTF): Use preferred spellings. * m4/virt-compile-warnings.m4 (-Wformat): Disable on older gcc.
181 lines
6.6 KiB
Plaintext
181 lines
6.6 KiB
Plaintext
dnl
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dnl Enable all known GCC compiler warnings, except for those
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dnl we can't yet cope with
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dnl
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AC_DEFUN([LIBVIRT_COMPILE_WARNINGS],[
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dnl ******************************
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dnl More compiler warnings
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dnl ******************************
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AC_ARG_ENABLE([werror],
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AS_HELP_STRING([--enable-werror], [Use -Werror (if supported)]),
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[set_werror="$enableval"],
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[if test -d $srcdir/.git; then
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is_git_version=true
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set_werror=yes
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else
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set_werror=no
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fi])
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# List of warnings that are not relevant / wanted
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# Don't care about C++ compiler compat
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dontwarn="$dontwarn -Wc++-compat"
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dontwarn="$dontwarn -Wabi"
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dontwarn="$dontwarn -Wdeprecated"
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# Don't care about ancient C standard compat
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dontwarn="$dontwarn -Wtraditional"
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# Don't care about ancient C standard compat
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dontwarn="$dontwarn -Wtraditional-conversion"
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# Ignore warnings in /usr/include
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dontwarn="$dontwarn -Wsystem-headers"
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# Happy for compiler to add struct padding
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dontwarn="$dontwarn -Wpadded"
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# GCC very confused with -O2
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dontwarn="$dontwarn -Wunreachable-code"
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# Too many to deal with
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dontwarn="$dontwarn -Wconversion"
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# Too many to deal with
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dontwarn="$dontwarn -Wsign-conversion"
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# GNULIB gettext.h violates
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dontwarn="$dontwarn -Wvla"
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# Many GNULIB header violations
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dontwarn="$dontwarn -Wundef"
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# Need to allow bad cast for execve()
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dontwarn="$dontwarn -Wcast-qual"
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# We need to use long long in many places
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dontwarn="$dontwarn -Wlong-long"
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# We allow manual list of all enum cases without default:
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dontwarn="$dontwarn -Wswitch-default"
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# We allow optional default: instead of listing all enum values
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dontwarn="$dontwarn -Wswitch-enum"
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# Not a problem since we don't use -fstrict-overflow
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dontwarn="$dontwarn -Wstrict-overflow"
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# Not a problem since we don't use -funsafe-loop-optimizations
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dontwarn="$dontwarn -Wunsafe-loop-optimizations"
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# Things like virAsprintf mean we can't use this
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dontwarn="$dontwarn -Wformat-nonliteral"
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# Gnulib's stat-time.h violates this
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dontwarn="$dontwarn -Waggregate-return"
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# Gnulib uses '#pragma GCC diagnostic push' to silence some
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# warnings, but older gcc doesn't support this.
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AC_CACHE_CHECK([whether pragma GCC diagnostic push works],
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[lv_cv_gcc_pragma_push_works], [
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save_CFLAGS=$CFLAGS
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CFLAGS='-Wunknown-pragmas -Werror'
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AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
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#pragma GCC diagnostic push
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#pragma GCC diagnostic pop
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]])],
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[lv_cv_gcc_pragma_push_works=yes],
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[lv_cv_gcc_pragma_push_works=no])
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CFLAGS=$save_CFLAGS])
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if test $lv_cv_gcc_pragma_push_works = no; then
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dontwarn="$dontwarn -Wmissing-prototypes"
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dontwarn="$dontwarn -Wmissing-declarations"
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fi
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# We might fundamentally need some of these disabled forever, but
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# ideally we'd turn many of them on
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dontwarn="$dontwarn -Wfloat-equal"
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dontwarn="$dontwarn -Wdeclaration-after-statement"
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dontwarn="$dontwarn -Wcast-qual"
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dontwarn="$dontwarn -Wconversion"
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dontwarn="$dontwarn -Wsign-conversion"
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dontwarn="$dontwarn -Wpacked"
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dontwarn="$dontwarn -Wunused-macros"
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dontwarn="$dontwarn -Woverlength-strings"
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dontwarn="$dontwarn -Wstack-protector"
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# Get all possible GCC warnings
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gl_MANYWARN_ALL_GCC([maybewarn])
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# Remove the ones we don't want, blacklisted earlier
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gl_MANYWARN_COMPLEMENT([wantwarn], [$maybewarn], [$dontwarn])
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# Check for $CC support of each warning
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for w in $wantwarn; do
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gl_WARN_ADD([$w])
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done
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# GNULIB uses '-W' (aka -Wextra) which includes a bunch of stuff.
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# Unfortunately, this means you can't simply use '-Wsign-compare'
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# with gl_MANYWARN_COMPLEMENT
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# So we have -W enabled, and then have to explicitly turn off...
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gl_WARN_ADD([-Wno-sign-compare])
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# GNULIB expects this to be part of -Wc++-compat, but we turn
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# that one off, so we need to manually enable this again
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gl_WARN_ADD([-Wjump-misses-init])
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# GNULIB turns on -Wformat=2 which implies -Wformat-nonliteral,
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# so we need to manually re-exclude it. Also, older gcc 4.2
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# added an implied ATTRIBUTE_NONNULL on any parameter marked
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# ATTRIBUTE_FMT_PRINT, which causes -Wformat failure on our
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# intentional use of virReportError(code, NULL).
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gl_WARN_ADD([-Wno-format-nonliteral])
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if test $lv_cv_gcc_pragma_push_works = no; then
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gl_WARN_ADD([-Wno-format])
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fi
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# This should be < 256 really. Currently we're down to 4096,
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# but using 1024 bytes sized buffers (mostly for virStrerror)
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# stops us from going down further
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gl_WARN_ADD([-Wframe-larger-than=4096])
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dnl gl_WARN_ADD([-Wframe-larger-than=256])
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# Silence certain warnings in gnulib, and use improved glibc headers
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AC_DEFINE([lint], [1],
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[Define to 1 if the compiler is checking for lint.])
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AH_VERBATIM([FORTIFY_SOURCE],
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[/* Enable compile-time and run-time bounds-checking, and some warnings,
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without upsetting newer glibc. */
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#if defined __OPTIMIZE__ && __OPTIMIZE__
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# define _FORTIFY_SOURCE 2
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#endif
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])
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# Extra special flags
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dnl -fstack-protector stuff passes gl_WARN_ADD with gcc
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dnl on Mingw32, but fails when actually used
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case $host in
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*-*-linux*)
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dnl Fedora only uses -fstack-protector, but doesn't seem to
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dnl be great overhead in adding -fstack-protector-all instead
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dnl gl_WARN_ADD([-fstack-protector])
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gl_WARN_ADD([-fstack-protector-all])
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gl_WARN_ADD([--param=ssp-buffer-size=4])
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;;
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esac
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gl_WARN_ADD([-fexceptions])
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gl_WARN_ADD([-fasynchronous-unwind-tables])
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gl_WARN_ADD([-fdiagnostics-show-option])
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gl_WARN_ADD([-funit-at-a-time])
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# Need -fipa-pure-const in order to make -Wsuggest-attribute=pure
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# fire even without -O.
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gl_WARN_ADD([-fipa-pure-const])
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# We should eventually enable this, but right now there are at
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# least 75 functions triggering warnings.
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gl_WARN_ADD([-Wno-suggest-attribute=pure])
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gl_WARN_ADD([-Wno-suggest-attribute=const])
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if test "$set_werror" = "yes"
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then
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gl_WARN_ADD([-Werror])
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fi
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WARN_LDFLAGS=$WARN_CFLAGS
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AC_SUBST([WARN_CFLAGS])
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AC_SUBST([WARN_LDFLAGS])
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dnl Needed to keep compile quiet on python 2.4
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save_WARN_CFLAGS=$WARN_CFLAGS
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WARN_CFLAGS=
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gl_WARN_ADD([-Wno-redundant-decls])
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WARN_PYTHON_CFLAGS=$WARN_CFLAGS
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AC_SUBST(WARN_PYTHON_CFLAGS)
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WARN_CFLAGS=$save_WARN_CFLAGS
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])
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