[libvirt] [PATCH 1/6] Use gnulib's manywarnings & warnings modules
Eric Blake
eblake at redhat.com
Mon Apr 4 20:29:06 UTC 2011
On 04/04/2011 10:19 AM, Daniel P. Berrange wrote:
> Remove custom code for checking compiler warnings, using
> gl_WARN_ADD instead. Don't list all flags ourselves, use
> gnulib's gl_MANYWARN_ALL_GCC to get all possible GCC flags,
> then turn off the ones we don't want yet.
>
> * acinclude.m4: Rewrite to use gl_WARN_ADD and gl_MANYWARN_ALL_GCC
> * bootstrap.conf: Add warnings & manywarnings
> * configure.ac: Switch to gl_WARN_ADD
> * m4/compiler-flags.m4: Obsoleted by gl_WARN_ADD
> ---
> acinclude.m4 | 158 +++++++++++++++++++++++++++-----------------------
> bootstrap.conf | 2 +
> configure.ac | 15 +++--
> m4/compiler-flags.m4 | 48 ---------------
> 4 files changed, 96 insertions(+), 127 deletions(-)
> delete mode 100644 m4/compiler-flags.m4
> +
> + # List of warnings that are not relevant / wanted
> + dontwarn="$dontwarn -Wc++-compat" # Don't care about C++ compiler compat
> + dontwarn="$dontwarn -Wtraditional" # Don't care about ancient C standard compat
> + dontwarn="$dontwarn -Wtraditional-conversion" # Don't care about ancient C standard compat
> + dontwarn="$dontwarn -Wsystem-headers" # Ignore warnings in /usr/include
> + dontwarn="$dontwarn -Wpadded" # Happy for compiler to add struct padding
> + dontwarn="$dontwarn -Wunreachable-code" # GCC very confused with -O2
> + dontwarn="$dontwarn -Wconversion" # Too many to deal with
> + dontwarn="$dontwarn -Wsign-conversion" # Too many to deal with
> + dontwarn="$dontwarn -Wvla" # GNULIB gettext.h violates
> + dontwarn="$dontwarn -Wundef" # Many GNULIB violations
> + dontwarn="$dontwarn -Wcast-qual" # Need to allow bad cast for execve()
> + dontwarn="$dontwarn -Wlong-long" # We need to use long long in many places
> + dontwarn="$dontwarn -Wswitch-default" # We allow manual list of all enum cases without default:
> + dontwarn="$dontwarn -Wswitch-enum" # We allow optional default: instead of listing all enum values
> + dontwarn="$dontwarn -Wstrict-overflow" # Not a problem since we don't use -fstrict-overflow
> + dontwarn="$dontwarn -Wunsafe-loop-optimizations" # Not a problem since we don't use -funsafe-loop-optimizations
Seems okay (but long lines - any way to break that into 80 columns?)
> +
> + # We might fundamentally need some of these disabled forever, but ideally
> + # we'd turn many of them on
> + dontwarn="$dontwarn -Wformat-nonliteral"
This one may need to always be disabled, thanks to virAsprintf (it would
be nicer if we could disable for just one or two files, rather than
globally).
> + dontwarn="$dontwarn -Wfloat-equal"
> + dontwarn="$dontwarn -Wdeclaration-after-statement"
If gcc would do better, I'd love to guarantee C99 and take advantage of
this (smaller scopes have maintenance benefits) - thus, I envision this
one being permanent (float it up to the earlier set).
> + dontwarn="$dontwarn -Wcast-qual"
> + dontwarn="$dontwarn -Wconversion"
> + dontwarn="$dontwarn -Wsign-conversion"
> + dontwarn="$dontwarn -Wold-style-definition"
> + dontwarn="$dontwarn -Wmissing-noreturn"
> + dontwarn="$dontwarn -Wpacked"
> + dontwarn="$dontwarn -Wunused-macros"
> + dontwarn="$dontwarn -Woverlength-strings"
> + dontwarn="$dontwarn -Wmissing-format-attribute"
> + dontwarn="$dontwarn -Wstack-protector"
Yes, I agree that the rest of these should be temporary, and are
probably worth fixing.
> +
> + # Get all possible GCC warnings
> + gl_MANYWARN_ALL_GCC([maybewarn])
> +
> + # Remove the ones we don't want, blacklisted earlier
> + gl_MANYWARN_COMPLEMENT([wantwarn], [$maybewarn], [$dontwarn])
> +
> + # Check for $CC support of each warning
> + for w in $wantwarn; do
> + gl_WARN_ADD([$w])
> + done
> +
> + # GNULIB uses '-W' which includes a bunch of stuff,
> + # kinda like -Wextra. Unfortunately, it means you
"kinda like"? Exactly like! -W was the old spelling, -Wextra was the
new one (added quite some time ago; something like gcc 3.4, off the top
of my head).
> + # can't simply use '-Wsign-compare' with gl_MANYWARN_COMPLEMENT
> + # So we have -W enabled, and then have to explicitly turn off
> + gl_WARN_ADD(-Wno-sign-compare)
> +
> + # This should be < 256 really, but with PATH_MAX everywhere
> + # we have doom, even with 4096. In fact we have some functions
> + # with several PATH_MAX sized variables :-( We should kill off
> + # all PATH_MAX usage and then lower this limit
> + gl_WARN_ADD([-Wframe-larger-than=65700])
> + dnl gl_WARN_ADD([-Wframe-larger-than=4096])
> + dnl gl_WARN_ADD([-Wframe-larger-than=256])
> +
> + # Extra special flags
> + gl_WARN_ADD([-Wp,-D_FORTIFY_SOURCE=2])
> + dnl Fedora only uses -fstack-protector, but doesn't seem to
> + dnl be great overhead in adding -fstack-protector-all instead
> + dnl gl_WARN_ADD([-fstack-protector])
> + gl_WARN_ADD([-fstack-protector-all])
> + gl_WARN_ADD([--param=ssp-buffer-size=4])
> + gl_WARN_ADD([-fexceptions])
> + gl_WARN_ADD([-fasynchronous-unwind-tables])
> + gl_WARN_ADD([-fdiagnostics-show-option])
> +
> + if test "$enable_compile_warnings" = "error"
> + then
> + gl_WARN_ADD([-Werror])
> + fi
Looks like a good conversion.
> @@ -81,6 +82,7 @@ timegm
> uname
> useless-if-before-free
> usleep
> +warnings
> vasprintf
> verify
> vc-list-files
Where did you learn to sort? :)
> diff --git a/configure.ac b/configure.ac
> index a8d223a..7874c30 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -1970,12 +1970,14 @@ AC_ARG_ENABLE([test-coverage],
> enable_coverage=$enableval
>
> if test "${enable_coverage}" = yes; then
> - COMPILER_FLAGS=
> - gl_COMPILER_FLAGS(-fprofile-arcs)
> - gl_COMPILER_FLAGS(-ftest-coverage)
> - AC_SUBST([COVERAGE_CFLAGS], [$COMPILER_FLAGS])
> - AC_SUBST([COVERAGE_LDFLAGS], [$COMPILER_FLAGS])
> - COMPILER_FLAGS=
> + save_WARN_CFLAGS=$WARN_CFLAGS
> + WARN_CFLAGS=
> + gl_WARN_ADD(-fprofile-arcs)
> + gl_WARN_ADD(-ftest-coverage)
Nit: use consistent m4 quoting: gl_WARN_ADD([-fprofile-arcs])
ACK with nits addressed.
--
Eric Blake eblake at redhat.com +1-801-349-2682
Libvirt virtualization library http://libvirt.org
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