[libvirt] [PATCH v2 14/42] m4: enforce that all enum cases are listed in switch statements

As a general rule any time we switch() on something that is an enum, we want to have a case for every enum constant. The -Wswitch warning will report any switch where we've violated this rule, except if that switch has a default case. Unfortunately it is reasonable to want to list all enum constants *and* also have a default case. To get a warning in that scenario requires that we turn on -Wswitch-enum. In a few cases where we explicitly don't want to list all enum cases, we can discard the enum type checking by casting the value to a plain int. Signed-off-by: Daniel P. Berrangé <berrange(a)redhat.com&gt; --- m4/virt-compile-warnings.m4 | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/m4/virt-compile-warnings.m4 b/m4/virt-compile-warnings.m4 index b9c9748420..918764d362 100644 --- a/m4/virt-compile-warnings.m4 +++ b/m4/virt-compile-warnings.m4 @@ -47,8 +47,6 @@ AC_DEFUN([LIBVIRT_COMPILE_WARNINGS],[ 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 @@ -182,6 +180,11 @@ AC_DEFUN([LIBVIRT_COMPILE_WARNINGS],[ # 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. Also, older gcc 4.2 # added an implied ATTRIBUTE_NONNULL on any parameter marked -- 2.14.3