Re: [PATCH] configure: Disable -Wtautological-type-limit-compare

[Philippe Mathieu-Daudé]

On 6/4/20 8:11 AM, Philippe Mathieu-Daudé wrote:
> On 6/4/20 5:45 AM, Richard Henderson wrote:
>> Clang 10 enables this by default with -Wtype-limit.
>>
>> All of the instances flagged by this Werror so far have been
>> cases in which we really do want the compiler to optimize away
>> the test completely.  Disabling the warning will avoid having
>> to add ifdefs to work around this.
>>
> 
> Fixes: https://bugs.launchpad.net/qemu/+bug/1878628
> 
> Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>

Clarifying: I tested with clang-10, but Alex/Cornelia reported on IRC
the failure persist with clang-9 until using --disabler-werror.

> 
> I dare to add:
> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> 
>> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
>> ---
>>  configure | 2 ++
>>  1 file changed, 2 insertions(+)
>>
>> diff --git a/configure b/configure
>> index f087d2bcd1..693f01327f 100755
>> --- a/configure
>> +++ b/configure
>> @@ -2009,6 +2009,8 @@ gcc_flags="-Wno-missing-include-dirs -Wempty-body 
>> -Wnested-externs $gcc_flags"
>>  gcc_flags="-Wendif-labels -Wno-shift-negative-value $gcc_flags"
>>  gcc_flags="-Wno-initializer-overrides -Wexpansion-to-defined $gcc_flags"
>>  gcc_flags="-Wno-string-plus-int -Wno-typedef-redefinition $gcc_flags"
>> +gcc_flags="$gcc_flags -Wno-tautological-type-limit-compare"
>> +
>>  # Note that we do not add -Werror to gcc_flags here, because that would
>>  # enable it for all configure tests. If a configure test failed due
>>  # to -Werror this would just silently disable some features,
>>
>