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

[Thomas Huth]

On 05/06/2020 14.51, Philippe Mathieu-Daudé wrote:
> 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.

Does -Wno-tautological-constant-compare help on Clang-9 instead?

 Thomas


>>
>> 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,
>>>
>>
> 
>