Re: [PATCH 1/4] pc-bios/s390-ccw: Silence warning from Clang by marking panic() as noreturn

[Markus Armbruster]

Philippe Mathieu-Daudé <philmd@redhat.com> writes:

> On 5/2/21 7:48 PM, Thomas Huth wrote:
>> When compiling the s390-ccw bios with Clang, the compiler emits a warning:
>> 
>>  pc-bios/s390-ccw/main.c:210:5: warning: variable 'found' is used 
>> uninitialized
>>   whenever switch default is taken [-Wsometimes-uninitialized]
>>      default:
>>      ^~~~~~~
>>  pc-bios/s390-ccw/main.c:214:16: note: uninitialized use occurs here
>>      IPL_assert(found, "Boot device not found\n");
>>                 ^~~~~
>> 
>> It's a false positive, it only happens because Clang is not smart enough
>> to see that the panic() function in the "default:" case can never return.
>> 
>> Anyway, let's explicitely mark panic() with "noreturn" to shut up the
>> warning.
>
> Why not simply initialize the variable instead?

Because telling an optimizing compiler the truth is a good idea?