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

[Philippe Mathieu-Daudé]

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?

> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
>  pc-bios/s390-ccw/s390-ccw.h | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/pc-bios/s390-ccw/s390-ccw.h b/pc-bios/s390-ccw/s390-ccw.h
> index 6cd92669e9..79db69ff54 100644
> --- a/pc-bios/s390-ccw/s390-ccw.h
> +++ b/pc-bios/s390-ccw/s390-ccw.h
> @@ -89,6 +89,7 @@ bool menu_is_enabled_enum(void);
>  
>  #define MAX_BOOT_ENTRIES  31
>  
> +__attribute__ ((__noreturn__))
>  static inline void panic(const char *string)
>  {
>      sclp_print(string);
>