Re: [PATCH] tty: hvc-iucv: fix function pointer casts

[Segher Boessenkool]

On Tue, Feb 13, 2024 at 11:17:49AM +0100, Arnd Bergmann wrote:
> clang warns about explicitly casting between incompatible function
> pointers:
> 
> drivers/tty/hvc/hvc_iucv.c:1100:23: error: cast from 'void (*)(const void *)' to 'void (*)(struct device *)' converts to incompatible function type [-Werror,-Wcast-function-type-strict]
>  1100 |         priv->dev->release = (void (*)(struct device *)) kfree;
>       |                              ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Such a cast of course is explicitly allowed by 6.3.2.3/8, only calling a
function using a non-compatible type is UB.  This warning message is
quite misleading.  Doubly so because of the -Werror, as always.

Your proposed new code of course is nice and simple (albeit a bit bigger
than it was before, both source and binary).  Such is life ;-)


Segher