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Date: Fri, 21 Feb 2025 17:14:55 -0500
From: Steven Rostedt <rostedt@goodmis.org>
To: Martin Uecker <uecker@tugraz.at>
Cc: Dan Carpenter <dan.carpenter@linaro.org>, Greg KH
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 <rust-for-linux@vger.kernel.org>, Linus Torvalds
 <torvalds@linux-foundation.org>, David Airlie <airlied@gmail.com>,
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Subject: Re: Rust kernel policy
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On Fri, 21 Feb 2025 19:23:38 +0100
Martin Uecker <uecker@tugraz.at> wrote:

> > where func is defined as:
> > 
> > 	void func(void) { return ; }  
> 
> Calling a function declared in this way with arguments
> would be rejected by the compiler, so I am not sure how
> this works now.
> 
> If you used 
> 
> void func();
> 
> to declare the function, this is not possible anymore in C23.

As the comment in the code states:

include/linux/static_call.h:

 *   This feature is strictly UB per the C standard (since it casts a function
 *   pointer to a different signature) and relies on the architecture ABI to
 *   make things work. In particular it relies on Caller Stack-cleanup and the
 *   whole return register being clobbered for short return values. All normal
 *   CDECL style ABIs conform.

Basically it's assigned via casts.

-- Steve