Thread (16 messages) 16 messages, 5 authors, 2024-10-07

Re: [PATCH v1] cleanup: adjust scoped_guard() to avoid potential warning

From: Peter Zijlstra <peterz@infradead.org>
Date: 2024-10-04 09:33:14
Also in: lkml

On Thu, Oct 03, 2024 at 08:51:46PM +0300, Andy Shevchenko wrote:
quoted
I would really like to understand why you don't like this; care to
elaborate Andy?
To me the idea of

int my_foo(...)
{
	NOT_my_foo_macro(...)
		return X;
}

is counter intuitive from C programming. Without knowing the magic behind the
scenes of NOT_my_foo_macro() I would eager to ask for adding a dead code like

int my_foo(...)
{
	NOT_my_foo_macro(...)
		return X;
	return 0;
}
Well, this is kernel coding, we don't really do (std) C anymore, and
using *anything* without knowing the magic behind it is asking for fail.

Also, something like:

int my_foo()
{
	for (;;)
		return X;
}

or

int my_foo()
{
	do {
		return X;
	} while (0);
}

is perfectly valid C that no compiler should be complaining about. Yes
its a wee bit daft, but if you want to write it, that's fine.

The point being that the compiler can determine there is no path not
hitting that return.

Apparently the current for loop is defeating the compiler, I see no
reason not to change it in such a way that the compiler is able to
determine wtf happens -- that can only help.
What I would agree on is

int my_foo(...)
{
	return NOT_my_foo_macro(..., X);
}
That just really won't work with things as they are ofcourse.
Or just using guard()().
That's always an option. You don't *have* to use the -- to you -- weird
form.
Keyboard shortcuts
hback out one level
jnext message in thread
kprevious message in thread
ldrill in
Escclose help / fold thread tree
?toggle this help