linux-kernel - RE: [PATCH] Drop -Wdeclaration-after-statement

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Date:   Fri, 25 Feb 2022 10:01:23 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Alexey Dobriyan' <adobriyan@...il.com>,
        "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH] Drop -Wdeclaration-after-statement

From: Alexey Dobriyan
> Sent: 25 February 2022 08:16
> 
> Putting declarations before statement is relict of single pass compiler
> era. It was necessary to allocate stack slots before generating code.
> 
> Recently added static_assert() is a declaration. -Wdeclaration-after-statement
> prevents its placement anywhere in the code for no reason.

That could enclose its declaration inside a block.
But then it wouldn't be usable at global scope (is it anyway?)

> Placing variable declarations in the beginning of the block increases
> variable "LOC lifetime" so to speak and chances that it will be misused.
> This is very low probability bug but still. Declaring variables right
> before first use will make "LOC lifetime" smaller.

NAK it makes it very hard for a human (some of us are) to find
the declaration.

Indeed putting them anywhere other that the top of a function
or the top of a very short code block makes them hard to find.

	David

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