Re: [PATCH] Drop -Wdeclaration-after-statement

[Andrew Morton]

On Fri, 25 Feb 2022 11:15:58 +0300 Alexey Dobriyan <adobriyan@xxxxxxxxx> wrote:

> 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.
> 
> 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.
> 
> 	{
> 		int x;
> 		[x is misused due to a typo]
> 		f(x);	// first correct use
> 	}
> 
> vs
> 
> 	{
> 		[can't misuse undeclared variable]
> 		int x;
> 		f(x);	// first correct use
> 	}
> 

Oh man.  I so wish you'd cc'ed Linus on this one so we could admire his
reaction.