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

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Message-Id: <20190311173845.53c2e4e4d2257a3701fa2033@linux-foundation.org>
Date:   Mon, 11 Mar 2019 17:38:45 -0700
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     Alexey Dobriyan <adobriyan@...il.com>
Cc:     linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Drop -Wdeclaration-after-statement

On Sun, 10 Mar 2019 16:35:35 +0300 Alexey Dobriyan <adobriyan@...il.com> wrote:

> Newly added static_assert() is formally a declaration, which will give
> a warning if used in the middle of the function.
> 
> ...
>
> --- a/Makefile
> +++ b/Makefile
> @@ -792,9 +792,6 @@ endif
>  # arch Makefile may override CC so keep this after arch Makefile is included
>  NOSTDINC_FLAGS += -nostdinc -isystem $(shell $(CC) -print-file-name=include)
>  
> -# warn about C99 declaration after statement
> -KBUILD_CFLAGS += -Wdeclaration-after-statement
> -
>  # Variable Length Arrays (VLAs) should not be used anywhere in the kernel
>  KBUILD_CFLAGS += $(call cc-option,-Wvla)

I do wish your changelogs were more elaborate :(

So the proposal is to disable -Wdeclaration-after-statement in all
cases for all time because static_assert() doesn't work correctly?

Surely there's something we can do to squish the static_assert() issue
while retaining -Wdeclaration-after-statement?  Perhaps by making
static_assert() a nop if -Wdeclaration-after-statement is in use. 
Perhaps simply by putting { } around the static_assert()?