Re: [PATCH 7/9] btrfs-progs: Fix Wmaybe-uninitialized warning

From: David Sterba <dsterba@suse.cz>
To: Qu Wenruo <wqu@suse.com>
Cc: linux-btrfs@vger.kernel.org
Subject: Re: [PATCH 7/9] btrfs-progs: Fix Wmaybe-uninitialized warning
Date: Tue, 4 Dec 2018 13:17:04 +0100	[thread overview]
Message-ID: <20181204121704.GL17773@twin.jikos.cz> (raw)
In-Reply-To: <20181116075426.4142-8-wqu@suse.com>

On Fri, Nov 16, 2018 at 03:54:24PM +0800, Qu Wenruo wrote:
> The only location is the following code:
> 
> 	int level = path->lowest_level + 1;
>  	BUG_ON(path->lowest_level + 1 >= BTRFS_MAX_LEVEL);
>  	while(level < BTRFS_MAX_LEVEL) {
> 		slot = path->slots[level] + 1;
> 		...
> 	}
> 	path->slots[level] = slot;
> 
> Again, it's the stupid compiler needs some hint for the fact that
> we will always enter the while loop for at least once, thus @slot should
> always be initialized.

Harsh words for the compiler, and I say not deserved. The same code
pasted to kernel a built with the same version does not report the
warning, so it's apparently a missing annotation of BUG_ON in
btrfs-progs that does not give the right hint.