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

From: Adam Borowski <kilobyte@angband.pl>
To: dsterba@suse.cz, Qu Wenruo <wqu@suse.com>, linux-btrfs@vger.kernel.org
Subject: Re: [PATCH 7/9] btrfs-progs: Fix Wmaybe-uninitialized warning
Date: Tue, 4 Dec 2018 13:22:48 +0100	[thread overview]
Message-ID: <20181204122248.liocpfkyqodb5vco@angband.pl> (raw)
In-Reply-To: <20181204121704.GL17773@twin.jikos.cz>

On Tue, Dec 04, 2018 at 01:17:04PM +0100, David Sterba wrote:
> 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.

It's be nice if the C language provided a kind of a while loop that executes
at least once...

-- 
⢀⣴⠾⠻⢶⣦⠀ 
⣾⠁⢠⠒⠀⣿⡁ Ivan was a worldly man: born in St. Petersburg, raised in
⢿⡄⠘⠷⠚⠋⠀ Petrograd, lived most of his life in Leningrad, then returned
⠈⠳⣄⠀⠀⠀⠀ to the city of his birth to die.