linux-kernel - Re: [PATCH][next] btrfs: remove shadowed declaration of variable i in for-loops

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Date:   Thu, 30 Nov 2023 23:50:33 +0100
From:   David Sterba <dsterba@...e.cz>
To:     Colin Ian King <colin.i.king@...il.com>
Cc:     Chris Mason <clm@...com>, Josef Bacik <josef@...icpanda.com>,
        David Sterba <dsterba@...e.com>, linux-btrfs@...r.kernel.org,
        kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH][next] btrfs: remove shadowed declaration of variable i
 in for-loops

On Thu, Nov 30, 2023 at 03:08:11PM +0000, Colin Ian King wrote:
> The variable i is declared at the start of function btrfs_qgroup_inherit
> however there are two for-loops that redeclare the variable using a C99
> declaration, causes name shadowing. I believe there is no need for this
> local scoping of i in the loop, so replace the declaration in the loops
> with assignments.
> 
> Cleans up clang scan build warnings:
> 
> fs/btrfs/qgroup.c:3194:12: warning: declaration shadows a local variable [-Wshadow]
>  3194 |                 for (int i = 0; i < inherit->num_qgroups; i++) {
>       |                          ^
> fs/btrfs/qgroup.c:3089:6: note: previous declaration is here
>  3089 |         int i;
>       |             ^
> fs/btrfs/qgroup.c:3321:12: warning: declaration shadows a local variable [-Wshadow]
>  3321 |                 for (int i = 0; i < inherit->num_qgroups; i++)
>       |                          ^
> fs/btrfs/qgroup.c:3089:6: note: previous declaration is here
>  3089 |         int i;
>       |             ^
> 
> Signed-off-by: Colin Ian King <colin.i.king@...il.com>
> ---
>  fs/btrfs/qgroup.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
> index ce446d9d7f23..b1f93dbf468c 100644
> --- a/fs/btrfs/qgroup.c
> +++ b/fs/btrfs/qgroup.c
> @@ -3191,7 +3191,7 @@ int btrfs_qgroup_inherit(struct btrfs_trans_handle *trans, u64 srcid,
>  			ret = -ENOMEM;
>  			goto out;
>  		}
> -		for (int i = 0; i < inherit->num_qgroups; i++) {
> +		for (i = 0; i < inherit->num_qgroups; i++) {

We want to use the for(...) local definitions, so this should change the
function scope 'i'.