Subject: Re: [PATCH] unpack-tree.c: remove dead code

From: Junio C Hamano <[email-masked]>
Date: Tue, 12 Aug 2014 15:24:42 -0700

Stefan Beller <[email-masked]> writes:

> In line 1763 of unpack-tree.c we have a condition on the current tree
> 	if (current) {
> 		...
> Within this block of code we can assume current to be non NULL, hence
> the code after the statement in line 1796:
> 	if (current)
> 		return ...
>
> cannot be reached.
>
> current/newtree/oldtree are used in the
> call to reject_merge() *only* for their path aka ce->name, and they
> all point at the same name (there is no rename funkies here); hence
> "all other failures" code path should just rely on current always
> being present.
>
> All referenced lines have been introduced in the same commit
> 076b0adc (2006-07-30, read-tree: move merge functions to the library),
> which was just moving the code around.
> The outer condition on the current tree (now in line 1763) was introduced
> in c859600954df4c292e, June 2005, [PATCH] read-tree: save more user hassles during fast-forward.
> The inner condition on the current tree was introduced in
> ee6566e8d70da682ac4926d, Sept. 2005, [PATCH] Rewrite read-tree
>
> This issue was found by coverity, Id:290002
>
> Signed-off-by: Stefan Beller <[email-masked]>
> Helped-by: Junio C Hamano <[email-masked]>
> ---
>  unpack-trees.c | 12 ++++--------
>  1 file changed, 4 insertions(+), 8 deletions(-)
>
> Did I understand you right, when changing to this one?

Something like that.  I've already pushed out the original with a
tentative "SQUASH???" on top for today's integration; I'll try to
remember replacing them with this version.

Thanks.

>
> diff --git a/unpack-trees.c b/unpack-trees.c
> index c6aa8fb..42ee84e 100644
> --- a/unpack-trees.c
> +++ b/unpack-trees.c
> @@ -1789,15 +1789,11 @@ int twoway_merge(const struct cache_entry * const *src,
>  			/* 20 or 21 */
>  			return merged_entry(newtree, current, o);
>  		}
> +		else if (o->gently) {
> +			return  -1 ;
> +		}
>  		else {
> -			/* all other failures */
> -			if (oldtree)
> -				return o->gently ? -1 : reject_merge(oldtree, o);
> -			if (current)
> -				return o->gently ? -1 : reject_merge(current, o);
> -			if (newtree)
> -				return o->gently ? -1 : reject_merge(newtree, o);
> -			return -1;
> +			reject_merge(current, o);
>  		}
>  	}
>  	else if (newtree) {