Re: [sort-of-BUG] merge-resolve cannot resolve "content/mode" conflict

[Jeff King <peff@peff.net>]

On Mon, Apr 04, 2016 at 10:34:34AM -0700, Junio C Hamano wrote:

> Jeff King <peff@peff.net> writes:
> 
> > Imagine a merge where one side changes the content of a path and the
> > other changes the mode. Here's a minimal reproduction:
> >
> >   git init repo && cd repo &&
> >
> >   echo base >file &&
> >   git add file &&
> >   git commit -m base &&
> >
> >   echo changed >file &&
> >   git commit -am content &&
> >
> >   git checkout -b side HEAD^
> >   chmod +x file &&
> >   git commit -am mode
> > ...
> > This is a leftover from my experiments with merge-resolve versus
> > merge-recursive last fall, which resulted in a few actual bug-fixes. I
> > looked into fixing this case, too, at that time. It seemed possible, but
> > a little more involved than you might think (because the logic is driven
> > by a bunch of case statements, and this adds a multiplicative layer to
> > the cases; we might need to resolve the permissions, and _then_ see if
> > the content can be resolved).
> 
> Perhaps I am missing some other codepath in the "multiplicative"
> layer, but is this not sufficient?

Sorry for the super-slow reply; just cleaning out my "to respond to"
pile, which has gotten pretty deep.

Looking at it again, I think you are right. I seemed to recall that
there were multiple case arms where we dealt with the permissions, but I
cannot find such a spot now. So I think the solution you outlined looks
good.

> -	if test "$6" != "$7"
> +	# Three-way merge of the permissions
> +	perm= ;# assume the result is the same from stage #2, i.e. $6
> +	if test "$6" = "$7" || test "$5" = "$7"
> +	then
> +		: nothing
> +	elif test "$5" = "$6"
>  	then
> +		case "$7" in
> +		100644)	perm=-x ;;
> +		100755) perm=+x ;;
> +		*) echo "ERROR: $7: funny filemode not handled." >&2 ;;
> +		esac

We reject symlinks and submodules earlier, so I think this "funny
filemode" error really should only be truly-funny entries. Good.

-Peff