Re: [PATCH 4/5] format-patch: do not respect diff.noprefix

> The output of format-patch respects diff.noprefix, but this usually ends
> up being a hassle for people receiving the patch, as they have to
> manually specify "-p0" in order to apply it.
> 
> I don't think there was any specific intention for it to behave this
> way. The noprefix option is handled by git_diff_ui_config(), and
> format-patch exists in a gray area between plumbing and porcelain.
> People do look at the output, and we'd expect it to colorize things,
> respect their choice of algorithm, and so on. But this particular option
> creates problems for the receiver (in theory so does diff.mnemonicprefix,
> but since we are always formatting commits, the mnemonic prefixes will
> always be "a/" and "b/").
> 
> So let's disable it. The slight downsides are:
> 
>   - people who have set diff.noprefix presumably like to see their
>     patches without prefixes. If they use format-patch to review their
>     series, they'll see prefixes. On the other hand, it is probably a
>     good idea for them to look at what will actually get sent out.
> 
>     We could try to play games here with "is stdout a tty", as we do for
>     color. But that's not a completely reliable signal, and it's
>     probably not worth the trouble. If you want to see the patch with
>     the usual bells and whistles, then you are better off using "git
>     log" or "git show".
> 
>   - if a project really does have a workflow that likes prefix-less
>     patches, and the receiver is prepared to use "-p0", then the sender
>     now has to manually say "--no-prefix" for each format-patch
>     invocation. That doesn't seem _too_ terrible given that the receiver
>     has to manually say "-p0" for each git-am invocation.
> 
> Signed-off-by: Jeff King <peff@peff.net>

> ---
>  builtin/log.c           | 9 +++++++++
>  t/t4014-format-patch.sh | 5 +++++
>  2 files changed, 14 insertions(+)
> 
> diff --git a/builtin/log.c b/builtin/log.c
> index a70fba198f9..eaf511aab86 100644
> --- a/builtin/log.c
> +++ b/builtin/log.c
> @@ -1085,6 +1085,15 @@ static int git_format_config(const char *var, const char *value, void *cb)
>  		return 0;
>  	}
>  
> +	/*
> +	 * ignore some porcelain config which would otherwise be parsed by
> +	 * git_diff_ui_config(), via git_log_config(); we can't just avoid
> +	 * diff_ui_config completely, because we do care about some ui options
> +	 * like color.
> +	 */
> +	if (!strcmp(var, "diff.noprefix"))
> +		return 0;
> +
>  	return git_log_config(var, value, cb);
>  }
>  
> diff --git a/t/t4014-format-patch.sh b/t/t4014-format-patch.sh
> index f3313b8c58f..f5a41fd47ed 100755
> --- a/t/t4014-format-patch.sh
> +++ b/t/t4014-format-patch.sh
> @@ -2386,4 +2386,9 @@ test_expect_success 'interdiff: solo-patch' '
>  	test_cmp expect actual
>  '
>  
> +test_expect_success 'format-patch does not respect diff.noprefix' '
> +	git -c diff.noprefix format-patch -1 --stdout >actual &&
> +	grep "^--- a/blorp" actual
> +'
> +
>  test_done