Re: [PATCH v2] add -p: fix 2.17.0-rc* regression due to moved code

On Sat, Mar 31 2018, Phillip Wood wrote:

On 31/03/18 13:50, Ævar Arnfjörð Bjarmason wrote:

quoted

Fix a regression in 88f6ffc1c2 ("add -p: only bind search key if
there's more than one hunk", 2018-02-13) which is present in
2.17.0-rc*, but not 2.16.0.

In Perl, regex variables like $1 always refer to the last regex
match. When the aforementioned change added a new regex match between
the old match and the corresponding code that was expecting $1, the $1
variable would always be undef, since the newly inserted regex match
doesn't have any captures.

As a result the "/" feature to search for a string in a hunk by regex
completely broke, on git.git:

Good catch, I could have sworn I'd tested my patch but I obviously
didn't notice the warning (I've got interactive.singlekey set so it
prints the warning and then prompts as it always has done). Calling it
completely broken is perhaps a little harsh as it does work if you
enter the regex again and with interactive.singlekey set you only have
to enter the regex once.

To clarify by "completely broken" I mean the "/" feature itself, but
yeah, you can still search by regex since we just so happen to have the
fallback codepath intended to catch "/" without an accompanying string,
which'll kick in and ask you for the regex since $1 will be undef at
that point, and will thus coerce stringwise to "".

Thanks for fixing it

Phillip

quoted

     $ perl -pi -e 's/Git/Tig/g' README.md
     $ ./git --exec-path=$PWD add -p
     [..]
     Stage this hunk [y,n,q,a,d,j,J,g,/,s,e,?]? s
     Split into 4 hunks.
     [...]
     Stage this hunk [y,n,q,a,d,j,J,g,/,s,e,?]? /Many
     Use of uninitialized value $1 in string eq at /home/avar/g/git/git-add--interactive line 1568, <STDIN> line 1.
     search for regex? Many

I.e. the initial "/regex" command wouldn't work, and would always emit
a warning and ask again for a regex, now it works as intended again.

Signed-off-by: Ævar Arnfjörð Bjarmason <redacted>
---

Of course I just noticed the grammar errors in the commit message
after sending. Here's a v2 with that fixed, also genreated the patch
with -U6 to make it clear what's going on.

  git-add--interactive.perl | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/git-add--interactive.perl b/git-add--interactive.perl
index d190469cd8..c1f52e457f 100755
--- a/git-add--interactive.perl
+++ b/git-add--interactive.perl

@@ -1561,13 +1561,13 @@ sub patch_update_file {
  			elsif ($line =~ m|^/(.*)|) {
  				my $regex = $1;
  				unless ($other =~ m|/|) {
  					error_msg __("No other hunks to search\n");
  					next;
  				}
-				if ($1 eq "") {
+				if ($regex eq "") {
  					print colored $prompt_color, __("search for regex? ");
  					$regex = <STDIN>;
  					if (defined $regex) {
  						chomp $regex;
  					}
  				}