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

[Junio C Hamano]

Ævar Arnfjörð Bjarmason   writes:

> 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? ");

Ah.  That "unless ... { }" thing is what was inserted recently, and
the patch is an obvious fix once the problem is pointed out.  Thanks
for a careful reading.

It makes me wonder what the original author, who already captured $1
in $regex, was thinking when he wrote the comparison with $1 there,
but that is OK---ithappend long time ago in early 2009.

Will apply.  Thanks.

>   $regex = ;
>   if (defined $regex) {
>   chomp $regex;
>   }
>   }

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

[Ævar Arnfjörð Bjarmason]

On Sat, Mar 31 2018, Phillip Wood wrote:

> On 31/03/18 13:50, Ævar Arnfjörð Bjarmason wrote:
>> 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
>>
>>  $ 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 $1 in string eq at 
>> /home/avar/g/git/git-add--interactive line 1568,  line 1.
>>  search for regex? Many
>>
>> I.e. the initial "/regex" command wouldn't work, and would always emit
>> a warning and ask again for a regex, now it works as intended again.
>>
>> Signed-off-by: Ævar Arnfjörð Bjarmason 
>> ---
>>
>> Of course I just noticed the grammar errors in the commit message
>> after sending. Here's a v2 with that fixed, also genreated the patch
>> with -U6 to make it clear what's going on.
>>
>>   git-add--interactive.perl | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/git-add--interactive.perl b/git-add--interactive.perl
>> index d190469cd8..c1f52e457f 100755
>> --- a/git-add--interactive.perl
>> +++ b/git-add--interactive.perl
>> @@ -1561,13 +1561,13 @@ sub patch_update_file {
>>  elsif ($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 = ;
>>  if (defined $regex) {
>>  chomp $regex;
>>  }
>>  }
>>

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

[Phillip Wood]

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

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.


Thanks for fixing it

Phillip


 $ 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,  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 
---

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 = ;
if (defined $regex) {
chomp $regex;
}
}