linux-kernel - Re: [PATCH v2] scripts: checkpatch: Check multiple blank lines when deleting code

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Date:   Wed, 6 Mar 2019 01:49:56 -0500
From:   Alex Ghiti <alex@...ti.fr>
To:     Joe Perches <joe@...ches.com>
Cc:     Andy Whitcroft <apw@...onical.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] scripts: checkpatch: Check multiple blank lines when
 deleting code

On 3/5/19 6:17 PM, Joe Perches wrote:
> On Tue, 2019-03-05 at 02:12 -0500, Alexandre Ghiti wrote:
>> By matching only current line starting with '+', we miss the case
>> when deleting code makes consecutive blank lines appear: this patch
>> then makes it possible to detect this case by also matching current
>> line starting with ' ', which is an already existing blank line.
> []
>> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
> []
>> @@ -2081,10 +2081,15 @@ sub fix_inserted_deleted_lines {
>>   		}
>>   
>>   		while (defined($inserted) && ${$inserted}{'LINENR'} == $old_linenr) {
>> +			my $len = 1;
>>   			push(@lines, ${$inserted}{'LINE'});
>> +			# Do not increment the length when inserting a deletion line.
>> +			if (${$inserted}{'LINE'} =~ /^\-/) {
>> +				$len = 0;
>> +			}
>>   			$inserted = @{$insertedRef}[$next_insert++];
>>   			$new_linenr++;
>> -			fixup_current_range(\$lines[$range_last_linenr], $delta_offset++, 1);
>> +			fixup_current_range(\$lines[$range_last_linenr], $delta_offset++, $len);
> I think this is confusing and unnecessary.
> Using --fix can not delete context lines from a patch.

Ok, I was expecting your comment on that, I agree with you.
So I'll get rid of the possibility to fix the deletion case, this will
only be a warning.

>>   		}
>>   
>>   		if ($save_line) {
>> @@ -3298,12 +3303,18 @@ sub process {
>>   
>>   # check for multiple consecutive blank lines
>>   		if ($prevline =~ /^[\+ ]\s*$/ &&
>> -		    $line =~ /^\+\s*$/ &&
>> +		    $line =~ /^[\+ ]\s*$/ &&
>>   		    $last_blank_line != ($linenr - 1)) {
>>   			if (CHK("LINE_SPACING",
>>   				"Please don't use multiple blank lines\n" . $hereprev) &&
>>   			    $fix) {
> It's simpler to add a check that $line starts /^\+/ before $fix
>
> Maybe it'd be better to have a separate test for this to make
> the output message clearer too.
>
> Something like
> 	"Avoid deleting lines that create consecutive blank lines"

Ok,

Thanks for your comments,

>>   				fix_delete_line($fixlinenr, $rawline);
>> +				if ($line =~ /^ \s*$/) {
>> +					# If the line is not an inserted blank line, the multiple
>> +					# consecutive blank lines are caused by deletion: fix this
>> +					# by replacing the blank line with a deletion line.
>> +					fix_insert_line($fixlinenr, "\-");
>> +				}
>>   			}
>>   
>>   			$last_blank_line = $linenr;