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

From: Joe Perches
Date: Tue Mar 05 2019 - 18:17:23 EST


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.

> }
>
> 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"

> 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;