Re: [PATCH v2] checkpatch: add double empty line check

Joe Perches
2012-11-20T21:59:03Z

On Tue, 2012-11-20 at 11:52 +0000, Andy Whitcroft wrote:
> On Sat, Nov 17, 2012 at 01:17:37PM +0200, Eilon Greenstein wrote:
> > Changes from previous attempt:
> > - Use CHK instead of WARN
> > - Issue only one warning per empty lines block
> >
> > Signed-off-by: Eilon Greenstein <eilong@broadcom.com>
> > ---
> > scripts/checkpatch.pl | 8 ++++++++
> > 1 file changed, 8 insertions(+)
> >
> > diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
> > index 21a9f5d..13d264f 100755
> > --- a/scripts/checkpatch.pl
> > +++ b/scripts/checkpatch.pl
> > @@ -3579,6 +3579,14 @@ sub process {
> > WARN("EXPORTED_WORLD_WRITABLE",
> > "Exporting world writable files is usually an error. Consider more restrictive permissions.\n" . $herecurr);
> > }
> > +
> > +# check for double empty lines
> > + if ($line =~ /^\+\s*$/ &&
> > + ($rawlines[$linenr] =~ /^\s*$/ ||
> > + $prevline =~ /^\+?\s*$/ && $rawlines[$linenr] !~ /^\+\s*$/)) {
> > + CHK("DOUBLE_EMPTY_LINE",
> > + "One empty line should be sufficient. Consider removing this one.\n" . $herecurr);
> > + }
> > }
> >
> > # If we have no input at all, then there is nothing to report on
>
> In your previous version you indicated you would be emiting one per group
> of lines, I do not see how this does that. Also this fails if the fragment
> is at the top of the hunk emiting a perl warning. We should probabally
> use the suppress approach.
>
> How about something like the below.
>
> -apw
>
>
> >From 848ebffa8656a1ff96a91788ec0f1c04dab9c3e9 Mon Sep 17 00:00:00 2001
> From: Andy Whitcroft <apw@canonical.com>
> Date: Sat, 17 Nov 2012 13:17:37 +0200
> Subject: [PATCH] checkpatch: strict warning for multiple blank lines
>
> Signed-off-by: Andy Whitcroft <apw@canonical.com>
> ---
> scripts/checkpatch.pl | 11 +++++++++++
> 1 file changed, 11 insertions(+)
>
> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
> index f18750e..dbc68f3 100755
> --- a/scripts/checkpatch.pl
> +++ b/scripts/checkpatch.pl
> @@ -1411,6 +1411,7 @@ sub process {
> my %suppress_whiletrailers;
> my %suppress_export;
> my $suppress_statement = 0;
> + my $suppress_multipleblank = -1;
>
> # Pre-scan the patch sanitizing the lines.
> # Pre-scan the patch looking for any __setup documentation.
> @@ -1521,6 +1522,7 @@ sub process {
> %suppress_whiletrailers = ();
> %suppress_export = ();
> $suppress_statement = 0;
> + $suppress_multipleblank = -1;
> next;
>
> # track the line number as we move through the hunk, note that
> @@ -1930,6 +1932,15 @@ sub process {
> "use the SSYNC() macro in asm/blackfin.h\n" . $herevet);
> }
>
> +# multiple blank lines.
> + if ($line =~ /^-/ || ($suppress_multipleblank == $linenr && $line =~ /^[ \+]\s*$/)) {
> + $suppress_multipleblank++;
> + } elsif ($prevline =~ /^\+\s*$/ and $line =~ /^\+\s*$/) {
> + $suppress_multipleblank = $linenr + 1;
> + CHK("MULTIPLE_EMPTY_LINE",
> + "One empty line should be sufficient. Consider removing this one.\n" . $herecurr);
> + }
> +
> # Check for potential 'bare' types
> my ($stat, $cond, $line_nr_next, $remain_next, $off_next,
> $realline_next);

What about:

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index d2d5ba1..ed4ec9d 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -1382,6 +1382,7 @@ sub process {
my $comment_edge = 0;
my $first_line = 0;
my $p1_prefix = '';
+ my $last_blank_linenr = 0;

my $prev_values = 'E';

@@ -3323,6 +3324,15 @@ sub process {
"sizeof $1 should be sizeof($1)\n" . $herecurr);
}

+# check for multiple blank lines, warn only on the second one in a block
+ if ($rawline =~ /^.\s*$/ &&
+ $prevrawline =~ /^.\s*$/ &&
+ $linenr != $last_blank_linenr + 1) {
+ CHK("DOUBLE_EMPTY_LINE",
+ "One blank line separating blocks is generally sufficient\n" . $herecurr);
+ $last_blank_linenr = $linenr;
+ }
+
# check for line continuations in quoted strings with odd counts of "
if ($rawline =~ /\\$/ && $rawline =~ tr/"/"/ % 2) {
WARN("LINE_CONTINUATIONS",