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From:   Alexandre Ghiti <alex@ghiti.fr>
To:     Andy Whitcroft <apw@canonical.com>, Joe Perches <joe@perches.com>,
        linux-kernel@vger.kernel.org
Cc:     Alexandre Ghiti <alex@ghiti.fr>
Subject: [PATCH v3] scripts: checkpatch: Check multiple blank lines when deleting code
Date:   Wed,  6 Mar 2019 14:53:24 -0500
Message-Id: <20190306195324.11634-1-alex@ghiti.fr>
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Sender: linux-kernel-owner@vger.kernel.org
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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.

Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
---

Changes in v3 as suggested by Joe Perches:
	- Do not try to fix this case
	- Make this test separate from the insertion one so that warning
	  is more explicit

Changes in v2:
	- Fix the --fix option

 scripts/checkpatch.pl | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index b737ca9d7204..c0728cff292f 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -3296,7 +3296,7 @@ sub process {
 			}
 		}
 
-# check for multiple consecutive blank lines
+# check for multiple consecutive blank lines caused by blank line insertion
 		if ($prevline =~ /^[\+ ]\s*$/ &&
 		    $line =~ /^\+\s*$/ &&
 		    $last_blank_line != ($linenr - 1)) {
@@ -3309,6 +3309,16 @@ sub process {
 			$last_blank_line = $linenr;
 		}
 
+# check for multiple consecutive blank lines caused by code deletion
+		if ($prevline =~ /^[\+ ]\s*$/ &&
+		    $line =~ /^ \s*$/ &&
+		    $last_blank_line != ($linenr - 1)) {
+			CHK("LINE_SPACING",
+			    "Avoid deleting lines that create consecutive blank lines\n" . $hereprev);
+
+			$last_blank_line = $linenr;
+		}
+
 # check for missing blank lines after declarations
 		if ($sline =~ /^\+\s+\S/ &&			#Not at char 1
 			# actual declarations
-- 
2.20.1