Re: diffs in changelogs

[Joe Perches <joe@perches.com>]

On Thu, 2015-06-11 at 13:40 -0700, Andrew Morton wrote:
> People often put diff snippets in changelogs.  This causes problems
> when one tries to apply a file containing both the changelog and the
> diff because patch(1) tries to apply the diff which it found in the
> changelog.
That 
> eg, something like
> 
> 	git show d24a6e1087030b6da | patch -p1
> 
> will go haywire.
> 
> So can we please have a checkpatch test warning people away from doing
> this?
> 
> 
> patch(1) seems to be really promiscuous in its detection of a patch.  I
> haven't had much success searching for "^--- " and similar.  What works
> best for me is searching for "^[whitespace]@@ -".

I don't think that's a good test.
Coccinelle uses @@

And how did that commit actually get applied?

I tried applying it to a new branch checked out at
ce2b3f595e1c56639085645e0130426e443008c0, it fails.

Anyway, maybe:
---
 scripts/checkpatch.pl | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 69c4716..2d87e37 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -2399,6 +2399,18 @@ sub process {
 			$in_commit_log = 1;
 		}
 
+# Check if the commit log has a diff which confuse patch
+
+		print("icl: <$in_commit_log> line: <$line>\n");
+		if ($in_commit_log &&
+		    (($line =~ m@^\s+diff\b.*a/[\w/]+@ &&
+		      $line =~ m@^\s+diff\b.*a/([\w/]+)\s+b/$1\b@) ||
+		     $line =~ m@^\s*(?:\-\-\-\s+a/|\+\+\+\s+b/)@ ||
+		     $line =~ m/^\s*\@\@ \-\d+,\d+ \+\d+,\d+ \@\@/)) {
+			ERROR("DIFF_IN_COMMIT_MSG",
+			      "It seems a diff exists in the commit message. This can confuse patch\n" . $herecurr);
+		}
+
 # Check if there is UTF-8 in a commit log when a mail header has explicitly
 # declined it, i.e defined some charset where it is missing.
 		if ($in_header_lines &&