On Mon, 13 Jul 2020, Mrinal Pandey wrote: > The usage of "capture group (...)" in the immediate condition after `&&` > results in `$1` being uninitialized. This issues a warning "Use of > uninitialized value $1 in regexp compilation at ./scripts/checkpatch.pl > line 2638". > > I noticed this bug while running checkpatch on the set of commits from > v5.7 to v5.8-rc1 of the kernel on the commits with a diff content in > their commit message. > > This bug was introduced in the script by commit e518e9a59ec3 > ("checkpatch: emit an error when there's a diff in a changelog"). It has > been in the script since then. > > The author intended to store the match made by capture group in variable > `$1`. This should have contained the name of the file as `[\w/]+` matched. > However, this couldn't be accomplished due to usage of capture group and > `$1` in the same regular expression. > > Fix this by placing the capture group in the condition before `&&`. > Thus, `$1` can be initialized to the text that capture group matches > thereby setting it to the desired and required value. > > Signed-off-by: Mrinal Pandey <mrinal...@gmail.com> > --- I have discussed the change on the mentees list before. So: Reviewed-by: Lukas Bulwahn <lukas.bulw...@gmail.com> I ran ./scripts/checkpatch.pl on: commit 6b3e0e2e0461 ("perf tools: Support CAP_PERFMON capability") commit 19ce2321739d ("perf flamegraph: Use /bin/bash for report and record scripts") before and after applying this patch. On those two patches, checkpatch.pl emits the warning before, and does not emit after this change. So: Tested-by: Lukas Bulwahn <lukas.bulw...@gmail.com> Lukas > scripts/checkpatch.pl | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl > index 4c820607540b..e73e998d582a 100755 > --- a/scripts/checkpatch.pl > +++ b/scripts/checkpatch.pl > @@ -2636,8 +2636,8 @@ sub process { > > # Check if the commit log has what seems like a diff which can confuse patch > if ($in_commit_log && !$commit_log_has_diff && > - (($line =~ m@^\s+diff\b.*a/[\w/]+@ && > - $line =~ m@^\s+diff\b.*a/([\w/]+)\s+b/$1\b@) || > + (($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", > -- > 2.25.1 > >