linux-kernel - [PATCH v2] checkpatch: fix incorrect camelcase detection on numeric constant

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Date:   Mon, 13 Jun 2022 12:00:55 +0200
From:   Antonio Borneo <borneo.antonio@...il.com>
To:     Joe Perches <joe@...ches.com>, Andy Whitcroft <apw@...onical.com>,
        Dwaipayan Ray <dwaipayanray1@...il.com>,
        Lukas Bulwahn <lukas.bulwahn@...il.com>
Cc:     Antonio Borneo <borneo.antonio@...il.com>,
        linux-kernel@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: [PATCH v2] checkpatch: fix incorrect camelcase detection on numeric constant

The code fragment below
	int foo(int *array, int index)
	{
		return array[index & 0xFF];
	}
triggers an incorrect camelcase detection by checking a substring
of the hex constant:
	CHECK: Avoid CamelCase: <xFF>
	#3: FILE: test.c:3:
	+	return array[index & 0xFF];

This is caused by passing the whole string "array[index & 0xFF]"
to the inner loop that iterates over a "$Ident" match.
The numeric constant is not a $Ident as it doesn't start with
[A-Za-z_] and should be excluded from the match.

Similar issue can be detected with other constants like "1uL",
"0xffffU".

Force the match to start at word boundary so the $Ident will be
properly checked starting from its first char and the constants
will be filtered-out.

Signed-off-by: Antonio Borneo <borneo.antonio@...il.com>
---

Well, already one year has passed from v1, but anyway here is v2.

Joe,
I have modified the commit message, hope it fully matches your
review.

v1 -> v2:
	fix description in commit message
	rebase on v5.19-rc2

---
 scripts/checkpatch.pl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 503e8abbb2c1..ef4c656a99b3 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -5720,7 +5720,7 @@ sub process {
 			    $var !~ /^(?:[a-z0-9_]*|[A-Z0-9_]*)?_?[a-z][A-Z](?:_[a-z0-9_]+|_[A-Z0-9_]+)?$/ &&
 #Ignore some three character SI units explicitly, like MiB and KHz
 			    $var !~ /^(?:[a-z_]*?)_?(?:[KMGT]iB|[KMGT]?Hz)(?:_[a-z_]+)?$/) {
-				while ($var =~ m{($Ident)}g) {
+				while ($var =~ m{\b($Ident)}g) {
 					my $word = $1;
 					next if ($word !~ /[A-Z][a-z]|[a-z][A-Z]/);
 					if ($check) {

base-commit: b13baccc3850ca8b8cccbf8ed9912dbaa0fdf7f3
-- 
2.36.1