linux-kernel - [PATCH] checkpatch: Prefer static const declarations

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Date:   Mon, 19 Oct 2020 12:19:02 -0700
From:   Joe Perches <joe@...ches.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Andy Whitcroft <apw@...onical.com>,
        LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH] checkpatch: Prefer static const declarations

There are about 100,000 uses of 'static const <type>' but about
400 uses
of 'static <type> const' in the kernel where type is
not a pointer.

The kernel almost always uses "static const" over "const static"
as there is a compiler warning for that declaration style.

But there is no compiler warning for "static <type> const".

So add a checkpatch warning for the atypical declaration uses of.

	const static <type> <foo>
and
	static <type> const <foo>

For example:

$ ./scripts/checkpatch.pl -f --emacs --quiet --nosummary -types=static_const arch/arm/crypto/aes-ce-glue.c
arch/arm/crypto/aes-ce-glue.c:75: WARNING: Move const after static - use 'static const u8'
#75: FILE: arch/arm/crypto/aes-ce-glue.c:75:
+	static u8 const rcon[] = {

Signed-off-by: Joe Perches <joe@...ches.com>
---
 scripts/checkpatch.pl | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index fab38b493cef..f82ec64f4fc7 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -4207,6 +4207,18 @@ sub process {
 			}
 		}
 
+# check for const static or static <non ptr type> const declarations
+# prefer 'static const <foo>' over 'const static <foo>' and 'static <foo> const'
+		if ($sline =~ /^\+\s*const\s+static\s+($Type)\b/ ||
+		    $sline =~ /^\+\s*static\s+($BasicType)\s+const\b/) {
+			if (WARN("STATIC_CONST",
+				 "Move const after static - use 'static const $1'\n" . $herecurr) &&
+			    $fix) {
+				$fixed[$fixlinenr] =~ s/\bconst\s+static\b/static const/;
+				$fixed[$fixlinenr] =~ s/\bstatic\s+($BasicType)\s+const\b/static const $1/;
+			}
+		}
+
 # check for non-global char *foo[] = {"bar", ...} declarations.
 		if ($line =~ /^.\s+(?:static\s+|const\s+)?char\s+\*\s*\w+\s*\[\s*\]\s*=\s*\{/) {
 			WARN("STATIC_CONST_CHAR_ARRAY",