checkpatch: fix multiple const * types

Commit 1574a29f8e76 ("checkpatch: allow multiple const * types") claims to
support repetition of pattern "const *", but it actually allows only one
extra instance.

Check the following lines
	int a(char const * const x[]);
	int b(char const * const *x);
	int c(char const * const * const x[]);
	int d(char const * const * const *x);

with command

	./scripts/checkpatch.pl --show-types -f filename

to find that only the first line passes the test, while a warning
is triggered by the other 3 lines:

	WARNING:FUNCTION_ARGUMENTS: function definition argument
	'char const * const' should also have an identifier name

The reason is that the pattern match halts at the second asterisk in the
line, thus the remaining text starting with asterisk fails to match a
valid name for a variable.

Fixed by replacing "?" (Match 1 or 0 times) with "{0,4}" (Match no more
than 4 times) in the regular expression.  Fix also the similar test for
types in unusual order.

Fixes: 1574a29f8e76 ("checkpatch: allow multiple const * types")
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Joe Perches <joe@perches.com>
Link: http://lkml.kernel.org/r/20200122163852.124417-1-borneo.antonio@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 879ccf3..0d2b950 100755 (executable)
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -804,12 +804,12 @@ sub build_types {
                  }x;
        $Type   = qr{
                        $NonptrType
-                       (?:(?:\s|\*|\[\])+\s*const|(?:\s|\*\s*(?:const\s*)?|\[\])+|(?:\s*\[\s*\])+)?
+                       (?:(?:\s|\*|\[\])+\s*const|(?:\s|\*\s*(?:const\s*)?|\[\])+|(?:\s*\[\s*\])+){0,4}
                        (?:\s+$Inline|\s+$Modifier)*
                  }x;
        $TypeMisordered = qr{
                        $NonptrTypeMisordered
-                       (?:(?:\s|\*|\[\])+\s*const|(?:\s|\*\s*(?:const\s*)?|\[\])+|(?:\s*\[\s*\])+)?
+                       (?:(?:\s|\*|\[\])+\s*const|(?:\s|\*\s*(?:const\s*)?|\[\])+|(?:\s*\[\s*\])+){0,4}
                        (?:\s+$Inline|\s+$Modifier)*
                  }x;
        $Declare        = qr{(?:$Storage\s+(?:$Inline\s+)?)?$Type};