checkpatch: warn when casting constants to c90 int or longer types

Linus Torvalds wrote:

> I can't but help to react that this:
>  #define IOMMU_ERROR_CODE       (~(unsigned long) 0)
> Not that this *matters*, but it's a bit odd to have to cast constants
> to perfectly regular C types.

So add a test that looks for constants that are cast to
standard C90 int or longer types and suggest using C90
"6.4.4.1 Integer constants" integer-suffixes instead.

Miscellanea:

o Add a --fix option too

Signed-off-by: Joe Perches <joe@perches.com>
Suggested-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 42 insertions, 0 deletions

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index c7bf1aa2eeb3..86457062db29 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -433,6 +433,28 @@ our @typeList = (
         qr{${Ident}_handler_fn},
         @typeListMisordered,
 );
+
+our $C90_int_types = qr{(?x:
+        long\s+long\s+int\s+(?:un)?signed|
+        long\s+long\s+(?:un)?signed\s+int|
+        long\s+long\s+(?:un)?signed|
+        (?:(?:un)?signed\s+)?long\s+long\s+int|
+        (?:(?:un)?signed\s+)?long\s+long|
+        int\s+long\s+long\s+(?:un)?signed|
+        int\s+(?:(?:un)?signed\s+)?long\s+long|
+
+        long\s+int\s+(?:un)?signed|
+        long\s+(?:un)?signed\s+int|
+        long\s+(?:un)?signed|
+        (?:(?:un)?signed\s+)?long\s+int|
+        (?:(?:un)?signed\s+)?long|
+        int\s+long\s+(?:un)?signed|
+        int\s+(?:(?:un)?signed\s+)?long|
+
+        int\s+(?:un)?signed|
+        (?:(?:un)?signed\s+)?int
+)};
+
 our @typeListFile = ();
 our @typeListWithAttr = (
         @typeList,
@@ -5272,6 +5294,26 @@ sub process {
                         }
                 }
 
+# check for cast of C90 native int or longer types constants
+                if ($line =~ /(\(\s*$C90_int_types\s*\)\s*)($Constant)\b/) {
+                        my $cast = $1;
+                        my $const = $2;
+                        if (WARN("TYPECAST_INT_CONSTANT",
+                                 "Unnecessary typecast of c90 int constant\n" . $herecurr) &&
+                            $fix) {
+                                my $suffix = "";
+                                my $newconst = $const;
+                                $newconst =~ s/${Int_type}$//;
+                                $suffix .= 'U' if ($cast =~ /\bunsigned\b/);
+                                if ($cast =~ /\blong\s+long\b/) {
+                                        $suffix .= 'LL';
+                                } elsif ($cast =~ /\blong\b/) {
+                                        $suffix .= 'L';
+                                }
+                                $fixed[$fixlinenr] =~ s/\Q$cast\E$const\b/$newconst$suffix/;
+                        }
+                }
+
 # check for sizeof(&)
                 if ($line =~ /\bsizeof\s*\(\s*\&/) {
                         WARN("SIZEOF_ADDRESS",