checkpatch: warn when using gcc's binary constant ("0b") extension

The gcc extension for binary constants that start with 0b is only
supported with gcc version 4.3 or higher.

The kernel can still be compiled with earlier versions of gcc, so have
checkpatch emit a warning for these constants.

Restructure checkpatch's constant finding code a bit to support finding
these binary constants.

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

scripts/checkpatch.pl

@@ -230,11 +230,15 @@ our $Inline	= qr{inline|__always_inline|noinline};
 our $Member	= qr{->$Ident|\.$Ident|\[[^]]*\]};
 our $Lval	= qr{$Ident(?:$Member)*};
 
+our $Int_type	= qr{(?i)llu|ull|ll|lu|ul|l|u};
+our $Binary	= qr{(?i)0b[01]+$Int_type?};
+our $Hex	= qr{(?i)0x[0-9a-f]+$Int_type?};
+our $Int	= qr{[0-9]+$Int_type?};
 our $Float_hex	= qr{(?i)0x[0-9a-f]+p-?[0-9]+[fl]?};
 our $Float_dec	= qr{(?i)(?:[0-9]+\.[0-9]*|[0-9]*\.[0-9]+)(?:e-?[0-9]+)?[fl]?};
 our $Float_int	= qr{(?i)[0-9]+e-?[0-9]+[fl]?};
 our $Float	= qr{$Float_hex|$Float_dec|$Float_int};
-our $Constant	= qr{$Float|(?i)(?:0x[0-9a-f]+|[0-9]+)[ul]*};
+our $Constant	= qr{$Float|$Binary|$Hex|$Int};
 our $Assignment	= qr{\*\=|/=|%=|\+=|-=|<<=|>>=|&=|\^=|\|=|=};
 our $Compare    = qr{<=|>=|==|!=|<|>};
 our $Operators	= qr{
@@ -2934,9 +2938,17 @@ sub process {
 			}
 		}
 
-#CamelCase
+#Specific variable tests
 		while ($line =~ m{($Constant|$Lval)}g) {
 			my $var = $1;
+
+#gcc binary extension
+			if ($var =~ /^$Binary$/) {
+				WARN("GCC_BINARY_CONSTANT",
+				     "Avoid gcc v4.3+ binary constant extension: <$var>\n" . $herecurr);
+			}
+
+#CamelCase
 			if ($var !~ /$Constant/ &&
 			    $var =~ /[A-Z][a-z]|[a-z][A-Z]/ &&
 			    $var !~ /"^(?:Clear|Set|TestClear|TestSet|)Page[A-Z]/ &&