[PATCH 2/2] checkpatch: Warn when using gcc's binary constant extension

[Joe Perches]

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.

Suggested-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Joe Perches <joe@xxxxxxxxxxx>
---
 scripts/checkpatch.pl | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index f1aad19..517da26 100755
--- a/scripts/checkpatch.pl
+++ b/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]/ &&
-- 
1.8.1.2.459.gbcd45b4.dirty

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