Commit 95e2c602 authored by Joe Perches's avatar Joe Perches Committed by Linus Torvalds

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: default avatarJoe Perches <>
Suggested-by: default avatarAndrew Morton <>
Cc: Andy Whitcroft <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent be79794b
......@@ -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 $Operators = qr{
......@@ -2934,9 +2938,17 @@ sub process {
#Specific variable tests
while ($line =~ m{($Constant|$Lval)}g) {
my $var = $1;
#gcc binary extension
if ($var =~ /^$Binary$/) {
"Avoid gcc v4.3+ binary constant extension: <$var>\n" . $herecurr);
if ($var !~ /$Constant/ &&
$var =~ /[A-Z][a-z]|[a-z][A-Z]/ &&
$var !~ /"^(?:Clear|Set|TestClear|TestSet|)Page[A-Z]/ &&
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