On Mon, Oct 26, 2020 at 9:23 AM Arnd Bergmann <[email protected]> wrote: > > From: Arnd Bergmann <[email protected]> > > gcc warns a few thousand times about the isdigit() shadow: > > include/linux/ctype.h:26:19: warning: declaration of 'isdigit' shadows a > built-in function [-Wshadow]
Don't all functions defined here shadow builtins in GCC? Why is `isdigit` unique? Is that because it's a `static inline` definition vs a function like macro? If that's the case, what's the harm in converting it to a function like macro if that silences the warning? > > As there is already a compiler builtin, just use that, and make > it clear we do that by defining a macro. Unfortunately, clang > does not have the isdigit() builtin, so this has to be conditional. TODO(Nick): finish the Clang patch that implements that. https://reviews.llvm.org/D86508 > > Signed-off-by: Arnd Bergmann <[email protected]> > --- > include/linux/ctype.h | 16 ++++++++++++---- > 1 file changed, 12 insertions(+), 4 deletions(-) > > diff --git a/include/linux/ctype.h b/include/linux/ctype.h > index 363b004426db..c407acb258c2 100644 > --- a/include/linux/ctype.h > +++ b/include/linux/ctype.h > @@ -23,10 +23,6 @@ extern const unsigned char _ctype[]; > #define isalnum(c) ((__ismask(c)&(_U|_L|_D)) != 0) > #define isalpha(c) ((__ismask(c)&(_U|_L)) != 0) > #define iscntrl(c) ((__ismask(c)&(_C)) != 0) > -static inline int isdigit(int c) > -{ > - return '0' <= c && c <= '9'; > -} > #define isgraph(c) ((__ismask(c)&(_P|_U|_L|_D)) != 0) > #define islower(c) ((__ismask(c)&(_L)) != 0) > #define isprint(c) ((__ismask(c)&(_P|_U|_L|_D|_SP)) != 0) > @@ -39,6 +35,18 @@ static inline int isdigit(int c) > #define isascii(c) (((unsigned char)(c))<=0x7f) > #define toascii(c) (((unsigned char)(c))&0x7f) > > +#if defined __has_builtin #ifdef only use `defined` explicitly when there's more than one condition being checked with logical `&&` or `||`. > +#if __has_builtin(__builtin_isdigit) GCC only recently gained the `__has_builtin` macro (I filed the bug); I would like to see something akin to include/linux/compiler_attributes.h but using `__has_builtin` like compiler_attributes.h uses `__has_attribute`. That way we avoid spaghetti like this throughout the kernel. > +#define isdigit(ch) __builtin_isdigit(ch) > +#endif > +#endif > +#ifndef isdigit > +static inline int isdigit(int c) > +{ > + return '0' <= c && c <= '9'; > +} > +#endif > + > static inline unsigned char __tolower(unsigned char c) > { > if (isupper(c)) > -- > 2.27.0 > -- Thanks, ~Nick Desaulniers
