On Thu, Mar 15, 2012 at 11:19:43AM +0100, Marc Espie wrote:
> On Thu, Mar 15, 2012 at 01:39:18AM +0000, Stuart Henderson wrote:
> > $ c++ -pedantic -c a.c
> > In file included from /usr/include/g++/memory:60,
> > from /usr/include/g++/string:48,
> > from a.c:1:
> > /usr/include/g++/limits: In static member function 'static char
> > std::numeric_limits<char>::min()':
> > /usr/include/g++/limits:375: warning: overflow in implicit constant
> > conversion
> > /usr/include/g++/limits: In static member function 'static wchar_t
> > std::numeric_limits<wchar_t>::max()':
> > /usr/include/g++/limits:530: warning: overflow in implicit constant
> > conversion
>
> It's not even fixed in gcc 4.6.2, not fully anyways.
>
> The following patch might work, it really needs to be read by people who
> understand this
>
> - the max warning comes from gcc 4.6.2, this one should be fine.
> - the min warning affects the specialization for char, but char is
> either signed char or unsigned char, so we can borrow the specializations
> from those types. Preferably directly, to avoid duplication. Obviously,
> gcc will whine at having definitions in the wrong order, so it's possible
> to reorder things to avoid that as well.
>
> Please test. I've "fixed" limits directly, then backfitted the patch to
> the right src file (been a while since I hacked on this), and I hope it's
> correct.
Can this be reviewed/commited ? Those warnings are really annoying and
hide real errors/warnings.
Landry
> Index: std_limits.h
> ===================================================================
> RCS file: /cvs/src/gnu/gcc/libstdc++-v3/include/std/std_limits.h,v
> retrieving revision 1.1.1.1
> diff -u -p -r1.1.1.1 std_limits.h
> --- std_limits.h 15 Oct 2009 17:11:32 -0000 1.1.1.1
> +++ std_limits.h 15 Mar 2012 10:16:04 -0000
> @@ -137,7 +137,9 @@
> (__glibcxx_signed (T) ? (T)1 << __glibcxx_digits (T) : (T)0)
>
> #define __glibcxx_max(T) \
> - (__glibcxx_signed (T) ? ((T)1 << __glibcxx_digits (T)) - 1 : ~(T)0)
> + (__glibcxx_signed (T) ? \
> + (((((T)1 << (__glibcxx_digits (T) - 1)) - 1) << 1) + 1) : ~(T)0)
> +
>
> #define __glibcxx_digits(T) \
> (sizeof(T) * __CHAR_BIT__ - __glibcxx_signed (T))
> @@ -365,57 +367,6 @@ _GLIBCXX_BEGIN_NAMESPACE(std)
> static const float_round_style round_style = round_toward_zero;
> };
>
> - /// numeric_limits<char> specialization.
> - template<>
> - struct numeric_limits<char>
> - {
> - static const bool is_specialized = true;
> -
> - static char min() throw()
> - { return __glibcxx_min(char); }
> - static char max() throw()
> - { return __glibcxx_max(char); }
> -
> - static const int digits = __glibcxx_digits (char);
> - static const int digits10 = __glibcxx_digits10 (char);
> - static const bool is_signed = __glibcxx_signed (char);
> - static const bool is_integer = true;
> - static const bool is_exact = true;
> - static const int radix = 2;
> - static char epsilon() throw()
> - { return 0; }
> - static char round_error() throw()
> - { return 0; }
> -
> - static const int min_exponent = 0;
> - static const int min_exponent10 = 0;
> - static const int max_exponent = 0;
> - static const int max_exponent10 = 0;
> -
> - static const bool has_infinity = false;
> - static const bool has_quiet_NaN = false;
> - static const bool has_signaling_NaN = false;
> - static const float_denorm_style has_denorm = denorm_absent;
> - static const bool has_denorm_loss = false;
> -
> - static char infinity() throw()
> - { return char(); }
> - static char quiet_NaN() throw()
> - { return char(); }
> - static char signaling_NaN() throw()
> - { return char(); }
> - static char denorm_min() throw()
> - { return static_cast<char>(0); }
> -
> - static const bool is_iec559 = false;
> - static const bool is_bounded = true;
> - static const bool is_modulo = true;
> -
> - static const bool traps = __glibcxx_integral_traps;
> - static const bool tinyness_before = false;
> - static const float_round_style round_style = round_toward_zero;
> - };
> -
> /// numeric_limits<signed char> specialization.
> template<>
> struct numeric_limits<signed char>
> @@ -508,6 +459,61 @@ _GLIBCXX_BEGIN_NAMESPACE(std)
> { return static_cast<unsigned char>(0); }
> static unsigned char denorm_min() throw()
> { return static_cast<unsigned char>(0); }
> +
> + static const bool is_iec559 = false;
> + static const bool is_bounded = true;
> + static const bool is_modulo = true;
> +
> + static const bool traps = __glibcxx_integral_traps;
> + static const bool tinyness_before = false;
> + static const float_round_style round_style = round_toward_zero;
> + };
> +
> + /// numeric_limits<char> specialization.
> + template<>
> + struct numeric_limits<char>
> + {
> + static const bool is_specialized = true;
> +
> + static char min() throw()
> + { return __glibcxx_signed(char) ?
> + numeric_limits<signed char>::min() :
> + numeric_limits<unsigned char>::min(); }
> + static char max() throw()
> + { return __glibcxx_signed(char) ?
> + numeric_limits<signed char>::max() :
> + numeric_limits<unsigned char>::max(); }
> +
> + static const int digits = __glibcxx_digits (char);
> + static const int digits10 = __glibcxx_digits10 (char);
> + static const bool is_signed = __glibcxx_signed (char);
> + static const bool is_integer = true;
> + static const bool is_exact = true;
> + static const int radix = 2;
> + static char epsilon() throw()
> + { return 0; }
> + static char round_error() throw()
> + { return 0; }
> +
> + static const int min_exponent = 0;
> + static const int min_exponent10 = 0;
> + static const int max_exponent = 0;
> + static const int max_exponent10 = 0;
> +
> + static const bool has_infinity = false;
> + static const bool has_quiet_NaN = false;
> + static const bool has_signaling_NaN = false;
> + static const float_denorm_style has_denorm = denorm_absent;
> + static const bool has_denorm_loss = false;
> +
> + static char infinity() throw()
> + { return char(); }
> + static char quiet_NaN() throw()
> + { return char(); }
> + static char signaling_NaN() throw()
> + { return char(); }
> + static char denorm_min() throw()
> + { return static_cast<char>(0); }
>
> static const bool is_iec559 = false;
> static const bool is_bounded = true;
