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a fix for "unsigned type always passes this test" warnings under GCC.

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[SVN r7999]
This commit is contained in:
Dave Abrahams
2000-10-18 13:52:09 +00:00
parent 15539c72c8
commit 906d09b511
1 changed files with 24 additions and 6 deletions
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30
include/boost/cast.hpp
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@@ -166,26 +166,44 @@ namespace boost
// between signed and unsigned values.
//
// "poor man's partial specialization" is in use here.
template <bool same_sign>
template <bool same_sign, bool x_is_signed>
struct greater_than_type_max;
template<>
struct greater_than_type_max<true>
struct greater_than_type_max<true, true>
{
template <class X, class Y>
static bool check(X x, Y y_max)
static inline bool check(X x, Y y_max)
{ return x > y_max; }
};
template <>
struct greater_than_type_max<false>
struct greater_than_type_max<false, true>
{
// What does the standard say about this? I think it's right, and it
// will work with every compiler I know of.
template <class X, class Y>
static bool check(X x, Y)
static inline bool check(X x, Y)
{ return x >= 0 && static_cast<X>(static_cast<Y>(x)) != x; }
};
template<>
struct greater_than_type_max<true, false>
{
template <class X, class Y>
static inline bool check(X x, Y y_max)
{ return x > y_max; }
};
template <>
struct greater_than_type_max<false, false>
{
// What does the standard say about this? I think it's right, and it
// will work with every compiler I know of.
template <class X, class Y>
static inline bool check(X x, Y)
{ return static_cast<X>(static_cast<Y>(x)) != x; }
};
#endif
template<typename Target, typename Source>
@@ -207,7 +225,7 @@ namespace boost
const bool same_sign = arg_is_signed == result_is_signed;
if (less_than_type_min<arg_is_signed, result_is_signed>::check(arg, result_traits::min())
|| greater_than_type_max<same_sign>::check(arg, result_traits::max())
|| greater_than_type_max<same_sign, arg_is_signed>::check(arg, result_traits::max())
)
#else // We need to use #pragma hacks if available