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Fix more constexpr

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This commit is contained in:
Krystian Stasiowski
2020-02-02 11:43:17 -05:00
parent 00d6d174fb
commit 497c84b5a1
2 changed files with 22 additions and 13 deletions
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24
include/boost/static_string/static_string.hpp
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@ -596,8 +596,9 @@ find_first_of(
return last;
}
// Check if a pointer lies within a range (inclusive) without unspecified behavior,
// allowing it to be used in a constant evaluation
// Check if a pointer lies within the range [src_first, src_last)
// without unspecified behavior, allowing it to be used
// in a constant evaluation.
template<typename T>
BOOST_STATIC_STRING_CPP14_CONSTEXPR
inline
@ -615,7 +616,7 @@ is_inside(
// no applications in constant expressions.
#ifdef BOOST_STATIC_STRING_CPP14
#ifdef BOOST_STATIC_STRING_NO_PTR_COMP_FUNCTIONS
#ifdef BOOST_STATIC_STRING_USE_IS_CONST_EVAL
#ifdef BOOST_STATIC_STRING_IS_CONST_EVAL
// Our second best option is to use is_constant_evaluated
// and a loop that checks for equality, since equality for
// pointer to object types is never unspecified in this case.
@ -626,18 +627,27 @@ is_inside(
return true;
return false;
}
#elif defined(__clang__) && __has_builtin(__builtin_constant_p)
// We can also try using __builtin_constant_p
if (__builtin_constant_p((ptr, src_first, src_last)))
{
for (; src_first != src_last; ++src_first)
if (src_first == ptr)
return true;
return false;
}
#else
// If library comparison functions don't work, and
// we cannot use is_constant_evaluated, we can use
// the builtin comparison operators instead.
return ptr >= src_first && ptr <= src_last;
// we cannot use any of the above, we can use
// try builtin comparison operators instead.
return ptr >= src_first && ptr < src_last;
#endif
#endif
#endif
// Use the library comparison functions if we can't use
// is_constant_evaluated or if we don't need to.
return std::greater_equal<const T*>()(ptr, src_first) &&
std::less_equal<const T*>()(ptr, src_last);
std::less<const T*>()(ptr, src_last);
}
} // detail
#endif