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[libcxx] Fix SFINAE in <cmath>. Patch from K-Ballo.

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Delay instantiation of `__numeric_type` within <cmath>, 
don't instantiate it when the `is_arithmetic` conditions do not hold as it causes
errors with user-defined types with ambiguous conversions. Fixes PR21083.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@219998 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Eric Fiselier
2014-10-17 00:31:47 +00:00
parent 66d529f0ad
commit 950ee77d24
3 changed files with 183 additions and 34 deletions
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26
include/type_traits
View File

@@ -218,6 +218,9 @@ template <class _If, class _Then>
template <bool _Bp, class _If, class _Then> using conditional_t = typename conditional<_Bp, _If, _Then>::type;
#endif
template <bool, class _Tp> struct _LIBCPP_TYPE_VIS_ONLY __lazy_enable_if {};
template <class _Tp> struct _LIBCPP_TYPE_VIS_ONLY __lazy_enable_if<true, _Tp> {typedef typename _Tp::type type;};
template <bool, class _Tp = void> struct _LIBCPP_TYPE_VIS_ONLY enable_if {};
template <class _Tp> struct _LIBCPP_TYPE_VIS_ONLY enable_if<true, _Tp> {typedef _Tp type;};
@@ -1208,43 +1211,46 @@ template <class _A1, class _A2 = void, class _A3 = void,
bool = __numeric_type<_A1>::value &&
__numeric_type<_A2>::value &&
__numeric_type<_A3>::value>
class __promote
class __promote_imp
{
public:
static const bool value = false;
};
template <class _A1, class _A2, class _A3>
class __promote<_A1, _A2, _A3, true>
class __promote_imp<_A1, _A2, _A3, true>
{
private:
typedef typename __promote<_A1>::type __type1;
typedef typename __promote<_A2>::type __type2;
typedef typename __promote<_A3>::type __type3;
typedef typename __promote_imp<_A1>::type __type1;
typedef typename __promote_imp<_A2>::type __type2;
typedef typename __promote_imp<_A3>::type __type3;
public:
typedef decltype(__type1() + __type2() + __type3()) type;
static const bool value = true;
};
template <class _A1, class _A2>
class __promote<_A1, _A2, void, true>
class __promote_imp<_A1, _A2, void, true>
{
private:
typedef typename __promote<_A1>::type __type1;
typedef typename __promote<_A2>::type __type2;
typedef typename __promote_imp<_A1>::type __type1;
typedef typename __promote_imp<_A2>::type __type2;
public:
typedef decltype(__type1() + __type2()) type;
static const bool value = true;
};
template <class _A1>
class __promote<_A1, void, void, true>
class __promote_imp<_A1, void, void, true>
{
public:
typedef typename __numeric_type<_A1>::type type;
static const bool value = true;
static const bool __does_not_throw = _NOEXCEPT_OR_FALSE(static_cast<type>(declval<_A1>()));
};
template <class _A1, class _A2 = void, class _A3 = void>
class __promote : public __promote_imp<_A1, _A2, _A3> {};
#ifdef _LIBCPP_STORE_AS_OPTIMIZATION
// __transform