[libcxx] Fix SFINAE in <cmath>. Patch from K-Ballo.
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
diff --git a/include/cmath b/include/cmath
index 4719aba..d3aa4be 100644
--- a/include/cmath
+++ b/include/cmath
@@ -727,11 +727,11 @@
template <class _A1, class _A2>
inline _LIBCPP_INLINE_VISIBILITY
-typename enable_if
+typename __lazy_enable_if
<
is_arithmetic<_A1>::value &&
is_arithmetic<_A2>::value,
- typename __promote<_A1, _A2>::type
+ __promote<_A1, _A2>
>::type
atan2(_A1 __lcpp_y, _A2 __lcpp_x) _NOEXCEPT
{
@@ -849,11 +849,11 @@
template <class _A1, class _A2>
inline _LIBCPP_INLINE_VISIBILITY
-typename enable_if
+typename __lazy_enable_if
<
is_arithmetic<_A1>::value &&
is_arithmetic<_A2>::value,
- typename __promote<_A1, _A2>::type
+ __promote<_A1, _A2>
>::type
fmod(_A1 __lcpp_x, _A2 __lcpp_y) _NOEXCEPT
{
@@ -952,11 +952,11 @@
template <class _A1, class _A2>
inline _LIBCPP_INLINE_VISIBILITY
-typename enable_if
+typename __lazy_enable_if
<
is_arithmetic<_A1>::value &&
is_arithmetic<_A2>::value,
- typename __promote<_A1, _A2>::type
+ __promote<_A1, _A2>
>::type
pow(_A1 __lcpp_x, _A2 __lcpp_y) _NOEXCEPT
{
@@ -1114,11 +1114,11 @@
template <class _A1, class _A2>
inline _LIBCPP_INLINE_VISIBILITY
-typename enable_if
+typename __lazy_enable_if
<
is_arithmetic<_A1>::value &&
is_arithmetic<_A2>::value,
- typename __promote<_A1, _A2>::type
+ __promote<_A1, _A2>
>::type
copysign(_A1 __lcpp_x, _A2 __lcpp_y) _NOEXCEPT
{
@@ -1192,11 +1192,11 @@
template <class _A1, class _A2>
inline _LIBCPP_INLINE_VISIBILITY
-typename enable_if
+typename __lazy_enable_if
<
is_arithmetic<_A1>::value &&
is_arithmetic<_A2>::value,
- typename __promote<_A1, _A2>::type
+ __promote<_A1, _A2>
>::type
fdim(_A1 __lcpp_x, _A2 __lcpp_y) _NOEXCEPT
{
@@ -1216,12 +1216,12 @@
template <class _A1, class _A2, class _A3>
inline _LIBCPP_INLINE_VISIBILITY
-typename enable_if
+typename __lazy_enable_if
<
is_arithmetic<_A1>::value &&
is_arithmetic<_A2>::value &&
is_arithmetic<_A3>::value,
- typename __promote<_A1, _A2, _A3>::type
+ __promote<_A1, _A2, _A3>
>::type
fma(_A1 __lcpp_x, _A2 __lcpp_y, _A3 __lcpp_z) _NOEXCEPT
{
@@ -1242,11 +1242,11 @@
template <class _A1, class _A2>
inline _LIBCPP_INLINE_VISIBILITY
-typename enable_if
+typename __lazy_enable_if
<
is_arithmetic<_A1>::value &&
is_arithmetic<_A2>::value,
- typename __promote<_A1, _A2>::type
+ __promote<_A1, _A2>
>::type
fmax(_A1 __lcpp_x, _A2 __lcpp_y) _NOEXCEPT
{
@@ -1266,11 +1266,11 @@
template <class _A1, class _A2>
inline _LIBCPP_INLINE_VISIBILITY
-typename enable_if
+typename __lazy_enable_if
<
is_arithmetic<_A1>::value &&
is_arithmetic<_A2>::value,
- typename __promote<_A1, _A2>::type
+ __promote<_A1, _A2>
>::type
fmin(_A1 __lcpp_x, _A2 __lcpp_y) _NOEXCEPT
{
@@ -1290,11 +1290,11 @@
template <class _A1, class _A2>
inline _LIBCPP_INLINE_VISIBILITY
-typename enable_if
+typename __lazy_enable_if
<
is_arithmetic<_A1>::value &&
is_arithmetic<_A2>::value,
- typename __promote<_A1, _A2>::type
+ __promote<_A1, _A2>
>::type
hypot(_A1 __lcpp_x, _A2 __lcpp_y) _NOEXCEPT
{
@@ -1459,11 +1459,11 @@
template <class _A1, class _A2>
inline _LIBCPP_INLINE_VISIBILITY
-typename enable_if
+typename __lazy_enable_if
<
is_arithmetic<_A1>::value &&
is_arithmetic<_A2>::value,
- typename __promote<_A1, _A2>::type
+ __promote<_A1, _A2>
>::type
nextafter(_A1 __lcpp_x, _A2 __lcpp_y) _NOEXCEPT
{
@@ -1496,11 +1496,11 @@
template <class _A1, class _A2>
inline _LIBCPP_INLINE_VISIBILITY
-typename enable_if
+typename __lazy_enable_if
<
is_arithmetic<_A1>::value &&
is_arithmetic<_A2>::value,
- typename __promote<_A1, _A2>::type
+ __promote<_A1, _A2>
>::type
remainder(_A1 __lcpp_x, _A2 __lcpp_y) _NOEXCEPT
{
@@ -1520,11 +1520,11 @@
template <class _A1, class _A2>
inline _LIBCPP_INLINE_VISIBILITY
-typename enable_if
+typename __lazy_enable_if
<
is_arithmetic<_A1>::value &&
is_arithmetic<_A2>::value,
- typename __promote<_A1, _A2>::type
+ __promote<_A1, _A2>
>::type
remquo(_A1 __lcpp_x, _A2 __lcpp_y, int* __lcpp_z) _NOEXCEPT
{
diff --git a/include/type_traits b/include/type_traits
index 5d21728..99cc7e1 100644
--- a/include/type_traits
+++ b/include/type_traits
@@ -218,6 +218,9 @@
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 @@
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