[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.

llvm-svn: 219998

1 files changed, 24 insertions, 24 deletions

diff --git a/libcxx/include/cmath b/libcxx/include/cmath
index 4719abad3ca..d3aa4beeb58 100644
--- a/libcxx/include/cmath
+++ b/libcxx/include/cmath
@@ -727,11 +727,11 @@ inline _LIBCPP_INLINE_VISIBILITY long double atan2(long double __lcpp_y, long do
 
 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 @@ inline _LIBCPP_INLINE_VISIBILITY long double fmod(long double __lcpp_x, long dou
 
 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 @@ inline _LIBCPP_INLINE_VISIBILITY long double pow(long double __lcpp_x, long doub
 
 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 @@ inline _LIBCPP_INLINE_VISIBILITY long double copysign(long double __lcpp_x, long
 
 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 @@ inline _LIBCPP_INLINE_VISIBILITY long double fdim(long double __lcpp_x, long dou
 
 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 @@ inline _LIBCPP_INLINE_VISIBILITY long double fma(long double __lcpp_x, long doub
 
 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 @@ inline _LIBCPP_INLINE_VISIBILITY long double fmax(long double __lcpp_x, long dou
 
 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 @@ inline _LIBCPP_INLINE_VISIBILITY long double fmin(long double __lcpp_x, long dou
 
 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 @@ inline _LIBCPP_INLINE_VISIBILITY long double hypot(long double __lcpp_x, long do
 
 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 @@ inline _LIBCPP_INLINE_VISIBILITY long double nextafter(long double __lcpp_x, lon
 
 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 @@ inline _LIBCPP_INLINE_VISIBILITY long double remainder(long double __lcpp_x, lon
 
 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 @@ inline _LIBCPP_INLINE_VISIBILITY long double remquo(long double __lcpp_x, long d
 
 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
 {