<complex>: Fix the pow(complex, arithmetic) overload set (#1299)

Co-authored-by: Stephan T. Lavavej <stl@microsoft.com>

stl/inc/complex

@@ -1853,65 +1853,22 @@ _NODISCARD complex<_Upgrade_to_double<_Ty>> proj(_Ty _Left) {
 // FUNCTION TEMPLATE pow
 template <class _Ty1, class _Ty2>
 _NODISCARD complex<_Common_float_type_t<_Ty1, _Ty2>> pow(const complex<_Ty1>& _Left, const complex<_Ty2>& _Right) {
-    using type = complex<_Common_float_type_t<_Ty1, _Ty2>>;
-    return _STD pow(type(_Left), type(_Right));
+    using _Type = complex<_Common_float_type_t<_Ty1, _Ty2>>;
+    return _STD pow(_Type(_Left), _Type(_Right));
 }
 
-template <class _Ty1, class _Ty2, enable_if_t<!is_integral_v<_Ty2>, int> = 0>
+template <class _Ty1, class _Ty2, enable_if_t<is_arithmetic_v<_Ty2>, int> = 0>
 _NODISCARD complex<_Common_float_type_t<_Ty1, _Ty2>> pow(const complex<_Ty1>& _Left, const _Ty2& _Right) {
-    using type = complex<_Common_float_type_t<_Ty1, _Ty2>>;
-    return _STD pow(type(_Left), type(_Right));
+    using _Promoted = _Common_float_type_t<_Ty1, _Ty2>;
+    using _Type     = complex<_Promoted>;
+    return _STD pow(_Type(_Left), _Type(static_cast<_Promoted>(_Right)));
 }
 
-template <class _Ty1, class _Ty2, enable_if_t<!is_integral_v<_Ty1> && is_integral_v<_Ty2>, int> = 0>
-_NODISCARD complex<_Common_float_type_t<_Ty1, _Ty2>> pow(const complex<_Ty1>& _Left, const _Ty2 _Right) {
-    using type = complex<_Common_float_type_t<_Ty1, _Ty2>>;
-
-    type _Tmp   = _Left;
-    auto _Count = static_cast<make_unsigned_t<_Ty2>>(_Right);
-
-    if (_Right < 0) {
-        _Count = 0 - _Count; // safe negation as unsigned
-    }
-
-    for (type _Zv(1);; _Tmp *= _Tmp) { // fold in _Left ^ (2 ^ _Count) as needed
-        if ((_Count & 1) != 0) {
-            _Zv *= _Tmp;
-        }
-
-        if ((_Count >>= 1) == 0) {
-            return _Right < 0 ? type(1) / _Zv : _Zv;
-        }
-    }
-}
-
-template <class _Ty1, class _Ty2, enable_if_t<is_integral_v<_Ty1> && is_integral_v<_Ty2>, int> = 0>
-_NODISCARD complex<_Ty1> pow(const complex<_Ty1>& _Left, _Ty2 _Right) {
-    // raise Gaussian integer to an integer power
-    using type = complex<_Ty1>;
-
-    type _Ans = type(1, 0);
-
-    if (_Right < 0) {
-        _Ans = type(0, 0); // ignore 1/type(0, 0) error
-    } else if (0 < _Right) { // raise to a positive power
-        for (type _Factor = _Left;; _Factor *= _Factor) { // fold in _Left^(2^N))
-            if ((_Right & 1) != 0) {
-                _Ans *= _Factor;
-            }
-
-            if ((_Right >>= 1) == 0) {
-                break;
-            }
-        }
-    }
-    return _Ans;
-}
-
-template <class _Ty1, class _Ty2>
+template <class _Ty1, class _Ty2, enable_if_t<is_arithmetic_v<_Ty1>, int> = 0>
 _NODISCARD complex<_Common_float_type_t<_Ty1, _Ty2>> pow(const _Ty1& _Left, const complex<_Ty2>& _Right) {
-    using type = complex<_Common_float_type_t<_Ty1, _Ty2>>;
-    return _STD pow(type(_Left), type(_Right));
+    using _Promoted = _Common_float_type_t<_Ty1, _Ty2>;
+    using _Type     = complex<_Promoted>;
+    return _STD pow(_Type(static_cast<_Promoted>(_Left)), _Type(_Right));
 }
 
 // FUNCTION TEMPLATE operator>>

tests/libcxx/expected_results.txt

@@ -530,9 +530,6 @@ std/input.output/file.streams/fstreams/filebuf.virtuals/underflow.pass.cpp FAIL
 # GH-1004 <regex>: Error C2664 in std::regex_traits::transform
 std/re/re.traits/transform.pass.cpp FAIL
 
-# GH-1260 <complex>: pow, incorrect type conversion
-std/numerics/complex.number/cmplx.over/pow.pass.cpp FAIL
-
 # GH-1295 <array>: array<const T, 0> allows fill() and swap()
 std/containers/sequences/array/array.fill/fill.fail.cpp FAIL
 std/containers/sequences/array/array.swap/swap.fail.cpp FAIL
@@ -752,6 +749,7 @@ std/iterators/predef.iterators/insert.iterators/insert.iterator/types.pass.cpp F
 
 # Tests emit warning C4244: 'argument': conversion from 'T' to 'const std::complex<double>::_Ty', possible loss of data
 std/numerics/complex.number/cmplx.over/conj.pass.cpp:0 FAIL
+std/numerics/complex.number/cmplx.over/pow.pass.cpp:0 FAIL
 std/numerics/complex.number/cmplx.over/proj.pass.cpp:0 FAIL
 
 # Assertion failed: std::abs(skew - x_skew) < 0.01

tests/libcxx/skipped_tests.txt

@@ -530,9 +530,6 @@ input.output\file.streams\fstreams\filebuf.virtuals\underflow.pass.cpp
 # GH-1004 <regex>: Error C2664 in std::regex_traits::transform
 re\re.traits\transform.pass.cpp
 
-# GH-1260 <complex>: pow, incorrect type conversion
-numerics\complex.number\cmplx.over\pow.pass.cpp
-
 # GH-1295 <array>: array<const T, 0> allows fill() and swap()
 containers\sequences\array\array.fill\fill.fail.cpp
 containers\sequences\array\array.swap\swap.fail.cpp
@@ -752,6 +749,7 @@ iterators\predef.iterators\insert.iterators\insert.iterator\types.pass.cpp
 
 # Tests emit warning C4244: 'argument': conversion from 'T' to 'const std::complex<double>::_Ty', possible loss of data
 numerics\complex.number\cmplx.over\conj.pass.cpp
+numerics\complex.number\cmplx.over\pow.pass.cpp
 numerics\complex.number\cmplx.over\proj.pass.cpp
 
 # Assertion failed: std::abs(skew - x_skew) < 0.01