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[libc++] Constrain additional overloads of pow for complex harder #110235

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Merged
merged 4 commits into from
Oct 29, 2024
Merged

[libc++] Constrain additional overloads of pow for complex harder #110235

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b3c2eea
[libc++] Constrain additional overloads of `pow` for `complex` harder
frederick-vs-ja Sep 27, 2024
84e7c7b
Address @ldionne's review comments
frederick-vs-ja Oct 19, 2024
602372d
Merge branch 'main' into complex-pow-constraints
frederick-vs-ja Oct 19, 2024
f6b91cf
Adopt @ldionne's clarification for comments
frederick-vs-ja Oct 27, 2024
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6 changes: 3 additions & 3 deletions libcxx/include/complex
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Original file line number Diff line number Diff line change
Expand Up @@ -1097,20 +1097,20 @@ inline _LIBCPP_HIDE_FROM_ABI complex<_Tp> pow(const complex<_Tp>& __x, const com
return std::exp(__y * std::log(__x));
}

template <class _Tp, class _Up>
template <class _Tp, class _Up, __enable_if_t<is_floating_point<_Tp>::value && is_floating_point<_Up>::value, int> = 0>
inline _LIBCPP_HIDE_FROM_ABI complex<typename __promote<_Tp, _Up>::type>
pow(const complex<_Tp>& __x, const complex<_Up>& __y) {
typedef complex<typename __promote<_Tp, _Up>::type> result_type;
return std::pow(result_type(__x), result_type(__y));
}

template <class _Tp, class _Up, __enable_if_t<is_arithmetic<_Up>::value, int> = 0>
template <class _Tp, class _Up, __enable_if_t<is_floating_point<_Tp>::value && is_arithmetic<_Up>::value, int> = 0>
inline _LIBCPP_HIDE_FROM_ABI complex<typename __promote<_Tp, _Up>::type> pow(const complex<_Tp>& __x, const _Up& __y) {
typedef complex<typename __promote<_Tp, _Up>::type> result_type;
return std::pow(result_type(__x), result_type(__y));
}

template <class _Tp, class _Up, __enable_if_t<is_arithmetic<_Tp>::value, int> = 0>
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Is there a reason why this isn't an issue for e.g. std::asinh(std::complex<T>) defined below? I'm wary of trying to work around something that is explicitly unspecified in the Standard.

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The original issue seemed caused by recent changes of __promote, and in <complex> only additional overloads of pow use __promote.
#81379 made __promote reject non-arithmetic types in an SFINAE-unfriendly way, and previously __promote accidently accepted some program-defined non-arithmetic types as long as their operator+'s work as expected.

template <class _Tp, class _Up, __enable_if_t<is_arithmetic<_Tp>::value && is_floating_point<_Up>::value, int> = 0>
inline _LIBCPP_HIDE_FROM_ABI complex<typename __promote<_Tp, _Up>::type> pow(const _Tp& __x, const complex<_Up>& __y) {
typedef complex<typename __promote<_Tp, _Up>::type> result_type;
return std::pow(result_type(__x), result_type(__y));
Expand Down
106 changes: 106 additions & 0 deletions libcxx/test/libcxx/numerics/complex.number/cmplx.over.pow.pass.cpp
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@@ -0,0 +1,106 @@
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

// <complex>

// template<class T, class U> complex<__promote<T, U>::type> pow(const complex<T>&, const U&);
// template<class T, class U> complex<__promote<T, U>::type> pow(const complex<T>&, const complex<U>&);
// template<class T, class U> complex<__promote<T, U>::type> pow(const T&, const complex<U>&);

// Test that these additional overloads are free from catching std::complex<non-floating-point>,
// which is expected by several 3rd party libraries, see https://github.com/llvm/llvm-project/issues/109858.

#include <cassert>
#include <cmath>
#include <complex>
#include <type_traits>

#include "test_macros.h"

namespace usr {
struct usr_tag {};

template <class T, class U>
TEST_CONSTEXPR
typename std::enable_if<(std::is_same<T, usr_tag>::value && std::is_floating_point<U>::value) ||
(std::is_floating_point<T>::value && std::is_same<U, usr_tag>::value),
int>::type
pow(const T&, const std::complex<U>&) {
return std::is_same<T, usr_tag>::value ? 0 : 1;
}

template <class T, class U>
TEST_CONSTEXPR
typename std::enable_if<(std::is_same<T, usr_tag>::value && std::is_floating_point<U>::value) ||
(std::is_floating_point<T>::value && std::is_same<U, usr_tag>::value),
int>::type
pow(const std::complex<T>&, const U&) {
return std::is_same<U, usr_tag>::value ? 2 : 3;
}

template <class T, class U>
TEST_CONSTEXPR
typename std::enable_if<(std::is_same<T, usr_tag>::value && std::is_floating_point<U>::value) ||
(std::is_floating_point<T>::value && std::is_same<U, usr_tag>::value),
int>::type
pow(const std::complex<T>&, const std::complex<U>&) {
return std::is_same<T, usr_tag>::value ? 4 : 5;
}
} // namespace usr

int main(int, char**) {
using std::pow;
using usr::pow;

TEST_CONSTEXPR usr::usr_tag tag;
TEST_CONSTEXPR_CXX14 const std::complex<usr::usr_tag> ctag;

assert(pow(tag, std::complex<float>(1.0f)) == 0);
assert(pow(std::complex<float>(1.0f), tag) == 2);
assert(pow(tag, std::complex<double>(1.0)) == 0);
assert(pow(std::complex<double>(1.0), tag) == 2);
assert(pow(tag, std::complex<long double>(1.0l)) == 0);
assert(pow(std::complex<long double>(1.0l), tag) == 2);

assert(pow(1.0f, ctag) == 1);
assert(pow(ctag, 1.0f) == 3);
assert(pow(1.0, ctag) == 1);
assert(pow(ctag, 1.0) == 3);
assert(pow(1.0l, ctag) == 1);
assert(pow(ctag, 1.0l) == 3);

assert(pow(ctag, std::complex<float>(1.0f)) == 4);
assert(pow(std::complex<float>(1.0f), ctag) == 5);
assert(pow(ctag, std::complex<double>(1.0)) == 4);
assert(pow(std::complex<double>(1.0), ctag) == 5);
assert(pow(ctag, std::complex<long double>(1.0l)) == 4);
assert(pow(std::complex<long double>(1.0l), ctag) == 5);

#if TEST_STD_VER >= 11
static_assert(pow(tag, std::complex<float>(1.0f)) == 0, "");
static_assert(pow(std::complex<float>(1.0f), tag) == 2, "");
static_assert(pow(tag, std::complex<double>(1.0)) == 0, "");
static_assert(pow(std::complex<double>(1.0), tag) == 2, "");
static_assert(pow(tag, std::complex<long double>(1.0l)) == 0, "");
static_assert(pow(std::complex<long double>(1.0l), tag) == 2, "");

static_assert(pow(1.0f, ctag) == 1, "");
static_assert(pow(ctag, 1.0f) == 3, "");
static_assert(pow(1.0, ctag) == 1, "");
static_assert(pow(ctag, 1.0) == 3, "");
static_assert(pow(1.0l, ctag) == 1, "");
static_assert(pow(ctag, 1.0l) == 3, "");

static_assert(pow(ctag, std::complex<float>(1.0f)) == 4, "");
static_assert(pow(std::complex<float>(1.0f), ctag) == 5, "");
static_assert(pow(ctag, std::complex<double>(1.0)) == 4, "");
static_assert(pow(std::complex<double>(1.0), ctag) == 5, "");
static_assert(pow(ctag, std::complex<long double>(1.0l)) == 4, "");
static_assert(pow(std::complex<long double>(1.0l), ctag) == 5, "");
#endif
}
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