[libc++] Constrain additional overloads of pow for complex harder
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@llvm/pr-subscribers-libcxx Author: A. Jiang (frederick-vs-ja) ChangesFixes #109858. The changes in #81379 broke some 3rd party library code that expected usability of Full diff: https://github.com/llvm/llvm-project/pull/110235.diff 2 Files Affected:
diff --git a/libcxx/include/complex b/libcxx/include/complex
index 4030d96b003d56..15e42800fbfa0a 100644
--- a/libcxx/include/complex
+++ b/libcxx/include/complex
@@ -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>
+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));
diff --git a/libcxx/test/libcxx/numerics/complex.number/cmplx.over.pow.pass.cpp b/libcxx/test/libcxx/numerics/complex.number/cmplx.over.pow.pass.cpp
new file mode 100644
index 00000000000000..64e679fed7435c
--- /dev/null
+++ b/libcxx/test/libcxx/numerics/complex.number/cmplx.over.pow.pass.cpp
@@ -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
+}
|
ldionne
reviewed
Oct 1, 2024
| 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.
ldionne
reviewed
Oct 15, 2024
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I am really ambivalent about this change. On the one hand it's a small change and it avoids an immediate breakage in the wild. On the other hand, it also seems to promise something that I'm not certain we want to (or will be able to) promise in the future, i.e. that libc++ std::complex works with non standard floating point types.
@philnik777 I'd like to have your opinion on this.
Comment on lines
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| #endif | ||
| } |
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Suggested change
| #endif | |
| } | |
| #endif | |
| return 0; | |
| } |
For -ffreestanding.
| struct usr_tag {}; | ||
|
|
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| template <class T, class U> | ||
| TEST_CONSTEXPR |
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constexpr here doesn't really buy you anything in the test. I'd suggest either dropping TEST_CONSTEXPR here or running the test both in constexpr and non-constexpr context (which doesn't seem to add much value).
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Fixes #109858.
The changes in #81379 broke some 3rd party library code that expected usability of
std::complex<NonFloatingPoint>. Although such code isn't portable per [complex.numbers.general]/2, it might be better to make these additional overloads not to interfere overload resolution too much.