[libc++] Implement constexpr {isfinite, isinf, isnan, isnormal}

[philnik]

Summary

This starts implementing P0533

[philnik]

Try to fix CI

[philnik]

Next try

[Mordante]

LGTM modulo some nits.

libcxx/docs/Status/Cxx2b.rst

43

I really like this, this makes it easier to keep track regarding what is and what is not done. Thanks!

libcxx/test/std/numerics/c.math/isfinite.pass.cpp

9

Please add a synopsis, the same for the other tests.

20

Please test min and denorm_min too.

[philnik]

• Address comments
• Try to fix CI

[philnik]

Try to fix CI

libcxx/docs/Status/Cxx2b.rst

 .. csv-table::
    :file: Cxx2bPapers.csv
    :header-rows: 1
    :widths: auto
 
 .. note::
 
    .. [#note-P2273] P2273: ``make_unique_for_overwrite`` isn't done yet since `P1020` hasn't been implemented yet.
+   .. [#note-P0533R9] P0533R9: ``isfinite``, ``isinf``, ``isnan`` and ``isnormal`` are implemented.
 
 .. _issues-status-cxx2b:
 
 Library Working Group Issues Status
 ====================================
 
 .. csv-table::
    :file: Cxx2bIssues.csv
    :header-rows: 1
    :widths: auto

libcxx/docs/Status/Cxx2bPapers.csv

 "`P2251R1 <https://wg21.link/P2251R1>`__","LWG","Require ``span`` & ``basic_string_view`` to be Trivially Copyable","October 2021","|Complete|","14.0"
 "`P2301R1 <https://wg21.link/P2301R1>`__","LWG","Add a ``pmr`` alias for ``std::stacktrace``","October 2021","",""
 "`P2321R2 <https://wg21.link/P2321R2>`__","LWG","``zip``","October 2021","|In Progress|","","|ranges|"
 "`P2340R1 <https://wg21.link/P2340R1>`__","LWG","Clarifying the status of the 'C headers'","October 2021","",""
 "`P2393R1 <https://wg21.link/P2393R1>`__","LWG","Cleaning up ``integer``-class types","October 2021","",""
 "`P2401R0 <https://wg21.link/P2401R0>`__","LWG","Add a conditional ``noexcept`` specification to ``std::exchange``","October 2021","|Complete|","14.0"
 "","","","","",""
 "`P0323R12 <https://wg21.link/P0323R12>`__","LWG","``std::expected``","February 2022","|Complete|","16.0"
-"`P0533R9 <https://wg21.link/P0533R9>`__","LWG","``constexpr`` for ``<cmath>`` and ``<cstdlib>``","February 2022","",""
+"`P0533R9 <https://wg21.link/P0533R9>`__","LWG","``constexpr`` for ``<cmath>`` and ``<cstdlib>``","February 2022","|In progress| [#note-P0533R9]_",""
 "`P0627R6 <https://wg21.link/P0627R6>`__","LWG","Function to mark unreachable code","February 2022","|Complete|","15.0"
 "`P1206R7 <https://wg21.link/P1206R7>`__","LWG","``ranges::to``: A function to convert any range to a container","February 2022","","","|ranges|"
 "`P1413R3 <https://wg21.link/P1413R3>`__","LWG","Deprecate ``std::aligned_storage`` and ``std::aligned_union``","February 2022","",""
 "`P2255R2 <https://wg21.link/P2255R2>`__","LWG","A type trait to detect reference binding to temporary","February 2022","",""
 "`P2273R3 <https://wg21.link/P2273R3>`__","LWG","Making ``std::unique_ptr`` constexpr","February 2022","|Partial| [#note-P2273]_","16.0"
 "`P2387R3 <https://wg21.link/P2387R3>`__","LWG","Pipe support for user-defined range adaptors","February 2022","","","|ranges|"
 "`P2440R1 <https://wg21.link/P2440R1>`__","LWG","``ranges::iota``, ``ranges::shift_left`` and ``ranges::shift_right``","February 2022","","","|ranges|"
 "`P2441R2 <https://wg21.link/P2441R2>`__","LWG","``views::join_with``","February 2022","","","|ranges|"

libcxx/include/math.h

 
 // The MSVC runtime already provides these functions as templates
 #ifndef _LIBCPP_MSVCRT
 
 // isfinite
 
 template <class _A1,
           std::__enable_if_t<std::is_arithmetic<_A1>::value && std::numeric_limits<_A1>::has_infinity, int> = 0>
-inline _LIBCPP_HIDE_FROM_ABI bool isfinite(_A1 __x) _NOEXCEPT {
+_LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool isfinite(_A1 __x) _NOEXCEPT {
   return __builtin_isfinite((typename std::__promote<_A1>::type)__x);
 }
 
 template <class _A1,
           std::__enable_if_t<std::is_arithmetic<_A1>::value && !std::numeric_limits<_A1>::has_infinity, int> = 0>
-inline _LIBCPP_HIDE_FROM_ABI bool isfinite(_A1) _NOEXCEPT {
+_LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool isfinite(_A1) _NOEXCEPT {
   return true;
 }
 
 // isinf
 
 template <class _A1,
           std::__enable_if_t<std::is_arithmetic<_A1>::value && std::numeric_limits<_A1>::has_infinity, int> = 0>
-inline _LIBCPP_HIDE_FROM_ABI bool isinf(_A1 __x) _NOEXCEPT {
+_LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool isinf(_A1 __x) _NOEXCEPT {
   return __builtin_isinf((typename std::__promote<_A1>::type)__x);
 }
 
 template <class _A1>
-inline _LIBCPP_HIDE_FROM_ABI
+_LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI
     typename std::enable_if< std::is_arithmetic<_A1>::value && !std::numeric_limits<_A1>::has_infinity, bool>::type
     isinf(_A1) _NOEXCEPT {
   return false;
 }
 
 #      ifdef _LIBCPP_PREFERRED_OVERLOAD
-inline _LIBCPP_HIDE_FROM_ABI bool isinf(float __x) _NOEXCEPT { return __builtin_isinf(__x); }
+inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool isinf(float __x) _NOEXCEPT {
+  return __builtin_isinf(__x);
+}
 
-inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_PREFERRED_OVERLOAD bool isinf(double __x) _NOEXCEPT { return __builtin_isinf(__x); }
+inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI _LIBCPP_PREFERRED_OVERLOAD bool isinf(double __x) _NOEXCEPT {
+  return __builtin_isinf(__x);
+}
 
-inline _LIBCPP_HIDE_FROM_ABI bool isinf(long double __x) _NOEXCEPT { return __builtin_isinf(__x); }
+inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool isinf(long double __x) _NOEXCEPT {
+  return __builtin_isinf(__x);
+}
 #      endif
 
 // isnan
 
 template <class _A1, std::__enable_if_t<std::is_floating_point<_A1>::value, int> = 0>
-inline _LIBCPP_HIDE_FROM_ABI bool isnan(_A1 __x) _NOEXCEPT {
+_LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool isnan(_A1 __x) _NOEXCEPT {
   return __builtin_isnan(__x);
 }
 
 template <class _A1, std::__enable_if_t<std::is_integral<_A1>::value, int> = 0>
-inline _LIBCPP_HIDE_FROM_ABI bool isnan(_A1) _NOEXCEPT {
+_LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool isnan(_A1) _NOEXCEPT {
   return false;
 }
 
 #      ifdef _LIBCPP_PREFERRED_OVERLOAD
-inline _LIBCPP_HIDE_FROM_ABI bool isnan(float __x) _NOEXCEPT { return __builtin_isnan(__x); }
+inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool isnan(float __x) _NOEXCEPT {
+  return __builtin_isnan(__x);
+}
 
-inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_PREFERRED_OVERLOAD bool isnan(double __x) _NOEXCEPT { return __builtin_isnan(__x); }
+inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI _LIBCPP_PREFERRED_OVERLOAD bool isnan(double __x) _NOEXCEPT {
+  return __builtin_isnan(__x);
+}
 
-inline _LIBCPP_HIDE_FROM_ABI bool isnan(long double __x) _NOEXCEPT { return __builtin_isnan(__x); }
+inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool isnan(long double __x) _NOEXCEPT {
+  return __builtin_isnan(__x);
+}
 #      endif
 
 // isnormal
 
 template <class _A1, std::__enable_if_t<std::is_floating_point<_A1>::value, int> = 0>
-inline _LIBCPP_HIDE_FROM_ABI bool isnormal(_A1 __x) _NOEXCEPT {
+_LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool isnormal(_A1 __x) _NOEXCEPT {
   return __builtin_isnormal(__x);
 }
 
 template <class _A1, std::__enable_if_t<std::is_integral<_A1>::value, int> = 0>
-inline _LIBCPP_HIDE_FROM_ABI bool isnormal(_A1 __x) _NOEXCEPT {
+_LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool isnormal(_A1 __x) _NOEXCEPT {
   return __x != 0;
 }
 
 // isgreater
 
 template <class _A1,
           class _A2,
           std::__enable_if_t<std::is_arithmetic<_A1>::value && std::is_arithmetic<_A2>::value, int> = 0>

libcxx/test/libcxx/numerics/c.math/constexpr-cxx2b-clang.pass.cpp

 // of the desired function become constexpr, the programmer switches
 // `ASSERT_NOT_CONSTEXPR_CXX23` to `ASSERT_CONSTEXPR_CXX23` and eventually the
 // paper is implemented in Clang.
 // The test also works as a reference list of unimplemented functions.
 //
 // REQUIRES: clang
 // UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
 
+// We don't control the implementation of these functions on windows
+// UNSUPPORTED: windows
+
 #include <cmath>
 #include <cstdlib>
 #include <cassert>
 
 int main(int, char**) {
   bool ImplementedP0533R9 = true;
 
 #define ASSERT_CONSTEXPR_CXX23(Expr) static_assert(__builtin_constant_p(Expr) && (Expr))
#define ASSERT_NOT_CONSTEXPR_CXX23(Expr)                                                                               \
   ASSERT_NOT_CONSTEXPR_CXX23(std::fma(1.0L, 1.0L, 1.0L) == 2.0L);
   ASSERT_NOT_CONSTEXPR_CXX23(std::fmaf(1.0f, 1.0f, 1.0f) == 2.0f);
   ASSERT_NOT_CONSTEXPR_CXX23(std::fmal(1.0L, 1.0L, 1.0L) == 2.0L);
 
   ASSERT_NOT_CONSTEXPR_CXX23(std::fpclassify(-1.0f) == FP_NORMAL);
   ASSERT_NOT_CONSTEXPR_CXX23(std::fpclassify(-1.0) == FP_NORMAL);
   ASSERT_NOT_CONSTEXPR_CXX23(std::fpclassify(-1.0L) == FP_NORMAL);
 
-  ASSERT_NOT_CONSTEXPR_CXX23(std::isfinite(-1.0f) == 1);
-  ASSERT_NOT_CONSTEXPR_CXX23(std::isfinite(-1.0) == 1);
-  ASSERT_NOT_CONSTEXPR_CXX23(std::isfinite(-1.0L) == 1);
-
-  ASSERT_NOT_CONSTEXPR_CXX23(std::isinf(-1.0f) == 0);
-  ASSERT_NOT_CONSTEXPR_CXX23(std::isinf(-1.0) == 0);
-  ASSERT_NOT_CONSTEXPR_CXX23(std::isinf(-1.0L) == 0);
-
-  ASSERT_NOT_CONSTEXPR_CXX23(std::isnan(-1.0f) == 0);
-  ASSERT_NOT_CONSTEXPR_CXX23(std::isnan(-1.0) == 0);
-  ASSERT_NOT_CONSTEXPR_CXX23(std::isnan(-1.0L) == 0);
-
-  ASSERT_NOT_CONSTEXPR_CXX23(std::isnormal(-1.0f) == 1);
-  ASSERT_NOT_CONSTEXPR_CXX23(std::isnormal(-1.0) == 1);
-  ASSERT_NOT_CONSTEXPR_CXX23(std::isnormal(-1.0L) == 1);
+  ASSERT_CONSTEXPR_CXX23(std::isfinite(-1.0f) == 1);
+  ASSERT_CONSTEXPR_CXX23(std::isfinite(-1.0) == 1);
+  ASSERT_CONSTEXPR_CXX23(std::isfinite(-1.0L) == 1);
+
+  ASSERT_CONSTEXPR_CXX23(std::isinf(-1.0f) == 0);
+  ASSERT_CONSTEXPR_CXX23(std::isinf(-1.0) == 0);
+  ASSERT_CONSTEXPR_CXX23(std::isinf(-1.0L) == 0);
+
+  ASSERT_CONSTEXPR_CXX23(std::isnan(-1.0f) == 0);
+  ASSERT_CONSTEXPR_CXX23(std::isnan(-1.0) == 0);
+  ASSERT_CONSTEXPR_CXX23(std::isnan(-1.0L) == 0);
+
+  ASSERT_CONSTEXPR_CXX23(std::isnormal(-1.0f) == 1);
+  ASSERT_CONSTEXPR_CXX23(std::isnormal(-1.0) == 1);
+  ASSERT_CONSTEXPR_CXX23(std::isnormal(-1.0L) == 1);
 
   ASSERT_NOT_CONSTEXPR_CXX23(std::signbit(-1.0f) == 1);
   ASSERT_NOT_CONSTEXPR_CXX23(std::signbit(-1.0) == 1);
   ASSERT_NOT_CONSTEXPR_CXX23(std::signbit(-1.0L) == 1);
 
   ASSERT_NOT_CONSTEXPR_CXX23(std::isgreater(-1.0f, 0.0f) == 0);
   ASSERT_NOT_CONSTEXPR_CXX23(std::isgreater(-1.0, 0.0) == 0);
   ASSERT_NOT_CONSTEXPR_CXX23(std::isgreater(-1.0L, 0.0L) == 0);

libcxx/test/libcxx/numerics/c.math/constexpr-cxx2b-gcc.pass.cpp

#define ASSERT_NOT_CONSTEXPR_CXX23(Expr)                                                                               \
   ASSERT_NOT_CONSTEXPR_CXX23(std::fma(1.0L, 1.0L, 1.0L) == 2.0L);
   ASSERT_CONSTEXPR_CXX23(std::fmaf(1.0f, 1.0f, 1.0f) == 2.0f);
   ASSERT_CONSTEXPR_CXX23(std::fmal(1.0L, 1.0L, 1.0L) == 2.0L);
 
   ASSERT_NOT_CONSTEXPR_CXX23(std::fpclassify(-1.0f) == FP_NORMAL);
   ASSERT_NOT_CONSTEXPR_CXX23(std::fpclassify(-1.0) == FP_NORMAL);
   ASSERT_NOT_CONSTEXPR_CXX23(std::fpclassify(-1.0L) == FP_NORMAL);
 
-  ASSERT_NOT_CONSTEXPR_CXX23(std::isfinite(-1.0f) == 1);
-  ASSERT_NOT_CONSTEXPR_CXX23(std::isfinite(-1.0) == 1);
-  ASSERT_NOT_CONSTEXPR_CXX23(std::isfinite(-1.0L) == 1);
-
-  ASSERT_NOT_CONSTEXPR_CXX23(std::isinf(-1.0f) == 0);
-  ASSERT_NOT_CONSTEXPR_CXX23(std::isinf(-1.0) == 0);
-  ASSERT_NOT_CONSTEXPR_CXX23(std::isinf(-1.0L) == 0);
-
-  ASSERT_NOT_CONSTEXPR_CXX23(std::isnan(-1.0f) == 0);
-  ASSERT_NOT_CONSTEXPR_CXX23(std::isnan(-1.0) == 0);
-  ASSERT_NOT_CONSTEXPR_CXX23(std::isnan(-1.0L) == 0);
-
-  ASSERT_NOT_CONSTEXPR_CXX23(std::isnormal(-1.0f) == 1);
-  ASSERT_NOT_CONSTEXPR_CXX23(std::isnormal(-1.0) == 1);
-  ASSERT_NOT_CONSTEXPR_CXX23(std::isnormal(-1.0L) == 1);
+  ASSERT_CONSTEXPR_CXX23(std::isfinite(-1.0f) == 1);
+  ASSERT_CONSTEXPR_CXX23(std::isfinite(-1.0) == 1);
+  ASSERT_CONSTEXPR_CXX23(std::isfinite(-1.0L) == 1);
+
+  ASSERT_CONSTEXPR_CXX23(std::isinf(-1.0f) == 0);
+  ASSERT_CONSTEXPR_CXX23(std::isinf(-1.0) == 0);
+  ASSERT_CONSTEXPR_CXX23(std::isinf(-1.0L) == 0);
+
+  ASSERT_CONSTEXPR_CXX23(std::isnan(-1.0f) == 0);
+  ASSERT_CONSTEXPR_CXX23(std::isnan(-1.0) == 0);
+  ASSERT_CONSTEXPR_CXX23(std::isnan(-1.0L) == 0);
+
+  ASSERT_CONSTEXPR_CXX23(std::isnormal(-1.0f) == 1);
+  ASSERT_CONSTEXPR_CXX23(std::isnormal(-1.0) == 1);
+  ASSERT_CONSTEXPR_CXX23(std::isnormal(-1.0L) == 1);
 
   ASSERT_NOT_CONSTEXPR_CXX23(std::signbit(-1.0f) == 1);
   ASSERT_NOT_CONSTEXPR_CXX23(std::signbit(-1.0) == 1);
   ASSERT_NOT_CONSTEXPR_CXX23(std::signbit(-1.0L) == 1);
 
   ASSERT_NOT_CONSTEXPR_CXX23(std::isgreater(-1.0f, 0.0f) == 0);
   ASSERT_NOT_CONSTEXPR_CXX23(std::isgreater(-1.0, 0.0) == 0);
   ASSERT_NOT_CONSTEXPR_CXX23(std::isgreater(-1.0L, 0.0L) == 0);

libcxx/test/std/numerics/c.math/isfinite.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// bool isfinite(floating-point-type x); // constexpr since C++23
+
+// We don't control the implementation on windows
+// UNSUPPORTED: windows
+
+#include <cassert>
+#include <cmath>
+#include <limits>
+
+#include "test_macros.h"
+#include "type_algorithms.h"
+
+struct TestFloat {
+  template <class T>
+  static TEST_CONSTEXPR_CXX23 bool test() {
+    assert(std::isfinite(std::numeric_limits<T>::max()));
+    assert(!std::isfinite(std::numeric_limits<T>::infinity()));
+    assert(std::isfinite(std::numeric_limits<T>::min()));
+    assert(std::isfinite(std::numeric_limits<T>::denorm_min()));
+    assert(std::isfinite(std::numeric_limits<T>::lowest()));
+    assert(!std::isfinite(-std::numeric_limits<T>::infinity()));
+    assert(std::isfinite(T(0)));
+    assert(!std::isfinite(std::numeric_limits<T>::quiet_NaN()));
+    assert(!std::isfinite(std::numeric_limits<T>::signaling_NaN()));
+
+    return true;
+  }
+
+  template <class T>
+  TEST_CONSTEXPR_CXX23 void operator()() {
+    test<T>();
+#if TEST_STD_VER >= 23
+    static_assert(test<T>());
+#endif
+  }
+};
+
+struct TestInt {
+  template <class T>
+  static TEST_CONSTEXPR_CXX23 bool test() {
+    assert(std::isfinite(std::numeric_limits<T>::max()));
+    assert(std::isfinite(std::numeric_limits<T>::lowest()));
+    assert(std::isfinite(T(0)));
+
+    return true;
+  }
+
+  template <class T>
+  TEST_CONSTEXPR_CXX23 void operator()() {
+    test<T>();
+#if TEST_STD_VER >= 23
+    static_assert(test<T>());
+#endif
+  }
+};
+
+int main(int, char**) {
+  meta::for_each(meta::floating_point_types(), TestFloat());
+  meta::for_each(meta::integral_types(), TestInt());
+
+  return 0;
+}

libcxx/test/std/numerics/c.math/isinf.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// bool isfinite(floating-point-type x); // constexpr since C++23
+
+// We don't control the implementation on windows
+// UNSUPPORTED: windows
+
+#include <cassert>
+#include <cmath>
+#include <limits>
+
+#include "test_macros.h"
+#include "type_algorithms.h"
+
+struct TestFloat {
+  template <class T>
+  static TEST_CONSTEXPR_CXX23 bool test() {
+    assert(!std::isinf(std::numeric_limits<T>::max()));
+    assert(std::isinf(std::numeric_limits<T>::infinity()));
+    assert(!std::isinf(std::numeric_limits<T>::min()));
+    assert(!std::isinf(std::numeric_limits<T>::denorm_min()));
+    assert(!std::isinf(std::numeric_limits<T>::lowest()));
+    assert(std::isinf(-std::numeric_limits<T>::infinity()));
+    assert(!std::isinf(T(0)));
+    assert(!std::isinf(std::numeric_limits<T>::quiet_NaN()));
+    assert(!std::isinf(std::numeric_limits<T>::signaling_NaN()));
+
+    return true;
+  }
+
+  template <class T>
+  TEST_CONSTEXPR_CXX23 void operator()() {
+    test<T>();
+#if TEST_STD_VER >= 23
+    static_assert(test<T>());
+#endif
+  }
+};
+
+struct TestInt {
+  template <class T>
+  static TEST_CONSTEXPR_CXX23 bool test() {
+    assert(!std::isinf(std::numeric_limits<T>::max()));
+    assert(!std::isinf(std::numeric_limits<T>::lowest()));
+    assert(!std::isinf(T(0)));
+
+    return true;
+  }
+
+  template <class T>
+  TEST_CONSTEXPR_CXX23 void operator()() {
+    test<T>();
+#if TEST_STD_VER >= 23
+    static_assert(test<T>());
+#endif
+  }
+};
+
+int main(int, char**) {
+  meta::for_each(meta::floating_point_types(), TestFloat());
+  meta::for_each(meta::integral_types(), TestInt());
+
+  return 0;
+}

libcxx/test/std/numerics/c.math/isnan.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// bool isfinite(floating-point-type x); // constexpr since C++23
+
+// We don't control the implementation on windows
+// UNSUPPORTED: windows
+
+#include <cassert>
+#include <cmath>
+#include <limits>
+
+#include "test_macros.h"
+#include "type_algorithms.h"
+
+struct TestFloat {
+  template <class T>
+  static TEST_CONSTEXPR_CXX23 bool test() {
+    assert(!std::isnan(std::numeric_limits<T>::max()));
+    assert(!std::isnan(std::numeric_limits<T>::infinity()));
+    assert(!std::isnan(std::numeric_limits<T>::min()));
+    assert(!std::isnan(std::numeric_limits<T>::denorm_min()));
+    assert(!std::isnan(std::numeric_limits<T>::lowest()));
+    assert(!std::isnan(-std::numeric_limits<T>::infinity()));
+    assert(!std::isnan(T(0)));
+    assert(std::isnan(std::numeric_limits<T>::quiet_NaN()));
+    assert(std::isnan(std::numeric_limits<T>::signaling_NaN()));
+
+    return true;
+  }
+
+  template <class T>
+  TEST_CONSTEXPR_CXX23 void operator()() {
+    test<T>();
+#if TEST_STD_VER >= 23
+    static_assert(test<T>());
+#endif
+  }
+};
+
+struct TestInt {
+  template <class T>
+  static TEST_CONSTEXPR_CXX23 bool test() {
+    assert(!std::isnan(std::numeric_limits<T>::max()));
+    assert(!std::isnan(std::numeric_limits<T>::lowest()));
+    assert(!std::isnan(T(0)));
+
+    return true;
+  }
+
+  template <class T>
+  TEST_CONSTEXPR_CXX23 void operator()() {
+    test<T>();
+#if TEST_STD_VER >= 23
+    static_assert(test<T>());
+#endif
+  }
+};
+
+int main(int, char**) {
+  meta::for_each(meta::floating_point_types(), TestFloat());
+  meta::for_each(meta::integral_types(), TestInt());
+
+  return 0;
+}

libcxx/test/std/numerics/c.math/isnormal.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// bool isfinite(floating-point-type x); // constexpr since C++23
+
+// We don't control the implementation on windows
+// UNSUPPORTED: windows
+
+#include <cassert>
+#include <cmath>
+#include <limits>
+
+#include "test_macros.h"
+#include "type_algorithms.h"
+
+struct TestFloat {
+  template <class T>
+  static TEST_CONSTEXPR_CXX23 bool test() {
+    assert(std::isnormal(std::numeric_limits<T>::max()));
+    assert(!std::isnormal(std::numeric_limits<T>::infinity()));
+    assert(std::isnormal(std::numeric_limits<T>::min()));
+    assert(!std::isnormal(std::numeric_limits<T>::denorm_min()));
+    assert(std::isnormal(std::numeric_limits<T>::lowest()));
+    assert(!std::isnormal(-std::numeric_limits<T>::infinity()));
+    assert(!std::isnormal(T(0)));
+    assert(!std::isnormal(std::numeric_limits<T>::quiet_NaN()));
+    assert(!std::isnormal(std::numeric_limits<T>::signaling_NaN()));
+
+    return true;
+  }
+
+  template <class T>
+  TEST_CONSTEXPR_CXX23 void operator()() {
+    test<T>();
+#if TEST_STD_VER >= 23
+    static_assert(test<T>());
+#endif
+  }
+};
+
+struct TestInt {
+  template <class T>
+  static TEST_CONSTEXPR_CXX23 bool test() {
+    assert(std::isnormal(std::numeric_limits<T>::max()));
+    assert(std::isnormal(std::numeric_limits<T>::lowest()) == std::is_signed<T>::value);
+    assert(!std::isnormal(T(0)));
+
+    return true;
+  }
+
+  template <class T>
+  TEST_CONSTEXPR_CXX23 void operator()() {
+    test<T>();
+#if TEST_STD_VER >= 23
+    static_assert(test<T>());
+#endif
+  }
+};
+
+int main(int, char**) {
+  meta::for_each(meta::floating_point_types(), TestFloat());
+  meta::for_each(meta::integral_types(), TestInt());
+
+  return 0;
+}