[libcxx-commits] [libcxx] [libc++][numeric] Refactor `std::midpoint` tests (PR #175531)

via libcxx-commits libcxx-commits at lists.llvm.org
Mon Jan 12 04:45:02 PST 2026


llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-libcxx

Author: eiytoq (eiytoq)

<details>
<summary>Changes</summary>

Extracted NFC changes from PR #<!-- -->175388.

---

Patch is 22.57 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/175531.diff


3 Files Affected:

- (modified) libcxx/test/std/numerics/numeric.ops/numeric.ops.midpoint/midpoint.float.pass.cpp (+134-104) 
- (modified) libcxx/test/std/numerics/numeric.ops/numeric.ops.midpoint/midpoint.integer.pass.cpp (+94-120) 
- (modified) libcxx/test/std/numerics/numeric.ops/numeric.ops.midpoint/midpoint.pointer.pass.cpp (+40-66) 


``````````diff
diff --git a/libcxx/test/std/numerics/numeric.ops/numeric.ops.midpoint/midpoint.float.pass.cpp b/libcxx/test/std/numerics/numeric.ops/numeric.ops.midpoint/midpoint.float.pass.cpp
index 0d28cff511dee..1332d714eb8b6 100644
--- a/libcxx/test/std/numerics/numeric.ops/numeric.ops.midpoint/midpoint.float.pass.cpp
+++ b/libcxx/test/std/numerics/numeric.ops/numeric.ops.midpoint/midpoint.float.pass.cpp
@@ -5,131 +5,161 @@
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
-//
-// UNSUPPORTED: c++03, c++11, c++14, c++17
+
+// REQUIRES: std-at-least-c++20
 
 // <numeric>
 
-// template <class _Float>
-// _Tp midpoint(_Float __a, _Float __b) noexcept
-//
+// template <class _Fp>
+// _Fp midpoint(_Fp __a, _Fp __b) noexcept
 
+#include <cassert>
+#include <cmath>
+#include <concepts>
 #include <limits>
 #include <numeric>
-#include <cassert>
 
 #include "test_macros.h"
 #include "fp_compare.h"
 
-//  Totally arbitrary picks for precision
 template <typename T>
-constexpr T fp_error_pct();
-
-template <>
-constexpr float fp_error_pct<float>() { return 1.0e-4f; }
-
-template <>
-constexpr double fp_error_pct<double>() { return 1.0e-12; }
+constexpr bool is_nan(T x) {
+  return x != x;
+}
 
-template <>
-constexpr long double fp_error_pct<long double>() { return 1.0e-13l; }
+template <typename T>
+constexpr T get_error_pct() {
+  if constexpr (std::same_as<T, float>)
+    return 1.0e-4f;
+  else if constexpr (std::same_as<T, double>)
+    return 1.0e-12;
+  else
+    return 1.0e-13l;
+}
 
+template <typename T>
+constexpr bool check_near(T a, T b, T expect) {
+  if (std::is_constant_evaluated())
+    return true;
+  return fptest_close_pct(std::midpoint(a, b), expect, get_error_pct<T>());
+}
 
 template <typename T>
-void fp_test()
-{
-    ASSERT_SAME_TYPE(T, decltype(std::midpoint(T(), T())));
-    ASSERT_NOEXCEPT(             std::midpoint(T(), T()));
-
-    constexpr T maxV = std::numeric_limits<T>::max();
-    constexpr T minV = std::numeric_limits<T>::min();
-
-//  Things that can be compared exactly
-    static_assert((std::midpoint(T(0), T(0))   == T(0)),   "");
-    static_assert((std::midpoint(T(2), T(4))   == T(3)),   "");
-    static_assert((std::midpoint(T(4), T(2))   == T(3)),   "");
-    static_assert((std::midpoint(T(3), T(4))   == T(3.5)), "");
-    static_assert((std::midpoint(T(0), T(0.4)) == T(0.2)), "");
-
-//  Things that can't be compared exactly
-    constexpr T pct = fp_error_pct<T>();
-    assert((fptest_close_pct(std::midpoint(T( 1.3), T(11.4)), T( 6.35),    pct)));
-    assert((fptest_close_pct(std::midpoint(T(11.33), T(31.45)), T(21.39),  pct)));
-    assert((fptest_close_pct(std::midpoint(T(-1.3), T(11.4)), T( 5.05),    pct)));
-    assert((fptest_close_pct(std::midpoint(T(11.4), T(-1.3)), T( 5.05),    pct)));
-    assert((fptest_close_pct(std::midpoint(T(0.1),  T(0.4)),  T(0.25),     pct)));
-
-    assert((fptest_close_pct(std::midpoint(T(11.2345), T(14.5432)), T(12.88885),  pct)));
-
-//  From e to pi
-    assert((fptest_close_pct(std::midpoint(T(2.71828182845904523536028747135266249775724709369995),
-                                      T(3.14159265358979323846264338327950288419716939937510)),
-                                      T(2.92993724102441923691146542731608269097720824653752),  pct)));
-
-    assert((fptest_close_pct(std::midpoint(maxV, T(0)), maxV/2, pct)));
-    assert((fptest_close_pct(std::midpoint(T(0), maxV), maxV/2, pct)));
-    assert((fptest_close_pct(std::midpoint(minV, T(0)), minV/2, pct)));
-    assert((fptest_close_pct(std::midpoint(T(0), minV), minV/2, pct)));
-    assert((fptest_close_pct(std::midpoint(maxV, maxV), maxV,   pct)));
-    assert((fptest_close_pct(std::midpoint(minV, minV), minV,   pct)));
-    assert((fptest_close_pct(std::midpoint(maxV, minV), maxV/2, pct)));
-    assert((fptest_close_pct(std::midpoint(minV, maxV), maxV/2, pct)));
-
-//  Near the min and the max
-    assert((fptest_close_pct(std::midpoint(maxV*T(0.75), maxV*T(0.50)),  maxV*T(0.625), pct)));
-    assert((fptest_close_pct(std::midpoint(maxV*T(0.50), maxV*T(0.75)),  maxV*T(0.625), pct)));
-    assert((fptest_close_pct(std::midpoint(minV*T(2),    minV*T(8)),     minV*T(5),     pct)));
-
-//  Big numbers of different signs
-    assert((fptest_close_pct(std::midpoint(maxV*T( 0.75),  maxV*T(-0.5)), maxV*T( 0.125), pct)));
-    assert((fptest_close_pct(std::midpoint(maxV*T(-0.75),  maxV*T( 0.5)), maxV*T(-0.125), pct)));
-
-//  Denormalized values
-//  TODO
-
-//  Check two values "close to each other"
-    T d1 = T(3.14);
-    T d0 = std::nextafter(d1, T(2));
-    T d2 = std::nextafter(d1, T(5));
-    assert(d0 < d1);  // sanity checking
-    assert(d1 < d2);  // sanity checking
+constexpr bool check_exact(T a, T b, T expect) {
+  T res = std::midpoint(a, b);
+  if (is_nan(expect)) {
+    return is_nan(res);
+  } else {
+    return res == expect;
+  }
+}
+
+template <std::floating_point T>
+constexpr bool test_ppc_edge_cases() {
+  if (std::is_constant_evaluated())
+    return true;
 
+// For 128 bit long double implemented as 2 doubles on PowerPC,
+// nextafterl() of libm gives imprecise results which fails the
+// midpoint() tests below. So skip the test for this case.
 #if defined(__PPC__) && (defined(__LONG_DOUBLE_128__) && __LONG_DOUBLE_128__) &&                                       \
     !(defined(__LONG_DOUBLE_IEEE128__) && __LONG_DOUBLE_IEEE128__)
-//  For 128 bit long double implemented as 2 doubles on PowerPC,
-//  nextafterl() of libm gives imprecise results which fails the
-//  midpoint() tests below. So skip the test for this case.
-    if constexpr (sizeof(T) != 16)
+  if constexpr (sizeof(T) == 16)
+    return true;
 #endif
-    {
-    //  Since there's nothing in between, the midpoint has to be one or the other
-        T res;
-        res = std::midpoint(d0, d1);
-        assert(res == d0 || res == d1);
-        assert(d0 <= res);
-        assert(res <= d1);
-        res = std::midpoint(d1, d0);
-        assert(res == d0 || res == d1);
-        assert(d0 <= res);
-        assert(res <= d1);
-
-        res = std::midpoint(d1, d2);
-        assert(res == d1 || res == d2);
-        assert(d1 <= res);
-        assert(res <= d2);
-        res = std::midpoint(d2, d1);
-        assert(res == d1 || res == d2);
-        assert(d1 <= res);
-        assert(res <= d2);
-    }
+
+  T d1 = 3.14;
+  T d0 = std::nextafter(d1, T{2});
+  T d2 = std::nextafter(d1, T{5});
+
+  auto verify = [](T res, T low, T high) { return (res == low || res == high) && (low <= res && res <= high); };
+
+  return verify(std::midpoint(d0, d1), d0, d1) && verify(std::midpoint(d1, d2), d1, d2);
 }
 
+template <typename T>
+constexpr bool test_floating_points() {
+  ASSERT_SAME_TYPE(T, decltype(std::midpoint(T{}, T{})));
+  ASSERT_NOEXCEPT(std::midpoint(T{}, T{}));
+
+  constexpr T max_v      = std::numeric_limits<T>::max();
+  constexpr T min_v      = std::numeric_limits<T>::min();
+  constexpr T denorm_min = std::numeric_limits<T>::denorm_min();
+  constexpr T inf        = std::numeric_limits<T>::infinity();
+  constexpr T qnan       = std::numeric_limits<T>::quiet_NaN();
+
+  // Things that can be compared exactly
+  assert(check_exact<T>(0, 0, 0));
+  assert(check_exact<T>(2, 4, 3));
+  assert(check_exact<T>(4, 2, 3));
+  assert(check_exact<T>(3, 4, 3.5));
+  assert(check_exact<T>(0, 0.4, 0.2));
+  assert(check_exact<T>(-2, -4, -3));
+  assert(check_exact<T>(-2, 2, 0));
+  assert(check_exact<T>(2, -2, 0));
+
+  // Infinity
+  assert(check_exact<T>(inf, inf, inf));
+  assert(check_exact<T>(-inf, -inf, -inf));
+  if (!std::is_constant_evaluated()) {
+    assert(check_exact<T>(inf, -inf, qnan));
+  }
+  assert(check_exact<T>(inf, 0, inf));
+
+  // NaN
+  if (!std::is_constant_evaluated()) {
+    assert(check_exact<T>(qnan, 0, qnan));
+    assert(check_exact<T>(qnan, qnan, qnan));
+  }
+
+  // Subnormal
+  assert(check_exact<T>(denorm_min, 0, 0));
+  assert(check_exact<T>(denorm_min, denorm_min, denorm_min));
+
+  // Things that can't be compared exactly
+  assert(check_near<T>(1.3, 11.4, 6.35));
+  assert(check_near<T>(11.33, 31.45, 21.39));
+  assert(check_near<T>(-1.3, 11.4, 5.05));
+  assert(check_near<T>(11.4, -1.3, 5.05));
+  assert(check_near<T>(11.2345, 14.5432, 12.88885));
+  assert(check_near<T>(2.71828182845904523536028747135266249775724709369995,
+                       3.14159265358979323846264338327950288419716939937510,
+                       2.92993724102441923691146542731608269097720824653752));
+
+  assert(check_near<T>(max_v, 0, max_v / 2));
+  assert(check_near<T>(0, max_v, max_v / 2));
+  assert(check_near<T>(min_v, 0, min_v / 2));
+  assert(check_near<T>(0, min_v, min_v / 2));
+  assert(check_near<T>(max_v, max_v, max_v));
+  assert(check_near<T>(min_v, min_v, min_v));
+  assert(check_near<T>(max_v, min_v, max_v / 2));
+  assert(check_near<T>(min_v, max_v, max_v / 2));
+
+  // Near the min and the max
+  assert(check_near<T>(max_v * 0.75, max_v * 0.50, max_v * 0.625));
+  assert(check_near<T>(max_v * 0.50, max_v * 0.75, max_v * 0.625));
+  assert(check_near<T>(min_v * 2, min_v * 8, min_v * 5));
+
+  // Big numbers of different signs
+  assert(check_near<T>(max_v * 0.75, max_v * -0.50, max_v * 0.125));
+  assert(check_near<T>(max_v * -0.75, max_v * 0.50, max_v * -0.125));
+
+  assert(test_ppc_edge_cases<T>());
+
+  return true;
+}
+
+constexpr bool test() {
+  test_floating_points<float>();
+  test_floating_points<double>();
+  test_floating_points<long double>();
+
+  return true;
+}
 
-int main (int, char**)
-{
-    fp_test<float>();
-    fp_test<double>();
-    fp_test<long double>();
+int main(int, char**) {
+  test();
+  static_assert(test());
 
-    return 0;
+  return 0;
 }
diff --git a/libcxx/test/std/numerics/numeric.ops/numeric.ops.midpoint/midpoint.integer.pass.cpp b/libcxx/test/std/numerics/numeric.ops/numeric.ops.midpoint/midpoint.integer.pass.cpp
index c506d0776a02c..c5ad2792fb2e3 100644
--- a/libcxx/test/std/numerics/numeric.ops/numeric.ops.midpoint/midpoint.integer.pass.cpp
+++ b/libcxx/test/std/numerics/numeric.ops/numeric.ops.midpoint/midpoint.integer.pass.cpp
@@ -5,140 +5,114 @@
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
-//
-// UNSUPPORTED: c++03, c++11, c++14, c++17
+
+// REQUIRES: std-at-least-c++20
+
 // <numeric>
 
 // template <class _Tp>
 // _Tp midpoint(_Tp __a, _Tp __b) noexcept
-//
+// Constraints:
+//   - T is an arithmetic type other than bool.
 
-#include <stdint.h>
-#include <limits>
-#include <numeric>
 #include <cassert>
+#include <concepts>
 #include <cstddef>
-#include <cstdint>
+#include <limits>
+#include <numeric>
+
 #include "test_macros.h"
+#include "type_algorithms.h"
 
 template <typename T>
-void signed_test()
-{
-    constexpr T zero{0};
-    constexpr T one{1};
-    constexpr T two{2};
-    constexpr T three{3};
-    constexpr T four{4};
-
-    ASSERT_SAME_TYPE(decltype(std::midpoint(T(), T())), T);
-    ASSERT_NOEXCEPT(          std::midpoint(T(), T()));
-    using limits = std::numeric_limits<T>;
-
-    static_assert(std::midpoint(one, three) == two, "");
-    static_assert(std::midpoint(three, one) == two, "");
-
-    assert(std::midpoint(zero, zero) == zero);
-    assert(std::midpoint(zero, two)  == one);
-    assert(std::midpoint(two, zero)  == one);
-    assert(std::midpoint(two, two)   == two);
-
-    assert(std::midpoint(one, four)    == two);
-    assert(std::midpoint(four, one)    == three);
-    assert(std::midpoint(three, four)  == three);
-    assert(std::midpoint(four, three)  == four);
-
-    assert(std::midpoint(T( 3), T( 4)) == T(3));
-    assert(std::midpoint(T( 4), T( 3)) == T(4));
-    assert(std::midpoint(T(-3), T( 4)) == T(0));
-    assert(std::midpoint(T(-4), T( 3)) == T(-1));
-    assert(std::midpoint(T( 3), T(-4)) == T(0));
-    assert(std::midpoint(T( 4), T(-3)) == T(1));
-    assert(std::midpoint(T(-3), T(-4)) == T(-3));
-    assert(std::midpoint(T(-4), T(-3)) == T(-4));
-
-    static_assert(std::midpoint(limits::min(), limits::max()) == T(-1), "");
-    static_assert(std::midpoint(limits::max(), limits::min()) == T( 0), "");
-
-    static_assert(std::midpoint(limits::min(), T(6)) == limits::min()/2 + 3, "");
-    assert(       std::midpoint(T(6), limits::min()) == limits::min()/2 + 3);
-    assert(       std::midpoint(limits::max(), T(6)) == limits::max()/2 + 4);
-    static_assert(std::midpoint(T(6), limits::max()) == limits::max()/2 + 3, "");
-
-    assert(       std::midpoint(limits::min(), T(-6)) == limits::min()/2 - 3);
-    static_assert(std::midpoint(T(-6), limits::min()) == limits::min()/2 - 3, "");
-    static_assert(std::midpoint(limits::max(), T(-6)) == limits::max()/2 - 2, "");
-    assert(       std::midpoint(T(-6), limits::max()) == limits::max()/2 - 3);
+constexpr void test_signed() {
+  ASSERT_SAME_TYPE(decltype(std::midpoint(T{}, T{})), T);
+  ASSERT_NOEXCEPT(std::midpoint(T{}, T{}));
+  using limits = std::numeric_limits<T>;
+
+  assert(std::midpoint(T{1}, T{3}) == T{2});
+  assert(std::midpoint(T{3}, T{1}) == T{2});
+
+  assert(std::midpoint(T{0}, T{0}) == T{0});
+  assert(std::midpoint(T{0}, T{2}) == T{1});
+  assert(std::midpoint(T{2}, T{0}) == T{1});
+  assert(std::midpoint(T{2}, T{2}) == T{2});
+
+  assert(std::midpoint(T{1}, T{4}) == T{2});
+  assert(std::midpoint(T{4}, T{1}) == T{3});
+  assert(std::midpoint(T{3}, T{4}) == T{3});
+  assert(std::midpoint(T{4}, T{3}) == T{4});
+
+  assert(std::midpoint(T{-3}, T{4}) == T{0});
+  assert(std::midpoint(T{-4}, T{3}) == T{-1});
+  assert(std::midpoint(T{3}, T{-4}) == T{0});
+  assert(std::midpoint(T{4}, T{-3}) == T{1});
+  assert(std::midpoint(T{-3}, T{-4}) == T{-3});
+  assert(std::midpoint(T{-4}, T{-3}) == T{-4});
+
+  assert(std::midpoint(limits::min(), limits::max()) == T{-1});
+  assert(std::midpoint(limits::max(), limits::min()) == T{0});
+
+  assert(std::midpoint(limits::min(), T{6}) == T{limits::min() / 2 + 3});
+  assert(std::midpoint(T{6}, limits::min()) == T{limits::min() / 2 + 3});
+
+  assert(std::midpoint(limits::max(), T{6}) == T{limits::max() / 2 + 4});
+  assert(std::midpoint(T{6}, limits::max()) == T{limits::max() / 2 + 3});
+
+  assert(std::midpoint(limits::min(), T{-6}) == T{limits::min() / 2 - 3});
+  assert(std::midpoint(T{-6}, limits::min()) == T{limits::min() / 2 - 3});
+
+  assert(std::midpoint(limits::max(), T{-6}) == T{limits::max() / 2 - 2});
+  assert(std::midpoint(T{-6}, limits::max()) == T{limits::max() / 2 - 3});
 }
 
 template <typename T>
-void unsigned_test()
-{
-    constexpr T zero{0};
-    constexpr T one{1};
-    constexpr T two{2};
-    constexpr T three{3};
-    constexpr T four{4};
-
-    ASSERT_SAME_TYPE(decltype(std::midpoint(T(), T())), T);
-    ASSERT_NOEXCEPT(          std::midpoint(T(), T()));
-    using limits = std::numeric_limits<T>;
-    const T half_way = (limits::max() - limits::min())/2;
-
-    static_assert(std::midpoint(one, three) == two, "");
-    static_assert(std::midpoint(three, one) == two, "");
-
-    assert(std::midpoint(zero, zero) == zero);
-    assert(std::midpoint(zero, two)  == one);
-    assert(std::midpoint(two, zero)  == one);
-    assert(std::midpoint(two, two)   == two);
-
-    assert(std::midpoint(one, four)    == two);
-    assert(std::midpoint(four, one)    == three);
-    assert(std::midpoint(three, four)  == three);
-    assert(std::midpoint(four, three)  == four);
-
-    assert(std::midpoint(limits::min(), limits::max()) == T(half_way));
-    assert(std::midpoint(limits::max(), limits::min()) == T(half_way + 1));
-
-    static_assert(std::midpoint(limits::min(), T(6)) == limits::min()/2 + 3, "");
-    assert(       std::midpoint(T(6), limits::min()) == limits::min()/2 + 3);
-    assert(       std::midpoint(limits::max(), T(6)) == half_way + 4);
-    static_assert(std::midpoint(T(6), limits::max()) == half_way + 3, "");
+constexpr void test_unsigned() {
+  ASSERT_SAME_TYPE(decltype(std::midpoint(T{}, T{})), T);
+  ASSERT_NOEXCEPT(std::midpoint(T{}, T{}));
+
+  using limits     = std::numeric_limits<T>;
+  const T half_way = (limits::max() - limits::min()) / 2;
+
+  assert(std::midpoint(T{1}, T{3}) == T{2});
+  assert(std::midpoint(T{3}, T{1}) == T{2});
+
+  assert(std::midpoint(T{0}, T{0}) == T{0});
+  assert(std::midpoint(T{0}, T{2}) == T{1});
+  assert(std::midpoint(T{2}, T{0}) == T{1});
+  assert(std::midpoint(T{2}, T{2}) == T{2});
+
+  assert(std::midpoint(T{1}, T{4}) == T{2});
+  assert(std::midpoint(T{4}, T{1}) == T{3});
+  assert(std::midpoint(T{3}, T{4}) == T{3});
+  assert(std::midpoint(T{4}, T{3}) == T{4});
+
+  assert(std::midpoint(limits::min(), limits::max()) == half_way);
+  assert(std::midpoint(limits::max(), limits::min()) == T{half_way + 1});
+
+  assert(std::midpoint(limits::min(), T{6}) == T{3});
+  assert(std::midpoint(T{6}, limits::min()) == T{3});
+
+  assert(std::midpoint(limits::max(), T{6}) == T{half_way + 4});
+  assert(std::midpoint(T{6}, limits::max()) == T{half_way + 3});
+}
+
+constexpr bool test() {
+  types::for_each(types::integer_types(), []<class T>() {
+    if constexpr (!std::same_as<T, bool>) {
+      if constexpr (std::signed_integral<T>) {
+        test_signed<T>();
+      } else {
+        test_unsigned<T>();
+      }
+    }
+  });
+  return true;
 }
 
+int main(int, char**) {
+  test();
+  static_assert(test());
 
-int main(int, char**)
-{
-    signed_test<signed char>();
-    signed_test<short>();
-    signed_test<int>();
-    signed_test<long>();
-    signed_test<long long>();
-
-    signed_test<std::int8_t>();
-    signed_test<std::int16_t>();
-    signed_test<std::int32_t>();
-    signed_test<std::int64_t>();
-
-    unsigned_test<unsigned char>();
-    unsigned_test<unsigned short>();
-    unsigned_test<unsigned int>();
-    unsigned_test<unsigned long>();
-    unsigned_test<unsigned long long>();
-
-    unsigned_test<std::uint8_t>();
-    unsigned_test<std::uint16_t>();
-    unsigned_test<std::uint32_t>();
-    unsigned_test<std::uint64_t>();
-
-#ifndef TEST_HAS_NO_INT128
-    unsigned_test<__uint128_t>();
-    signed_test<__int128_t>();
-#endif
-
-//     int_test<char>();
-    signed_test<std::ptrdiff_t>();
-    unsigned_test<std::size_t>();
-
-    return 0;
+  return 0;
 }
diff --git a/libcxx/test/std/numerics/numeric.ops/numeric.ops.midpoint/midpoint.pointer.pass.cpp b/libcxx/test/std/numerics/numeric.ops/numeric.ops.midpoint/midpoint.pointer.pass.cpp
index e8a25c174076a..a6639bd8529de 100644
--- a/libcxx/test/std/numerics/numeric.ops/numeric.ops.midpoint/midpoint.pointer.pass.cpp
+++ b/libcxx/test/std/numerics/numeric.ops/numeric.ops.midpoint/midpoint.pointer.pass.cpp
@@ -5,8 +5,8 @@
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
-//
-// UNSUPPORTED: c++03, c++11, c++14, c++17
+
+// REQUIRES: std-at-least-c++20
 
 // MSVC warning C5215: a function parameter with a volatile qualified type is deprecated in C++20
 // MSVC warning C5216: a volatile qualified return type is deprecated in C++20
@@ -16,83 +16,57 @@
 
 // template <class _Tp>
 // _Tp* midpoint(_Tp* __a, _Tp* __b) noexcept
-//
+// Constraints:
+//  - T is a complete object type.
 
-#include <numeric>
 #include <cassert>
+#include <cstddef>
+#include <numeric>
+#include <type_traits>
+#include <utility>
 
 #include "test_macros.h"
 
-
-
 template <typename T>
-constexpr void constexpr_test()
-{
-    constexpr T array[1000] = {};
-    ASSERT_SAME_TYPE(decltype(std::midpoint(array, array)), const T*);
-    ASSERT_NOEXCEPT(          std::midpoint(array, array));
-
-    static_assert(std::midpoint(array, array)        == array, "");
-    static_assert(std::midpoint(array, array + 1000) == array + 500, "");
-
-    static_assert(std::midpoint(array, array +    9) == array + 4, "");
-    static_assert(std::midpoint(array, array +   10) == array + 5, "");
-    static_assert(std::midpoint(array, array +   11) == array + 5, "");
-    static_assert(std::midpoint(array +    9, array) == array + 5, "");
-    static_assert(std::midpoint(array +   10, array) == array + 5, "");
-    static_assert(std::midpoint(array +   11, array) == array + 6, "");
+constexpr bool check(T* base, std::ptrdiff_t i, std::ptrdiff_t j, std::ptrdiff_t expect) {
+  return std::midpoint(base + i, base + j) == base + expect;
 }
 
 template <typename T>
-void runtime_test()
-{
-    T array[10...
[truncated]

``````````

</details>


https://github.com/llvm/llvm-project/pull/175531


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