Add polyfills for Math.Clamp(...)

PolyShim.Tests/Net60/MathTests.cs

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+using System;
+using FluentAssertions;
+using Xunit;
+
+namespace PolyShim.Tests.Net60;
+
+public class MathTests
+{
+    [Fact]
+    public void Clamp_Test()
+    {
+        // Act & assert
+        Math.Clamp((nint)5, (nint)1, (nint)10).Should().Be((nint)5);
+        Math.Clamp((nint)0, (nint)1, (nint)10).Should().Be((nint)1);
+        Math.Clamp((nint)15, (nint)1, (nint)10).Should().Be((nint)10);
+    }
+}

PolyShim.Tests/NetCore20/MathTests.cs

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+using System;
+using FluentAssertions;
+using Xunit;
+
+namespace PolyShim.Tests.NetCore20;
+
+public class MathTests
+{
+    [Fact]
+    public void Clamp_Test()
+    {
+        // Act & assert
+        Math.Clamp(5, 1, 10).Should().Be(5);
+        Math.Clamp(0, 1, 10).Should().Be(1);
+        Math.Clamp(15, 1, 10).Should().Be(10);
+        Math.Clamp(5.5, 1.0, 10.0).Should().Be(5.5);
+        Math.Clamp(0.5, 1.0, 10.0).Should().Be(1.0);
+        Math.Clamp(15.5, 1.0, 10.0).Should().Be(10.0);
+    }
+}

PolyShim/Net60/Math.cs

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+// The following comment is required to instruct analyzers to skip this file
+// <auto-generated/>
+
+#if (NETCOREAPP && !NET6_0_OR_GREATER) || (NETFRAMEWORK) || (NETSTANDARD)
+#nullable enable
+// ReSharper disable RedundantUsingDirective
+// ReSharper disable CheckNamespace
+// ReSharper disable InconsistentNaming
+// ReSharper disable PartialTypeWithSinglePart
+
+using System;
+
+internal static partial class PolyfillExtensions
+{
+    extension(Math)
+    {
+        // https://learn.microsoft.com/dotnet/api/system.math.clamp#system-math-clamp(system-intptr-system-intptr-system-intptr)
+        public static IntPtr Clamp(IntPtr value, IntPtr min, IntPtr max)
+        {
+            var valueAsLong = value.ToInt64();
+            var minAsLong = min.ToInt64();
+            var maxAsLong = max.ToInt64();
+
+            if (valueAsLong < minAsLong)
+                return min;
+
+            if (valueAsLong > maxAsLong)
+                return max;
+
+            return value;
+        }
+    }
+}
+#endif

PolyShim/NetCore20/Math.cs

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+// The following comment is required to instruct analyzers to skip this file
+// <auto-generated/>
+
+#if (NETCOREAPP && !NETCOREAPP2_0_OR_GREATER) || (NETFRAMEWORK) || (NETSTANDARD && !NETSTANDARD2_1_OR_GREATER)
+#nullable enable
+// ReSharper disable RedundantUsingDirective
+// ReSharper disable CheckNamespace
+// ReSharper disable InconsistentNaming
+// ReSharper disable PartialTypeWithSinglePart
+
+using System;
+
+internal static partial class PolyfillExtensions
+{
+    extension(Math)
+    {
+        // https://learn.microsoft.com/dotnet/api/system.math.clamp
+        // Technically, the original implementation has overloads for each separate numeric type,
+        // but this generic version is fully source-compatible and simpler to maintain.
+        public static T Clamp<T>(T value, T min, T max) where T : IComparable<T>
+        {
+            if (value.CompareTo(min) < 0)
+                return min;
+
+            if (value.CompareTo(max) > 0)
+                return max;
+
+            return value;
+        }
+    }
+}
+#endif