add IsOSPlatformOrLater and IsOSPlatformEarlierThan methods

src/libraries/System.Runtime.InteropServices.RuntimeInformation/ref/System.Runtime.InteropServices.RuntimeInformation.cs

@@ -39,5 +39,15 @@ public static partial class RuntimeInformation
         public static string OSDescription { get { throw null; } }
         public static System.Runtime.InteropServices.Architecture ProcessArchitecture { get { throw null; } }
         public static bool IsOSPlatform(System.Runtime.InteropServices.OSPlatform osPlatform) { throw null; }
+        public static bool IsOSPlatformOrLater(string platformName) { throw null; }
+        public static bool IsOSPlatformOrLater(System.Runtime.InteropServices.OSPlatform osPlatform, int major) { throw null; }
+        public static bool IsOSPlatformOrLater(System.Runtime.InteropServices.OSPlatform osPlatform, int major, int minor) { throw null; }
+        public static bool IsOSPlatformOrLater(System.Runtime.InteropServices.OSPlatform osPlatform, int major, int minor, int build) { throw null; }
+        public static bool IsOSPlatformOrLater(System.Runtime.InteropServices.OSPlatform osPlatform, int major, int minor, int build, int revision) { throw null; }
+        public static bool IsOSPlatformEarlierThan(string platformName) { throw null; }
+        public static bool IsOSPlatformEarlierThan(System.Runtime.InteropServices.OSPlatform osPlatform, int major) { throw null; }
+        public static bool IsOSPlatformEarlierThan(System.Runtime.InteropServices.OSPlatform osPlatform, int major, int minor) { throw null; }
+        public static bool IsOSPlatformEarlierThan(System.Runtime.InteropServices.OSPlatform osPlatform, int major, int minor, int build) { throw null; }
+        public static bool IsOSPlatformEarlierThan(System.Runtime.InteropServices.OSPlatform osPlatform, int major, int minor, int build, int revision) { throw null; }
     }
 }

src/libraries/System.Runtime.InteropServices.RuntimeInformation/src/Resources/Strings.resx

@@ -60,6 +60,9 @@
   <data name="Argument_EmptyValue" xml:space="preserve">
     <value>Value cannot be empty.</value>
   </data>
+  <data name="Argument_InvalidPlatfromName" xml:space="preserve">
+    <value>"{0}" is not a valid platform name. It must contain both name and version (with at least major and minor number specified). Example: "ios14.0".</value>
+  </data>
   <data name="PlatformNotSupported_RuntimeInformation" xml:space="preserve">
     <value>RuntimeInformation is not supported for Portable Class Libraries.</value>
   </data>

src/libraries/System.Runtime.InteropServices.RuntimeInformation/src/System.Runtime.InteropServices.RuntimeInformation.csproj

@@ -7,6 +7,7 @@
   </PropertyGroup>
   <ItemGroup>
     <Compile Include="System\Runtime\InteropServices\RuntimeInformation\RuntimeInformation.cs" />
+    <Compile Include="System\Runtime\InteropServices\RuntimeInformation\RuntimeInformation.PlatformVersion.cs" />
     <Compile Include="System\Runtime\InteropServices\RuntimeInformation\Architecture.cs" />
     <Compile Include="System\Runtime\InteropServices\RuntimeInformation\OSPlatform.cs" />
   </ItemGroup>
@@ -45,5 +46,6 @@
     <Reference Include="System.Runtime" />
     <Reference Include="System.Runtime.InteropServices" />
     <Reference Include="System.Threading" />
+    <Reference Include="System.Memory" />
   </ItemGroup>
 </Project>

src/libraries/System.Runtime.InteropServices.RuntimeInformation/src/System/Runtime/InteropServices/RuntimeInformation/RuntimeInformation.PlatformVersion.cs

@@ -0,0 +1,131 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+namespace System.Runtime.InteropServices
+{
+    public static partial class RuntimeInformation
+    {
+        /// <summary>
+        /// Check for the OS with a >= version comparison. Used to guard APIs that were added in the given OS release.
+        /// </summary>
+        /// <param name="platformName">OS name concatenated with a version number.</param>
+        /// <remarks>The version number must contain at least major and minor numbers separated with a dot.
+        /// Example: "ios14.0" is OK, "ios14" is NOT OK.</remarks>
+        public static bool IsOSPlatformOrLater(string platformName)
+        {
+            (OSPlatform platform, Version version) = Parse(platformName);
+
+            return IsOSPlatformOrLater(platform, version.Major, version.Minor, version.Build, version.Revision);
+        }
+
+        /// <summary>
+        /// Check for the OS with a >= version comparison. Used to guard APIs that were added in the given OS release.
+        /// </summary>
+        public static bool IsOSPlatformOrLater(OSPlatform osPlatform, int major)
+            => IsOSPlatform(osPlatform) && Environment.OSVersion.Version.Major >= major;
+
+        /// <summary>
+        /// Check for the OS with a >= version comparison. Used to guard APIs that were added in the given OS release.
+        /// </summary>
+        public static bool IsOSPlatformOrLater(OSPlatform osPlatform, int major, int minor)
+            => IsOSPlatform(osPlatform) && IsOSVersionOrLater(major, minor, int.MinValue, int.MinValue);
+
+        /// <summary>
+        /// Check for the OS with a >= version comparison. Used to guard APIs that were added in the given OS release.
+        /// </summary>
+        public static bool IsOSPlatformOrLater(OSPlatform osPlatform, int major, int minor, int build)
+            => IsOSPlatform(osPlatform) && IsOSVersionOrLater(major, minor, build, int.MinValue);
+
+        /// <summary>
+        /// Check for the OS with a >= version comparison. Used to guard APIs that were added in the given OS release.
+        /// </summary>
+        public static bool IsOSPlatformOrLater(OSPlatform osPlatform, int major, int minor, int build, int revision)
+            => IsOSPlatform(osPlatform) && IsOSVersionOrLater(major, minor, build, revision);
+
+        /// <summary>
+        /// Check for the OS with a &lt; version comparison. Used to guard APIs that were obsoleted or removed in the given OS release.
+        /// </summary>
+        /// <param name="platformName">OS name concatenated with a version number.</param>
+        /// <remarks>The version number must contain at least major and minor numbers separated with a dot.
+        /// Example: "ios14.0" is OK, "ios14" is NOT OK.</remarks>
+        public static bool IsOSPlatformEarlierThan(string platformName)
+        {
+            (OSPlatform platform, Version version) = Parse(platformName);
+
+            return IsOSPlatformEarlierThan(platform, version.Major, version.Minor, version.Build, version.Revision);
+        }
+
+        /// <summary>
+        /// Check for the OS with a &lt; version comparison. Used to guard APIs that were obsoleted or removed in the given OS release.
+        /// </summary>
+        public static bool IsOSPlatformEarlierThan(OSPlatform osPlatform, int major)
+            => IsOSPlatform(osPlatform) && Environment.OSVersion.Version.Major < major;
+
+        /// <summary>
+        /// Check for the OS with a &lt; version comparison. Used to guard APIs that were obsoleted or removed in the given OS release.
+        /// </summary>
+        public static bool IsOSPlatformEarlierThan(OSPlatform osPlatform, int major, int minor)
+            => IsOSPlatform(osPlatform) && !IsOSVersionOrLater(major, minor, int.MinValue, int.MinValue);
+
+        /// <summary>
+        /// Check for the OS with a &lt; version comparison. Used to guard APIs that were obsoleted or removed in the given OS release.
+        /// </summary>
+        public static bool IsOSPlatformEarlierThan(OSPlatform osPlatform, int major, int minor, int build)
+            => IsOSPlatform(osPlatform) && !IsOSVersionOrLater(major, minor, build, int.MinValue);
+
+        /// <summary>
+        /// Check for the OS with a &lt; version comparison. Used to guard APIs that were obsoleted or removed in the given OS release.
+        /// </summary>
+        public static bool IsOSPlatformEarlierThan(OSPlatform osPlatform, int major, int minor, int build, int revision)
+            => IsOSPlatform(osPlatform) && !IsOSVersionOrLater(major, minor, build, revision);
+
+        private static bool IsOSVersionOrLater(int major, int minor, int build, int revision)
+        {
+            Version current = Environment.OSVersion.Version;
+            if (current.Major != major)
+            {
+                return current.Major > major;
+            }
+            if (current.Minor != minor)
+            {
+                return current.Minor > minor;
+            }
+            if (current.Build != build)
+            {
+                return current.Build > build;
+            }
+
+            return current.Revision >= revision;
+        }
+
+        private static (OSPlatform, Version) Parse(string platformName)
+        {
+            if (platformName == null)
+            {
+                throw new ArgumentNullException(nameof(platformName));
+            }
+            if (platformName.Length == 0)
+            {
+                throw new ArgumentException(SR.Argument_EmptyValue, nameof(platformName));
+            }
+
+            // iterate from the begining, as digits in the middle of the names are not supported by design
+            for (int i = 0; i < platformName.Length; i++)
+            {
+                if (char.IsDigit(platformName[i]))
+                {
+                    if (i > 0 && Version.TryParse(platformName.AsSpan(i), out Version? version))
+                    {
+                        return (OSPlatform.Create(platformName.Substring(0, i)), version);
+                    }
+                    else
+                    {
+                        break;
+                    }
+                }
+            }
+
+            throw new ArgumentException(SR.Format(SR.Argument_InvalidPlatfromName, platformName), nameof(platformName));
+        }
+    }
+}