Generate target platform assembly attributes

global.json

@@ -1,6 +1,6 @@
 {
   "tools": {
-    "dotnet": "5.0.100-preview.8.20351.5",
+    "dotnet": "5.0.100-preview.8.20359.7",
     "runtimes": {
       "dotnet": [
         "$(MicrosoftNETCoreAppRuntimePackageVersion)"

src/Tasks/Microsoft.NET.Build.Tasks/targets/Microsoft.NET.GenerateAssemblyInfo.targets

@@ -115,6 +115,15 @@ Copyright (c) .NET Foundation. All rights reserved.
         <_Parameter2>%(AssemblyMetadata.Value)</_Parameter2>
       </AssemblyAttribute>
     </ItemGroup>
+
+    <ItemGroup Condition="'$(TargetPlatformIdentifier)' != ''
+                         and '$(MinimumOSPlatform)' != ''
+                         and '$(TargetFrameworkIdentifier)' == '.NETCoreApp'
+                         and $([MSBuild]::VersionGreaterThanOrEquals($(_TargetFrameworkVersionWithoutV), '5.0'))">
+      <AssemblyAttribute Include="System.Runtime.Versioning.MinimumOSPlatformAttribute">
+        <_Parameter1>$(TargetPlatformIdentifier)$(MinimumOSPlatform)</_Parameter1>
+      </AssemblyAttribute>
+    </ItemGroup>
   </Target>
 
   <!-- 

src/Tasks/Microsoft.NET.Build.Tasks/targets/Microsoft.NET.TargetFrameworkInference.targets

@@ -88,6 +88,11 @@ Copyright (c) .NET Foundation. All rights reserved.
     <_UnsupportedTargetFrameworkError>true</_UnsupportedTargetFrameworkError>
   </PropertyGroup>
 
+  <!--Default MinimumOSPlatform to TargetPlatformVersion-->
+  <PropertyGroup Condition="'$(MinimumOSPlatform)' == '' and '$(TargetPlatformVersion)' != ''">
+    <MinimumOSPlatform>$(TargetPlatformVersion)</MinimumOSPlatform>
+  </PropertyGroup>
+
   <!--
     NOTE: We must not validate the TFM before restore target runs as it prevents adding additional TFM 
           support from being provided by a nuget package such as MSBuild.Sdk.Extras.

src/Tests/Microsoft.NET.Build.Tests/GivenThatWeWantToBuildALibraryWithOSMinimumVersion.cs

@@ -0,0 +1,112 @@
+// Copyright (c) .NET Foundation and contributors. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+using System.IO;
+using Microsoft.NET.TestFramework;
+using Microsoft.NET.TestFramework.Assertions;
+using Microsoft.NET.TestFramework.Commands;
+using Xunit;
+using FluentAssertions;
+using Xunit.Abstractions;
+using Microsoft.NET.TestFramework.ProjectConstruction;
+
+namespace Microsoft.NET.Build.Tests
+{
+    public class GivenThatWeWantToBuildALibraryWithOSMinimumVersion : SdkTest
+    {
+        public GivenThatWeWantToBuildALibraryWithOSMinimumVersion(ITestOutputHelper log) : base(log)
+        {
+        }
+
+        [Fact]
+        public void WhenPropertiesAreNotSetItShouldNotGenerateMinimumOSPlatformAttribute()
+        {
+            TestProject testProject = SetUpProject();
+            var testAsset = _testAssetsManager.CreateTestProject(testProject);
+
+            var runCommand = new DotnetCommand(Log, "run");
+            runCommand.WorkingDirectory = Path.Combine(testAsset.TestRoot, testProject.Name);
+            runCommand.Execute()
+                .Should()
+                .Pass().And.HaveStdOutContaining("NO ATTRIBUTE");
+        }
+
+        [Fact]
+        public void WhenPropertiesAreSetItCanGenerateMinimumOSPlatformAttribute()
+        {
+            TestProject testProject = SetUpProject();
+
+            var targetPlatformIdentifier = "iOS";
+            testProject.AdditionalProperties["TargetPlatformIdentifier"] = targetPlatformIdentifier;
+            testProject.AdditionalProperties["MinimumOSPlatform"] = "13.2";
+            testProject.AdditionalProperties["TargetPlatformVersion"] = "14.0";
+
+            var testAsset = _testAssetsManager.CreateTestProject(testProject);
+
+            var runCommand = new DotnetCommand(Log, "run");
+            runCommand.WorkingDirectory = Path.Combine(testAsset.TestRoot, testProject.Name);
+            runCommand.Execute()
+                .Should()
+                .Pass().And.HaveStdOutContaining("PlatformName:iOS13.2");
+        }
+
+        [Fact]
+        public void WhenMinimumOSPlatformISNotSetTargetPlatformVersionIsSetItCanGenerateMinimumOSPlatformAttribute()
+        {
+            TestProject testProject = SetUpProject();
+
+            var targetPlatformIdentifier = "iOS";
+            testProject.AdditionalProperties["TargetPlatformIdentifier"] = targetPlatformIdentifier;
+            testProject.AdditionalProperties["TargetPlatformVersion"] = "13.2";
+
+            var testAsset = _testAssetsManager.CreateTestProject(testProject);
+
+            var runCommand = new DotnetCommand(Log, "run");
+            runCommand.WorkingDirectory = Path.Combine(testAsset.TestRoot, testProject.Name);
+            runCommand.Execute()
+                .Should()
+                .Pass().And.HaveStdOutContaining("PlatformName:iOS13.2");
+        }
+
+        private static TestProject SetUpProject()
+        {
+            TestProject testProject = new TestProject()
+            {
+                Name = "Project",
+                IsSdkProject = true,
+                IsExe = true,
+                TargetFrameworks = "net5.0",
+            };
+
+            testProject.SourceFiles["PrintAttribute.cs"] = _printAttribute;
+            return testProject;
+        }
+
+        private static readonly string _printAttribute = @"
+using System;
+using System.Runtime.Versioning;
+
+namespace CustomAttributesTestApp
+{
+    internal static class CustomAttributesTestApp
+    {
+        public static void Main()
+        {
+            var assembly = typeof(CustomAttributesTestApp).Assembly;
+            object[] attributes = assembly.GetCustomAttributes(typeof(System.Runtime.Versioning.MinimumOSPlatformAttribute), false);
+            if (attributes.Length > 0)
+            {
+                var attribute = attributes[0] as System.Runtime.Versioning.MinimumOSPlatformAttribute;
+                Console.WriteLine($""PlatformName:{attribute.PlatformName}"");
+            }
+            else
+            {
+                Console.WriteLine(""NO ATTRIBUTE"");
+            }
+        }
+    }
+}
+";
+
+    }
+}

src/Tests/Microsoft.NET.Publish.Tests/GivenThatWeWantToPublishASingleFileApp.cs

@@ -202,7 +202,7 @@ public void It_generates_a_single_file_for_self_contained_apps()
                 .Should()
                 .Pass();
 
-            string[] expectedFiles = { SingleFile, PdbFile, SmallNameDirWord, LargeNameDirWord, GetNativeDll("coreclr"), GetNativeDll("clrjit") };
+            string[] expectedFiles = { SingleFile, PdbFile, SmallNameDirWord, LargeNameDirWord };
             string[] unexpectedFiles = { GetNativeDll("hostfxr"), GetNativeDll("hostpolicy") };
 
             GetPublishDirectory(publishCommand)