Updates to TFM support for reference pkg src generator

Author: mthalman

src/referencePackageSourceGenerator/ReferencePackageProjectTemplate.xml

@@ -2,14 +2,14 @@
 
   <PropertyGroup>
     <TargetFrameworks>$$TargetFrameworks$$</TargetFrameworks>
-    <NuspecFile>$(ArtifactsBinDir)$$RelativePath$$/$$LowerCaseFileName$$.nuspec</NuspecFile>$$KeyFileTag$$$$EnableImplicitReferencesTag$$
+    <NuspecFile>$(ArtifactsBinDir)$$RelativePath$$/$$LowerCaseFileName$$.nuspec</NuspecFile>$$KeyFileTag$$
   </PropertyGroup>
 
   <PropertyGroup>
     <OutputPath>$(ArtifactsBinDir)$$RelativePath$$/ref/</OutputPath>
     <IntermediateOutputPath>$(ArtifactsObjDir)$$RelativePath$$</IntermediateOutputPath>
   </PropertyGroup>
-$$OutputPathByTfm$$  <ItemGroup>
+$$TfmSpecificProperties$$  <ItemGroup>
     <Compile Include="**/ref/$(TargetFramework)/*.cs" />
     <Compile Include="**/lib/$(TargetFramework)/*.cs" />
   </ItemGroup>

src/referencePackageSourceGenerator/ReferencePackageSourceGenerator.proj

@@ -8,6 +8,9 @@
     <!-- The following target frameworks aren't buildable with the current SDK and as they don't contribute to the set of
          source build target verticals, can be safely excluded. -->
     <ExcludeTargetFrameworks>netcore50;net463;portable-*;xamarin*;monotouch*;monoandroid*;win8;wp8;wpa81</ExcludeTargetFrameworks>
+    <!-- The following target frameworks should be excluded even though they are supported by the current SDK because there is no need to have them.
+         Only exclude them when target frameworks to include aren't provided. -->
+    <ExcludeTargetFrameworks Condition="'$(IncludeTargetFrameworks)' == ''">$(ExcludeTargetFrameworks);netcoreapp3.1</ExcludeTargetFrameworks>
   </PropertyGroup>
 
   <PropertyGroup Condition="'$(PackageName)' != '' and '$(PackageVersion)' != ''">

src/referencePackageSourceGenerator/ReferencePackageSourceTask/GenerateProject.cs

@@ -40,7 +40,7 @@ public override bool Execute()
             string projectTemplateContent = File.ReadAllText(ProjectTemplate);
             string pkgProjectOutput = projectTemplateContent;
             string packageReferenceIncludes = "\n";
-            string outputPathByTfm = "\n";
+            string tfmSpecificProperties = "\n";
 
             // Make sure that we always use the same directory separator.
             string relativePath = Path.GetRelativePath(BaseTargetPath, Path.GetDirectoryName(TargetPath)).Replace('\\', '/');
@@ -55,7 +55,7 @@ public override bool Execute()
                 string packageReferences = "";
                 string netStandardTag = "NETStandardImplicitPackageVersion";
 
-                if (targetFramework == "netstandard2.0" && !includesNetStandard21 && !includesNetCoreApp30)
+                if (targetFramework == "netstandard2.0")
                 {
                     packageReferences += $"    <PackageReference Include=\"NETStandard.Library\" Version=\"$({netStandardTag})\" />\n";
                 }
@@ -135,12 +135,18 @@ public override bool Execute()
                     }
                 }
 
+                tfmSpecificProperties += $"  <PropertyGroup Condition=\" '$(TargetFramework)' == '{targetFramework}' \">\n";
                 if (subPath == "lib")
                 {
-                    outputPathByTfm += $"  <PropertyGroup Condition=\" '$(TargetFramework)' == '{targetFramework}' \">\n";
-                    outputPathByTfm += $"    <OutputPath>$(ArtifactsBinDir){relativePath}/{subPath}/</OutputPath>\n";
-                    outputPathByTfm += $"  </PropertyGroup>\n\n";
+                    tfmSpecificProperties += $"    <OutputPath>$(ArtifactsBinDir){relativePath}/{subPath}/</OutputPath>\n";
                 }
+                if (targetFramework == "netstandard2.1" ||
+                    targetFramework == "netcoreapp3.0" ||
+                    targetFramework == "net6.0")
+                {
+                    tfmSpecificProperties += "    <DisableImplicitFrameworkReferences>false</DisableImplicitFrameworkReferences>\n";
+                }
+                tfmSpecificProperties += $"  </PropertyGroup>\n\n";
             }
 
             // If necessary, write the strong name key into the project file.
@@ -151,19 +157,12 @@ public override bool Execute()
                 keyFileTag = $"\n    <StrongNameKeyId>{strongNameData.Id}</StrongNameKeyId>";
             }
 
-            string enableImplicitReferencesTag = "";
-            if (includesNetStandard21 || includesNetCoreApp30)
-            {
-                enableImplicitReferencesTag = "\n    <DisableImplicitFrameworkReferences>false</DisableImplicitFrameworkReferences>";
-            }
-
             pkgProjectOutput = pkgProjectOutput.Replace("$$LowerCaseFileName$$", PackageId.ToLowerInvariant());
-            pkgProjectOutput = pkgProjectOutput.Replace("$$OutputPathByTfm$$", outputPathByTfm);
+            pkgProjectOutput = pkgProjectOutput.Replace("$$TfmSpecificProperties$$", tfmSpecificProperties);
             pkgProjectOutput = pkgProjectOutput.Replace("$$RelativePath$$", relativePath);
             pkgProjectOutput = pkgProjectOutput.Replace("$$PackageReferences$$", packageReferenceIncludes);
             pkgProjectOutput = pkgProjectOutput.Replace("$$TargetFrameworks$$", string.Join(';', orderedTargetFrameworks));
             pkgProjectOutput = pkgProjectOutput.Replace("$$KeyFileTag$$", keyFileTag);
-            pkgProjectOutput = pkgProjectOutput.Replace("$$EnableImplicitReferencesTag$$", enableImplicitReferencesTag);
 
             // Generate the project file
             Directory.CreateDirectory(Path.GetDirectoryName(TargetPath));