Take latest from dotnet-tools feed and see what happens

Directory.Packages.props

@@ -14,8 +14,8 @@
     <PackageVersion Include="K4os.Compression.LZ4" Version="1.3.8" />
     <PackageVersion Include="McMaster.Extensions.CommandLineUtils" Version="4.1.1" />
     <PackageVersion Include="McMaster.Extensions.Hosting.CommandLine" Version="4.1.1" />
-    <PackageVersion Include="Microsoft.CodeAnalysis.CSharp" Version="4.14.0" />
-    <PackageVersion Include="Microsoft.CodeAnalysis.VisualBasic" Version="4.14.0" />
+    <PackageVersion Include="Microsoft.CodeAnalysis.CSharp" Version="5.0.0-2.25364.13" />
+    <PackageVersion Include="Microsoft.CodeAnalysis.VisualBasic" Version="5.0.0-2.25364.13" />
     <PackageVersion Include="Microsoft.DiaSymReader.Converter.Xml" Version="1.1.0-beta2-22171-02" />
     <PackageVersion Include="Microsoft.DiaSymReader" Version="1.4.0" />
     <PackageVersion Include="Microsoft.DiaSymReader.Native" Version="17.0.0-beta1.21524.1" />

ILSpy.sln

@@ -42,6 +42,7 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Solution Items", "Solution
 		Directory.Build.props = Directory.Build.props
 		Directory.Packages.props = Directory.Packages.props
 		global.json = global.json
+		NuGet.config = NuGet.config
 	EndProjectSection
 EndProject
 Global

NuGet.config

@@ -19,6 +19,7 @@
     <packageSource key="dotnet-tools">
       <package pattern="Microsoft.DiaSymReader.Converter.Xml" />
       <package pattern="Microsoft.DiaSymReader.PortablePdb" />
+      <package pattern="Microsoft.CodeAnalysis.*" />
     </packageSource>
   </packageSourceMapping>
 </configuration>