Merge pull request #1103 from filipw/feature/script-SupersedeLowerVer…

…sions

Feature/script supersede lower versions

CHANGELOG.md

@@ -1,7 +1,8 @@
 # Changelog
 All changes to the project will be documented in this file.
 
-## [1.29.1] - Not Yet Released
+## [1.30.0] - not yet released
+* Ensure that the lower assembly versions are always superseded in C# scripts (PR: [#1103](https://github.com/OmniSharp/omnisharp-roslyn/pull/1103))
 * Fixed duplicate diagnostics in C# ([omnisharp-vscode#1830](https://github.com/OmniSharp/omnisharp-vscode/issues/1830), PR: [#1107](https://github.com/OmniSharp/omnisharp-roslyn/pull/1107))
 
 ## [1.29.0] - 2018-1-29

src/OmniSharp.Script/ScriptHelper.cs

@@ -16,6 +16,7 @@ public class ScriptHelper
     {
         private const string BinderFlagsType = "Microsoft.CodeAnalysis.CSharp.BinderFlags";
         private const string TopLevelBinderFlagsProperty = "TopLevelBinderFlags";
+        private const string ReferencesSupersedeLowerVersionsProperty = "ReferencesSupersedeLowerVersions_internal_protected_set";
         private const string IgnoreCorLibraryDuplicatedTypesField = "IgnoreCorLibraryDuplicatedTypes";
         private const string RuntimeMetadataReferenceResolverType = "Microsoft.CodeAnalysis.Scripting.Hosting.RuntimeMetadataReferenceResolver";
         private const string ResolverField = "_resolver";
@@ -73,6 +74,11 @@ private CSharpCompilationOptions CreateCompilationOptions()
                 topLevelBinderFlagsProperty?.SetValue(compilationOptions, ignoreCorLibraryDuplicatedTypesValue);
             }
 
+            // in scripts, the option to supersede lower versions is ALWAYS enabled
+            // see: https://github.com/dotnet/roslyn/blob/version-2.6.0-beta3/src/Compilers/CSharp/Portable/Compilation/CSharpCompilation.cs#L199
+            var referencesSupersedeLowerVersionsProperty = typeof(CompilationOptions).GetProperty(ReferencesSupersedeLowerVersionsProperty, BindingFlags.Instance | BindingFlags.NonPublic);
+            referencesSupersedeLowerVersionsProperty?.SetValue(compilationOptions, true);
+
             return compilationOptions;
         }