FSharpLanguageVersion: invalidate on toolset change (#858)

Author: DedSec256

ReSharper.FSharp/src/FSharp/FSharp.Common/src/ProjectModel/FSharpLanguageLevelProvider.fs

@@ -183,6 +183,11 @@ type FSharpLanguageLevelProjectProperty(lifetime, locks, projectPropertiesListen
 
     override this.LanguageLevelComparer = FSharpLanguageLevelComparer.Instance :> _
 
+    interface ISolutionToolsetListener with
+        member this.Changed _ =
+            compilerPathToLanguageLevels.Clear()
+
+
 [<SolutionFeaturePart(InstantiationEx.LegacyDefault)>]
 type FSharpLanguageLevelProvider(projectProperty: FSharpLanguageLevelProjectProperty) =
     let (|PsiModule|) (psiModule: IPsiModule) =

ReSharper.FSharp/src/FSharp/FSharp.Psi.Daemon/src/Stages/FSharpFileStructureExplorer.fs

@@ -5,6 +5,7 @@ open JetBrains.ReSharper.Feature.Services.Daemon
 open JetBrains.ReSharper.Plugins.FSharp.Psi.Impl.Tree
 open JetBrains.ReSharper.Plugins.FSharp.Psi.Tree
 open JetBrains.ReSharper.Psi.Tree
+open JetBrains.ReSharper.Psi.Util
 
 type DisableByNowarnCodeInspectionSection(warningId, range) =
     interface IDisableCodeInspectionSection with
@@ -49,4 +50,5 @@ type FSharpFileStructureExplorer() =
             let fsFile = file.As<IFSharpFile>()
             if isNull fsFile then null else
 
+            PsiFileCachedDataUtil.InvalidateAllData(fsFile)
             FSharpFileStructure(fsFile)