Signature tweak to the grammar.

ReSharper.FSharp/src/FSharp.Psi.Features/src/CodeCompletion/FSharpCodeCompletionContext.fs

@@ -8,6 +8,7 @@ open JetBrains.DocumentModel
 open JetBrains.ReSharper.Feature.Services.CodeCompletion
 open JetBrains.ReSharper.Feature.Services.CodeCompletion.Impl
 open JetBrains.ReSharper.Feature.Services.CodeCompletion.Infrastructure
+open JetBrains.ReSharper.Plugins.FSharp
 open JetBrains.ReSharper.Plugins.FSharp.Psi
 open JetBrains.ReSharper.Plugins.FSharp.Psi.Features
 open JetBrains.ReSharper.Plugins.FSharp.Psi.Features.CodeCompletion
@@ -53,7 +54,7 @@ type FSharpReparseContext(fsFile: IFSharpFile, treeTextRange: TreeTextRange) =
             let document = documentFactory.CreateSimpleDocumentFromText(source, moniker)
 
             // todo: reparse as sig?
-            let parser = fsFile.GetFSharpLanguageService().CreateParser(document, fsFile.GetSourceFile(), true)
+            let parser = fsFile.GetFSharpLanguageService().CreateParser(document, fsFile.GetSourceFile(), FSharpProjectFileType.FsExtension)
             let newFile =
                 try
                     let newFile =

ReSharper.FSharp/src/FSharp.Psi.Features/src/LanguageService/FSharpElementFactory.fs

@@ -1,5 +1,6 @@
 namespace JetBrains.ReSharper.Plugins.FSharp.Psi.Features.LanguageService
 
+open System.Runtime.InteropServices
 open FSharp.Compiler.Symbols
 open FSharp.Compiler.Syntax
 open JetBrains.Diagnostics
@@ -19,7 +20,8 @@ open JetBrains.ReSharper.Psi.Naming
 open JetBrains.ReSharper.Psi.Tree
 open JetBrains.ReSharper.Resources.Shell
 
-type FSharpElementFactory(languageService: IFSharpLanguageService, sourceFile: IPsiSourceFile, psiModule: IPsiModule) =
+type FSharpElementFactory(languageService: IFSharpLanguageService, sourceFile: IPsiSourceFile, psiModule: IPsiModule,
+                          [<Optional; DefaultParameterValue(null)>] extension: string) =
     let [<Literal>] moniker = "F# element factory"
 
     let getNamingService () =
@@ -31,14 +33,19 @@ type FSharpElementFactory(languageService: IFSharpLanguageService, sourceFile: I
 
     let createFile source =
         let document = createDocument source
-        let parser = languageService.CreateParser(document, sourceFile)
+        let parser = languageService.CreateParser(document, sourceFile, extension)
 
         let fsFile = parser.ParseFSharpFile(noCache = true, StandaloneDocument = document)
         SandBox.CreateSandBoxFor(fsFile, psiModule)
         fsFile
 
+    let createFileWithModule source =
+        createFile $"module X
+{source}
+"
+
     let getModuleDeclaration source =
-        let fsFile = createFile source
+        let fsFile = createFileWithModule source
         fsFile.ModuleDeclarations.First()
 
     let getModuleMember source =
@@ -395,3 +402,25 @@ type FSharpElementFactory(languageService: IFSharpLanguageService, sourceFile: I
             let source = $"member val P = 3 with {accessors}"
             let t = getTypeDecl source
             t.MemberDeclarations[0].As<IAutoPropertyDeclaration>().AccessorsClause
+
+        member this.CreateEmptyFile() = createFile ""
+
+        member this.CreateModule(name) =
+            let file = createFile $"module {name}"
+            file.ModuleDeclarations.[0] :?> INamedModuleDeclaration
+
+        member this.CreateNamespace(name) =
+            let file = createFile $"namespace {name}"
+            file.ModuleDeclarations.[0] :?> INamespaceDeclaration
+
+        member this.CreateNestedModule(name) =
+            let file = createFileWithModule $"module {name} = begin end"
+            file.ModuleDeclarations.[0].Members.[0] :?> INestedModuleDeclaration
+
+        member this.CreateModuleMember(source) =
+            let file = createFileWithModule source
+            file.ModuleDeclarations.[0].Members.[0]
+
+        member this.CreateTypeMemberSignature(source) =
+            (getTypeDecl source).TypeMembers.[0]
+            :> IFSharpTypeMemberDeclaration

ReSharper.FSharp/src/FSharp.Psi.Features/src/LanguageService/FSharpLanguageService.fs

@@ -142,8 +142,9 @@ type FSharpLanguageService(languageType, constantValueService, cacheProvider: FS
     override x.GetTypeConversionRule(_, _) = ClrPredefinedTypeConversionRule.INSTANCE
 
     interface IFSharpLanguageService with
-        member x.CreateParser(document: IDocument, sourceFile, [<Optional; DefaultParameterValue(false)>] useFsExtension) =
+        member x.CreateParser(document: IDocument, sourceFile, [<Optional; DefaultParameterValue(null)>] overrideExtension) =
             let lexer = TokenBuffer(lexerFactory.CreateLexer(document.Buffer)).CreateLexer()
-            FSharpParser(lexer, document, sourceFile, checkerService, null, useFsExtension) :> _
+            FSharpParser(lexer, document, sourceFile, checkerService, null, overrideExtension) :> _
 
-        member x.CreateElementFactory(sourceFile, psiModule) = FSharpElementFactory(x, sourceFile, psiModule) :> _
+        member x.CreateElementFactory(sourceFile, psiModule, [<Optional; DefaultParameterValue(null)>] extension) =
+            FSharpElementFactory(x, sourceFile, psiModule, extension) :> _

ReSharper.FSharp/src/FSharp.Psi.Features/src/Parsing/FSharpParser.fs

@@ -64,9 +64,11 @@ type FSharpParser(lexer: ILexer, document: IDocument, path: VirtualFileSystemPat
         let path = if isNotNull sourceFile then sourceFile.GetLocation() else null
         FSharpParser(lexer, document, path, sourceFile, checkerService, symbolsCache)
 
-    new (lexer, document, sourceFile: IPsiSourceFile, checkerService, symbolsCache, useFsExtension) =
+    new (lexer, document, sourceFile: IPsiSourceFile, checkerService, symbolsCache, overrideExtension: string) =
         let path =
-            if not useFsExtension && isNotNull sourceFile && sourceFile.LanguageType.Is<FSharpSignatureProjectFileType>() then
+            if isNotNull overrideExtension && overrideExtension = ".fsi" then
+                FSharpParser.SandBoxSignaturePath
+            elif isNull overrideExtension && isNotNull sourceFile && sourceFile.LanguageType.Is<FSharpSignatureProjectFileType>() then
                 FSharpParser.SandBoxSignaturePath
             else
                 FSharpParser.SandBoxPath

ReSharper.FSharp/src/FSharp.Psi.Features/src/Parsing/FSharpSigTreeBuilder.fs

@@ -18,15 +18,20 @@ type internal FSharpSigTreeBuilder(sourceFile, lexer, sigs, lifetime, path) =
     member x.ProcessTopLevelSignature(SynModuleOrNamespaceSig(lid, _, isModule, sigDecls, XmlDoc xmlDoc, attrs, _, range, _)) =
         let mark, elementType = x.StartTopLevelDeclaration(lid, attrs, isModule, xmlDoc, range)
         for sigDecl in sigDecls do
-            x.ProcessModuleMemberSignature(sigDecl)
+            x.ProcessModuleMemberSignature(sigDecl, range)
         x.FinishTopLevelDeclaration(mark, range, elementType)
 
-    member x.ProcessModuleMemberSignature(moduleMember) =
+    member x.ProcessModuleMemberSignature(moduleMember, parentRange) =
         match moduleMember with
         | SynModuleSigDecl.NestedModule(SynComponentInfo(attrs, _, _, _, XmlDoc xmlDoc, _, _, _), _, memberSigs, range, _) ->
             let mark = x.MarkAndProcessIntro(attrs, xmlDoc, null, range)
             for memberSig in memberSigs do
-                x.ProcessModuleMemberSignature(memberSig)
+                x.ProcessModuleMemberSignature(memberSig, parentRange)
+
+            if memberSigs.IsEmpty then
+                x.AdvanceToTokenOrRangeEnd(FSharpTokenType.END, parentRange)
+                x.Advance()
+
             x.Done(mark, ElementType.NESTED_MODULE_DECLARATION)
 
         | SynModuleSigDecl.Types(typeSigs, range) ->

ReSharper.FSharp/src/FSharp.Psi/src/FSharp.psi

@@ -99,7 +99,7 @@ namedNamespaceDeclaration options { stubBase="FSharpDeclarationBase"; }:
   topLevelNamedDeclarationName
   moduleMember<MODULE_MEMBER, Members>*;
 
-globalNamespaceDeclaration options { stubBase="FSharpDeclarationBase"; }:
+globalNamespaceDeclaration options { stubBase="NamedNamespaceDeclaration"; }:
   NAMESPACE<NAMESPACE, ModuleOrNamespaceKeyword>
   REC<REC, RecKeyword>?
   GLOBAL<GLOBAL, GlobalKeyword>

ReSharper.FSharp/src/FSharp.Psi/src/IFSharpElementFactory.cs

@@ -1,6 +1,7 @@
 using System;
 using FSharp.Compiler.Symbols;
 using JetBrains.ReSharper.Plugins.FSharp.Psi.Tree;
+using JetBrains.ReSharper.Psi.Tree;
 using Microsoft.FSharp.Collections;
 
 namespace JetBrains.ReSharper.Plugins.FSharp.Psi
@@ -64,5 +65,13 @@ public interface IFSharpElementFactory
     ITypeParameterDeclarationList CreateTypeParameterOfTypeList(FSharpList<string> names);
 
     IAccessorsNamesClause CreateAccessorsNamesClause(bool withGetter, bool withSetter);
+
+    IFSharpFile CreateEmptyFile();
+    INamedModuleDeclaration CreateModule(string name);
+    INamespaceDeclaration CreateNamespace(string name);
+    INestedModuleDeclaration CreateNestedModule(string name);
+
+    IModuleMember CreateModuleMember(string source);
+    IFSharpTypeMemberDeclaration CreateTypeMemberSignature(string source);
   }
 }

ReSharper.FSharp/src/FSharp.Psi/src/IFSharpLanguageService.cs

@@ -7,7 +7,7 @@ namespace JetBrains.ReSharper.Plugins.FSharp.Psi
 {
   public interface IFSharpLanguageService
   {
-    IFSharpParser CreateParser(IDocument document, IPsiSourceFile sourceFile, bool useFsExtension = false);
-    IFSharpElementFactory CreateElementFactory(IPsiSourceFile sourceFile, IPsiModule psiModule);
+    IFSharpParser CreateParser(IDocument document, IPsiSourceFile sourceFile, string overrideExtension = null);
+    IFSharpElementFactory CreateElementFactory(IPsiSourceFile sourceFile, IPsiModule psiModule, string overrideExtension = null);
   }
 }

ReSharper.FSharp/src/FSharp.Psi/src/Tree/IGlobalNamespaceDeclaration.cs

@@ -0,0 +1,8 @@
+using JetBrains.ReSharper.Psi.Tree;
+
+namespace JetBrains.ReSharper.Plugins.FSharp.Psi.Tree
+{
+  public partial interface IGlobalNamespaceDeclaration : INamespaceDeclaration
+  {
+  }
+}

ReSharper.FSharp/test/data/parsing/signatures/_.fsi

@@ -0,0 +1 @@
+module X

ReSharper.FSharp/test/src/FSharp.Tests/Parsing/FSharpParserTest.fs

@@ -684,6 +684,9 @@ type FSharpSignatureParserTest() =
 
     override x.RelativeTestDataPath = "parsing/signatures"
 
+    /// Use this test case to dump the psi tree for a given file, see `_.fsi`. 
+    [<Test; Explicit>] member x.``_``() = x.DoNamedTest()
+
     [<Test>] member x.``Type decl - Union 01 - After nested module``() = x.DoNamedTest()
     [<Test>] member x.``Type decl - Union 02 - FullType``() = x.DoNamedTest()
     [<Test>] member x.``Type decl - Delegate``() = x.DoNamedTest()