Raw outline of feature proposal.

Author: nojaf

ReSharper.FSharp/src/FSharp.Psi.Intentions/FSharp.Psi.Intentions.fsproj

@@ -25,6 +25,7 @@
     <Compile Include="src\Intentions\SetNameAction.fs" />
     <Compile Include="src\Intentions\LetToUseAction.fs" />
     <Compile Include="src\Intentions\RenameFileToMatchTypeNameAction.fs" />
+    <Compile Include="src\Intentions\GenerateSignatureFileAction.fs" />
     <Compile Include="src\QuickFixes\FSharpQuickFixBase.fs" />
     <Compile Include="src\QuickFixes\RemoveUnusedOpensFix.fs" />
     <Compile Include="src\QuickFixes\ReplaceUseWithLetFix.fs" />

ReSharper.FSharp/src/FSharp.Psi.Intentions/src/Intentions/GenerateSignatureFileAction.fs

@@ -0,0 +1,28 @@
+namespace JetBrains.ReSharper.Plugins.FSharp.Psi.Features.ContextActions
+
+open System.IO
+open JetBrains.Application.UI.ActionsRevised.Menu
+open JetBrains.ReSharper.Plugins.FSharp.Psi.Features.Intentions
+
+type GenerateSignatureFileAction(dataProvider: FSharpContextActionDataProvider) =
+    interface IExecutableAction with
+        member this.Update(context, presentation, nextUpdate) =
+            let sourceFile = dataProvider.SourceFile.Name
+            let fsiFile = Path.ChangeExtension(sourceFile, ".fsi")
+            not (File.Exists fsiFile)
+            
+        member this.Execute(context, nextExecute) =
+            let sourceFile = dataProvider.SourceFile.Name
+            let fsiFile = Path.ChangeExtension(sourceFile, ".fsi")
+            let currentFSharpFile = dataProvider.PsiFile
+            let fcsService = currentFSharpFile.FcsCheckerService
+            let checkResult = fcsService.ParseAndCheckFile(currentFSharpFile.GetSourceFile(), "for signature file", true)
+            match checkResult with
+            | None -> ()
+            | Some { CheckResults = checkResult } ->
+            
+            match checkResult.GenerateSignature() with
+            | None -> ()
+            | Some signatureSourceText ->
+                let content = string signatureSourceText
+                File.WriteAllText(fsiFile, content)