return the last-computed value when evaluating script code (#7524)

* return the last-computed value when evaluating script code

* manually track last produced value

* set last value on all branches

Author: brettfo

src/fsharp/fsi/fsi.fs

@@ -1139,6 +1139,7 @@ type internal FsiDynamicCompiler
         let newState = { istate with tcState = tcState.NextStateAfterIncrementalFragment(tcEnvAtEndOfLastInput) }
 
         // Find all new declarations the EvaluationListener
+        let mutable lastValue = None
         try
             let contents = FSharpAssemblyContents(tcGlobals, tcState.Ccu, Some tcState.CcuSig, tcImports, declaredImpls)
             let contentFile = contents.ImplementationFiles.[0]
@@ -1163,20 +1164,21 @@ type internal FsiDynamicCompiler
                         let symbol = FSharpSymbol.Create(cenv, v.Item)
                         let symbolUse = FSharpSymbolUse(tcGlobals, newState.tcState.TcEnvFromImpls.DisplayEnv, symbol, ItemOccurence.Binding, v.DeclarationLocation)
                         fsi.TriggerEvaluation (fsiValueOpt, symbolUse, decl)
+                        lastValue <- fsiValueOpt
                     | FSharpImplementationFileDeclaration.Entity (e,_) ->
                         // Report a top-level module or namespace definition
                         let symbol = FSharpSymbol.Create(cenv, e.Item)
                         let symbolUse = FSharpSymbolUse(tcGlobals, newState.tcState.TcEnvFromImpls.DisplayEnv, symbol, ItemOccurence.Binding, e.DeclarationLocation)
                         fsi.TriggerEvaluation (None, symbolUse, decl)
+                        lastValue <- None
                     | FSharpImplementationFileDeclaration.InitAction _ ->
                         // Top level 'do' bindings are not reported as incremental declarations
-                        ()
+                        lastValue <- None
             | _ -> ()
         with _ -> ()
 
-        newState
-      
-     
+        newState, Completed lastValue
+
     /// Evaluate the given expression and produce a new interactive state.
     member fsiDynamicCompiler.EvalParsedExpression (ctok, errorLogger: ErrorLogger, istate, expr: SynExpr) =
         let tcConfig = TcConfig.Create (tcConfigB, validate=false)
@@ -1186,7 +1188,7 @@ type internal FsiDynamicCompiler
         let defs = fsiDynamicCompiler.BuildItBinding expr
 
         // Evaluate the overall definitions.
-        let istate = fsiDynamicCompiler.EvalParsedDefinitions (ctok, errorLogger, istate, false, true, defs)
+        let istate = fsiDynamicCompiler.EvalParsedDefinitions (ctok, errorLogger, istate, false, true, defs) |> fst
         // Snarf the type for 'it' via the binding
         match istate.tcState.TcEnvFromImpls.NameEnv.FindUnqualifiedItem itName with 
         | NameResolution.Item.Value vref -> 
@@ -1787,7 +1789,7 @@ type internal FsiInteractionProcessor
             | IDefns ([  SynModuleDecl.DoExpr(_,expr,_)],_) ->
                 fsiDynamicCompiler.EvalParsedExpression(ctok, errorLogger, istate, expr)
             | IDefns (defs,_) -> 
-                fsiDynamicCompiler.EvalParsedDefinitions (ctok, errorLogger, istate, true, false, defs),Completed None
+                fsiDynamicCompiler.EvalParsedDefinitions (ctok, errorLogger, istate, true, false, defs)
 
             | IHash (ParsedHashDirective("load",sourceFiles,m),_) -> 
                 fsiDynamicCompiler.EvalSourceFiles (ctok, istate, m, sourceFiles, lexResourceManager, errorLogger),Completed None
@@ -2085,7 +2087,7 @@ type internal FsiInteractionProcessor
     /// Send a dummy interaction through F# Interactive, to ensure all the most common code generation paths are 
     /// JIT'ed and ready for use.
     member __.LoadDummyInteraction(ctok, errorLogger) =
-        setCurrState (currState |> InteractiveCatch errorLogger (fun istate ->  fsiDynamicCompiler.EvalParsedDefinitions (ctok, errorLogger, istate, true, false, []), Completed None) |> fst)
+        setCurrState (currState |> InteractiveCatch errorLogger (fun istate ->  fsiDynamicCompiler.EvalParsedDefinitions (ctok, errorLogger, istate, true, false, []) |> fst, Completed None) |> fst)
 
     member __.EvalInteraction(ctok, sourceText, scriptFileName, errorLogger) =
         use _unwind1 = ErrorLogger.PushThreadBuildPhaseUntilUnwind(ErrorLogger.BuildPhase.Interactive)