Fixes #17438 - Ensure that isinteractive multi-emit backing fields are not public

docs/release-notes/.FSharp.Compiler.Service/9.0.100.md

@@ -15,5 +15,6 @@
 * Treat `{ new Foo() }` as `SynExpr.ObjExpr` ([PR #17388](https://github.com/dotnet/fsharp/pull/17388))
 * Optimize metadata reading for type members and custom attributes. ([PR #17364](https://github.com/dotnet/fsharp/pull/17364))
 * Enforce `AttributeTargets` on unions. ([PR #17389](https://github.com/dotnet/fsharp/pull/17389))
+* Ensure that isinteractive multi-emit backing fields are not public. ([Issue #17439](https://github.com/dotnet/fsharp/issues/17438)), ([PR #17439](https://github.com/dotnet/fsharp/pull/17439))
 
 ### Breaking Changes

src/Compiler/CodeGen/IlxGen.fs

@@ -2082,14 +2082,7 @@ type AnonTypeGenerationTable() =
                 mkILFields
                     [
                         for _, fldName, fldTy in flds ->
-
-                            let access =
-                                if cenv.options.isInteractive && cenv.options.fsiMultiAssemblyEmit then
-                                    ILMemberAccess.Public
-                                else
-                                    ILMemberAccess.Private
-
-                            let fdef = mkILInstanceField (fldName, fldTy, None, access)
+                            let fdef = mkILInstanceField (fldName, fldTy, None, ILMemberAccess.Private)
                             let attrs = [ g.CompilerGeneratedAttribute; g.DebuggerBrowsableNeverAttribute ]
                             fdef.With(customAttrs = mkILCustomAttrs attrs)
                     ]
@@ -11059,13 +11052,7 @@ and GenTypeDef cenv mgbuf lazyInitInfo eenv m (tycon: Tycon) : ILTypeRef option
                         // The IL field is hidden if the property/field is hidden OR we're using a property
                         // AND the field is not mutable (because we can take the address of a mutable field).
                         // Otherwise fields are always accessed via their property getters/setters
-                        //
-                        // Additionally, don't hide fields for multiemit in F# Interactive
-                        let isFieldHidden =
-                            isPropHidden
-                            || (not useGenuineField
-                                && not isFSharpMutable
-                                && not (cenv.options.isInteractive && cenv.options.fsiMultiAssemblyEmit))
+                        let isFieldHidden = isPropHidden || (not useGenuineField && not isFSharpMutable)
 
                         let extraAttribs =
                             match tyconRepr with

src/Compiler/Driver/OptimizeInputs.fs

@@ -389,7 +389,6 @@ let ApplyAllOptimizations
                 importMap,
                 prevFile.FirstLoopRes.OptEnv,
                 isIncrementalFragment,
-                tcConfig.fsiMultiAssemblyEmit,
                 tcConfig.emitTailcalls,
                 prevFile.FirstLoopRes.HidingInfo,
                 file
@@ -436,7 +435,6 @@ let ApplyAllOptimizations
                 importMap,
                 prevFile.OptEnvExtraLoop,
                 isIncrementalFragment,
-                tcConfig.fsiMultiAssemblyEmit,
                 tcConfig.emitTailcalls,
                 prevPhase.FirstLoopRes.HidingInfo,
                 file
@@ -507,7 +505,6 @@ let ApplyAllOptimizations
                 importMap,
                 prevFile.OptEnvFinalSimplify,
                 isIncrementalFragment,
-                tcConfig.fsiMultiAssemblyEmit,
                 tcConfig.emitTailcalls,
                 prevPhase.FirstLoopRes.HidingInfo,
                 file

src/Compiler/Interactive/fsi.fs

@@ -1861,7 +1861,12 @@ type internal FsiDynamicCompiler
 
         let asm =
             match opts.pdbfile, pdbBytes with
-            | (Some pdbfile), (Some pdbBytes) -> File.WriteAllBytes(pdbfile, pdbBytes)
+            | (Some pdbfile), (Some pdbBytes) ->
+                File.WriteAllBytes(pdbfile, pdbBytes)
+#if FOR_TESTING
+                Directory.CreateDirectory(scriptingSymbolsPath.Value) |> ignore
+                File.WriteAllBytes(Path.ChangeExtension(pdbfile, ".dll"), assemblyBytes)
+#endif
             | _ -> ()
 
             match pdbBytes with

src/Compiler/Optimize/Optimizer.fs

@@ -4348,8 +4348,7 @@ and OptimizeModuleDefs cenv (env, bindInfosColl) defs =
     let defs, minfos = List.unzip defs
     (defs, UnionOptimizationInfos minfos), (env, bindInfosColl)
 
-and OptimizeImplFileInternal cenv env isIncrementalFragment fsiMultiAssemblyEmit hidden implFile =
-    let g = cenv.g
+and OptimizeImplFileInternal cenv env isIncrementalFragment hidden implFile =
     let (CheckedImplFile (qname, pragmas, signature, contents, hasExplicitEntryPoint, isScript, anonRecdTypes, namedDebugPointsForInlinedCode)) = implFile
     let env, contentsR, minfo, hidden = 
         // FSI compiles interactive fragments as if you're typing incrementally into one module.
@@ -4361,35 +4360,23 @@ and OptimizeImplFileInternal cenv env isIncrementalFragment fsiMultiAssemblyEmit
             // This optimizes and builds minfo ignoring the signature
             let (defR, minfo), (_env, _bindInfosColl) = OptimizeModuleContents cenv (env, []) contents
             let hidden = ComputeImplementationHidingInfoAtAssemblyBoundary defR hidden
-            let minfo =
-                // In F# interactive multi-assembly mode, no internals are accessible across interactive fragments.
-                // In F# interactive single-assembly mode, internals are accessible across interactive fragments.
-                if fsiMultiAssemblyEmit then
-                    AbstractLazyModulInfoByHiding true hidden minfo
-                else
-                    AbstractLazyModulInfoByHiding false hidden minfo
+            let minfo = AbstractLazyModulInfoByHiding false hidden minfo
             let env = BindValsInModuleOrNamespace cenv minfo env
             env, defR, minfo, hidden
         else
             // This optimizes and builds minfo w.r.t. the signature
             let mexprR, minfo = OptimizeModuleExprWithSig cenv env signature contents
             let hidden = ComputeSignatureHidingInfoAtAssemblyBoundary signature hidden
             let minfoExternal = AbstractLazyModulInfoByHiding true hidden minfo
-            let env =
-                // In F# interactive multi-assembly mode, internals are not accessible in the 'env' used intra-assembly
-                // In regular fsc compilation, internals are accessible in the 'env' used intra-assembly
-                if g.isInteractive && fsiMultiAssemblyEmit then
-                    BindValsInModuleOrNamespace cenv minfoExternal env
-                else
-                    BindValsInModuleOrNamespace cenv minfo env
+            let env = BindValsInModuleOrNamespace cenv minfo env
             env, mexprR, minfoExternal, hidden
 
     let implFileR = CheckedImplFile (qname, pragmas, signature, contentsR, hasExplicitEntryPoint, isScript, anonRecdTypes, namedDebugPointsForInlinedCode)
 
     env, implFileR, minfo, hidden
 
 /// Entry point
-let OptimizeImplFile (settings, ccu, tcGlobals, tcVal, importMap, optEnv, isIncrementalFragment, fsiMultiAssemblyEmit, emitTailcalls, hidden, mimpls) =
+let OptimizeImplFile (settings, ccu, tcGlobals, tcVal, importMap, optEnv, isIncrementalFragment,  emitTailcalls, hidden, mimpls) =
     let cenv = 
         { settings=settings
           scope=ccu 
@@ -4404,7 +4391,7 @@ let OptimizeImplFile (settings, ccu, tcGlobals, tcVal, importMap, optEnv, isIncr
           realsig = tcGlobals.realsig
         }
 
-    let env, _, _, _ as results = OptimizeImplFileInternal cenv optEnv isIncrementalFragment fsiMultiAssemblyEmit hidden mimpls  
+    let env, _, _, _ as results = OptimizeImplFileInternal cenv optEnv isIncrementalFragment hidden mimpls
 
     let optimizeDuringCodeGen disableMethodSplitting expr =
         let env = { env with disableMethodSplitting = env.disableMethodSplitting || disableMethodSplitting }

src/Compiler/Optimize/Optimizer.fsi

@@ -85,7 +85,6 @@ val internal OptimizeImplFile:
     Import.ImportMap *
     IncrementalOptimizationEnv *
     isIncrementalFragment: bool *
-    fsiMultiAssemblyEmit: bool *
     emitTailcalls: bool *
     SignatureHidingInfo *
     CheckedImplFile ->

tests/FSharp.Compiler.ComponentTests/Scripting/Interactive.fs

@@ -3,9 +3,9 @@
 namespace Scripting
 
 open Xunit
+
 open System
 open FSharp.Test.Compiler
-open FSharp.Compiler.Interactive.Shell
 open FSharp.Test.ScriptHelpers
 
 module ``Interactive tests`` =
@@ -89,3 +89,38 @@ module ``External FSI tests`` =
         |> runFsi
         |> shouldSucceed
 
+
+module MultiEmit =
+
+    [<Theory>]
+    [<InlineData(true)>]
+    [<InlineData(false)>]
+    let ``FSharp record in script`` (useMultiEmit) =
+
+        let args : string array = [| if useMultiEmit then "--multiemit+" else "--multiemit-"|]
+        use session = new FSharpScript(additionalArgs=args)
+
+        let scriptIt submission =
+
+            let result, errors = session.Eval(submission)
+            Assert.Empty(errors)
+            match result with
+            | Ok _ -> ()
+            | _ -> Assert.True(false, $"Failed in line: {submission}")
+
+        [|
+            """type R = { x: int }"""
+            """let a = { x = 7 } """
+            """if a.x <> 7 then failwith $"1: Failed {a.x} <> 7" """
+            """if a.x <> 7 then failwith $"2: Failed {a.x} <> 7" """
+            """if a.x <> 7 then failwith $"3: Failed {a.x} <> 7" """
+            """if a.x <> 7 then failwith $"4: Failed {a.x} <> 7" """
+            """let b = { x = 9 }"""
+            """if a.x <> 7 then failwith $"5: Failed {a.x} <> 7" """
+            """if b.x <> 9 then failwith $"6: Failed {b.x} <> 9" """
+            """let A = {| v = 7.2 |}"""
+            """if A.v <> 7.2 then failwith $"7: Failed {A.v} <> 7.2" """
+            """let B = {| v = 9.3 |}"""
+            """if A.v <> 7.2 then failwith $"8: Failed {A.v} <> 7.2" """
+            """if B.v <> 9.3 then failwith $"9: Failed {A.v} <> 9.3" """
+        |] |> Seq.iter(fun item -> item |> scriptIt)