Fix #13197

src/Compiler/AbstractIL/il.fs

@@ -54,6 +54,14 @@ type PrimaryAssembly =
         | System_Runtime -> "System.Runtime"
         | NetStandard -> "netstandard"
 
+    static member IsPossiblePrimaryAssembly(fileName: string) =
+        let name = System.IO.Path.GetFileNameWithoutExtension(fileName)
+
+        String.Compare(name, "mscorlib", true) <> 0
+        || String.Compare(name, "System.Runtime", true) <> 0
+        || String.Compare(name, "netstandard", true) <> 0
+        || String.Compare(name, "System.Private.CoreLib", true) <> 0
+
 // --------------------------------------------------------------------
 // Utilities: type names
 // --------------------------------------------------------------------
@@ -2803,12 +2811,16 @@ and [<Sealed>] ILTypeDefs(f: unit -> ILPreTypeDef[]) =
         member x.GetEnumerator() =
             (seq { for pre in array.Value -> pre.GetTypeDef() }).GetEnumerator()
 
-    member x.AsArrayOfPreTypeDefs() = array.Value
+    member _.AsArrayOfPreTypeDefs() = array.Value
 
-    member x.FindByName nm =
+    member _.FindByName nm =
         let ns, n = splitILTypeName nm
         dict.Value[ (ns, n) ].GetTypeDef()
 
+    member _.ExistsByName nm =
+        let ns, n = splitILTypeName nm
+        dict.Value.ContainsKey((ns, n))
+
 and [<NoEquality; NoComparison>] ILPreTypeDef =
     abstract Namespace: string list
     abstract Name: string
@@ -3331,15 +3343,9 @@ let tname_UIntPtr = "System.UIntPtr"
 let tname_TypedReference = "System.TypedReference"
 
 [<NoEquality; NoComparison; StructuredFormatDisplay("{DebugText}")>]
-type ILGlobals
-    (
-        primaryScopeRef: ILScopeRef,
-        assembliesThatForwardToPrimaryAssembly: ILAssemblyRef list,
-        fsharpCoreAssemblyScopeRef: ILScopeRef
-    ) =
+type ILGlobals(primaryScopeRef: ILScopeRef, equivPrimaryAssemblyRefs: ILAssemblyRef list, fsharpCoreAssemblyScopeRef: ILScopeRef) =
 
-    let assembliesThatForwardToPrimaryAssembly =
-        Array.ofList assembliesThatForwardToPrimaryAssembly
+    let equivPrimaryAssemblyRefs = Array.ofList equivPrimaryAssemblyRefs
 
     let mkSysILTypeRef nm = mkILTyRef (primaryScopeRef, nm)
 
@@ -3394,17 +3400,16 @@ type ILGlobals
 
     member x.IsPossiblePrimaryAssemblyRef(aref: ILAssemblyRef) =
         aref.EqualsIgnoringVersion x.primaryAssemblyRef
-        || assembliesThatForwardToPrimaryAssembly
-           |> Array.exists aref.EqualsIgnoringVersion
+        || equivPrimaryAssemblyRefs |> Array.exists aref.EqualsIgnoringVersion
 
     /// For debugging
     [<DebuggerBrowsable(DebuggerBrowsableState.Never)>]
     member x.DebugText = x.ToString()
 
     override x.ToString() = "<ILGlobals>"
 
-let mkILGlobals (primaryScopeRef, assembliesThatForwardToPrimaryAssembly, fsharpCoreAssemblyScopeRef) =
-    ILGlobals(primaryScopeRef, assembliesThatForwardToPrimaryAssembly, fsharpCoreAssemblyScopeRef)
+let mkILGlobals (primaryScopeRef, equivPrimaryAssemblyRefs, fsharpCoreAssemblyScopeRef) =
+    ILGlobals(primaryScopeRef, equivPrimaryAssemblyRefs, fsharpCoreAssemblyScopeRef)
 
 let mkNormalCall mspec = I_call(Normalcall, mspec, None)
 

src/Compiler/AbstractIL/il.fsi

@@ -8,6 +8,7 @@ open FSharp.Compiler.IO
 open System.Collections.Generic
 open System.Reflection
 
+/// Represents the target primary assembly
 [<RequireQualifiedAccess>]
 type internal PrimaryAssembly =
     | Mscorlib
@@ -16,6 +17,11 @@ type internal PrimaryAssembly =
 
     member Name: string
 
+    /// Checks if an assembly resolution may represent a primary assembly that actually contains the
+    /// definition of Sytem.Object.  Note that the chosen target primary assembly may not actually be the one
+    /// that contains the definition of System.Object - it is just the one we are choosing to emit for.
+    static member IsPossiblePrimaryAssembly: fileName: string -> bool
+
 /// Represents guids
 type ILGuid = byte[]
 
@@ -1407,12 +1413,12 @@ type ILTypeDefs =
     /// Get some information about the type defs, but do not force the read of the type defs themselves.
     member internal AsArrayOfPreTypeDefs: unit -> ILPreTypeDef[]
 
-    /// Calls to <c>FindByName</c> will result in any laziness in the overall
-    /// set of ILTypeDefs being read in in addition
-    /// to the details for the type found, but the remaining individual
-    /// type definitions will not be read.
+    /// Calls to <c>FindByName</c> will result in all the ILPreTypeDefs being read.
     member internal FindByName: string -> ILTypeDef
 
+    /// Calls to <c>ExistsByName</c> will result in all the ILPreTypeDefs being read.
+    member internal ExistsByName: string -> bool
+
 /// Represents IL Type Definitions.
 [<NoComparison; NoEquality>]
 type ILTypeDef =
@@ -1841,10 +1847,11 @@ type internal ILGlobals =
     member IsPossiblePrimaryAssemblyRef: ILAssemblyRef -> bool
 
 /// Build the table of commonly used references given functions to find types in system assemblies
+///
+///   primaryScopeRef is the primary assembly we are emitting
+///   equivPrimaryAssemblyRefs are ones regarded as equivalent
 val internal mkILGlobals:
-    primaryScopeRef: ILScopeRef *
-    assembliesThatForwardToPrimaryAssembly: ILAssemblyRef list *
-    fsharpCoreAssemblyScopeRef: ILScopeRef ->
+    primaryScopeRef: ILScopeRef * equivPrimaryAssemblyRefs: ILAssemblyRef list * fsharpCoreAssemblyScopeRef: ILScopeRef ->
         ILGlobals
 
 val internal PrimaryAssemblyILGlobals: ILGlobals

src/Compiler/Driver/CompilerImports.fs

@@ -2321,13 +2321,13 @@ and [<Sealed>] TcImports
                 | _, [ ResolvedImportedAssembly ccu ] -> ccu.FSharpViewOfMetadata.ILScopeRef
                 | _ -> failwith "primaryScopeRef - unexpected"
 
+            let resolvedAssemblies = tcResolutions.GetAssemblyResolutions()
+
             let primaryAssemblyResolvedPath =
                 match primaryAssemblyResolution with
                 | [ primaryAssemblyResolution ] -> primaryAssemblyResolution.resolvedPath
                 | _ -> failwith "primaryAssemblyResolvedPath - unexpected"
 
-            let resolvedAssemblies = tcResolutions.GetAssemblyResolutions()
-
             let readerSettings: ILReaderOptions =
                 {
                     pdbDirPath = None
@@ -2336,28 +2336,28 @@ and [<Sealed>] TcImports
                     tryGetMetadataSnapshot = tcConfig.tryGetMetadataSnapshot
                 }
 
-            let tryFindAssemblyByExportedType manifest (exportedType: ILExportedTypeOrForwarder) =
-                match exportedType.ScopeRef, primaryScopeRef with
-                | ILScopeRef.Assembly aref1, ILScopeRef.Assembly aref2 when aref1.EqualsIgnoringVersion aref2 ->
-                    mkRefToILAssembly manifest |> Some
-                | _ -> None
-
-            let tryFindAssemblyThatForwardsToPrimaryAssembly manifest =
-                manifest.ExportedTypes.TryFindByName "System.Object"
-                |> Option.bind (tryFindAssemblyByExportedType manifest)
-
-            // Determine what other assemblies could have been the primary assembly
-            // by checking to see if "System.Object" is an exported type.
-            let assembliesThatForwardToPrimaryAssembly =
-                resolvedAssemblies
-                |> List.choose (fun resolvedAssembly ->
-                    if primaryAssemblyResolvedPath <> resolvedAssembly.resolvedPath then
-                        let reader = OpenILModuleReader resolvedAssembly.resolvedPath readerSettings
-
-                        reader.ILModuleDef.Manifest
-                        |> Option.bind tryFindAssemblyThatForwardsToPrimaryAssembly
-                    else
-                        None)
+            let tryFindEquivPrimaryAssembly (resolvedAssembly: AssemblyResolution) =
+                if primaryAssemblyResolvedPath = resolvedAssembly.resolvedPath then
+                    None
+                else
+                    let reader = OpenILModuleReader resolvedAssembly.resolvedPath readerSettings
+                    let mdef = reader.ILModuleDef
+
+                    // We check the exported types of all assemblies, since many may forward System.Object,
+                    // but only check the actual type definitions for specific assemblies that we know
+                    // might actually declare System.Object.
+                    match mdef.Manifest with
+                    | Some manifest when
+                        manifest.ExportedTypes.TryFindByName "System.Object" |> Option.isSome
+                        || PrimaryAssembly.IsPossiblePrimaryAssembly resolvedAssembly.resolvedPath
+                           && mdef.TypeDefs.ExistsByName "System.Object"
+                        ->
+                        mkRefToILAssembly manifest |> Some
+                    | _ -> None
+
+            // Find assemblies which also declare System.Object
+            let equivPrimaryAssemblyRefs =
+                resolvedAssemblies |> List.choose tryFindEquivPrimaryAssembly
 
             let! fslibCcu, fsharpCoreAssemblyScopeRef =
                 node {
@@ -2406,7 +2406,7 @@ and [<Sealed>] TcImports
                 sysCcus |> Array.tryFind (fun ccu -> ccuHasType ccu path typeName)
 
             let ilGlobals =
-                mkILGlobals (primaryScopeRef, assembliesThatForwardToPrimaryAssembly, fsharpCoreAssemblyScopeRef)
+                mkILGlobals (primaryScopeRef, equivPrimaryAssemblyRefs, fsharpCoreAssemblyScopeRef)
 
             // OK, now we have both mscorlib.dll and FSharp.Core.dll we can create TcGlobals
             let tcGlobals =

tests/FSharp.Compiler.UnitTests/FsiTests.fs

@@ -6,6 +6,13 @@ open FluentAssertions
 open FSharp.Compiler.Interactive.Shell
 open FSharp.Test
 open Xunit
+open System.Threading
+
+type Sentinel () =
+    let x = ()
+
+module MyModule =
+    let test(x: int) = ()
 
 [<Collection("SingleThreaded")>]
 module FsiTests =
@@ -636,3 +643,38 @@ module FsiTests =
         let boundValue = fsiSession.GetBoundValues() |> List.exactlyOne
         Assert.shouldBe typeof<CustomType2[,]> boundValue.Value.ReflectionType
         boundValue.Value.ReflectionValue.Should().Be(mdArr, "") |> ignore
+
+#if NETCOREAPP
+    [<Fact>]
+    let ``Evaluating simple reference and code succeeds under permutations``() =
+
+        for useSdkRefsFlag in ["/usesdkrefs"; "/usesdkrefs-"] do
+            for multiemitFlag in ["/multiemit"; "/multiemit-"] do
+                let config = FsiEvaluationSession.GetDefaultConfiguration()
+                let argv = [|
+                    typeof<Sentinel>.Assembly.Location
+                    "--noninteractive"
+                    "--targetprofile:netcore"
+                    "--langversion:preview"
+                    multiemitFlag
+                    useSdkRefsFlag
+                    |]
+                let fsi = FsiEvaluationSession.Create(config, argv, TextReader.Null, TextWriter.Null, TextWriter.Null)
+                let assemblyPath = typeof<Sentinel>.Assembly.Location.Replace("\\", "/")
+                let code = $@"
+            #r ""{assemblyPath}""
+            FSharp.Compiler.UnitTests.MyModule.test(3)"
+                let ch, errors = fsi.EvalInteractionNonThrowing(code, CancellationToken.None)
+                errors
+                |> Array.iter (fun e -> printfn "error: %A" e)
+                match ch with
+                | Choice1Of2 v ->
+                    let v =
+                        match v with
+                        | Some v -> sprintf "%A" v.ReflectionValue
+                        | None -> "(none)"
+                    printfn "value: %A" v
+                | Choice2Of2 e ->
+                    printfn "exception: %A" e
+                    raise e
+#endif