Nullness bugfix - change isObjTy early returns in ConstraintSolver

.fantomasignore

@@ -117,6 +117,9 @@ src/Compiler/Facilities/AsyncMemoize.fsi
 src/Compiler/Facilities/AsyncMemoize.fs
 src/Compiler/AbstractIL/il.fs
 
+src/Compiler/Driver/GraphChecking/Graph.fsi
+src/Compiler/Driver/GraphChecking/Graph.fs
+
 # Fantomas limitations on implementation files  (to investigate)
 
 src/Compiler/AbstractIL/ilwrite.fs

docs/release-notes/.FSharp.Compiler.Service/9.0.200.md

@@ -1,11 +1,11 @@
 ### Fixed
 
+* Fix false negatives for passing null to "obj" arguments. Only "obj | null" can now subsume any type ([PR #17757](https://github.com/dotnet/fsharp/pull/17757))
 * Fix internal error when calling 'AddSingleton' and other overloads only differing in generic arity ([PR #17804](https://github.com/dotnet/fsharp/pull/17804))
 * Fix extension methods support for non-reference system assemblies ([PR #17799](https://github.com/dotnet/fsharp/pull/17799))
 * Ensure `frameworkTcImportsCache` mutations are thread-safe. ([PR #17795](https://github.com/dotnet/fsharp/pull/17795))
 * Fix concurrency issue in `ILPreTypeDefImpl`  ([PR #17812](https://github.com/dotnet/fsharp/pull/17812))
 
-
 ### Added
 
 

src/Compiler/AbstractIL/ilreflect.fs

@@ -277,7 +277,7 @@ type TypeBuilder with
 
         match m with
         | null -> raise (MissingMethodException nm)
-        | m -> m.Invoke(null, args)
+        | m -> m.Invoke(null, (args: obj array))
 
     member typB.SetCustomAttributeAndLog(cinfo, bytes) =
         if logRefEmitCalls then

src/Compiler/Checking/AttributeChecking.fs

@@ -466,9 +466,9 @@ let MethInfoIsUnseen g (m: range) (ty: TType) minfo =
 
     let isUnseenByHidingAttribute () = 
 #if !NO_TYPEPROVIDERS
-        not (isObjTy g ty) &&
+        not (isObjTyAnyNullness g ty) &&
         isAppTy g ty &&
-        isObjTy g minfo.ApparentEnclosingType &&
+        isObjTyAnyNullness g minfo.ApparentEnclosingType &&
         let tcref = tcrefOfAppTy g ty 
         match tcref.TypeReprInfo with 
         | TProvidedTypeRepr info -> 

src/Compiler/Checking/Expressions/CheckExpressions.fs

@@ -3283,7 +3283,7 @@ let AnalyzeArbitraryExprAsEnumerable (cenv: cenv) (env: TcEnv) localAlloc m expr
 
         let enumElemTy =
 
-            if isObjTy g enumElemTy then
+            if isObjTyAnyNullness g enumElemTy then
                 // Look for an 'Item' property, or a set of these with consistent return types
                 let allEquivReturnTypes (minfo: MethInfo) (others: MethInfo list) =
                     let returnTy = minfo.GetFSharpReturnType(cenv.amap, m, [])
@@ -6195,7 +6195,7 @@ and TcExprObjectExpr (cenv: cenv) overallTy env tpenv (synObjTy, argopt, binds,
                 errorR(Error(FSComp.SR.tcCannotInheritFromErasedType(), m))
             (m, intfTy, overrides), tpenv)
 
-    let realObjTy = if isObjTy g objTy && not (isNil extraImpls) then (p23 (List.head extraImpls)) else objTy
+    let realObjTy = if isObjTyAnyNullness g objTy && not (isNil extraImpls) then (p23 (List.head extraImpls)) else objTy
 
     TcPropagatingExprLeafThenConvert cenv overallTy realObjTy env (* canAdhoc *) m (fun () ->
         TcObjectExpr cenv env tpenv (objTy, realObjTy, argopt, binds, extraImpls, mObjTy, mNewExpr, m)
@@ -7320,7 +7320,7 @@ and TcFormatStringExpr cenv (overallTy: OverallTy) env m tpenv (fmtString: strin
     let formatTy = mkPrintfFormatTy g aty bty cty dty ety
 
     // This might qualify as a format string - check via a type directed rule
-    let ok = not (isObjTy g overallTy.Commit) && AddCxTypeMustSubsumeTypeUndoIfFailed env.DisplayEnv cenv.css m overallTy.Commit formatTy
+    let ok = not (isObjTyAnyNullness g overallTy.Commit) && AddCxTypeMustSubsumeTypeUndoIfFailed env.DisplayEnv cenv.css m overallTy.Commit formatTy
 
     if ok then
         // Parse the format string to work out the phantom types
@@ -7399,7 +7399,7 @@ and TcInterpolatedStringExpr cenv (overallTy: OverallTy) env m tpenv (parts: Syn
             Choice1Of2 (true, newFormatMethod)
 
         // ... or if that fails then may be a FormattableString by a type-directed rule....
-        elif (not (isObjTy g overallTy.Commit) &&
+        elif (not (isObjTyAnyNullness g overallTy.Commit) &&
               ((g.system_FormattableString_tcref.CanDeref && AddCxTypeMustSubsumeTypeUndoIfFailed env.DisplayEnv cenv.css m overallTy.Commit g.system_FormattableString_ty)
                || (g.system_IFormattable_tcref.CanDeref && AddCxTypeMustSubsumeTypeUndoIfFailed env.DisplayEnv cenv.css m overallTy.Commit g.system_IFormattable_ty))) then
 
@@ -7420,7 +7420,7 @@ and TcInterpolatedStringExpr cenv (overallTy: OverallTy) env m tpenv (parts: Syn
             | None -> languageFeatureNotSupportedInLibraryError LanguageFeature.StringInterpolation m
 
         // ... or if that fails then may be a PrintfFormat by a type-directed rule....
-        elif not (isObjTy g overallTy.Commit) && AddCxTypeMustSubsumeTypeUndoIfFailed env.DisplayEnv cenv.css m overallTy.Commit formatTy then
+        elif not (isObjTyAnyNullness g overallTy.Commit) && AddCxTypeMustSubsumeTypeUndoIfFailed env.DisplayEnv cenv.css m overallTy.Commit formatTy then
 
             // And if that succeeds, the printerTy and printerResultTy must be the same (there are no curried arguments)
             UnifyTypes cenv env m printerTy printerResultTy

src/Compiler/Checking/InfoReader.fs

@@ -1082,7 +1082,7 @@ let TryDestStandardDelegateType (infoReader: InfoReader) m ad delTy =
     let g = infoReader.g
     let (SigOfFunctionForDelegate(_, delArgTys, delRetTy, _)) = GetSigOfFunctionForDelegate infoReader delTy m ad
     match delArgTys with 
-    | senderTy :: argTys when (isObjTy g senderTy) && not (List.exists (isByrefTy g) argTys)  -> Some(mkRefTupledTy g argTys, delRetTy)
+    | senderTy :: argTys when (isObjTyAnyNullness g senderTy) && not (List.exists (isByrefTy g) argTys)  -> Some(mkRefTupledTy g argTys, delRetTy)
     | _ -> None
 
 

src/Compiler/Checking/MethodCalls.fs

@@ -1319,7 +1319,7 @@ let BuildNewDelegateExpr (eventInfoOpt: EventInfo option, g, amap, delegateTy, d
                     | Some einfo -> 
                         match delArgVals with 
                         | [] -> error(nonStandardEventError einfo.EventName m)
-                        | h :: _ when not (isObjTy g h.Type) -> error(nonStandardEventError einfo.EventName m)
+                        | h :: _ when not (isObjTyAnyNullness g h.Type) -> error(nonStandardEventError einfo.EventName m)
                         | h :: t -> [exprForVal m h; mkRefTupledVars g m t] 
                     | None -> 
                         if isNil delArgTys then [mkUnit g m] else List.map (exprForVal m) delArgVals

src/Compiler/Checking/NameResolution.fs

@@ -4422,14 +4422,14 @@ let ResolveCompletionsInType (ncenv: NameResolver) nenv (completionTargets: Reso
         //
         // Don't show GetHashCode or Equals for F# types that admit equality as an abnormal operation
         let isUnseenDueToBasicObjRules =
-            not (isObjTy g ty) &&
+            not (isObjTyAnyNullness g ty) &&
             not minfo.IsExtensionMember &&
             match minfo.LogicalName with
             | "GetType"  -> false
-            | "GetHashCode"  -> isObjTy g minfo.ApparentEnclosingType && not (AugmentTypeDefinitions.TypeDefinitelyHasEquality g ty)
+            | "GetHashCode"  -> isObjTyAnyNullness g minfo.ApparentEnclosingType && not (AugmentTypeDefinitions.TypeDefinitelyHasEquality g ty)
             | "ToString" -> false
             | "Equals" ->
-                if not (isObjTy g minfo.ApparentEnclosingType) then
+                if not (isObjTyAnyNullness g minfo.ApparentEnclosingType) then
                     // declaring type is not System.Object - show it
                     false
                 elif minfo.IsInstance then
@@ -4440,7 +4440,7 @@ let ResolveCompletionsInType (ncenv: NameResolver) nenv (completionTargets: Reso
                     true
             | _ ->
                 // filter out self methods of obj type
-                isObjTy g minfo.ApparentEnclosingType
+                isObjTyAnyNullness g minfo.ApparentEnclosingType
 
         let result =
             not isUnseenDueToBasicObjRules &&
@@ -5121,14 +5121,14 @@ let ResolveCompletionsInTypeForItem (ncenv: NameResolver) nenv m ad statics ty (
                 //
                 // Don't show GetHashCode or Equals for F# types that admit equality as an abnormal operation
                 let isUnseenDueToBasicObjRules =
-                    not (isObjTy g ty) &&
+                    not (isObjTyAnyNullness g ty) &&
                     not minfo.IsExtensionMember &&
                     match minfo.LogicalName with
                     | "GetType"  -> false
-                    | "GetHashCode"  -> isObjTy g minfo.ApparentEnclosingType && not (AugmentTypeDefinitions.TypeDefinitelyHasEquality g ty)
+                    | "GetHashCode"  -> isObjTyAnyNullness g minfo.ApparentEnclosingType && not (AugmentTypeDefinitions.TypeDefinitelyHasEquality g ty)
                     | "ToString" -> false
                     | "Equals" ->
-                        if not (isObjTy g minfo.ApparentEnclosingType) then
+                        if not (isObjTyAnyNullness g minfo.ApparentEnclosingType) then
                             // declaring type is not System.Object - show it
                             false
                         elif minfo.IsInstance then
@@ -5139,7 +5139,7 @@ let ResolveCompletionsInTypeForItem (ncenv: NameResolver) nenv m ad statics ty (
                             true
                     | _ ->
                         // filter out self methods of obj type
-                        isObjTy g minfo.ApparentEnclosingType
+                        isObjTyAnyNullness g minfo.ApparentEnclosingType
                 let result =
                     not isUnseenDueToBasicObjRules &&
                     not minfo.IsInstance = statics &&

src/Compiler/Checking/NicePrint.fs

@@ -2191,7 +2191,7 @@ module TastDefinitionPrinting =
         let inherits = 
             [ if not (suppressInheritanceAndInterfacesForTyInSimplifiedDisplays g amap m ty) then 
                 match GetSuperTypeOfType g amap m ty with 
-                | Some superTy when not (isObjTy g superTy) && not (isValueTypeTy g superTy) ->
+                | Some superTy when not (isObjTyAnyNullness g superTy) && not (isValueTypeTy g superTy) ->
                     superTy
                 | _ -> ()
             ]

src/Compiler/Checking/TypeHierarchy.fs

@@ -67,7 +67,7 @@ let GetSuperTypeOfType g amap m ty =
                 Some (instType (mkInstForAppTy g ty) (superOfTycon g tcref.Deref))
             elif isArrayTy g ty then
                 Some g.system_Array_ty
-            elif isRefTy g ty && not (isObjTy g ty) then
+            elif isRefTy g ty && not (isObjTyAnyNullness g ty) then
                 Some g.obj_ty_noNulls
             elif isStructTupleTy g ty then
                 Some g.system_Value_ty

src/Compiler/Checking/TypeRelations.fs

@@ -117,7 +117,7 @@ let rec TypeFeasiblySubsumesType ndeep g amap m ty1 canCoerce ty2 =
 
     | _ -> 
         // F# reference types are subtypes of type 'obj' 
-        (isObjTy g ty1 && (canCoerce = CanCoerce || isRefTy g ty2)) 
+        (isObjTyAnyNullness g ty1 && (canCoerce = CanCoerce || isRefTy g ty2)) 
         ||
         (isAppTy g ty2 &&
          (canCoerce = CanCoerce || isRefTy g ty2) && 

src/Compiler/Checking/infos.fs

@@ -207,7 +207,7 @@ type OptionalArgInfo =
                     if isByrefTy g ty then
                         let ty = destByrefTy g ty
                         PassByRef (ty, analyze ty)
-                    elif isObjTy g ty then
+                    elif isObjTyAnyNullness g ty then
                         match ilParam.Marshal with
                         | Some(ILNativeType.IUnknown | ILNativeType.IDispatch | ILNativeType.Interface) -> Constant ILFieldInit.Null
                         | _ ->
@@ -296,7 +296,7 @@ let CrackParamAttribsInfo g (ty: TType, argInfo: ArgReprInfo) =
             | None ->
                 // Do a type-directed analysis of the type to determine the default value to pass.
                 // Similar rules as OptionalArgInfo.FromILParameter are applied here, except for the COM and byref-related stuff.
-                CallerSide (if isObjTy g ty then MissingValue else DefaultValue)
+                CallerSide (if isObjTyAnyNullness g ty then MissingValue else DefaultValue)
             | Some attr ->
                 let defaultValue = OptionalArgInfo.ValueOfDefaultParameterValueAttrib attr
                 match defaultValue with
@@ -364,7 +364,9 @@ type ILFieldInit with
             | :? uint32 as i -> ILFieldInit.UInt32 i
             | :? int64 as i -> ILFieldInit.Int64 i
             | :? uint64 as i -> ILFieldInit.UInt64 i
-            | _ -> error(Error(FSComp.SR.infosInvalidProvidedLiteralValue(try !!v.ToString() with _ -> "?"), m))
+            | _ -> 
+                let txt = match v with | null -> "?" | v -> try !!v.ToString() with _ -> "?"
+                error(Error(FSComp.SR.infosInvalidProvidedLiteralValue(txt), m))
 
 
 /// Compute the OptionalArgInfo for a provided parameter.
@@ -382,7 +384,7 @@ let OptionalArgInfoOfProvidedParameter (amap: ImportMap) m (provParam : Tainted<
                 if isByrefTy g ty then
                     let ty = destByrefTy g ty
                     PassByRef (ty, analyze ty)
-                elif isObjTy g ty then MissingValue
+                elif isObjTyAnyNullness g ty then MissingValue
                 else  DefaultValue
 
             let paramTy = ImportProvidedType amap m (provParam.PApply((fun p -> p.ParameterType), m))

src/Compiler/CodeGen/IlxGen.fs

@@ -3782,11 +3782,11 @@ and GenCoerce cenv cgbuf eenv (e, tgtTy, m, srcTy) sequel =
     else
         GenExpr cenv cgbuf eenv e Continue
 
-        if not (isObjTy g srcTy) then
+        if not (isObjTyAnyNullness g srcTy) then
             let ilFromTy = GenType cenv m eenv.tyenv srcTy
             CG.EmitInstr cgbuf (pop 1) (Push [ g.ilg.typ_Object ]) (I_box ilFromTy)
 
-        if not (isObjTy g tgtTy) then
+        if not (isObjTyAnyNullness g tgtTy) then
             let ilToTy = GenType cenv m eenv.tyenv tgtTy
             CG.EmitInstr cgbuf (pop 1) (Push [ ilToTy ]) (I_unbox_any ilToTy)
 
@@ -12118,7 +12118,7 @@ let LookupGeneratedValue (cenv: cenv) (ctxt: ExecutionContext) eenv (v: Val) =
         None
 
 // Invoke the set_Foo method for a declaration with a value. Used to create variables with values programmatically in fsi.exe.
-let SetGeneratedValue (ctxt: ExecutionContext) eenv isForced (v: Val) (value: obj) =
+let SetGeneratedValue (ctxt: ExecutionContext) eenv isForced (v: Val) (value: objnull) =
     try
         match StorageForVal v.Range v eenv with
         | StaticPropertyWithField(fspec, _, hasLiteralAttr, _, _, _, _f, ilSetterMethRef, _) ->

src/Compiler/DependencyManager/DependencyProvider.fs

@@ -160,19 +160,19 @@ type ReflectionDependencyManagerProvider
 
     let instance =
         if not (isNull (theType.GetConstructor([| typeof<string option>; typeof<bool> |]))) then
-            Activator.CreateInstance(theType, [| outputDir :> obj; useResultsCache :> obj |])
+            Activator.CreateInstance(theType, [| outputDir :> objnull; useResultsCache :> objnull |])
         else
-            Activator.CreateInstance(theType, [| outputDir :> obj |])
+            Activator.CreateInstance(theType, [| outputDir :> objnull |])
 
-    let nameProperty = nameProperty.GetValue >> string
-    let keyProperty = keyProperty.GetValue >> string
+    let nameProperty (x: objnull) = x |> nameProperty.GetValue |> string
+    let keyProperty (x: objnull) = x |> keyProperty.GetValue |> string
 
-    let helpMessagesProperty =
-        let toStringArray (o: obj) = o :?> string[]
+    let helpMessagesProperty (x: objnull) =
+        let toStringArray (o: objnull) = o :?> string[]
 
         match helpMessagesProperty with
-        | Some helpMessagesProperty -> helpMessagesProperty.GetValue >> toStringArray
-        | None -> fun _ -> [||]
+        | Some helpMessagesProperty -> x |> helpMessagesProperty.GetValue |> toStringArray
+        | None -> [||]
 
     static member InstanceMaker(theType: Type, outputDir: string option, useResultsCache: bool) =
         match
@@ -453,14 +453,18 @@ type ReflectionDependencyManagerProvider
                     None, [||]
 
             match method with
+            | None -> ReflectionDependencyManagerProvider.MakeResultFromFields(false, [||], [||], Seq.empty, Seq.empty, Seq.empty)
             | Some m ->
-                let result = m.Invoke(instance, arguments)
+                match m.Invoke(instance, arguments) with
+                | null -> ReflectionDependencyManagerProvider.MakeResultFromFields(false, [||], [||], Seq.empty, Seq.empty, Seq.empty)
 
                 // Verify the number of arguments returned in the tuple returned by resolvedependencies, it can be:
                 //     1 - object with properties
                 //     3 - (bool * string list * string list)
                 // Support legacy api return shape (bool, seq<string>, seq<string>) --- original paket packagemanager
-                if FSharpType.IsTuple(result.GetType()) then
+                | result when FSharpType.IsTuple(result.GetType()) |> not ->
+                    ReflectionDependencyManagerProvider.MakeResultFromObject(result)
+                | result ->
                     // Verify the number of arguments returned in the tuple returned by resolvedependencies, it can be:
                     //     3 - (bool * string list * string list)
                     let success, sourceFiles, packageRoots =
@@ -474,10 +478,6 @@ type ReflectionDependencyManagerProvider
                         | _ -> false, seqEmpty, seqEmpty
 
                     ReflectionDependencyManagerProvider.MakeResultFromFields(success, [||], [||], Seq.empty, sourceFiles, packageRoots)
-                else
-                    ReflectionDependencyManagerProvider.MakeResultFromObject(result)
-
-            | None -> ReflectionDependencyManagerProvider.MakeResultFromFields(false, [||], [||], Seq.empty, Seq.empty, Seq.empty)
 
 /// Provides DependencyManagement functions.
 /// Class is IDisposable

src/Compiler/Driver/GraphChecking/Graph.fs

@@ -83,7 +83,7 @@ module internal Graph =
         graph
         |> Seq.iter (fun (KeyValue(file, deps)) -> printfn $"{file} -> {deps |> Array.map nodePrinter |> join}")
 
-    let print (graph: Graph<'Node>) : unit =
+    let print (graph: Graph<'Node> when 'Node: not null) : unit =
         printCustom graph (fun node -> node.ToString() |> string)
 
     let serialiseToMermaid (graph: Graph<FileIndex * string>) =

src/Compiler/Driver/GraphChecking/Graph.fsi

@@ -20,7 +20,7 @@ module internal Graph =
     /// Create a reverse of the graph.
     val reverse<'Node when 'Node: equality> : originalGraph: Graph<'Node> -> Graph<'Node>
     /// Print the contents of the graph to the standard output.
-    val print: graph: Graph<'Node> -> unit
+    val print: graph: Graph<'Node> -> unit when 'Node: not null
     /// Create a simple Mermaid graph
     val serialiseToMermaid: graph: Graph<FileIndex * string> -> string
     /// Create a simple Mermaid graph and save it under the path specified.

src/Compiler/Facilities/prim-parsing.fs

@@ -14,7 +14,7 @@ exception Accept of obj
 
 [<Sealed>]
 type internal IParseState
-    (ruleStartPoss: Position[], ruleEndPoss: Position[], lhsPos: Position[], ruleValues: obj[], lexbuf: LexBuffer<char>) =
+    (ruleStartPoss: Position[], ruleEndPoss: Position[], lhsPos: Position[], ruleValues: objnull[], lexbuf: LexBuffer<char>) =
     member _.LexBuffer = lexbuf
 
     member _.InputRange index =
@@ -125,7 +125,7 @@ type Stack<'a>(n) =
 
     member buf.PrintStack() =
         for i = 0 to (count - 1) do
-            Console.Write("{0}{1}", contents[i], (if i = count - 1 then ":" else "-"))
+            Console.Write("{0}{1}", contents[i] :> objnull, (if i = count - 1 then ":" else "-"))
 
 module Flags =
 #if DEBUG
@@ -231,7 +231,7 @@ module internal Implementation =
     [<NoEquality; NoComparison>]
     [<Struct>]
     type ValueInfo =
-        val value: obj
+        val value: objnull
         val startPos: Position
         val endPos: Position
 
@@ -269,7 +269,7 @@ module internal Implementation =
         // The 100 here means a maximum of 100 elements for each rule
         let ruleStartPoss = (Array.zeroCreate 100: Position[])
         let ruleEndPoss = (Array.zeroCreate 100: Position[])
-        let ruleValues = (Array.zeroCreate 100: obj[])
+        let ruleValues = (Array.zeroCreate 100: objnull[])
         let lhsPos = (Array.zeroCreate 2: Position[])
         let reductions = tables.reductions
         let cacheSize = 7919 // the 1000'th prime