Let provided types be non-nullable

commit edc4d9bf4a3a6ac017ccf85c1e765374cc63b529
Author: latkin <latkin@microsoft.com>
Date:   Mon Dec 1 13:32:55 2014 -0800

    Updating surface area tests

commit 9380ad5e64cfead4af96558a3bbd9fa121d10860
Author: latkin <latkin@microsoft.com>
Date:   Mon Dec 1 11:27:14 2014 -0800

    Fixups to correct build issues

commit b280e160d717966e0b3128e0e608988ec31e0af3
Merge: 48f3fd6c 7deeeca
Author: latkin <latkin@microsoft.com>
Date:   Mon Dec 1 10:29:45 2014 -0800

    Merge branch 'feature1' of https://git01.codeplex.com/forks/dsyme/cleanup into nonullprovtypes

commit 7deeeca8ef04d2d776e38f33721ef24f3197255c
Author: Don Syme <dsyme@microsoft.com>
Date:   Tue Jun 24 19:53:03 2014 +0100

    Let provided types be non-nullable

src/fsharp/FSharp.Core.Unittests/SurfaceArea.4.0.fs

@@ -741,12 +741,15 @@ Microsoft.FSharp.Core.AbstractClassAttribute: Void .ctor()
 Microsoft.FSharp.Core.AllowNullLiteralAttribute: Boolean Equals(System.Object)
 Microsoft.FSharp.Core.AllowNullLiteralAttribute: Boolean IsDefaultAttribute()
 Microsoft.FSharp.Core.AllowNullLiteralAttribute: Boolean Match(System.Object)
+Microsoft.FSharp.Core.AllowNullLiteralAttribute: Boolean Value
+Microsoft.FSharp.Core.AllowNullLiteralAttribute: Boolean get_Value()
 Microsoft.FSharp.Core.AllowNullLiteralAttribute: Int32 GetHashCode()
 Microsoft.FSharp.Core.AllowNullLiteralAttribute: System.Object TypeId
 Microsoft.FSharp.Core.AllowNullLiteralAttribute: System.Object get_TypeId()
 Microsoft.FSharp.Core.AllowNullLiteralAttribute: System.String ToString()
 Microsoft.FSharp.Core.AllowNullLiteralAttribute: System.Type GetType()
 Microsoft.FSharp.Core.AllowNullLiteralAttribute: Void .ctor()
+Microsoft.FSharp.Core.AllowNullLiteralAttribute: Void .ctor(Boolean)
 Microsoft.FSharp.Core.AutoOpenAttribute: Boolean Equals(System.Object)
 Microsoft.FSharp.Core.AutoOpenAttribute: Boolean IsDefaultAttribute()
 Microsoft.FSharp.Core.AutoOpenAttribute: Boolean Match(System.Object)

src/fsharp/FSharp.Core.Unittests/SurfaceArea.Portable.fs

@@ -734,12 +734,15 @@ Microsoft.FSharp.Core.AbstractClassAttribute: Void .ctor()
 Microsoft.FSharp.Core.AllowNullLiteralAttribute: Boolean Equals(System.Object)
 Microsoft.FSharp.Core.AllowNullLiteralAttribute: Boolean IsDefaultAttribute()
 Microsoft.FSharp.Core.AllowNullLiteralAttribute: Boolean Match(System.Object)
+Microsoft.FSharp.Core.AllowNullLiteralAttribute: Boolean Value
+Microsoft.FSharp.Core.AllowNullLiteralAttribute: Boolean get_Value()
 Microsoft.FSharp.Core.AllowNullLiteralAttribute: Int32 GetHashCode()
 Microsoft.FSharp.Core.AllowNullLiteralAttribute: System.Object TypeId
 Microsoft.FSharp.Core.AllowNullLiteralAttribute: System.Object get_TypeId()
 Microsoft.FSharp.Core.AllowNullLiteralAttribute: System.String ToString()
 Microsoft.FSharp.Core.AllowNullLiteralAttribute: System.Type GetType()
 Microsoft.FSharp.Core.AllowNullLiteralAttribute: Void .ctor()
+Microsoft.FSharp.Core.AllowNullLiteralAttribute: Void .ctor(Boolean)
 Microsoft.FSharp.Core.AutoOpenAttribute: Boolean Equals(System.Object)
 Microsoft.FSharp.Core.AutoOpenAttribute: Boolean IsDefaultAttribute()
 Microsoft.FSharp.Core.AutoOpenAttribute: Boolean Match(System.Object)

src/fsharp/FSharp.Core/prim-types.fs

@@ -127,8 +127,10 @@ namespace Microsoft.FSharp.Core
       
     [<AttributeUsage(AttributeTargets.Class,AllowMultiple=false)>]
     [<Sealed>]
-    type AllowNullLiteralAttribute() =
+    type AllowNullLiteralAttribute(value: bool) =
         inherit System.Attribute()
+        member x.Value = value
+        new () = new AllowNullLiteralAttribute(true)
       
     [<AttributeUsage(AttributeTargets.Field,AllowMultiple=false)>]
     [<Sealed>]

src/fsharp/FSharp.Core/prim-types.fsi

@@ -238,6 +238,13 @@ namespace Microsoft.FSharp.Core
         /// <returns>AllowNullLiteralAttribute</returns>
         new : unit -> AllowNullLiteralAttribute
 
+        /// <summary>Creates an instance of the attribute with the specified value</summary>
+        /// <returns>AllowNullLiteralAttribute</returns>
+        new : value: bool -> AllowNullLiteralAttribute
+
+        /// <summary>The value of the attribute, indicating whether the type allows the null literal or not</summary>
+        member Value: bool
+
     /// <summary>Adding this attribute to a value causes it to be compiled as a CLI constant literal.</summary>
     [<AttributeUsage (AttributeTargets.Field,AllowMultiple=false)>]  
     [<Sealed>]

src/fsharp/check.fs

@@ -900,14 +900,7 @@ and CheckAttribs cenv env (attribs: Attribs) =
         |> Seq.map fst 
         |> Seq.toList
         // Filter for allowMultiple = false
-        |> List.filter (fun (tcref,m) -> 
-                let allowMultiple = 
-                    Infos.AttributeChecking.TryBindTyconRefAttribute cenv.g m cenv.g.attrib_AttributeUsageAttribute tcref 
-                             (fun (_,named)             -> named |> List.tryPick (function ("AllowMultiple",_,_,ILAttribElem.Bool res) -> Some res | _ -> None))
-                             (fun (Attrib(_,_,_,named,_,_,_)) -> named |> List.tryPick (function AttribNamedArg("AllowMultiple",_,_,AttribBoolArg(res) ) -> Some res | _ -> None))
-                             (fun _ -> None)
-                
-                (allowMultiple <> Some(true)))
+        |> List.filter (fun (tcref,m) -> TryFindAttributeUsageAttribute cenv.g m tcref <> Some(true))
     if cenv.reportErrors then 
        for (tcref,m) in duplicates do
           errorR(Error(FSComp.SR.chkAttrHasAllowMultiFalse(tcref.DisplayName), m))
@@ -1384,7 +1377,7 @@ let CheckEntityDefn cenv env (tycon:Entity) =
                 let zeroInitUnsafe = TryFindFSharpBoolAttribute cenv.g cenv.g.attrib_DefaultValueAttribute f.FieldAttribs
                 if zeroInitUnsafe = Some(true) then
                    let ty' = generalizedTyconRef (mkLocalTyconRef tycon)
-                   if not (TypeHasDefaultValue cenv.g ty') then 
+                   if not (TypeHasDefaultValue cenv.g m ty') then 
                        errorR(Error(FSComp.SR.chkValueWithDefaultValueMustHaveDefaultValue(), m));
             )
         match tycon.TypeAbbrev with                          (* And type abbreviations *)

src/fsharp/csolve.fs

@@ -1585,7 +1585,7 @@ and SolveTypSupportsNull (csenv:ConstraintSolverEnv) ndeep m2 trace ty =
     if isTyparTy g ty then 
         AddConstraint csenv ndeep m2 trace (destTyparTy g ty) (TyparConstraint.SupportsNull(m))
     elif 
-        TypeSatisfiesNullConstraint g ty then CompleteD
+        TypeSatisfiesNullConstraint g m ty then CompleteD
     else 
         match ty with 
         | NullableTy g _ ->
@@ -1757,7 +1757,7 @@ and SolveTypRequiresDefaultConstructor (csenv:ConstraintSolverEnv) ndeep m2 trac
     let ty = stripTyEqnsAndMeasureEqns g typ
     if isTyparTy g ty then 
         AddConstraint csenv ndeep m2 trace (destTyparTy g ty) (TyparConstraint.RequiresDefaultConstructor(m))
-    elif isStructTy g ty && TypeHasDefaultValue g ty then 
+    elif isStructTy g ty && TypeHasDefaultValue g m ty then 
         CompleteD
     elif
         GetIntrinsicConstructorInfosOfType csenv.InfoReader m ty 

src/fsharp/env.fs

@@ -812,7 +812,7 @@ let mkTcGlobals (compilingFslib,sysCcu,ilg,fslibCcu,directoryToResolveRelativePa
       
 
   let mk_MFCore_attrib nm : BuiltinAttribInfo = 
-      AttribInfo(mkILTyRef(IlxSettings.ilxFsharpCoreLibScopeRef (), nm),mk_MFCore_tcref fslibCcu nm) 
+      AttribInfo(mkILTyRef(IlxSettings.ilxFsharpCoreLibScopeRef (), FSharpLib.Core + "." + nm),mk_MFCore_tcref fslibCcu nm) 
     
   let mkAttrib (nm:string) scopeRef : BuiltinAttribInfo = 
       let path, typeName = splitILTypeName nm

src/fsharp/est.fs

@@ -609,7 +609,7 @@ module internal ExtensionTyping =
         abstract GetDefinitionLocationAttribute : provider:ITypeProvider -> (string * int * int) option 
         abstract GetXmlDocAttributes : provider:ITypeProvider -> string[]
         abstract GetHasTypeProviderEditorHideMethodsAttribute : provider:ITypeProvider -> bool
-        abstract GetAttributeConstructorArgs: provider:ITypeProvider * attribName:string -> obj option list option
+        abstract GetAttributeConstructorArgs: provider:ITypeProvider * attribName:string -> (obj option list * (string * obj option) list) option
 
     and ProvidedCustomAttributeProvider =
         static member Create (attributes :(ITypeProvider -> System.Collections.Generic.IList<CustomAttributeData>)) : IProvidedCustomAttributeProvider = 
@@ -622,9 +622,15 @@ module internal ExtensionTyping =
                       attributes(provider) 
                         |> Seq.tryFind (findAttribByName  attribName)  
                         |> Option.map (fun a -> 
-                            a.ConstructorArguments 
-                            |> Seq.toList 
-                            |> List.map (function Arg null -> None | Arg obj -> Some obj | _ -> None))
+                            let ctorArgs = 
+                                a.ConstructorArguments 
+                                |> Seq.toList 
+                                |> List.map (function Arg null -> None | Arg obj -> Some obj | _ -> None)
+                            let namedArgs = 
+                                a.NamedArguments 
+                                |> Seq.toList 
+                                |> List.map (fun arg -> arg.MemberName, match arg.TypedValue with Arg null -> None | Arg obj -> Some obj | _ -> None)
+                            ctorArgs, namedArgs)
 
                   member __.GetHasTypeProviderEditorHideMethodsAttribute provider = 
                       attributes(provider) 

src/fsharp/est.fsi

@@ -178,7 +178,7 @@ module internal ExtensionTyping =
         abstract GetHasTypeProviderEditorHideMethodsAttribute : provider:ITypeProvider -> bool
         abstract GetDefinitionLocationAttribute : provider:ITypeProvider -> (string * int * int) option 
         abstract GetXmlDocAttributes : provider:ITypeProvider -> string[]
-        abstract GetAttributeConstructorArgs: provider:ITypeProvider * attribName:string -> obj option list option
+        abstract GetAttributeConstructorArgs: provider:ITypeProvider * attribName:string -> (obj option list * (string * obj option) list) option
         
     and [<AllowNullLiteral; Sealed; Class>] 
         ProvidedAssembly = 

src/fsharp/infos.fs

@@ -2496,29 +2496,6 @@ exception ObsoleteError of string * range
 /// formats.
 module AttributeChecking = 
 
-    /// Analyze three cases for attributes declared on type definitions: IL-declared attributes, F#-declared attributes and
-    /// provided attributes.
-    //
-    // This is used for AttributeUsageAttribute, DefaultMemberAttribute and ConditionalAttribute (on attribute types)
-    let TryBindTyconRefAttribute g m (AttribInfo (atref,_) as args) (tcref:TyconRef) f1 f2 f3 = 
-        ignore m; ignore f3
-        match metadataOfTycon tcref.Deref with 
-#if EXTENSIONTYPING
-        | ProvidedTypeMetadata info -> 
-            let provAttribs = info.ProvidedType.PApply((fun a -> (a :> IProvidedCustomAttributeProvider)),m)
-            match provAttribs.PUntaint((fun a -> a.GetAttributeConstructorArgs(provAttribs.TypeProvider.PUntaintNoFailure(id), atref.FullName)),m) with
-            | Some args -> f3 args
-            | None -> None
-#endif
-        | ILTypeMetadata (_,tdef) -> 
-            match TryDecodeILAttribute g atref (Some(atref.Scope)) tdef.CustomAttrs with 
-            | Some attr -> f1 attr
-            | _ -> None
-        | FSharpOrArrayOrByrefOrTupleOrExnTypeMetadata -> 
-            match TryFindFSharpAttribute g args tcref.Attribs with 
-            | Some attr -> f2 attr
-            | _ -> None
-
     /// Analyze three cases for attributes declared on methods: IL-declared attributes, F#-declared attributes and
     /// provided attributes.
     let BindMethInfoAttributes m minfo f1 f2 f3 = 
@@ -2553,7 +2530,7 @@ module AttributeChecking =
         TryBindMethInfoAttribute g m attribSpec minfo 
                      (function ([ILAttribElem.String (Some msg) ],_) -> Some msg | _ -> None) 
                      (function (Attrib(_,_,[ AttribStringArg msg ],_,_,_,_)) -> Some msg | _ -> None)
-                     (function [ Some ((:? string as msg) : obj) ] -> Some msg | _ -> None)
+                     (function ([ Some ((:? string as msg) : obj) ],_) -> Some msg | _ -> None)
 
     /// Check if a method has a specific attribute.
     let MethInfoHasAttribute g m attribSpec minfo  =
@@ -2563,22 +2540,6 @@ module AttributeChecking =
                      (fun _ -> Some ())
           |> Option.isSome
 
-    /// Try to find a specific attribute on a type definition, where the attribute accepts a string argument.
-    ///
-    /// This is used to detect the 'DefaultMemberAttribute' and 'ConditionalAttribute' attributes (on type definitions)
-    let TryFindTyconRefStringAttribute g m attribSpec tcref  =
-        TryBindTyconRefAttribute g m attribSpec tcref 
-                 (function ([ILAttribElem.String (Some(msg)) ],_) -> Some msg | _ -> None)
-                 (function (Attrib(_,_,[ AttribStringArg(msg) ],_,_,_,_))  -> Some msg | _ -> None)
-                 (function [ Some ((:? string as msg) : obj) ] -> Some msg | _ -> None)
-
-    /// Check if a type definition has a specific attribute
-    let TyconRefHasAttribute g m attribSpec tcref  =
-        TryBindTyconRefAttribute g m attribSpec tcref 
-                     (fun _ -> Some ()) 
-                     (fun _ -> Some ())
-                     (fun _ -> Some ())
-          |> Option.isSome
 
 
     /// Check IL attributes for 'ObsoleteAttribute', returning errors and warnings as data
@@ -2652,13 +2613,13 @@ module AttributeChecking =
     let private CheckProvidedAttributes g m (provAttribs: Tainted<IProvidedCustomAttributeProvider>)  = 
         let (AttribInfo(tref,_)) = g.attrib_SystemObsolete
         match provAttribs.PUntaint((fun a -> a.GetAttributeConstructorArgs(provAttribs.TypeProvider.PUntaintNoFailure(id), tref.FullName)),m) with
-        | Some [ Some (:? string as msg) ] -> WarnD(ObsoleteWarning(msg,m))
-        | Some [ Some (:? string as msg); Some (:?bool as isError) ]  ->
+        | Some ([ Some (:? string as msg) ], _) -> WarnD(ObsoleteWarning(msg,m))
+        | Some ([ Some (:? string as msg); Some (:?bool as isError) ], _)  ->
             if isError then 
                 ErrorD (ObsoleteError(msg,m))
             else 
                 WarnD (ObsoleteWarning(msg,m))
-        | Some [ None ] -> 
+        | Some ([ None ], _) -> 
             WarnD(ObsoleteWarning("",m))
         | Some _ -> 
             WarnD(ObsoleteWarning("",m))

src/fsharp/opt.fs

@@ -2470,7 +2470,7 @@ and TryDevirtualizeApplication cenv env (f,tyargs,args,m) =
     // target type isn't 'NullNotLiked', i.e. that the target type is not an F# union, record etc. 
     // Note UnboxFast is just the .NET IL 'unbox.any' instruction. 
     | Expr.Val(v,_,_),[ty],_ when valRefEq cenv.g v cenv.g.unbox_vref && 
-                                   canUseUnboxFast cenv.g ty ->
+                                   canUseUnboxFast cenv.g m ty ->
 
         Some(DevirtualizeApplication cenv env cenv.g.unbox_fast_vref ty tyargs args m)
         

src/fsharp/tastops.fs

@@ -2554,6 +2554,68 @@ let TryFindILAttributeOpt attr attrs =
     | Some (AttribInfo (atref,_)) -> HasILAttribute atref attrs
     | _ -> false
 
+/// Analyze three cases for attributes declared on type definitions: IL-declared attributes, F#-declared attributes and
+/// provided attributes.
+//
+// This is used for AttributeUsageAttribute, DefaultMemberAttribute and ConditionalAttribute (on attribute types)
+let TryBindTyconRefAttribute g (m:range) (AttribInfo (atref,_) as args) (tcref:TyconRef) f1 f2 f3 = 
+    ignore m; ignore f3
+    match metadataOfTycon tcref.Deref with 
+#if EXTENSIONTYPING
+    | ProvidedTypeMetadata info -> 
+        let provAttribs = info.ProvidedType.PApply((fun a -> (a :> IProvidedCustomAttributeProvider)),m)
+        match provAttribs.PUntaint((fun a -> a.GetAttributeConstructorArgs(provAttribs.TypeProvider.PUntaintNoFailure(id), atref.FullName)),m) with
+        | Some args -> f3 args
+        | None -> None
+#endif
+    | ILTypeMetadata (_,tdef) -> 
+        match TryDecodeILAttribute g atref (Some(atref.Scope)) tdef.CustomAttrs with 
+        | Some attr -> f1 attr
+        | _ -> None
+    | FSharpOrArrayOrByrefOrTupleOrExnTypeMetadata -> 
+        match TryFindFSharpAttribute g args tcref.Attribs with 
+        | Some attr -> f2 attr
+        | _ -> None
+
+let TryFindTyconRefBoolAttribute g m attribSpec tcref  =
+    TryBindTyconRefAttribute g m attribSpec tcref 
+                (function 
+                   | ([ ],_) -> Some true
+                   | ([ILAttribElem.Bool (v) ],_) -> Some v 
+                   | _ -> None)
+                (function 
+                   | (Attrib(_,_,[ ],_,_,_,_))  -> Some true
+                   | (Attrib(_,_,[ AttribBoolArg v ],_,_,_,_))  -> Some v 
+                   | _ -> None)
+                (function 
+                   | ([ ],_) -> Some true
+                   | ([ Some ((:? bool as v) : obj) ],_) -> Some v 
+                   | _ -> None)
+
+let TryFindAttributeUsageAttribute g m tcref  =
+    TryBindTyconRefAttribute g m g.attrib_AttributeUsageAttribute tcref 
+                (fun (_,named)             -> named |> List.tryPick (function ("AllowMultiple",_,_,ILAttribElem.Bool res) -> Some res | _ -> None))
+                (fun (Attrib(_,_,_,named,_,_,_)) -> named |> List.tryPick (function AttribNamedArg("AllowMultiple",_,_,AttribBoolArg(res) ) -> Some res | _ -> None))
+                (fun (_,named)             -> named |> List.tryPick (function ("AllowMultiple", Some ((:? bool as res) : obj)) -> Some res | _ -> None))
+
+
+/// Try to find a specific attribute on a type definition, where the attribute accepts a string argument.
+///
+/// This is used to detect the 'DefaultMemberAttribute' and 'ConditionalAttribute' attributes (on type definitions)
+let TryFindTyconRefStringAttribute g m attribSpec tcref  =
+    TryBindTyconRefAttribute g m attribSpec tcref 
+                (function ([ILAttribElem.String (Some(msg)) ],_) -> Some msg | _ -> None)
+                (function (Attrib(_,_,[ AttribStringArg(msg) ],_,_,_,_))  -> Some msg | _ -> None)
+                (function ([ Some ((:? string as msg) : obj) ], _) -> Some msg | _ -> None)
+
+/// Check if a type definition has a specific attribute
+let TyconRefHasAttribute g m attribSpec tcref  =
+    TryBindTyconRefAttribute g m attribSpec tcref 
+                    (fun _ -> Some ()) 
+                    (fun _ -> Some ())
+                    (fun _ -> Some ())
+        |> Option.isSome
+
 //-------------------------------------------------------------------------
 // List and reference types...
 //------------------------------------------------------------------------- 
@@ -6841,28 +6903,34 @@ let TypeNullNever g ty =
     (isStructTy g underlyingTy) ||
     (isByrefTy g underlyingTy)
 
-let TypeNullIsExtraValue g ty = 
-    isILReferenceTy g ty ||
-    isDelegateTy g ty ||
-    (not (TypeNullNever g ty) && 
-     isAppTy g ty && 
-     TryFindFSharpBoolAttribute  g g.attrib_AllowNullLiteralAttribute (tyconOfAppTy g ty).Attribs = Some(true))
+
+
+/// Indicates if the type admits the use of 'null' as a value
+let TypeNullIsExtraValue g m ty = 
+    if isILReferenceTy g ty || isDelegateTy g ty then
+        // Putting AllowNullLiteralAttribute(false) on an IL or provided type means 'null' can't be used with that type
+        not (isAppTy g ty && TryFindTyconRefBoolAttribute g m g.attrib_AllowNullLiteralAttribute (tcrefOfAppTy g ty) = Some(false))
+    elif TypeNullNever g ty then 
+        false
+    else 
+        // Putting AllowNullLiteralAttribute(true) on an F# type means 'null' can be used with that type
+        isAppTy g ty && TryFindTyconRefBoolAttribute g m g.attrib_AllowNullLiteralAttribute (tcrefOfAppTy g ty) = Some(true)
 
 let TypeNullIsTrueValue g ty = 
     (isAppTy g ty && IsUnionTypeWithNullAsTrueValue g (tyconOfAppTy g ty))  ||
     (isUnitTy g ty)
 
-let TypeNullNotLiked g ty = 
-       not (TypeNullIsExtraValue g ty) 
+let TypeNullNotLiked g m ty = 
+       not (TypeNullIsExtraValue g m ty) 
     && not (TypeNullIsTrueValue g ty) 
     && not (TypeNullNever g ty) 
 
-let TypeSatisfiesNullConstraint g ty = 
-    TypeNullIsExtraValue g ty  
+let TypeSatisfiesNullConstraint g m ty = 
+    TypeNullIsExtraValue g m ty  
 
-let rec TypeHasDefaultValue g ty = 
+let rec TypeHasDefaultValue g m ty = 
     let ty = stripTyEqnsAndMeasureEqns g ty
-    TypeSatisfiesNullConstraint g ty  
+    TypeSatisfiesNullConstraint g m ty  
     || (isStructTy g ty &&
         // Is it an F# struct type?
         (if isFSharpStructTy g ty then 
@@ -6873,9 +6941,9 @@ let rec TypeHasDefaultValue g ty =
                   // We can ignore fields with the DefaultValue(false) attribute 
                   |> List.filter (fun fld -> not (TryFindFSharpBoolAttribute g g.attrib_DefaultValueAttribute fld.FieldAttribs = Some(false)))
 
-            flds |> List.forall (actualTyOfRecdField (mkTyconRefInst tcref tinst) >> TypeHasDefaultValue g)
+            flds |> List.forall (actualTyOfRecdField (mkTyconRefInst tcref tinst) >> TypeHasDefaultValue g m)
          elif isTupleStructTy g ty then 
-            destTupleTy g ty |> List.forall (TypeHasDefaultValue g)
+            destTupleTy g ty |> List.forall (TypeHasDefaultValue g m)
          else
             // All struct types defined in other .NET languages have a DefaultValue regardless of their
             // instantiation
@@ -6909,9 +6977,9 @@ let canUseTypeTestFast g ty =
      not (TypeNullNever g ty)
 
 // Can we use the fast helper for the 'LanguagePrimitives.IntrinsicFunctions.UnboxGeneric'? 
-let canUseUnboxFast g ty = 
+let canUseUnboxFast g m ty = 
      not (isTyparTy g ty) && 
-     not (TypeNullNotLiked g ty)
+     not (TypeNullNotLiked g m ty)
      
      
 //--------------------------------------------------------------------------

src/fsharp/tastops.fsi

@@ -999,13 +999,13 @@ val ModuleNameIsMangled : TcGlobals -> Attribs -> bool
 
 val CompileAsEvent : TcGlobals -> Attribs -> bool
 
-val TypeNullIsExtraValue : TcGlobals -> TType -> bool
+val TypeNullIsExtraValue : TcGlobals -> range -> TType -> bool
 val TypeNullIsTrueValue : TcGlobals -> TType -> bool
-val TypeNullNotLiked : TcGlobals -> TType -> bool
+val TypeNullNotLiked : TcGlobals -> range -> TType -> bool
 val TypeNullNever : TcGlobals -> TType -> bool
 
-val TypeSatisfiesNullConstraint : TcGlobals -> TType -> bool
-val TypeHasDefaultValue : TcGlobals -> TType -> bool
+val TypeSatisfiesNullConstraint : TcGlobals -> range -> TType -> bool
+val TypeHasDefaultValue : TcGlobals -> range -> TType -> bool
 
 val isAbstractTycon : Tycon -> bool
 
@@ -1112,7 +1112,7 @@ val mkCallGetGenericEREqualityComparer : TcGlobals -> range -> Expr
 val mkCallGetGenericPEREqualityComparer : TcGlobals -> range -> Expr
 
 val mkCallUnboxFast  : TcGlobals -> range -> TType -> Expr -> Expr
-val canUseUnboxFast  : TcGlobals -> TType -> bool
+val canUseUnboxFast  : TcGlobals -> range -> TType -> bool
 
 val mkCallDispose     : TcGlobals -> range -> TType -> Expr -> Expr
 val mkCallSeq         : TcGlobals -> range -> TType -> Expr -> Expr
@@ -1196,6 +1196,20 @@ val TryFindFSharpBoolAttribute     : TcGlobals -> Env.BuiltinAttribInfo -> Attri
 val TryFindFSharpStringAttribute   : TcGlobals -> Env.BuiltinAttribInfo -> Attribs -> string option
 val TryFindFSharpInt32Attribute    : TcGlobals -> Env.BuiltinAttribInfo -> Attribs -> int32 option
 
+/// Try to find a specific attribute on a type definition, where the attribute accepts a string argument.
+///
+/// This is used to detect the 'DefaultMemberAttribute' and 'ConditionalAttribute' attributes (on type definitions)
+val TryFindTyconRefStringAttribute : TcGlobals -> range -> Env.BuiltinAttribInfo -> TyconRef -> string option
+
+/// Try to find a specific attribute on a type definition, where the attribute accepts a bool argument.
+val TryFindTyconRefBoolAttribute : TcGlobals -> range -> Env.BuiltinAttribInfo -> TyconRef -> bool option
+
+/// Try to find a specific attribute on a type definition
+val TyconRefHasAttribute : TcGlobals -> range -> Env.BuiltinAttribInfo -> TyconRef -> bool
+
+/// Try to find the AttributeUsage attribute, looking for the value of the AllowMultiple named parameter
+val TryFindAttributeUsageAttribute : TcGlobals -> range -> TyconRef -> bool option
+
 #if EXTENSIONTYPING
 /// returns Some(assemblyName) for success
 val TryDecodeTypeProviderAssemblyAttr : ILGlobals -> ILAttribute -> string option

src/fsharp/tc.fs

@@ -2042,7 +2042,7 @@ module GeneralizationHelpers =
             TrimUngeneralizableTypars genConstrainedTyparFlag inlineFlag generalizedTypars freeInEnv
 
     /// Condense type variables in positive position
-    let CondenseTypars (cenv, denv:DisplayEnv, generalizedTypars: Typars, tauTy) =
+    let CondenseTypars (cenv, denv:DisplayEnv, generalizedTypars: Typars, tauTy, m) =
 
         // The type of the value is ty11 * ... * ty1N -> ... -> tyM1 * ... * tyMM -> retTy
         // This is computed REGARDLESS of the arity of the expression.
@@ -2058,7 +2058,7 @@ module GeneralizationHelpers =
             match tp.Constraints |> List.partition (function (TyparConstraint.CoercesTo _) -> true | _ -> false) with 
             | [TyparConstraint.CoercesTo(cxty,_)], others -> 
                  // Throw away null constraints if they are implied 
-                 match others |> List.filter (function (TyparConstraint.SupportsNull(_)) -> not (TypeSatisfiesNullConstraint cenv.g cxty) | _ -> true) with
+                 match others |> List.filter (function (TyparConstraint.SupportsNull(_)) -> not (TypeSatisfiesNullConstraint cenv.g m cxty) | _ -> true) with
                  | [] -> Some cxty
                  | _ -> None
             | _ -> None
@@ -2132,7 +2132,7 @@ module GeneralizationHelpers =
                 let ty =  mkTyparTy tp
                 error(Error(FSComp.SR.tcNotSufficientlyGenericBecauseOfScope(NicePrint.prettyStringOfTy denv ty),m)))
             
-        let generalizedTypars = CondenseTypars(cenv,denv,generalizedTypars,tauTy)    
+        let generalizedTypars = CondenseTypars(cenv, denv, generalizedTypars, tauTy, m)    
 
         let generalizedTypars =  
             if canInferTypars then generalizedTypars 
@@ -13905,8 +13905,8 @@ module EstablishTypeDefinitionCores = begin
                 
             let allowNullLiteralAttributeCheck() = 
                 if hasAllowNullLiteralAttr then 
-                    tycon.TypeContents.tcaug_super |> Option.iter (fun ty -> if not (TypeNullIsExtraValue cenv.g ty) then errorR (Error(FSComp.SR.tcAllowNullTypesMayOnlyInheritFromAllowNullTypes(),m)))
-                    tycon.ImmediateInterfaceTypesOfFSharpTycon |> List.iter (fun ty -> if not (TypeNullIsExtraValue cenv.g ty) then errorR (Error(FSComp.SR.tcAllowNullTypesMayOnlyInheritFromAllowNullTypes(),m)))
+                    tycon.TypeContents.tcaug_super |> Option.iter (fun ty -> if not (TypeNullIsExtraValue cenv.g m ty) then errorR (Error(FSComp.SR.tcAllowNullTypesMayOnlyInheritFromAllowNullTypes(),m)))
+                    tycon.ImmediateInterfaceTypesOfFSharpTycon |> List.iter (fun ty -> if not (TypeNullIsExtraValue cenv.g m ty) then errorR (Error(FSComp.SR.tcAllowNullTypesMayOnlyInheritFromAllowNullTypes(),m)))
                 
                 
             let structLayoutAttributeCheck(allowed) = 

src/fsharp/typrelns.fs

@@ -461,8 +461,8 @@ module SignatureConformance = begin
                 elif fNull && not aNull then 
                   errorR(err(FSComp.SR.DefinitionsInSigAndImplNotCompatibleSignatureSaysNull))
 
-                let aNull2 = TypeNullIsExtraValue g (generalizedTyconRef (mkLocalTyconRef implTycon))
-                let fNull2 = TypeNullIsExtraValue g (generalizedTyconRef (mkLocalTyconRef implTycon))
+                let aNull2 = TypeNullIsExtraValue g m (generalizedTyconRef (mkLocalTyconRef implTycon))
+                let fNull2 = TypeNullIsExtraValue g m (generalizedTyconRef (mkLocalTyconRef implTycon))
                 if aNull2 && not fNull2 then 
                     errorR(err(FSComp.SR.DefinitionsInSigAndImplNotCompatibleImplementationSaysNull2))
                 elif fNull2 && not aNull2 then 
@@ -2166,7 +2166,7 @@ let BuildMethodCall tcVal g amap isMutable m isProp minfo valUseFlags minst objA
 
         // Build a 'call' to a struct default constructor 
         | DefaultStructCtor (g,typ) -> 
-            if not (TypeHasDefaultValue g typ) then 
+            if not (TypeHasDefaultValue g m typ) then 
                 errorR(Error(FSComp.SR.tcDefaultStructConstructorCall(),m))
             mkDefault (m,typ), typ)
 

tests/fsharp/typeProviders/helloWorld/provider.fsx

@@ -41,6 +41,11 @@ module Utils =
                 member __.ConstructorArguments = upcast [| CustomAttributeTypedArgument(typeof<string>, msg)  |]
                 member __.NamedArguments = upcast [| |] }
 
+    let mkAllowNullLiteralValueAttributeData(value: bool) = 
+        { new CustomAttributeData() with 
+                member __.Constructor =  typeof<Microsoft.FSharp.Core.AllowNullLiteralAttribute>.GetConstructors().[0]
+                member __.ConstructorArguments = upcast [| CustomAttributeTypedArgument(typeof<bool>, value)  |]
+                member __.NamedArguments = upcast [| |] }
 
 type public Runtime() =
     static member Id x = x
@@ -232,8 +237,11 @@ type public Provider() =
                    yield TypeBuilder.CreateConstructor(theNestedType,(fun _ -> [| |])) :> MemberInfo
                     |]  
 
-        and theType = TypeBuilder.CreateSimpleType(TypeContainer.Namespace(modul, namespaceName),className,members=allMembers,baseType=baseType)
-        and theNestedType = TypeBuilder.CreateSimpleType(TypeContainer.Type(theType),"NestedType",members=allMembersOfNestedType)
+        and theType = TypeBuilder.CreateSimpleType(TypeContainer.Namespace(modul, namespaceName),className,members=allMembers,baseType=baseType, 
+                                                   getCustomAttributes=(fun () -> [| mkAllowNullLiteralValueAttributeData(false) |]))
+
+        and theNestedType = TypeBuilder.CreateSimpleType(TypeContainer.Type(theType),"NestedType",members=allMembersOfNestedType, 
+                                                         getCustomAttributes=(fun () -> [| mkAllowNullLiteralValueAttributeData(true) |]))
 
         theType
     let helloWorldType = mkHelloWorldType rootNamespace "HelloWorldType" (typeof<obj>)

tests/fsharp/typeProviders/helloWorld/test.fsx

@@ -111,6 +111,15 @@ module BasicErasedProvidedTypeTest =
         [| 3;6 |]
 
 
+    check "cwkeonwe09a13355 - null attrib can't be used"
+        (null: FSharp.HelloWorld.HelloWorldType.NestedType) // should NOT  give a type error - this explicitly has AllowNullLiteralAttribute(true), so a null literal is allowed
+        null
+
+    // should NOT give a type error - this doesn't have any attributes, and a null literal is allowed by default
+    check "cwkeonwe09a13355 - null attrib"
+        (null : FSharp.HelloWorld.HelloWorldSubType) 
+        null
+
     check "cwkeonwe09a13355"
         (FSharp.HelloWorld.HelloWorldType.ReturnsEmptyNewArray())
         [| |]

tests/fsharp/typeProviders/negTests/neg1.bsl

@@ -1447,3 +1447,5 @@ neg1.fsx(448,9,448,107): typecheck error FS3148: Too many static parameters. Exp
 neg1.fsx(449,105,449,110): typecheck error FS3083: The static parameter 'Count' has already been given a value
 
 neg1.fsx(450,9,450,119): typecheck error FS3148: Too many static parameters. Expected at most 1 parameters, but got 0 unnamed and 2 named parameters.
+
+neg1.fsx(455,14,455,18): typecheck error FS0043: The type 'FSharp.HelloWorld.HelloWorldType' does not have 'null' as a proper value

tests/fsharp/typeProviders/negTests/neg1.fsx

@@ -449,3 +449,7 @@ module TooManyArgs =
         FSharp.GoodProviderForNegativeStaticParameterTypeTests.HelloWorldTypeWithStaticInt32Parameter<3,Count=2>.StaticProperty1 |> ignore
         FSharp.GoodProviderForNegativeStaticParameterTypeTests.HelloWorldTypeWithStaticInt32Parameter<Count=3,Count=2>.StaticProperty1 |> ignore
         //FSharp.GoodProviderForNegativeStaticParameterTypeTests.HelloWorldTypeWithStaticStringParameter<s>.StaticProperty1 |> ignore
+
+module NullLiteralNotAllowed =
+
+    let v = (null : FSharp.HelloWorld.HelloWorldType) // should give a type error - this explicitly has AllowNullLiteralAttribute(false), so a null literal is not allowed

tests/fsharp/typeProviders/negTests/provider.fsx

@@ -22,6 +22,12 @@ type public Runtime() =
 module Utils = 
     let doEvil() = failwith "deliberate error for testing purposes"
 
+    let mkAllowNullLiteralValueAttributeData(value: bool) = 
+        { new CustomAttributeData() with 
+                member __.Constructor =  typeof<Microsoft.FSharp.Core.AllowNullLiteralAttribute>.GetConstructors().[0]
+                member __.ConstructorArguments = upcast [| CustomAttributeTypedArgument(typeof<bool>, value)  |]
+                member __.NamedArguments = upcast [| |] }
+
 [<TypeProvider>]
 type public GoodProviderForNegativeTypeTests1() =
     let modul = typeof<GoodProviderForNegativeTypeTests1>.Assembly.GetModules().[0]
@@ -307,7 +313,8 @@ type public GoodProviderForNegativeStaticParameterTypeTests() =
 
         and theType = 
             let container = TypeContainer.Namespace(modul, rootNamespace)
-            TypeBuilder.CreateSimpleType(container,"HelloWorldType",members=allMembers)
+            TypeBuilder.CreateSimpleType(container,"HelloWorldType",members=allMembers,
+                                         getCustomAttributes=(fun () -> [| mkAllowNullLiteralValueAttributeData(false) |]))
 
         theType