Set serializable bit for all serializable types (#4211)

src/fsharp/IlxGen.fs

@@ -3747,8 +3747,8 @@ and GenClosureTypeDefs cenv (tref:ILTypeRef, ilGenParams, attrs, ilCloFreeVars,
       Properties = emptyILProperties
       Methods= mkILMethods mdefs 
       MethodImpls= mkILMethodImpls mimpls 
-      IsSerializable= cenv.g.attrib_SerializableAttribute.IsSome
-      IsComInterop= false    
+      IsSerializable=true
+      IsComInterop= false
       IsSpecialName= true
       NestedTypes=emptyILTypeDefs
       Encoding= ILDefaultPInvokeEncoding.Auto
@@ -3803,8 +3803,8 @@ and GenLambdaClosure cenv (cgbuf:CodeGenBuffer) eenv isLocalTypeFunc selfv expr
                       Properties = emptyILProperties
                       Methods= mkILMethods ilContractMeths 
                       MethodImpls= emptyILMethodImpls 
-                      IsSerializable= cenv.g.attrib_SerializableAttribute.IsSome 
-                      IsComInterop=false    
+                      IsSerializable=true
+                      IsComInterop=false
                       IsSpecialName= true
                       NestedTypes=emptyILTypeDefs
                       Encoding= ILDefaultPInvokeEncoding.Auto
@@ -6563,9 +6563,8 @@ and GenTypeDef cenv mgbuf lazyInitInfo eenv m (tycon:Tycon) =
         let ilFields = mkILFields ilFieldDefs
         
         let tdef, tdefDiscards = 
-           let isSerializable = (TryFindFSharpBoolAttribute cenv.g cenv.g.attrib_AutoSerializableAttribute tycon.Attribs <> Some(false)) 
-                             && cenv.g.attrib_SerializableAttribute.IsSome
-                                       
+           let isSerializable = (TryFindFSharpBoolAttribute cenv.g cenv.g.attrib_AutoSerializableAttribute tycon.Attribs <> Some(false))
+
            match tycon.TypeReprInfo with 
            | TILObjectRepr _ ->
                let td = tycon.ILTyconRawMetadata
@@ -6817,11 +6816,10 @@ and GenExnDef cenv mgbuf eenv m (exnc:Tycon) =
             else
                 []
 
-        
         let serializationRelatedMembers =
-            // do not emit serialization related members if target framework lacks SerializableAttribute or SerializationInfo
-          match cenv.g.attrib_SerializableAttribute, cenv.g.iltyp_SerializationInfo, cenv.g.iltyp_StreamingContext with 
-          | Some _,  Some serializationInfoType, Some streamingContextType -> 
+          // do not emit serialization related members if target framework lacks SerializationInfo or StreamingContext
+          match cenv.g.iltyp_SerializationInfo, cenv.g.iltyp_StreamingContext with 
+          | Some serializationInfoType, Some streamingContextType -> 
             let ilCtorDefForSerialziation = 
                 mkILCtor(ILMemberAccess.Family,
                         [mkILParamNamed("info", serializationInfoType);mkILParamNamed("context",streamingContextType)],
@@ -6880,7 +6878,7 @@ and GenExnDef cenv mgbuf eenv m (exnc:Tycon) =
              emptyILEvents,
              mkILCustomAttrs [mkCompilationMappingAttr cenv.g (int SourceConstructFlags.Exception)],
              ILTypeInit.BeforeField)
-        let tdef = { tdef with IsSerializable = cenv.g.attrib_SerializableAttribute.IsSome }
+        let tdef = { tdef with IsSerializable = true }
         mgbuf.AddTypeDef(tref, tdef, false, false, None)
 
 

src/fsharp/TcGlobals.fs

@@ -1005,7 +1005,6 @@ type public TcGlobals(compilingFslib: bool, ilg:ILGlobals, fslibCcu: CcuThunk, d
   member val attrib_ProjectionParameterAttribute           = mk_MFCore_attrib "ProjectionParameterAttribute"
   member val attrib_CustomOperationAttribute               = mk_MFCore_attrib "CustomOperationAttribute"
   member val attrib_NonSerializedAttribute                 = tryFindSysAttrib "System.NonSerializedAttribute"
-  member val attrib_SerializableAttribute                 = tryFindSysAttrib "System.SerializableAttribute"
   
   member val attrib_AutoSerializableAttribute              = mk_MFCore_attrib "AutoSerializableAttribute"
   member val attrib_RequireQualifiedAccessAttribute        = mk_MFCore_attrib "RequireQualifiedAccessAttribute"

src/fsharp/fsc.fs

@@ -1968,12 +1968,10 @@ let main2b (tcImportsCapture,dynamicAssemblyCreator) (Args (ctok, tcConfig: TcCo
     use unwindBuildPhase = PushThreadBuildPhaseUntilUnwind BuildPhase.IlxGen
     let ilxGenerator = CreateIlxAssemblyGenerator (tcConfig, tcImports, tcGlobals, (LightweightTcValForUsingInBuildMethodCall tcGlobals), generatedCcu)
 
-    // Check if System.SerializableAttribute exists in mscorlib.dll, 
-    // so that make sure the compiler only emits "serializable" bit into IL metadata when it is available.
-    // Note that SerializableAttribute may be relocated in the future but now resides in mscorlib.
     let codegenResults = GenerateIlxCode ((if Option.isSome dynamicAssemblyCreator then IlReflectBackend else IlWriteBackend), Option.isSome dynamicAssemblyCreator, false, tcConfig, topAttrs, optimizedImpls, generatedCcu.AssemblyName, ilxGenerator)
     let casApplied = new Dictionary<Stamp, bool>()
     let securityAttrs, topAssemblyAttrs = topAttrs.assemblyAttrs |> List.partition (fun a -> TypeChecker.IsSecurityAttribute tcGlobals (tcImports.GetImportMap()) casApplied a rangeStartup)
+
     // remove any security attributes from the top-level assembly attribute list
     let topAttrs = {topAttrs with assemblyAttrs=topAssemblyAttrs}
     let permissionSets = ilxGenerator.CreatePermissionSets securityAttrs