Print attributes for layoutArgInfo.

src/Compiler/Checking/NicePrint.fs

@@ -997,34 +997,46 @@ module PrintTypes =
     and layoutType denv ty = 
         layoutTypeWithInfo denv SimplifyTypes.typeSimplificationInfo0 ty
 
+    /// Layout '[<attrib1; attrib2>]' for parameters
+    and layoutAttribsOneline denv attribs =
+        match attribs with
+        | [] -> emptyL
+        | attribs ->
+            let attrsL =
+                [ for attr in attribs do layoutAttrib denv attr ]
+
+            squareAngleL (sepListL (rightL (tagPunctuation ";")) attrsL)
+
     // Format each argument, including its name and type 
     let layoutArgInfo denv env (ty, argInfo: ArgReprInfo) = 
         let g = denv.g
 
         // Detect an optional argument 
         let isOptionalArg = HasFSharpAttribute g g.attrib_OptionalArgumentAttribute argInfo.Attribs
-        let isParamArray = HasFSharpAttribute g g.attrib_ParamArrayAttribute argInfo.Attribs
 
-        match argInfo.Name, isOptionalArg, isParamArray, tryDestOptionTy g ty with 
+        match argInfo.Name, isOptionalArg, tryDestOptionTy g ty with 
         // Layout an optional argument 
-        | Some id, true, _, ValueSome ty -> 
+        | Some id, true, ValueSome ty -> 
             let idL = ConvertValLogicalNameToDisplayLayout false (tagParameter >> rightL) id.idText
+            let attrsLayout =
+                argInfo.Attribs
+                |> List.filter (fun a -> not (IsMatchingFSharpAttribute g g.attrib_OptionalArgumentAttribute a))
+                |> layoutAttribsOneline denv 
+
+            attrsLayout ^^
             LeftL.questionMark ^^ 
             (idL |> addColonL) ^^
             layoutTypeWithInfoAndPrec denv env 2 ty 
 
-        // Layout an unnamed argument 
-        | None, _, _, _ -> 
+        // Layout an unnamed argument
+        // Cannot have any attributes
+        | None, _, _ -> 
             layoutTypeWithInfoAndPrec denv env 2 ty
 
         // Layout a named argument 
-        | Some id, _, isParamArray, _ -> 
+        | Some id, _, _ -> 
             let idL = ConvertValLogicalNameToDisplayLayout false (tagParameter >> wordL) id.idText
-            let prefix =
-                if isParamArray then
-                    layoutBuiltinAttribute denv g.attrib_ParamArrayAttribute ^^ idL
-                else
-                    idL
+            let prefix = layoutAttribsOneline denv argInfo.Attribs ^^ idL
             (prefix |> addColonL) ^^ layoutTypeWithInfoAndPrec denv env 2 ty
 
     let layoutCurriedArgInfos denv env argInfos =

tests/FSharp.Compiler.ComponentTests/Conformance/MethodResolution/ParametersResolution.fs

@@ -266,6 +266,6 @@ let _, _ = Thing.Do()
         |> typecheck
         |> shouldFail
         |> withDiagnostics [
-            (Error 501, Line 6, Col 12, Line 6, Col 22, "The member or object constructor 'Do' takes 1 argument(s) but is here given 0. The required signature is 'static member Thing.Do: i: outref<bool> -> bool'.")
+            (Error 501, Line 6, Col 12, Line 6, Col 22, "The member or object constructor 'Do' takes 1 argument(s) but is here given 0. The required signature is 'static member Thing.Do: [<Optional>] i: outref<bool> -> bool'.")
         ]
 

tests/FSharp.Compiler.ComponentTests/Signatures/TestCasesForGenerationRoundTrip/attributes.fsx

@@ -0,0 +1,23 @@
+module Attributes
+
+open System
+
+type XAttribute() =
+    inherit Attribute()
+
+let a ([<X>] b: int) : int = 0
+
+type YAttribute(y: string) =
+    inherit Attribute()
+
+let a2 ([<X; Y "meh">] g: string) ([<Y "buzz">] h) ([<X; Y "ii">] i: int) =
+    printfn "h is %i" h
+    g
+
+type Boo() =
+    member _.Do ([<X; Y "meh">] g: string) ([<Y "buzz">] h) =
+        printfn "h is %i" h
+        g
+
+    member _.Maybe([<X>] ?s: int) = ()
+    member _.Forever([<X>][<Y "zzz">][<ParamArray>] args: string array) = ()

tests/fsharp/typecheck/overloads/neg_generic_known_argument_types.bsl

@@ -4,5 +4,5 @@ neg_generic_known_argument_types.fsx(9,16,9,49): typecheck error FS0041: A uniqu
 Known types of arguments: ^fa * 'fb * 'a * argD: 'c when ^fa: (member X: ^b -> ^b) and ^b: (member BBBB: unit -> unit)
 
 Candidates:
- - static member A.Foo: argA1: 'a * argB1: ('a -> 'b) * argC1: ('a -> 'b) * argD: ('a -> 'b) * argZ1: 'zzz -> 'b
- - static member A.Foo: argA2: 'a * argB2: ('a -> 'b) * argC2: ('b -> 'c) * argD: ('c -> 'd) * argZ2: 'zzz -> 'd
+ - static member A.Foo: argA1: 'a * argB1: ('a -> 'b) * argC1: ('a -> 'b) * argD: ('a -> 'b) * [<Optional>] argZ1: 'zzz -> 'b
+ - static member A.Foo: argA2: 'a * argB2: ('a -> 'b) * argC2: ('b -> 'c) * argD: ('c -> 'd) * [<Optional>] argZ2: 'zzz -> 'd

tests/fsharp/typecheck/sigs/neg106.bsl

@@ -46,16 +46,16 @@ neg106.fs(40,18,40,32): typecheck error FS0041: No overloads match for method 'M
 Known types of arguments: string * inref<int>
 
 Available overloads:
- - static member C.M: a: int * x: byref<int> -> unit // Argument 'a' doesn't match
- - static member C.M: a: string * x: byref<int> -> unit // Argument 'x' doesn't match
+ - static member C.M: a: int * [<System.Runtime.InteropServices.Out>] x: byref<int> -> unit // Argument 'a' doesn't match
+ - static member C.M: a: string * [<System.Runtime.InteropServices.Out>] x: byref<int> -> unit // Argument 'x' doesn't match
 
 neg106.fs(41,19,41,31): typecheck error FS0041: No overloads match for method 'M'.
 
 Known types of arguments: int * inref<int>
 
 Available overloads:
- - static member C.M: a: int * x: byref<int> -> unit // Argument 'x' doesn't match
- - static member C.M: a: string * x: byref<int> -> unit // Argument 'a' doesn't match
+ - static member C.M: a: int * [<System.Runtime.InteropServices.Out>] x: byref<int> -> unit // Argument 'x' doesn't match
+ - static member C.M: a: string * [<System.Runtime.InteropServices.Out>] x: byref<int> -> unit // Argument 'a' doesn't match
 
 neg106.fs(49,22,49,26): typecheck error FS0001: Type mismatch. Expecting a
     'byref<int>'    

tests/fsharp/typecheck/sigs/neg106.vsbsl

@@ -46,16 +46,16 @@ neg106.fs(40,18,40,32): typecheck error FS0041: No overloads match for method 'M
 Known types of arguments: string * inref<int>
 
 Available overloads:
- - static member C.M: a: int * x: byref<int> -> unit // Argument 'a' doesn't match
- - static member C.M: a: string * x: byref<int> -> unit // Argument 'x' doesn't match
+ - static member C.M: a: int * [<System.Runtime.InteropServices.Out>] x: byref<int> -> unit // Argument 'a' doesn't match
+ - static member C.M: a: string * [<System.Runtime.InteropServices.Out>] x: byref<int> -> unit // Argument 'x' doesn't match
 
 neg106.fs(41,19,41,31): typecheck error FS0041: No overloads match for method 'M'.
 
 Known types of arguments: int * inref<int>
 
 Available overloads:
- - static member C.M: a: int * x: byref<int> -> unit // Argument 'x' doesn't match
- - static member C.M: a: string * x: byref<int> -> unit // Argument 'a' doesn't match
+ - static member C.M: a: int * [<System.Runtime.InteropServices.Out>] x: byref<int> -> unit // Argument 'x' doesn't match
+ - static member C.M: a: string * [<System.Runtime.InteropServices.Out>] x: byref<int> -> unit // Argument 'a' doesn't match
 
 neg106.fs(49,22,49,26): typecheck error FS0001: Type mismatch. Expecting a
     'byref<int>'    

tests/service/Symbols.fs

@@ -663,4 +663,18 @@ type ImmutableArrayViaBuilder<'T>(builder: ImmutableArray<'T>.Builder) =
     class end
 """
             (8, 29, "type ImmutableArrayViaBuilder<'T>(builder: ImmutableArray<'T>.Builder) =", ".ctor")
-#endif
+#endif
+
+    [<Test>]
+    let ``Includes attribute for parameter`` () =
+        assertSignature
+            "val a: [<B>] c: int -> int"
+            """
+module Telplin
+
+type BAttribute() =
+    inherit System.Attribute()
+
+let a ([<B>] c: int) : int = 0
+"""
+            (7, 5, "let a ([<B>] c: int) : int = 0", "a")