Fix internal Id type being selected in overload resolution (#633)

Author: gusty

src/FSharpPlus/Control/Collection.fs

@@ -301,6 +301,7 @@ type DistinctBy =
 
 type GroupBy =
     static member GroupBy (x: Id<'T>  , f: 'T->'Key, _: Id<'Key*Id<'T>>    , [<Optional>]_impl: GroupBy) = let a = Id.run x in Id.create (f a, x)
+    static member GroupBy (x: Id2<'T> , f: 'T->'Key, _: Id2<'Key*Id2<'T>>  , [<Optional>]_impl: GroupBy) = let a = Id2.run x in Id2.create (f a, x)
     static member GroupBy (x: seq<'T> , f: 'T->'Key, _: seq<'Key*seq<'T>>  , [<Optional>]_impl: GroupBy) = Seq.groupBy f x
     static member GroupBy (x: list<'T>, f: 'T->'Key, _: list<'Key*list<'T>>, [<Optional>]_impl: GroupBy) = Seq.groupBy f x |> Seq.map (fun (x, y) -> x, Seq.toList  y) |> Seq.toList
     static member GroupBy (x: 'T []   , f: 'T->'Key, _: ('Key*('T [])) []  , [<Optional>]_impl: GroupBy) = Seq.groupBy f x |> Seq.map (fun (x, y) -> x, Seq.toArray y) |> Seq.toArray

src/FSharpPlus/Internals.fs

@@ -105,6 +105,16 @@ module Id =
     let map f (x: Id<_>) = Id (f x.getValue)
     let create x = Id x
 
+type Id2<'t> (v: 't) =
+   let value = v
+   member _.getValue = value
+
+[<RequireQualifiedAccess>]
+module Id2 =
+    let run   (x: Id2<_>) = x.getValue
+    let map f (x: Id2<_>) = Id2 (f x.getValue)
+    let create x = Id2 x
+
 type Id0 (v: string) =
    let value = v
    member _.getValue = value

tests/FSharpPlus.Tests/Collections.fs

@@ -291,3 +291,10 @@ module Collections =
 
         let m = choose Some ((ofSeq :seq<_*_> -> Map<_,_>) (seq ["a", 1; "b", 2]))
         Assert.IsInstanceOf<Option<Map<string,int>>> (Some m)
+
+    // Compile tests
+    
+    let inline mapOfGroup (key: 'T -> 'Key when 'Key : equality) (sequence: '``Collection<'T>``) : Map<'Key, '``Collection<'T>``> =
+        sequence
+        |> groupBy key
+        |> Map.ofSeq