Rust - Support [<Emit(type)>] on a type to assist with binding to built in types

src/Fable.Transforms/Rust/AST/Rust.AST.Helpers.fs

@@ -1100,6 +1100,10 @@ module Types =
         mkGenericTypeArgs tys
         |> mkGenericPathTy path
 
+    let mkExtMacroTy value tys: Ty =
+        TyKind.EmitTypeExpression(value, mkVec tys)
+        |> mkTy
+
     let TODO_TYPE name: Ty =
         mkGenericPathTy ["TODO_TYPE_" + name] None
 

src/Fable.Transforms/Rust/AST/Rust.AST.State.fs

@@ -236,6 +236,75 @@ let visibility_qualified(vis: ast.Visibility, s: string): string =
 //     member self.deref_mut().Target =
 //         self.s
 
+let print_emit_expr self value (args: Vec<_>, printArgs) =
+        let args = args.ToArray()
+        // printer.AddLocation(loc)
+
+        let inline replace pattern (f: System.Text.RegularExpressions.Match -> string) input =
+            System.Text.RegularExpressions.Regex.Replace(input, pattern, f)
+
+        let printSegment (printer: Pretty.Printer) (value: string) segmentStart segmentEnd =
+            let segmentLength = segmentEnd - segmentStart
+            if segmentLength > 0 then
+                let segment = value.Substring(segmentStart, segmentLength)
+                self.s.word(segment)
+
+        // Macro transformations
+        // https://fable.io/docs/communicate/js-from-fable.html#Emit-when-F-is-not-enough
+        let value =
+            value
+            |> replace @"\$(\d+)\.\.\." (fun m ->
+                let rep = ResizeArray()
+                let i = int m.Groups.[1].Value
+                for j = i to args.Length - 1 do
+                    rep.Add("$" + string j)
+                String.concat ", " rep)
+
+            // |> replace @"\{\{\s*\$(\d+)\s*\?(.*?)\:(.*?)\}\}" (fun m ->
+            //     let i = int m.Groups.[1].Value
+            //     match args.[i] with
+            //     | Literal(BooleanLiteral(value=value)) when value -> m.Groups.[2].Value
+            //     | _ -> m.Groups.[3].Value)
+
+            |> replace @"\{\{([^\}]*\$(\d+).*?)\}\}" (fun m ->
+                let i = int m.Groups.[2].Value
+                match Array.tryItem i args with
+                | Some _ -> m.Groups.[1].Value
+                | None -> "")
+
+            // If placeholder is followed by !, emit string literals as JS: "let $0! = $1"
+            // |> replace @"\$(\d+)!" (fun m ->
+            //     let i = int m.Groups.[1].Value
+            //     match Array.tryItem i args with
+            //     | Some(Literal(Literal.StringLiteral(StringLiteral(value, _)))) -> value
+            //     | _ -> "")
+
+        let matches = System.Text.RegularExpressions.Regex.Matches(value, @"\$\d+")
+        if matches.Count > 0 then
+            for i = 0 to matches.Count - 1 do
+                let m = matches.[i]
+                let isSurroundedWithParens =
+                    m.Index > 0
+                    && m.Index + m.Length < value.Length
+                    && value.[m.Index - 1] = '('
+                    && value.[m.Index + m.Length] = ')'
+
+                let segmentStart =
+                    if i > 0 then matches.[i-1].Index + matches.[i-1].Length
+                    else 0
+
+                printSegment self.s value segmentStart m.Index
+
+                let argIndex = int m.Value.[1..]
+                match Array.tryItem argIndex args with
+                | Some e -> printArgs e
+                | None -> self.s.word("undefined")
+
+            let lastMatch = matches.[matches.Count - 1]
+            printSegment self.s value (lastMatch.Index + lastMatch.Length) value.Length
+        else
+            printSegment self.s value 0 value.Length
+
 type PrintState = State
     // abstract comments: unit -> Option<Comments>
     // abstract print_ident: ident: Ident -> unit
@@ -868,6 +937,9 @@ type State with
                 self.print_mac(m)
             | ast.TyKind.CVarArgs ->
                 self.s.word("...")
+            | ast.TyKind.EmitTypeExpression(m, p) ->
+                print_emit_expr self m (p, self.print_type)
+                ()
         self.s.end_()
 
     member self.print_foreign_item(item: ast.ForeignItem) =
@@ -1427,76 +1499,6 @@ type State with
             m.span()
         )
 
-    member self.print_emit_expr(value, args: Vec<Types.Expr>) =
-        let args = args.ToArray()
-        // printer.AddLocation(loc)
-
-        let inline replace pattern (f: System.Text.RegularExpressions.Match -> string) input =
-            System.Text.RegularExpressions.Regex.Replace(input, pattern, f)
-
-        let printSegment (printer: Pretty.Printer) (value: string) segmentStart segmentEnd =
-            let segmentLength = segmentEnd - segmentStart
-            if segmentLength > 0 then
-                let segment = value.Substring(segmentStart, segmentLength)
-                self.s.word(segment)
-
-        // Macro transformations
-        // https://fable.io/docs/communicate/js-from-fable.html#Emit-when-F-is-not-enough
-        let value =
-            value
-            |> replace @"\$(\d+)\.\.\." (fun m ->
-                let rep = ResizeArray()
-                let i = int m.Groups.[1].Value
-                for j = i to args.Length - 1 do
-                    rep.Add("$" + string j)
-                String.concat ", " rep)
-
-            // |> replace @"\{\{\s*\$(\d+)\s*\?(.*?)\:(.*?)\}\}" (fun m ->
-            //     let i = int m.Groups.[1].Value
-            //     match args.[i] with
-            //     | Literal(BooleanLiteral(value=value)) when value -> m.Groups.[2].Value
-            //     | _ -> m.Groups.[3].Value)
-
-            |> replace @"\{\{([^\}]*\$(\d+).*?)\}\}" (fun m ->
-                let i = int m.Groups.[2].Value
-                match Array.tryItem i args with
-                | Some _ -> m.Groups.[1].Value
-                | None -> "")
-
-            // If placeholder is followed by !, emit string literals as JS: "let $0! = $1"
-            // |> replace @"\$(\d+)!" (fun m ->
-            //     let i = int m.Groups.[1].Value
-            //     match Array.tryItem i args with
-            //     | Some(Literal(Literal.StringLiteral(StringLiteral(value, _)))) -> value
-            //     | _ -> "")
-
-        let matches = System.Text.RegularExpressions.Regex.Matches(value, @"\$\d+")
-        if matches.Count > 0 then
-            for i = 0 to matches.Count - 1 do
-                let m = matches.[i]
-                let isSurroundedWithParens =
-                    m.Index > 0
-                    && m.Index + m.Length < value.Length
-                    && value.[m.Index - 1] = '('
-                    && value.[m.Index + m.Length] = ')'
-
-                let segmentStart =
-                    if i > 0 then matches.[i-1].Index + matches.[i-1].Length
-                    else 0
-
-                printSegment self.s value segmentStart m.Index
-
-                let argIndex = int m.Value.[1..]
-                match Array.tryItem argIndex args with
-                | Some e when isSurroundedWithParens -> self.print_expr(e)
-                | Some e -> self.print_expr(e)
-                | None -> self.s.word("undefined")
-
-            let lastMatch = matches.[matches.Count - 1]
-            printSegment self.s value (lastMatch.Index + lastMatch.Length) value.Length
-        else
-            printSegment self.s value 0 value.Length
-
     member self.print_call_post(args: Vec<P<ast.Expr>>) =
         self.s.popen()
         self.commasep_exprs(pp.Breaks.Inconsistent, args)
@@ -2018,7 +2020,7 @@ type State with
                 self.s.pclose()
             | ast.ExprKind.MacCall(m) -> self.print_mac(m)
             | ast.ExprKind.EmitExpression(e, args) ->
-                self.print_emit_expr(e, args)
+                print_emit_expr self e (args, self.print_expr)
             | ast.ExprKind.Paren(e) ->
                 self.s.popen()
                 self.print_inner_attributes_inline(attrs)

src/Fable.Transforms/Rust/AST/Rust.AST.Types.fs

@@ -964,7 +964,7 @@ type ExprKind =
     /// Placeholder for an expression that wasn't syntactically well formed in some way.
     | Err
 
-    /// Escape hatch to allow adding custom macros - This is not in the core rust AST - Use with caution!!!
+    /// Escape hatch to allow adding custom macros - This is |not in the core rust AST - Use with caution!!!
     | EmitExpression of value: string * args: Vec<Expr>
 
 /// The explicit `Self` type in a "qualified path". The actual
@@ -1232,6 +1232,9 @@ type TyKind =
     | Err
     /// Placeholder for a `va_list`.
     | CVarArgs
+    /// Escape hatch to allow adding custom macros - This is not in the core rust AST - Use with caution!!!
+    | EmitTypeExpression of value: string * args: Vec<Ty>
+
 
 /// Syntax used to declare a trait object.
 [<RequireQualifiedAccess>]

src/Fable.Transforms/Rust/Fable2Rust.fs

@@ -378,9 +378,13 @@ module TypeInfo =
             -> true
 
         // conditionally Rc-wrapped
-        | Replacements.Util.Builtin (Replacements.Util.FSharpChoice _)
-        | Fable.DeclaredType _ ->
+        | Replacements.Util.Builtin (Replacements.Util.FSharpChoice _) ->
             not (isCopyableType com Set.empty t)
+        | Fable.DeclaredType (entRef, _) ->
+            match com.GetEntity(entRef) with
+            | HasEmitAttribute _ -> false // do not make custom types Rc-wrapped by default. This prevents inconsistency between type and implementation emit
+            | _ ->
+                not (isCopyableType com Set.empty t)
 
     let isCloneableType (com: IRustCompiler) t =
         match t with
@@ -588,11 +592,23 @@ module TypeInfo =
         let bounds = [mkTypeTraitGenericBound pathNames genArgs]
         mkDynTraitTy bounds
 
+    let (|HasEmitAttribute|_|) (ent: Fable.Entity) =
+        ent.Attributes |> Seq.tryPick (fun att ->
+            if att.Entity.FullName.StartsWith(Atts.emit) then
+                match att.ConstructorArgs with
+                | [:? string as macro] -> Some macro
+                | _ -> None
+            else None)
+
     let transformDeclaredType (com: IRustCompiler) ctx entRef genArgs: Rust.Ty =
-        let ent = com.GetEntity(entRef)
-        if ent.IsInterface then
+        match com.GetEntity(entRef) with
+        | HasEmitAttribute tmpl ->
+            let genArgs = genArgs |> List.map (transformType com ctx)
+            mkExtMacroTy tmpl genArgs
+        | ent when ent.IsInterface = true ->
             transformInterfaceType com ctx entRef genArgs
-        else
+
+        | ent ->
             let genArgs = transformGenArgs com ctx genArgs
             makeFullNamePathTy ent.FullName genArgs
 

tests/Rust/tests/src/InteropTests.fs

@@ -9,7 +9,7 @@ module Subs =
     [<Emit("$0 * $1")>]
     let mul a b = jsNative
 
-    [<Emit("{ let mut v = std::vec::Vec::new(); v.append(&mut vec![$0,$1]); MutCell::from(v) }")>]
+    [<Emit("{ let mut v = std::vec::Vec::new(); v.append(&mut vec![$0,$1]); Rc::from(MutCell::from(v)) }")>]
     let fixedVec a b = jsNative
 
     //doesn't currently work, but would be preferred
@@ -19,16 +19,24 @@ module Subs =
     //     member x.Push a = jsNative
 
     module Vec =
-        [<Erase>]
-        type VecT =
+        [<Emit("Rc<MutCell<Vec<$0>>>")>]
+        type VecT<'a> =
             [<Emit("$0.get_mut().push($1)")>]
             abstract Push: 'a -> unit
-        [<Emit("MutCell::from(std::vec::Vec::new())")>]
-        let create (): VecT = jsNative
+        [<Emit("Rc::from(MutCell::from(std::vec::Vec::new()))")>]
+        let create (): VecT<'a> = jsNative
         [<Emit("$1.get_mut().push($0)")>]
-        let push item (vec: VecT) = jsNative
+        let push (item: 'a) (vec: VecT<'a>) = jsNative
         [<Emit("{ $1.get_mut().append(&mut vec![$0]); $1 }")>]
-        let append item (vec: VecT): VecT = jsNative
+        let append (item: 'a) (vec: VecT<'a>): VecT<'a> = jsNative
+
+        [<Emit("$0.len()")>]
+        let len (vec: VecT<'a>): nativeint = jsNative
+
+        module FnExps =
+            let push42 (v: VecT<_>) = 
+                v.Push 42
+                v
 
     module Float =
         [<Emit("$0.sin()")>]
@@ -82,4 +90,14 @@ let ``vec instance mutable push should work`` () =
     b.Push 2
     a |> equal b
 
+[<Fact>]
+let ``vec instance type emit should work`` () =
+    let a = Subs.Vec.create()
+    a.Push 42
+
+[<Fact>]
+let ``vec instance pass over boundary should work`` () =
+    let a = Subs.Vec.create()
+    let res = Subs.Vec.FnExps.push42 a
+    res |> Subs.Vec.len |> int |> equal 1
 #endif