[typer] allow type parameters in rvalue functions

see #11513

src/typing/typer.ml

@@ -1221,7 +1221,13 @@ and type_local_function ctx kind f with_type p =
 	let params = TypeloadFunction.type_function_params ctx f TPHLocal (match name with None -> "localfun" | Some (n,_) -> n) p in
 	if params <> [] then begin
 		if name = None then display_error ctx.com "Type parameters not supported in unnamed local functions" p;
-		if with_type <> WithType.NoValue then raise_typing_error "Type parameters are not supported for rvalue functions" p
+		begin match ctx.com.platform with
+		| Java | Cs ->
+			(* gencommon just can't *)
+			if with_type <> WithType.NoValue then raise_typing_error "Type parameters are not supported for rvalue functions" p
+		| _ ->
+			()
+		end
 	end;
 	let v,pname = (match name with
 		| None -> None,p
@@ -1323,6 +1329,13 @@ and type_local_function ctx kind f with_type p =
 	| _ ->
 		());
 	let ft = TFun (targs,rt) in
+	let ft = match with_type with
+		| WithType.NoValue ->
+			ft
+		| _ ->
+			(* We want to apply params as if we accessed the function by name (see type_ident_raise). *)
+			apply_params params (Monomorph.spawn_constrained_monos (fun t -> t) params) ft
+	in
 	let v = (match v with
 		| None -> None
 		| Some v ->
@@ -1364,7 +1377,7 @@ and type_local_function ctx kind f with_type p =
 			else []
 		in
 		let exprs =
-			if is_rec then begin
+			if is_rec || (params <> [] && with_type <> WithType.NoValue) then begin
 				if inline then display_error ctx.com "Inline function cannot be recursive" e.epos;
 				(mk (TVar (v,Some (mk (TConst TNull) ft p))) ctx.t.tvoid p) ::
 				(mk (TBinop (OpAssign,mk (TLocal v) ft p,e)) ft p) ::

tests/unit/src/unit/issues/Issue11513.hx

@@ -0,0 +1,24 @@
+package unit.issues;
+
+private enum abstract Message<TBody>(Int) {
+	final move_to:Message<{x:Int, y:Int}>;
+}
+
+private typedef Listener = {
+	function send<TBody>(name:Message<TBody>, body:TBody):Void;
+}
+
+private final listener:Listener = {
+	send: function send<T>(message:Message<T>, body:T) {
+		switch (message) {
+			case move_to:
+		}
+	}
+}
+
+class Issue11513 extends Test {
+	function test() {
+		listener.send(move_to, {x: 1, y: 2});
+		noAssert();
+	}
+}