[java] don't check native signatures on extern functions

closes #11131

src/typing/typeloadFields.ml

@@ -1655,7 +1655,7 @@ let init_field (ctx,cctx,fctx) f =
 		delay ctx PTypeField (fun() -> InheritDoc.build_class_field_doc ctx (Some c) cf);
 	cf
 
-let check_overload ctx f fs =
+let check_overload ctx f fs is_extern_class =
 	try
 		let f2 =
 			List.find (fun f2 ->
@@ -1667,15 +1667,16 @@ let check_overload ctx f fs =
 		display_error ~depth:1 ctx.com (compl_msg "The second field is declared here") f2.cf_pos;
 		false
 	with Not_found -> try
-		(* OVERLOADTODO: generalize this and respect whether or not we actually generate the functions *)
-		if ctx.com.platform <> Java then raise Not_found;
+		if ctx.com.platform <> Java || is_extern_class then raise Not_found;
 		let get_vmtype = ambiguate_funs in
 		let f2 =
 			List.find (fun f2 ->
 				f != f2 &&
 				Overloads.same_overload_args ~get_vmtype f.cf_type f2.cf_type f f2
 			) fs
 		in
+		(* Don't bother checking this on externs and assume the users know what they're doing (issue #11131) *)
+		if has_class_field_flag f CfExtern && has_class_field_flag f2 CfExtern then raise Not_found;
 		display_error ctx.com (
 			"Another overloaded field of similar signature was already declared : " ^
 			f.cf_name ^
@@ -1688,10 +1689,11 @@ let check_overload ctx f fs =
 
 let check_overloads ctx c =
 	(* check if field with same signature was declared more than once *)
+	let is_extern = has_class_flag c CExtern in
 	let check_field f =
 		if has_class_field_flag f CfOverload then begin
 			let all = f :: f.cf_overloads in
-			ignore(List.fold_left (fun b f -> b && check_overload ctx f all) true all)
+			ignore(List.fold_left (fun b f -> b && check_overload ctx f all is_extern) true all)
 		end
 	in
 	List.iter check_field c.cl_ordered_fields;

tests/misc/java/projects/Issue11131/Main.hx

@@ -0,0 +1,38 @@
+@:native("test.MathOperation")
+extern class MathOperation {
+	public static inline overload function perform(op:Int->Int, value:Int) {
+		return op(value);
+	}
+
+	public static inline overload function perform(op:Int->Int->Int, value:Int) {
+		return op(value, value);
+	}
+}
+
+@:native("test.MathOperation")
+class MathOperationNotExtern {
+	public static extern inline overload function perform(op:Int->Int, value:Int) {
+		return op(value);
+	}
+
+	public static extern inline overload function perform(op:Int->Int->Int, value:Int) {
+		return op(value, value);
+	}
+}
+
+class Main {
+	static function main() {
+		Sys.println(MathOperation.perform(double, 3));
+		Sys.println(MathOperation.perform(multiply, 3));
+		Sys.println(MathOperationNotExtern.perform(double, 3));
+		Sys.println(MathOperationNotExtern.perform(multiply, 3));
+	}
+
+	static function double(a):Int {
+		return a * 2;
+	}
+
+	static function multiply(a, b):Int {
+		return a * b;
+	}
+}

tests/misc/java/projects/Issue11131/MainFail.hx

@@ -0,0 +1,25 @@
+@:native("test.MathOperation")
+class MathOperation {
+	public static inline overload function perform(op:Int->Int, value:Int) {
+		return op(value);
+	}
+
+	public static inline overload function perform(op:Int->Int->Int, value:Int) {
+		return op(value, value);
+	}
+}
+
+class MainFail {
+	static function main() {
+		Sys.println(MathOperation.perform(double, 3));
+		Sys.println(MathOperation.perform(multiply, 3));
+	}
+
+	static function double(a):Int {
+		return a * 2;
+	}
+
+	static function multiply(a, b):Int {
+		return a * b;
+	}
+}

tests/misc/java/projects/Issue11131/compile-fail.hxml

@@ -0,0 +1,3 @@
+-cp src
+-main MainFail
+--jvm run.jar

tests/misc/java/projects/Issue11131/compile-fail.hxml.stderr

@@ -0,0 +1,3 @@
+MainFail.hx:3: lines 3-5 : Another overloaded field of similar signature was already declared : perform
+MainFail.hx:3: lines 3-5 : ... The signatures are different in Haxe, but not in the target language
+MainFail.hx:7: lines 7-9 : ... The second field is declared here

tests/misc/java/projects/Issue11131/compile.hxml

@@ -0,0 +1,4 @@
+-cp src
+-main Main
+--jvm run.jar
+--cmd java -jar run.jar

tests/misc/java/projects/Issue11131/compile.hxml.stdout

@@ -0,0 +1,4 @@
+6
+9
+6
+9