only disallow for foreign modules

src/typing/macroContext.ml

@@ -492,14 +492,6 @@ let make_macro_api ctx mctx p =
 				()
 		);
 		MacroApi.define_module = (fun m types imports usings ->
-			let mpath = Ast.parse_path m in
-			if ctx.com.module_lut#mem mpath then begin
-				let m = ctx.com.module_lut#find mpath in
-				let pos = { pfile = (Path.UniqueKey.lazy_path m.m_extra.m_file); pmin = 0; pmax = 0 } in
-				raise_typing_error_ext (make_error ~sub:[
-					make_error ~depth:1 (Custom "Previously defined here") pos
-				] (Custom (Printf.sprintf "Cannot redefine module %s" (s_type_path mpath))) p);
-			end;
 			let types = List.map (fun v ->
 				let _, tdef, pos = (try Interp.decode_type_def v with MacroApi.Invalid_expr -> Interp.exc_string "Invalid type definition") in
 				tdef, pos
@@ -511,11 +503,23 @@ let make_macro_api ctx mctx p =
 				EUsing (List.map (fun s -> s,null_pos) sl),pos
 			) usings in
 			let types = imports @ usings @ types in
-			let mnew = TypeloadModule.type_module ctx.com ctx.g mpath (ctx.com.file_keys#generate_virtual ctx.com.compilation_step) types pos in
-			mnew.m_extra.m_kind <- MFake;
-			add_dependency mnew ctx.m.curmod MDepFromMacro;
-			add_dependency ctx.m.curmod mnew MDepFromMacroDefine;
-			ctx.com.module_nonexistent_lut#clear;
+			let mpath = Ast.parse_path m in
+			begin try
+				let m = ctx.com.module_lut#find mpath in
+				if m != ctx.m.curmod then begin
+					let pos = { pfile = (Path.UniqueKey.lazy_path m.m_extra.m_file); pmin = 0; pmax = 0 } in
+					raise_typing_error_ext (make_error ~sub:[
+						make_error ~depth:1 (Custom "Previously defined here") pos
+					] (Custom (Printf.sprintf "Cannot redefine module %s" (s_type_path mpath))) p);
+				end else
+					ignore(TypeloadModule.type_types_into_module ctx.com ctx.g m types pos)
+			with Not_found ->
+				let mnew = TypeloadModule.type_module ctx.com ctx.g mpath (ctx.com.file_keys#generate_virtual ctx.com.compilation_step) types pos in
+				mnew.m_extra.m_kind <- MFake;
+				add_dependency mnew ctx.m.curmod MDepFromMacro;
+				add_dependency ctx.m.curmod mnew MDepFromMacroDefine;
+				ctx.com.module_nonexistent_lut#clear;
+			end
 		);
 		MacroApi.module_dependency = (fun mpath file ->
 			let m = typing_timer ctx false (fun ctx ->

tests/misc/projects/Issue4160/compile.hxml

@@ -0,0 +1,2 @@
+--main test.Main
+--interp

tests/misc/projects/Issue4160/compile.hxml.stderr

@@ -0,0 +1 @@
+foo

tests/misc/projects/Issue4160/test/Main.hx

@@ -0,0 +1,51 @@
+package test;
+
+import haxe.macro.Context;
+import haxe.macro.Expr;
+
+private class Bar {
+	public function new() { }
+	public function getValue() {
+		return "foo";
+	}
+}
+
+class Main
+{
+    static function main()
+    {
+        defineFooExtendsBarInLocalModule();
+		#if !macro
+		var foo = new Foo();
+		Sys.stderr().writeString(foo.getValue());
+		#end
+    }
+
+    macro static function defineFooExtendsBarInLocalModule(?e)
+    {
+        var infos = Context.getPosInfos(Context.currentPos());
+        var position = Context.makePosition({min:0, max:0, file:infos.file});
+
+        var superTypePath:TypePath =
+        {
+            pack: [],
+            name: "Bar",
+            sub: null
+        }
+
+        var kind:TypeDefKind = TypeDefKind.TDClass(superTypePath);
+
+        var Foo:TypeDefinition =
+        {
+            name: "Foo",
+            pack: ["test"],
+            pos: position,
+            kind: kind,
+            fields: []
+        }
+
+        Context.defineModule(Context.getLocalModule(), [Foo]);
+
+        return e;
+    }
+}

tests/misc/projects/Issue6006/Macro.hx

@@ -4,7 +4,7 @@ import haxe.macro.Expr;
 class Macro {
     static function build() {
         var pos = Context.currentPos();
-        Context.defineModule("A", [{
+        Context.defineModule(Context.getLocalModule(), [{
             pos: pos,
             pack: [],
             name: "A",