disallow defining types into existing modules

src/typing/macroContext.ml

@@ -492,6 +492,14 @@ 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
@@ -503,17 +511,11 @@ 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 mpath = Ast.parse_path m in
-			begin try
-				let m = ctx.com.module_lut#find mpath in
-				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
+			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;
 		);
 		MacroApi.module_dependency = (fun mpath file ->
 			let m = typing_timer ctx false (fun ctx ->

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(Context.getLocalModule(), [{
+        Context.defineModule("A", [{
             pos: pos,
             pack: [],
             name: "A",