added type aliasing check and warning. -- noch

src/compiler/OPP.Mod

@@ -922,6 +922,12 @@ MODULE OPP;  (* NW, RC 6.3.89 / 10.2.94 *)  (* object model 4.12.93 *)
           OPT.Insert(OPS.name, obj); obj^.mode := OPT.Typ; obj^.typ := OPT.undftyp;
           CheckMark(obj^.vis);
           IF sym = OPS.eql THEN
+		    IF (obj^.name = "INTEGER") OR (obj^.name = "SHORTINT") OR
+			   (obj^.name = "LONGINT") OR (obj^.name = "HUGEINT") OR
+			   (obj^.name = "LONGREAL") OR (obj^.name = "REAL") OR
+			   (obj^.name = "CHAR") THEN
+              OPM.Mark(-310, OPM.curpos); (* notice about aliasing of predefined type *) 
+			END;
             OPS.Get(sym); TypeDecl(obj^.typ, obj^.typ)
           ELSIF (sym = OPS.becomes) OR (sym = OPS.colon) THEN
             err(OPS.eql); OPS.Get(sym); TypeDecl(obj^.typ, obj^.typ)

src/runtime/Errors.Txt

@@ -177,6 +177,7 @@ Compiler Warnings
 307 no ELSE symbol after CASE statement sequence may lead to trap
 308 SYSTEM.VAL result includes memory past end of source variable; use SYSTEM.GET
 309 you should name this parameter type, or else no actual parameter will match
+310 aliasing of predefined type
 
 Run-time Error Messages
  -1 assertion failed, cf. SYSTEM_assert