Properly detect name collisions at library level

runtime/vm/parser.cc

Index: runtime/vm/parser.cc
===================================================================
--- runtime/vm/parser.cc	(revision 1908)
+++ runtime/vm/parser.cc	(working copy)
@@ -2940,6 +2940,17 @@
     if (library_.LookupObject(var_name) != Object::null()) {
       ErrorMsg(name_pos, "'%s' is already defined", var_name.ToCString());
     }
+    String& accessor_name = String::Handle(Field::GetterName(var_name));
+    if (library_.LookupObject(accessor_name) != Object::null()) {
+      ErrorMsg(name_pos, "getter for '%s' is already defined",
+               var_name.ToCString());
+    }
+    accessor_name = Field::SetterName(var_name);
+    if (library_.LookupObject(accessor_name) != Object::null()) {
+      ErrorMsg(name_pos, "setter for '%s' is already defined",
+               var_name.ToCString());
+    }
+
     Field& field = Field::ZoneHandle(
         Field::New(var_name, is_static, is_final, name_pos));
     field.set_type(type);
@@ -2992,6 +3003,16 @@
   if (library_.LookupObject(func_name) != Object::null()) {
     ErrorMsg(name_pos, "'%s' is already defined", func_name.ToCString());
   }
+  String& accessor_name = String::Handle(Field::GetterName(func_name));
+  if (library_.LookupObject(accessor_name) != Object::null()) {
+    ErrorMsg(name_pos, "'%s' is already defined as getter",
+             func_name.ToCString());
+  }
+  accessor_name = Field::SetterName(func_name);
+  if (library_.LookupObject(accessor_name) != Object::null()) {
+    ErrorMsg(name_pos, "'%s' is already defined as setter",
+             func_name.ToCString());
+  }
 
   if (CurrentToken() != Token::kLPAREN) {
     ErrorMsg("'(' expected");
@@ -3069,6 +3090,16 @@
              is_getter ? "getter" : "setter");
   }
 
+  if (library_.LookupObject(*field_name) != Object::null()) {
+    ErrorMsg(name_pos, "'%s' is already defined in this library",
+             field_name->ToCString());
+  }
+  if (library_.LookupObject(accessor_name) != Object::null()) {
+    ErrorMsg(name_pos, "%s for '%s' is already defined",
+             is_getter ? "getter" : "setter",
+             field_name->ToCString());
+  }
+
   if (CurrentToken() == Token::kLBRACE) {
     SkipBlock();
   } else if (CurrentToken() == Token::kARROW) {