duplicate_definition

The name '{0}' is already defined.

The analyzer produces this diagnostic when a name is declared, and there is a previous declaration with the same name in the same scope.

The following code produces this diagnostic because the name x is declared twice:

int x = 0;
int x = 1;

Choose a different name for one of the declarations.

int x = 0;
int y = 1;

Unless stated otherwise, the documentation on this site reflects Dart 3.8.0. Page last updated on 2025-05-08. View source or report an issue.