equal_keys_in_map

Two keys in a map literal shouldn't be equal.

The analyzer produces this diagnostic when a key in a non-constant map is the same as a previous key in the same map. If two keys are the same, then the second value overwrites the first value, which makes having both pairs pointless and likely signals a bug.

The following code produces this diagnostic because the keys a and b have the same value:

const a = 1;
const b = 1;
var m = <int, String>{a: 'a', b: 'b'};

If both entries should be included in the map, then change one of the keys:

const a = 1;
const b = 2;
var m = <int, String>{a: 'a', b: 'b'};

If only one of the entries is needed, then remove the one that isn't needed:

const a = 1;
var m = <int, String>{a: 'a'};

Note that literal maps preserve the order of their entries, so the choice of which entry to remove might affect the order in which the keys and values are returned by an iterator.

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.