equal_keys_in_map_pattern

Two keys in a map pattern can't be equal.

The analyzer produces this diagnostic when a map pattern contains more than one key with the same name. The same key can't be matched twice.

The following code produces this diagnostic because the key 'a' appears twice:

void f(Map<String, int> x) {
  if (x case {'a': 1, 'a': 2}) {}
}

If you are trying to match two different keys, then change one of the keys in the pattern:

void f(Map<String, int> x) {
  if (x case {'a': 1, 'b': 2}) {}
}

If you are trying to match the same key, but allow any one of multiple patterns to match, the use a logical-or pattern:

void f(Map<String, int> x) {
  if (x case {'a': 1 || 2}) {}
}

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.