empty_map_pattern

A map pattern must have at least one entry.

The analyzer produces this diagnostic when a map pattern is empty.

The following code produces this diagnostic because the map pattern is empty:

void f(Map<int, String> x) {
  if (x case {}) {}
}

If the pattern should match any map, then replace it with an object pattern:

void f(Map<int, String> x) {
  if (x case Map()) {}
}

If the pattern should only match an empty map, then check the length in the pattern:

void f(Map<int, String> x) {
  if (x case Map(isEmpty: true)) {}
}

除非另有说明，文档之所提及适用于 Dart 3.7.3 版本，本页面最后更新时间: 2025-05-08。 查看文档源码 或者 报告页面问题。