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avoid-async-call-in-sync-function

added in: 1.8.0
warning
Pro+

Warns when an async function is invoked in non-async blocks.

Making asynchronous calls in non-asynchronous functions is usually a sign of a bug. In general, such functions should be marked async, and such futures should likely be awaited.

Example​

❌ Bad:

Future<void> asyncValue() async => 'value';

class SomeClass {
  SomeClass() {
    asyncValue(); // LINT: Avoid invoking async functions in non-async blocks. Try awaiting it, wrapping in 'unawaited(...)' or calling '.ignore()'.
  }

  Future<void> asyncMethod() => asyncValue();

  Future<void> anotherAsyncMethod() async => asyncValue();

  void syncFn() => asyncValue(); // LINT: Avoid invoking async functions in non-async blocks. Try awaiting it, wrapping in 'unawaited(...)' or calling '.ignore()'.
}

✅ Good:

Future<void> asyncValue() async => 'value';

class SomeClass {
  SomeClass() {
    unawaited(asyncValue()); // Correct, unawaited
  }

  Future<void> asyncMethod() => asyncValue();

  Future<void> anotherAsyncMethod() async => asyncValue(); // Correct, async method
}

Additional Resources​