Fix type of onError. #1339
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Fix type of onError. #1339
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The function passed to Stream.handleError needs to accept either a single argument of type `Object`, or an `Object` and a `StackTrace`. Since this can't be expressed by the type system, it's checked at runtime. As a result, the `check` function (as previously written) would fail if ever instantiated with a type `T` that was narrower than `Object`. Prior to implementation of dart-lang/language#731 (improved inference for fold etc.), this worked fine, because type inference always supplied an argument type of `dynamic` or `Object` for the function literals passed to `check`. However, with the inference improvement enabled, it starts to infer other types, causing runtime failures. The correct fix is to give the `event` argument of `onError` an appropriate type.
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This reverts commit 9849573.
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2022-05-09 [email protected] Fix type of onError. (dart-lang/co19#1339) Change-Id: I78b2c218acb97881b9feb05e74c9775a2f6cd360 Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/244102 Commit-Queue: William Hesse <[email protected]> Reviewed-by: Alexander Thomas <[email protected]>
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The function passed to Stream.handleError needs to accept either a
single argument of type
Object, or anObjectand aStackTrace.Since this can't be expressed by the type system, it's checked at
runtime. As a result, the
checkfunction (as previously written)would fail if ever instantiated with a type
Tthat was narrower thanObject.Prior to implementation of
dart-lang/language#731 (improved inference
for fold etc.), this worked fine, because type inference always
supplied an argument type of
dynamicorObjectfor the functionliterals passed to
check. However, with the inference improvementenabled, it starts to infer other types, causing runtime failures.
The correct fix is to give the
eventargument ofonErroranappropriate type.