When the CFE encounters an ill-typed spread element in an ambiguous
set/map literal, it replaces it with a synthetic MapEntry object
pointing to an InvalidExpression. If there is no non-synthetic
MapEntry in the set/map, and it is decided to disambiguate to a set,
then all of the entries are fed into the `convertToElement` method.
Before this CL, this method would see the synthetic MapEntry and
assume the user had explicitly written a key-value pair in a set
literal, so it would try to report the error `Expected ',' before
this` at the location of the `:` in the key-value pair. But since the
MapEntry was synthetic, there was no `:` and the message was very
confusing.
This CL changes `convertToElement` so that it detects when a MapEntry
has arisen from an error, and avoids creating a follow-on error.
Fixes#45174.
Bug: https://github.com/dart-lang/sdk/issues/45174
Change-Id: I37dc82a130b4bf858b3fb7411bb9c64f7450bd16
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/188940
Reviewed-by: Johnni Winther <johnniwinther@google.com>
Commit-Queue: Paul Berry <paulberry@google.com>
A spread element in a collection literal, e.g., `[...e]` or `{...?e}`,
can have an `e` of type `Null` or a subtype thereof. This CL adds a test
where this situation is created for different types (`Null`, `Never`,
`X extends Null`) with different collection literals, and with and
without elements of other types. In general, the spread does not
contribute any elements, and hence the element/key/value type is `Never`
such that it has no effect on the element/key/value type of the
collection.
Cf. https://github.com/dart-lang/language/pull/1079.
Change-Id: Ib760bcba18045b1afaa50f65c0e7d0a7fe9a8ab6
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/154693
Commit-Queue: Erik Ernst <eernst@google.com>
Reviewed-by: Nate Bosch <nbosch@google.com>
Paul Berry