Find all the usages of `--enable-experimental-feature` or
`--enable-upcoming-feature` in the tests and replace some of the
`REQUIRES: asserts` to use `REQUIRES: swift-feature-Foo` instead, which
should correctly apply to depending on the asserts/noasserts mode of the
toolchain for each feature.
Remove some comments that talked about enabling asserts since they don't
apply anymore (but I might had miss some).
All this was done with an automated script, so some formatting weirdness
might happen, but I hope I fixed most of those.
There might be some tests that were `REQUIRES: asserts` that might run
in `noasserts` toolchains now. This will normally be because their
feature went from experimental to upcoming/base and the tests were not
updated.
When recovering from a parser error in an expression, we resumed parsing at a '{'. I assume this was because we wanted to continue inside e.g. an if-body if parsing the condition failed, but it's actually causing more issue because when parsing e.g.
```swift
expr + has - error +
functionTakesClosure {
}
```
we continue parsing at the `{` of the trailing closure, which is a completely garbage location to continue parsing.
The motivating example for this change was (in a result builder)
```swift
Text("\(island.#^COMPLETE^#)")
takeTrailingClosure {}
```
Here `Text(…)` has an error (because it contains a code completion token) and thus we skip `takeTrailingClosure`, effectively parsing
```swift
Text(….) {}
```
which the type checker wasn’t very happy with and thus refused to provide code completion. With this change, we completely drop `takeTrailingClosure {}`. The type checker is a lot happier with that.
Emit the specialized extraneous trailing closure
diagnostic for multiple trailing closures and
unlabelled unary argument lists, and add a
specialized trailing closure version for the multiple
extraneous case.
