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.
Instead, use the `%target-swift-5.1-abi-triple` substitution to compile the tests
for deployment to the minimum OS versions required for use of _Concurrency APIs.
When using an experimental feature that is not available
in production, a test needs to have `REQUIRES: asserts`
so that non-assert builds don't unexpectedly fail.
The latter example NIODefaultSerialEventLoopExecutor when the type is
more available than the enqueue implementation provided via an
extrension would issue a warning that that this enqueue(ExecutorJob)
would not be used which is not true.
We need to filter out all "default impls" from the stdlib as we issue
this warning.
We also put a note on the offending declaration that one can remove now,
to ease getting rid of warnings when possible
Resolves rdar://115166475
