Previously only some random decl attributes were included in the dump
with the source spelling (e.g. @objc), or some affected how the decl is
dumped. But the full attribute list has not been dumped. Dumping
attributes are useful for debugging attribute handling.
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.
Rather than adding custom parsing to SwiftSyntax, we can parse this as a custom attribute and convert it to a built-in one in ASTGen. Test that this works correctly (and fix a bug where it wasn’t).
