SR-14221: Add tricky parsing test case for trailing closure

[chenhongjing]

This PR adds a tricky parsing test case to ensure there is a correct interpretation of trailing closure.

Resolves SR-14221

[chenhongjing]

@varungandhi-apple Could you please review it? Thanks.

[chenhongjing]

@swift-ci please smoke test

[varungandhi-apple]

Hi, thanks for submitting the patch. Couple of points:

1. I think it would be helpful for this to be in a file with tests for trailing closures, instead of being its own file. I think you can rename test/Parse/multiple_trailing_closures.swift to trailing_closures.swift and add this check there.
2. New contributors can't trigger CI due to some trouble we've had in the past, but I can do that for you after you're done with making changes.

[varungandhi-apple]

Nit: Please try to keep the spacing and line widths consistent with the rest of the project. This means that comments should have a space after the //, and they need to be wrapped to 80 columns.

For functions, the arrow should have spaces on both sides (and similarly, there needs to be a space before an opening brace).

func f()->Int{ 42 } // right now
func f() -> Int { 42 } // match existing style

[chenhongjing]

Thanks for your kind instruction. I've made the changes. A small question--when will I be qualified to trigger CI?

[varungandhi-apple]

There is a commit access section on https://swift.org/contributing/#contributing-code which describes the details. Usually commit access and swift-ci access are granted together.

[varungandhi-apple]

@swift-ci smoke test

[varungandhi-apple]

CI is passing; merged! 🚢