Terminating comma syntax isn't supported for tuples in pattern matches.

[mstewartgallus]

For example, one can do let (x, y) = (0, 4,); x but not let (x, y,) = (0, 4,); x which is is inconsistent and annoying when implementing macros.

[bstrie]

If we're going to be consistent, then we need to commit to allowing trailing commas everywhere that commas can appear (such as function definitions).

Nominating for Well-Defined.

[huonw]

Triage: still not parsed.

This issue is similar to #6506, #8788, and (less so) #5905.

[catamorphism]

Accepted for milestone 1, well-defined