60985130cb
There are four major fixes here: 1. some eof tokens were being pattern matched with the wrong arity 2. tuples that are too long actually speculatively parse as an untyped tuple, and then complain that there were too many elements, 3. singleton tuples with a trailing comma are now handled differently to grouping parentheses, consistently between typed and untyped logic 4. the extra return values used to detect untyped singleton tuples are also used to pass the close paren position, so that too_many_elements can report the correct file position too. Point 4. also completely removes the need for tracking open paren positions that I was doing, and that I thought I would need to do even more of in the ambiguous-open-paren-stack case.