Misleading "Precedence parsing error" when using an undefined operator
I was using QuickCheck and wrote something like this:
a > 0 ==> a == b
But I hadn't imported (==>), and I got an error about mixing two operators with the same fixity (the two comparisons). This error was misleading, since once I imported ==>, which has a lower fixity, there was no problem.
I have a complete example file to attach.
This might be identical to #2993 (closed), but the situation there was not quite the same, so I am filing a new bug rather than reopening it.