This fixes Trac #15180 by changing the throw function type signature.
hvr bgamari sighingnow
- rGHC8ae7c1b5033b: Make Control.Exception.throw levity polymorphic.
- Trac Issues
We're getting stat failures on OS X; at a quick glance it looks like making throw more polymorphic causes GHC to allocate too much (but not by a lot) on OS X for two test cases. Looking at the test cases, I can't see why that would be - neither involves any explicit exception functionality. But since the difference is only a tiny bit above the threshold (5.3% vs. acceptable 5%), it is very well possible that this change produces a slight performance degradation across the board, and these two test cases on OS X are the only ones that are pushed over the edge.
So one thing I might do is to do two runs of validate, with and without this patch, and check whether the performance metrics do indeed get worse overall (even though staying within the margins).