On 03/11/2013 07:04 PM, Simon Peyton-Jones wrote:
Aha. It is indeed true that
ghc -fdefer-type-errors -w
does not suppress the warnings that arise from the type errors; indeed there is no current way to do so. How to do that?
To be kosher there should really be a flag to switch off those warnings alone, perhaps -fno-warn-type-errors
So then -fwarn-type-errors is on by default, but is only relevant when -fdefer-type-errors is on. Once -fdefer-type-errors is on, -fno-warn-type-errors and -fwarn-type-errors suppress or enable the warnings. -w would then include -fno-warn-type-errors.
GCC has a concept -Werror=unused-variable for example: each warning can be disabled, a warning, or an error. If GHC had that, we could have "type-errors" be a warning whose default state is -Werror. That's cleaner in a certain way, but it also seems fishy. Just throwing the idea out there. -Isaac