Can you give me read/write access to your github repo? I'm simonpj on github. That way I can add comments/questions in code, and generally clean up. It would make things easier if you could merge with HEAD so that I don't have to mess around moving libraries back in time. ------------------------------ You've put "LANGUAGE Holes" in TcErrors which means I can't bootstrap. ------------------------------ You have this in your patch file, which can't be right + | CHoleCan { + cc_ev :: CtEvidence, + cc_hole_ty :: TcTauType, -- Not a Xi! See same not as above + cc_depth :: SubGoalDepth -- See Note [WorkList] + } + \end{code} \begin{code} @@ -933,6 +940,9 @@ ctPred (CTyEqCan { cc_tyvar = tv, cc_rhs = xi }) ctPred (CFunEqCan { cc_fun = fn, cc_tyargs = xis1, cc_rhs = xi2 }) = mkTcEqPred (mkTyConApp fn xis1) xi2 ctPred (CIrredEvCan { cc_ty = xi }) = xi +ctPred (CHoleCan { cc_flavor = fl, cc_hole_ty = xi }) + = xi + since c_flavor isn't a field of CHoleCan. ----------------------- | The 3 currently remaining issues: | | - Free type variables are not tidied consistently. For every one of | these hole warnings, the same TidyEnv is reused, without taking the | updates from the other holes into account. I'm pretty sure I know where | this happens and how I could fix it. This should be easy. * TcErrors.reportUnsolved uses tyVarsOfWC to find the free type variables of unsolved constraints * It then uses tidyFreeTyVars to assign them names * And that gives an env used in tidying. So it should just work. I hope you are letting the various 'tidy' calls in TcErrors do the work. | - What I thought would be the local environment doesn't actually seem | to be it. The holes store in their origin the result of `getLclTypeEnv' | at their location, but as the Note [Bindings with closed types] says, | the TopLevelFlag of these don't actually differentiate the top level | from the non-top level bindings. I think it would be more helpful to | only show the non-top level bindings at the hole's location, any hints | about how to obtain just these would be appreciated. In this context "local" means "this module" rather than "not top level". Use isExternalName to distinguish top-level things from nested things. | - The holes do not have very accurate source location information, like | some other errors have. The hole has its origin, ("test2.hs:3:16"), but | somehow not something like: "In the expression: folder _ x _, In an | equation for `test': test x = foldr _ x _". Help with how that is | supposed to work would also be appreciated. That's odd. Every Wanted constraint has a WantedLoc (TcRnTypes), which includes a [ErrCtxt], which is that stack of "In ..; In... " stuff you see. Code looks plausible.