Added code for dead code elimination to the ext-core library. This can be used in concert with Language.Core.Merge to produce a single self-contained module without unnecessary cruft.
Changed the ext-core syntax to include primitive coercions (left, right, sym, trans, etc.) as syntax rather than referring them to their names as in GHC. (I hope I updated the docs to reflect this...)
See comments for details.
…ingle module I added a new module, Merge, to the ext-core library that combines a list of ext-core modules into a new, uniquely renamed module. See comments in Merge.hs for more details.
We used to always copy old_size
I did the wrong checkSigTyVars, which (happily) triggered an ASSERT failure. This should fix it.
In refactoring instance declarations I'd taken a short cut over scoped type variables, but it wasn't right as #2572 shows. Fixing it required a significant chunk of further refactoring, alas. But it's done! Quite tidily as it turns out. The main issue is that when typechecking a default method, we need two sets of type variables in scope class C a where op :: forall b. ... op = e In 'e', *both* 'a' and 'b' are in scope. But the type of the default method has a nested flavour op :: forall a. C a => forall b. .... and our normal scoping mechanisms don't bring 'b' into scope. (And probably shouldn't.) Solution (which is done for instance methods too) is to use a local defintion, like this: $dmop :: forall a. C a => forall b. .... $dmop a d = let op :: forall b. ... op = e in op and now the scoping works out. I hope I have now see the last of this code for a bit!
Bryan discovered that a non-trivial record selector (non-trivial in the sense that it has to reconstruct the result value because of UNPACK directives) weren't being inlined. The reason was that the unfolding generated by MkId.mRecordSelId was never being optimised *at all*, and hence looked big, and hence wasn't inlined. (The out-of-line version *is* put into the code of the module and *is* optimised, which made this bug pretty puzzling. But the unfolding inside the record-selector-Id itself, which is a GlobalId and hence does not get its inlining updated like LocalIds, was big and fat.) Solution: I wrote a very simple optimiser, CoreUnfold.simplOptExpr, which does enough optimisation to solve this particular problem. It's short, simple, and will be useful in other contexts.
HsWrappers are horribly inconsistent at the moment. I intended that WpLam, WpApp are for evidence abstraction/application WpTyLam, WpTyApp are for type abstraction/application But when we zonk (WpApp co), where co is a coercion variable, we get a *coercion* not a coercion *variable*. So for now I'm making it into a WpTyApp, which the desugarer handles perfectly well. (I'd forgotten to zonk it properly at all; that is the bug that this patch fixes.)
This one was missed when the error-ids all moved to Control.Exception.Base (The nofib test 'fluid' showed it up.)
See Note [Floating in past a lambda group]. The new thing here is that we previously were not floating in past a group that had (\(a:*) \(x:State# a). e), with a type var *and* a one-shot lambda. The fix makes wave4main allocate 2% less, and doesn't change any other nofib number, so it's not a big deal.