Commit c5d888d4 authored by Committed by Marge Bot
PmCheck: No ConLike instantiation in pmcheck
`pmcheck` used to call `refineToAltCon` which would refine the knowledge we had about a variable by equating it to a `ConLike` application. Since we weren't particularly smart about this in the Check module, we simply freshened the constructors existential and term binders utimately through a call to `mkOneConFull`. But that instantiation is unnecessary for when we match against a concrete pattern! The pattern will already have fresh binders and field types. So we don't call `refineToAltCon` from `Check` anymore. Subsequently, we can simplify a couple of call sites and functions in `PmOracle`. Also implementing `computeCovered` becomes viable and we don't have to live with the hack that was `addVarPatVecCt` anymore. A side-effect of not indirectly calling `mkOneConFull` anymore is that we don't generate the proper strict argument field constraints anymore. Instead we now desugar ConPatOuts as if they had bangs on their strict fields. This implies that `PmVar` now carries a `HsImplBang` that we need to respect by a (somewhat ephemeral) non-void check. We fix #17234 in doing so.
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