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| author | Richard Eisenberg <rae@richarde.dev> | 2021-01-05 22:40:53 -0500 |
|---|---|---|
| committer | Richard Eisenberg <rae@richarde.dev> | 2021-01-15 23:14:13 -0500 |
| commit | 7d550ff71ee06c681756f60fbd3731559484afa3 (patch) | |
| tree | eab8a083e327c06272f1c95833174ecf347bea45 /compiler/GHC/Tc/Solver/Interact.hs | |
| parent | 0dba78410887ffc3d219639081e284ef7b67560a (diff) | |
| download | haskell-wip/T19106.tar.gz | |
Make matchableGivens more reliably correct.wip/T19106
This has two fixes:
1. Take TyVarTvs into account in matchableGivens. This
fixes #19106.
2. Don't allow unifying alpha ~ Maybe alpha. This fixes
#19107.
This patch also removes a redundant Note and redirects
references to a better replacement.
Also some refactoring/improvements around the BindFun
in the pure unifier, which now can take the RHS type
into account.
Close #19106.
Close #19107.
Test case: partial-sigs/should_compile/T19106,
typecheck/should_compile/T19107
Diffstat (limited to 'compiler/GHC/Tc/Solver/Interact.hs')
| -rw-r--r-- | compiler/GHC/Tc/Solver/Interact.hs | 19 |
1 files changed, 10 insertions, 9 deletions
diff --git a/compiler/GHC/Tc/Solver/Interact.hs b/compiler/GHC/Tc/Solver/Interact.hs index e8ab8ad82a..b02b22f854 100644 --- a/compiler/GHC/Tc/Solver/Interact.hs +++ b/compiler/GHC/Tc/Solver/Interact.hs @@ -2151,7 +2151,7 @@ Other notes: - natural numbers - Typeable -* See also Note [What might match later?] in GHC.Tc.Solver.Monad. +* See also Note [What might equal later?] in GHC.Tc.Solver.Monad. * The given-overlap problem is arguably not easy to appear in practice due to our aggressive prioritization of equality solving over other @@ -2263,8 +2263,8 @@ matchLocalInst :: TcPredType -> CtLoc -> TcS ClsInstResult -- Look up the predicate in Given quantified constraints, -- which are effectively just local instance declarations. matchLocalInst pred loc - = do { ics <- getInertCans - ; case match_local_inst (inert_insts ics) of + = do { inerts@(IS { inert_cans = ics }) <- getTcSInerts + ; case match_local_inst inerts (inert_insts ics) of ([], False) -> do { traceTcS "No local instance for" (ppr pred) ; return NoInstance } ([(dfun_ev, inst_tys)], unifs) @@ -2281,14 +2281,15 @@ matchLocalInst pred loc where pred_tv_set = tyCoVarsOfType pred - match_local_inst :: [QCInst] + match_local_inst :: InertSet + -> [QCInst] -> ( [(CtEvidence, [DFunInstType])] , Bool ) -- True <=> Some unify but do not match - match_local_inst [] + match_local_inst _inerts [] = ([], False) - match_local_inst (qci@(QCI { qci_tvs = qtvs, qci_pred = qpred + match_local_inst inerts (qci@(QCI { qci_tvs = qtvs, qci_pred = qpred , qci_ev = ev }) - : qcis) + : qcis) | let in_scope = mkInScopeSet (qtv_set `unionVarSet` pred_tv_set) , Just tv_subst <- ruleMatchTyKiX qtv_set (mkRnEnv2 in_scope) emptyTvSubstEnv qpred pred @@ -2303,5 +2304,5 @@ matchLocalInst pred loc (matches, unif || this_unif) where qtv_set = mkVarSet qtvs - this_unif = mightMatchLater qpred (ctEvLoc ev) pred loc - (matches, unif) = match_local_inst qcis + this_unif = mightEqualLater inerts qpred (ctEvLoc ev) pred loc + (matches, unif) = match_local_inst inerts qcis |