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| author | Richard Eisenberg <rae@richarde.dev> | 2021-01-05 22:40:53 -0500 |
|---|---|---|
| committer | Marge Bot <ben+marge-bot@smart-cactus.org> | 2021-01-23 15:29:58 -0500 |
| commit | 8fd855f09db0090df74a2e35eace7da973f62c86 (patch) | |
| tree | d40af8ffa28d1b05411869aa1a972091d3eca07c /compiler/GHC/Tc/Instance | |
| parent | 420ef55a0d28a177fab981655a1c44291b441382 (diff) | |
| download | haskell-8fd855f09db0090df74a2e35eace7da973f62c86.tar.gz | |
Make matchableGivens more reliably correct.
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/Instance')
| -rw-r--r-- | compiler/GHC/Tc/Instance/FunDeps.hs | 4 |
1 files changed, 1 insertions, 3 deletions
diff --git a/compiler/GHC/Tc/Instance/FunDeps.hs b/compiler/GHC/Tc/Instance/FunDeps.hs index c89a13dae8..3abb0140b1 100644 --- a/compiler/GHC/Tc/Instance/FunDeps.hs +++ b/compiler/GHC/Tc/Instance/FunDeps.hs @@ -656,9 +656,7 @@ checkFunDeps inst_envs (ClsInst { is_tvs = qtvs1, is_cls = cls (ltys1, rtys1) = instFD fd cls_tvs tys1 (ltys2, rtys2) = instFD fd cls_tvs tys2 qtv_set2 = mkVarSet qtvs2 - bind_fn tv | tv `elemVarSet` qtv_set1 = BindMe - | tv `elemVarSet` qtv_set2 = BindMe - | otherwise = Skolem + bind_fn = matchBindFun (qtv_set1 `unionVarSet` qtv_set2) eq_inst i1 i2 = instanceDFunId i1 == instanceDFunId i2 -- A single instance may appear twice in the un-nubbed conflict list |