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| author | Simon Peyton Jones <simonpj@microsoft.com> | 2020-07-18 23:16:19 +0100 |
|---|---|---|
| committer | Marge Bot <ben+marge-bot@smart-cactus.org> | 2020-07-24 18:13:35 -0400 |
| commit | ba205046e4f2ea94b1c978c050b917de4daaf092 (patch) | |
| tree | 6b249028512e4d08cd0a3581d6f54e3f34868285 /testsuite/tests/polykinds/T18451b.hs | |
| parent | c1f4f81d3a439cd1a8128e4ab11c7caac7cc0ad8 (diff) | |
| download | haskell-ba205046e4f2ea94b1c978c050b917de4daaf092.tar.gz | |
Care with occCheckExpand in kind of occurrences
Issue #18451 showed that we could get an infinite type, through
over-use of occCheckExpand in the kind of an /occurrence/ of a
type variable.
See Note [Occurrence checking: look inside kinds] in GHC.Core.Type
This patch fixes the problem by making occCheckExpand less eager
to expand synonyms in kinds.
It also improves pretty printing of kinds, by *not* suppressing
the kind on a tyvar-binder like
(a :: Const Type b)
where type Const p q = p. Even though the kind of 'a' is Type,
we don't want to suppress the kind ascription. Example: the
error message for polykinds/T18451{a,b}. See GHC.Core.TyCo.Ppr
Note [Suppressing * kinds].
Diffstat (limited to 'testsuite/tests/polykinds/T18451b.hs')
| -rw-r--r-- | testsuite/tests/polykinds/T18451b.hs | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/testsuite/tests/polykinds/T18451b.hs b/testsuite/tests/polykinds/T18451b.hs new file mode 100644 index 0000000000..9b5248c30f --- /dev/null +++ b/testsuite/tests/polykinds/T18451b.hs @@ -0,0 +1,11 @@ +{-# LANGUAGE RankNTypes #-} +{-# LANGUAGE TypeInType #-} +module Bug where + +import Data.Kind +import Data.Proxy + +type Const a b = a + +foo :: forall a b (c :: Const Type b). Proxy '[a, c] +foo = error "ruk" |