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authorSimon Peyton Jones <simonpj@microsoft.com>2020-12-02 10:27:47 +0000
committerMarge Bot <ben+marge-bot@smart-cactus.org>2020-12-08 15:31:41 -0500
commit62ed6957463a9c0f711ea698d7ed4371e00fb122 (patch)
treeeb13107435b357117fda5e787ce4a70bd111a8f8 /testsuite/tests/patsyn
parent8fac4b9333ef3607e75b4520d847054316cb8c2d (diff)
downloadhaskell-62ed6957463a9c0f711ea698d7ed4371e00fb122.tar.gz
Fix kind inference for data types. Again.
This patch fixes several aspects of kind inference for data type declarations, especially data /instance/ declarations Specifically 1. In kcConDecls/kcConDecl make it clear that the tc_res_kind argument is only used in the H98 case; and in that case there is no result kind signature; and hence no need for the disgusting splitPiTys in kcConDecls (now thankfully gone). The GADT case is a bit different to before, and much nicer. This is what fixes #18891. See Note [kcConDecls: kind-checking data type decls] 2. Do not look at the constructor decls of a data/newtype instance in tcDataFamInstanceHeader. See GHC.Tc.TyCl.Instance Note [Kind inference for data family instances]. This was a new realisation that arose when doing (1) This causes a few knock-on effects in the tests suite, because we require more information than before in the instance /header/. New user-manual material about this in "Kind inference in data type declarations" and "Kind inference for data/newtype instance declarations". 3. Minor improvement in kcTyClDecl, combining GADT and H98 cases 4. Fix #14111 and #8707 by allowing the header of a data instance to affect kind inferece for the the data constructor signatures; as described at length in Note [GADT return types] in GHC.Tc.TyCl This led to a modest refactoring of the arguments (and argument order) of tcConDecl/tcConDecls. 5. Fix #19000 by inverting the sense of the test in new_locs in GHC.Tc.Solver.Canonical.canDecomposableTyConAppOK.
Diffstat (limited to 'testsuite/tests/patsyn')
-rw-r--r--testsuite/tests/patsyn/should_fail/T15685.stderr10
1 files changed, 5 insertions, 5 deletions
diff --git a/testsuite/tests/patsyn/should_fail/T15685.stderr b/testsuite/tests/patsyn/should_fail/T15685.stderr
index e081453659..723d0fcff3 100644
--- a/testsuite/tests/patsyn/should_fail/T15685.stderr
+++ b/testsuite/tests/patsyn/should_fail/T15685.stderr
@@ -1,13 +1,13 @@
T15685.hs:13:24: error:
- • Could not deduce: a ~ [k0]
- from the context: as ~ (a1 : as1)
+ • Could not deduce: k ~ [k0]
+ from the context: as ~ (a : as1)
bound by a pattern with constructor:
- Here :: forall {a1} (f :: a1 -> *) (a2 :: a1) (as :: [a1]).
- f a2 -> NS f (a2 : as),
+ Here :: forall {k} (f :: k -> *) (a :: k) (as :: [k]).
+ f a -> NS f (a : as),
in a pattern synonym declaration
at T15685.hs:13:19-26
- ‘a’ is a rigid type variable bound by
+ ‘k’ is a rigid type variable bound by
the inferred type of HereNil :: NS f as
at T15685.hs:13:9-15
Possible fix: add a type signature for ‘HereNil’