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| author | Simon Peyton Jones <simonpj@microsoft.com> | 2020-12-02 10:27:47 +0000 |
|---|---|---|
| committer | Marge Bot <ben+marge-bot@smart-cactus.org> | 2020-12-08 15:31:41 -0500 |
| commit | 62ed6957463a9c0f711ea698d7ed4371e00fb122 (patch) | |
| tree | eb13107435b357117fda5e787ce4a70bd111a8f8 /testsuite/tests/dependent | |
| parent | 8fac4b9333ef3607e75b4520d847054316cb8c2d (diff) | |
| download | haskell-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/dependent')
| -rw-r--r-- | testsuite/tests/dependent/should_fail/T13780a.stderr | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/testsuite/tests/dependent/should_fail/T13780a.stderr b/testsuite/tests/dependent/should_fail/T13780a.stderr index 6cdcf96369..3e3fa61a9b 100644 --- a/testsuite/tests/dependent/should_fail/T13780a.stderr +++ b/testsuite/tests/dependent/should_fail/T13780a.stderr @@ -3,7 +3,7 @@ T13780a.hs:9:40: error: • Couldn't match kind ‘a’ with ‘Bool’ Expected kind ‘Foo a’, but ‘MkFoo’ has kind ‘Foo Bool’ ‘a’ is a rigid type variable bound by - a family instance declaration + the data constructor ‘SMkFoo’ at T13780a.hs:9:20-31 • In the second argument of ‘(~)’, namely ‘MkFoo’ In the definition of data constructor ‘SMkFoo’ |