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| author | Ryan Scott <ryan.gl.scott@gmail.com> | 2020-09-08 07:20:02 -0400 |
|---|---|---|
| committer | Marge Bot <ben+marge-bot@smart-cactus.org> | 2020-09-09 00:46:41 -0400 |
| commit | 822f10575d207a2a47b21ac853dcf28c655041c4 (patch) | |
| tree | 73fed8f93e7b3b46d880e6088fb415c1332bc80d /testsuite/tests/indexed-types/should_fail/T18648.hs | |
| parent | e5a2899ce8e06b8645946fbb67041807cd3a4fe5 (diff) | |
| download | haskell-822f10575d207a2a47b21ac853dcf28c655041c4.tar.gz | |
Postpone associated tyfam default checks until after typechecking
Previously, associated type family defaults were validity-checked
during typechecking. Unfortunately, the error messages that these
checks produce run the risk of printing knot-tied type constructors,
which will cause GHC to diverge. In order to preserve the current
error message's descriptiveness, this patch postpones these validity
checks until after typechecking, which are now located in the new
function `GHC.Tc.Validity.checkValidAssocTyFamDeflt`.
Fixes #18648.
Diffstat (limited to 'testsuite/tests/indexed-types/should_fail/T18648.hs')
| -rw-r--r-- | testsuite/tests/indexed-types/should_fail/T18648.hs | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/testsuite/tests/indexed-types/should_fail/T18648.hs b/testsuite/tests/indexed-types/should_fail/T18648.hs new file mode 100644 index 0000000000..92502b77c8 --- /dev/null +++ b/testsuite/tests/indexed-types/should_fail/T18648.hs @@ -0,0 +1,10 @@ +{-# LANGUAGE TypeFamilies #-} +module T18648 where + +class Foo1 a where + type Bar1 a + type Bar1 (f a) = Bar1 a + +class Foo2 a where + type Bar2 a + type Bar2 (Bar2 a) = a |