diff options
| author | Ryan Scott <ryan.gl.scott@gmail.com> | 2019-10-14 11:21:45 -0400 |
|---|---|---|
| committer | Marge Bot <ben+marge-bot@smart-cactus.org> | 2019-10-15 01:36:14 -0400 |
| commit | 426b0ddc79890f80a8ceeef135371533f066b9ba (patch) | |
| tree | a2eefaa3d05d2007090d36b8e82c781ed662a0e5 /testsuite/tests/typecheck/should_fail/T17355.stderr | |
| parent | a2d3594ca173905502d3de2f4e25ef9e36d41906 (diff) | |
| download | haskell-426b0ddc79890f80a8ceeef135371533f066b9ba.tar.gz | |
Don't skip validity checks for built-in classes (#17355)
Issue #17355 occurred because the control flow for
`TcValidity.check_valid_inst_head` was structured in such a way that
whenever it checked a special, built-in class (like `Generic` or
`HasField`), it would skip the most important check of all:
`checkValidTypePats`, which rejects nonsense like this:
```hs
instance Generic (forall a. a)
```
This fixes the issue by carving out `checkValidTypePats` from
`check_valid_inst_head` so that `checkValidTypePats` is always
invoked. `check_valid_inst_head` has also been renamed to
`check_special_inst_head` to reflect its new purpose of _only_
checking for instances headed by special classes.
Fixes #17355.
Diffstat (limited to 'testsuite/tests/typecheck/should_fail/T17355.stderr')
| -rw-r--r-- | testsuite/tests/typecheck/should_fail/T17355.stderr | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/testsuite/tests/typecheck/should_fail/T17355.stderr b/testsuite/tests/typecheck/should_fail/T17355.stderr new file mode 100644 index 0000000000..5212ef8787 --- /dev/null +++ b/testsuite/tests/typecheck/should_fail/T17355.stderr @@ -0,0 +1,9 @@ + +T17355.hs:9:10: error: + • Illegal polymorphic type: forall a. a + • In the instance declaration for ‘Generic (forall a. a)’ + +T17355.hs:10:10: error: + • Illegal polymorphic type: forall a. a -> a + • In the instance declaration for + ‘HasField "myPoly" Foo (forall a. a -> a)’ |