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| author | Ryan Scott <ryan.gl.scott@gmail.com> | 2018-04-19 12:36:42 -0400 |
|---|---|---|
| committer | Ben Gamari <ben@smart-cactus.org> | 2018-04-19 13:18:14 -0400 |
| commit | b08a6d75e0440f33260bea5319b8c3f871b42f6e (patch) | |
| tree | eeae0a52bc64aac7a1a9e2d83e25053f0b87e243 /testsuite/tests/partial-sigs/should_compile/Defaulting2MROff.stderr | |
| parent | cac8be611e7e80ed80e24b15faac9e1ac0a07247 (diff) | |
| download | haskell-b08a6d75e0440f33260bea5319b8c3f871b42f6e.tar.gz | |
Fix #15012 with a well-placed use of Any
Previously, derived `Generic1` instances could have associated `Rep1`
type family instances with unbound variables, such as in the following
example:
```lang=haskell
data T a = MkT (FakeOut a) deriving Generic1
type FakeOut a = Int
==>
instance Generic1 T where
type Rep1 T = ... (Rec0 (FakeOut a))
```
Yikes! To avoid this, we simply map the last type variable in a
derived `Generic1` instance to `Any`.
Test Plan: make test TEST=T15012
Reviewers: bgamari
Reviewed By: bgamari
Subscribers: simonpj, thomie, carter
GHC Trac Issues: #15012
Differential Revision: https://phabricator.haskell.org/D4602
Diffstat (limited to 'testsuite/tests/partial-sigs/should_compile/Defaulting2MROff.stderr')
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