GHC panic on type wildcard in left-hand side of data family
While playing around with data families I received the following output by ghc/ghci:
ghc: panic! (the 'impossible' happened)
(GHC version 7.10.3 for x86_64-unknown-linux):
rnHsTyKi HsWildcardTy
Please report this as a GHC bug: http://www.haskell.org/ghc/reportabugI had accidentally left a wildcard _ on the left-hand side of a data instance definition.
To reproduce enter the following code into a file and try to load that file into ghci, or try to compile it with ghc:
data family Bug x
data instance Bug _ = BugThe expected behavior would be a (non-panic) error message of some sort.
Trac metadata
| Trac field | Value |
|---|---|
| Version | 7.10.3 |
| Type | Bug |
| TypeOfFailure | OtherFailure |
| Priority | normal |
| Resolution | Unresolved |
| Component | Compiler |
| Test case | |
| Differential revisions | |
| BlockedBy | |
| Related | |
| Blocking | |
| CC | |
| Operating system | |
| Architecture |