Contexts on empty data decls falsely rejected
HList uses EmptyDataDecls and contains
data HNat x => Label x ns desc
which fails with
Data/HList/Label3.hs:37:0:
No context is allowed on a GADT-style data declaration
(You can put a context on each contructor, though.)
, regressing from 6.10.
My crystal ball tells me someone has been simplifying the implementation of EmptyDataDecls to be GADTs without where
, and missed the corner case.
Trac metadata
Trac field | Value |
---|---|
Version | 6.12.1 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Compiler (Type checker) |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | |
Operating system | |
Architecture |