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 |