Ambiguity when exporting a data constructor despite qualification
$ cat A.hs
module A where
data T = Cons
$ cat B.hs
module B (T(T)) where
import qualified A
data T = T
$ ghc-8.2.0.20170422 -Wall B.hs
[2 of 2] Compiling B ( B.hs, B.o ) [A changed]
B.hs:1:11: error:
• Ambiguous occurrence ‘T’
It could refer to either ‘A.T’,
imported qualified from ‘A’ at B.hs:3:1-18
or ‘T’, defined at B.hs:5:1
• In the export: T(T)
|
1 | module B (T(T)) where
| ^^^^
There should be no ambiguity, because there is only one data constructor named T
.
Even if A.T
's data constructor would also be called T
there would be no ambiguity because A
is imported with qualification.
The problem does not appear, if B.T
's data constructor is named Cons
.
Trac metadata
Trac field | Value |
---|---|
Version | 8.2.1-rc2 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Compiler (Parser) |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | |
Operating system | |
Architecture |