Report unrecognized pragmas earlier
In the following example, I have a typo in the UndecidableInstances
pragma (LANGUAGE
is misspelled), however, GHC only reports that UndecidableInstances
is required. This is very confusing, since it appears that I have enabled that pragma.
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANUGAGE UndecidableInstances #-}
instance (Num [a]) => Num a
Only when I comment out the instance does GHC report that there is an unrecognized pragma, at which point it became obvious that there was a typo. It would be very helpful if GHC reported the warning about the unrecognized pragma before or at the same time as the error about needing UndecidableInstances
.
Trac metadata
Trac field | Value |
---|---|
Version | 8.0.2 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Compiler |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | |
Operating system | |
Architecture |