Warn about possible missing -XScopedTypeVariables on errors.
Suggest that the user they may wish to add -XScopedTypeVariables, if an error results from a free type variable which would be bound in its scope with the flag enabled. (i.e. if its name exists as a variable in the type declaration).
I ran into this problem on code similar to this:
instance (Sized a n, Nat n) => Rep a where
emptyRep = replicate (toInt (undefined :: n)) 0and it took me some time to solve, and only by having vague knowledge that such a flag existed.
Trac metadata
| Trac field | Value |
|---|---|
| Version | 7.6.1 |
| Type | FeatureRequest |
| TypeOfFailure | OtherFailure |
| Priority | normal |
| Resolution | Unresolved |
| Component | Compiler |
| Test case | |
| Differential revisions | |
| BlockedBy | |
| Related | |
| Blocking | |
| CC | |
| Operating system | |
| Architecture |