Warn about derivable instances
GHC can derive a lot of instances by itself, and can sometimes (with GeneralizedNewtypeDeriving
) do so better than anyone else. I'd like to be able to get a warning about any instance that's "obviously equivalent" to the one that would be derived, for some suitable values of "obviously" and "equivalent".
Trac metadata
Trac field | Value |
---|---|
Version | 7.9 |
Type | FeatureRequest |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Compiler |
Test case | |
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