Don't permit type variables in the context unless they are in the type
GHC accepts the following:
f :: Eq a => b -> b
f b = bThis is not valid Haskell 2010[0], so we should not permit it.
[0] «The context cx must only contain type variables referenced in t», https://www.haskell.org/report/node/2010/haskellch4.html#x10-660004.1.3
Trac metadata
| Trac field | Value |
|---|---|
| Version | |
| Type | Bug |
| TypeOfFailure | OtherFailure |
| Priority | normal |
| Resolution | Unresolved |
| Component | Compiler (Type checker) |
| Test case | |
| Differential revisions | |
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| Related | |
| Blocking | |
| CC | |
| Operating system | |
| Architecture |