PartialTypeSignatures mishandles type variables that begin with an underscore
The following GHCi exchange was reported here (you need not follow the link to understand this ticket, though).
Prelude Language.Haskell.TH> runQ [d|foo :: forall _a . _a -> _a;foo x = x|]
[SigD foo_6 (ForallT [PlainTV _a_5] [] (AppT (AppT ArrowT (WildCardT (Just _a_5))) (WildCardT (Just _a_5)))),FunD foo_6 [Clause [VarP x_7] (NormalB (VarE x_7)) []]]The problem is that the quoted expression uses no wildcards, yet the TH output does. That quoted expression just uses a type variable that begins with an underscore. Such an expression was allowed in Haskell long before wildcards.
Trac metadata
| Trac field | Value |
|---|---|
| Version | 7.10.2 |
| Type | Bug |
| TypeOfFailure | OtherFailure |
| Priority | normal |
| Resolution | Unresolved |
| Component | Template Haskell |
| Test case | |
| Differential revisions | |
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Edited by Richard Eisenberg