GHCi should not defer typed holes
In the function tcUserStmt in compiler/typecheck/TcRnDriver.hs, before going over the different ways ('plans') to lift an expression typed at the prompt into the GHCi monad, Opt_DeferTypeErrors is disabled. Here is the accompanying comment:
-- Ensure that type errors don't get deferred when type checking the
-- naked expression. Deferring type errors here is unhelpful because the
-- expression gets evaluated right away anyway. It also would potentially
-- emit redundant type-error warnings, one from each plan.
; plan <- unsetGOptM Opt_DeferTypeErrors $
Since Opt_DeferTypeErrors implies Opt_DeferTypedHoles, Opt_DeferTypedHoles should be disabled here as well. This will improve the error message for T10248.
Trac metadata
| Trac field | Value |
|---|---|
| Version | 7.10.2 |
| Type | Bug |
| TypeOfFailure | OtherFailure |
| Priority | normal |
| Resolution | Unresolved |
| Component | GHCi |
| Test case | |
| Differential revisions | |
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| Related | |
| Blocking | |
| CC | |
| Operating system | |
| Architecture |