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 improves
the error message for T10248 (it doesn't mention ghciStepIO anymore).
This is a partial fix for #10249, and a complete fix for #11130.

Depends on D1526

Reviewers: simonpj, austin, bgamari

Reviewed By: simonpj

Subscribers: simonpj

Differential Revision: https://phabricator.haskell.org/D1527

GHC Trac Issues: #10249, #11130

1 files changed, 2 insertions, 1 deletions

diff --git a/compiler/typecheck/TcRnDriver.hs b/compiler/typecheck/TcRnDriver.hs
index fb27c26cb9..3c68dcf462 100644
--- a/compiler/typecheck/TcRnDriver.hs
+++ b/compiler/typecheck/TcRnDriver.hs
@@ -1641,7 +1641,8 @@ tcUserStmt (L loc (BodyStmt expr _ _ _))
         -- naked expression. Deferring type errors here is unhelpful because the
         -- expression gets evaluated right away anyway. It also would potentially
         -- emit two redundant type-error warnings, one from each plan.
-        ; plan <- unsetGOptM Opt_DeferTypeErrors $ runPlans [
+        ; plan <- unsetGOptM Opt_DeferTypeErrors $
+                  unsetGOptM Opt_DeferTypedHoles $ runPlans [
                     -- Plan A
                     do { stuff@([it_id], _) <- tcGhciStmts [bind_stmt, print_it]
                        ; it_ty <- zonkTcType (idType it_id)