diff options
| -rw-r--r-- | compiler/typecheck/TcRnMonad.hs | 16 |
1 files changed, 14 insertions, 2 deletions
diff --git a/compiler/typecheck/TcRnMonad.hs b/compiler/typecheck/TcRnMonad.hs index f3c16cb555..f576e335e5 100644 --- a/compiler/typecheck/TcRnMonad.hs +++ b/compiler/typecheck/TcRnMonad.hs @@ -125,7 +125,9 @@ initTc hsc_env hsc_src keep_rn_syntax mod loc do_this tcg_rdr_env = emptyGlobalRdrEnv, tcg_fix_env = emptyNameEnv, tcg_field_env = RecFields emptyNameEnv emptyNameSet, - tcg_default = Nothing, + tcg_default = if modulePackageKey mod == primPackageKey + then Just [] -- See Note [Default types] + else Nothing, tcg_type_env = emptyNameEnv, tcg_type_env_var = type_env_var, tcg_inst_env = emptyInstEnv, @@ -225,7 +227,17 @@ initTcForLookup hsc_env thing_inside Nothing -> throwIO $ mkSrcErr $ snd msgs Just x -> return x } -{- +{- Note [Default types] +~~~~~~~~~~~~~~~~~~~~~~~ +The Integer type is simply not available in package ghc-prim (it is +declared in integer-gmp). So we set the defaulting types to (Just +[]), meaning there are no default types, rather then Nothing, which +means "use the default default types of Integer, Double". + +If you don't do this, attempted defaulting in package ghc-prim causes +an actual crash (attempting to look up the Integer type). + + ************************************************************************ * * Initialisation |