diff options
Diffstat (limited to 'compiler')
| -rw-r--r-- | compiler/typecheck/TcSimplify.lhs | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/compiler/typecheck/TcSimplify.lhs b/compiler/typecheck/TcSimplify.lhs index e7495709c5..7b6a0dee3c 100644 --- a/compiler/typecheck/TcSimplify.lhs +++ b/compiler/typecheck/TcSimplify.lhs @@ -1183,7 +1183,9 @@ in the cache! \begin{code} applyTyVarDefaulting :: WantedConstraints -> TcS () applyTyVarDefaulting wc - = do { let tvs = varSetElems (tyVarsOfWC wc) + = do { let tvs = filter isMetaTyVar (varSetElems (tyVarsOfWC wc)) + -- We might have runtime-skolems in GHCi, and + -- we definitely don't want to try to assign to those! ; traceTcS "applyTyVarDefaulting {" (ppr tvs) ; mapM_ defaultTyVar tvs ; traceTcS "applyTyVarDefaulting end }" empty } @@ -1250,6 +1252,8 @@ findDefaultableGroups (default_tys, (ovl_strings, extended_defaults)) wanteds find_unary cc | Just (cls,[ty]) <- getClassPredTys_maybe (ctPred cc) , Just tv <- tcGetTyVar_maybe ty + , isMetaTyVar tv -- We might have runtime-skolems in GHCi, and + -- we definitely don't want to try to assign to those! = Left (cc, cls, tv) find_unary cc = Right cc -- Non unary or non dictionary |