diff options
| -rw-r--r-- | compiler/GHC/Core/Utils.hs | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/compiler/GHC/Core/Utils.hs b/compiler/GHC/Core/Utils.hs index 57a1ccacc3..4c040b5fb4 100644 --- a/compiler/GHC/Core/Utils.hs +++ b/compiler/GHC/Core/Utils.hs @@ -706,7 +706,11 @@ filterAlts :: TyCon -- ^ Type constructor of scrutinee's type (us -- in a "case" statement then they will need to manually add a dummy case branch that just -- calls "error" or similar. filterAlts _tycon inst_tys imposs_cons alts - = (imposs_deflt_cons, addDefault trimmed_alts maybe_deflt) + = imposs_deflt_cons `seqList` + (imposs_deflt_cons, addDefault trimmed_alts maybe_deflt) + -- Very important to force `imposs_deflt_cons` as that forces `alt_cons`, which + -- is essentially as retaining `alts_wo_default` or any `Alt b` for that matter + -- leads to a huge space leak (see #22102 and !8896) where (alts_wo_default, maybe_deflt) = findDefault alts alt_cons = [con | Alt con _ _ <- alts_wo_default] |