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| author | Csongor Kiss <kiss.csongor.kiss@gmail.com> | 2016-03-16 15:26:59 -0400 |
|---|---|---|
| committer | Richard Eisenberg <eir@cis.upenn.edu> | 2016-03-17 10:07:22 -0400 |
| commit | c5ed41cbcaa40068763c8bd01badcada38cdbd03 (patch) | |
| tree | e03fbe5e17251b238ccf7c960d8a6ed3534f80e5 | |
| parent | b5565f1a79fd24fc45a6f1a58821a317852d4b89 (diff) | |
| download | haskell-c5ed41cbcaa40068763c8bd01badcada38cdbd03.tar.gz | |
typechecker: fix trac issue #11708
Summary: Fixes T11708
Reviewers: austin, bgamari, goldfire, simonpj
Reviewed By: goldfire, simonpj
Subscribers: simonpj, goldfire, thomie
Differential Revision: https://phabricator.haskell.org/D2006
GHC Trac Issues: #11708
| -rw-r--r-- | compiler/typecheck/TcHsType.hs | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/compiler/typecheck/TcHsType.hs b/compiler/typecheck/TcHsType.hs index f931073ae1..37a867590a 100644 --- a/compiler/typecheck/TcHsType.hs +++ b/compiler/typecheck/TcHsType.hs @@ -938,8 +938,11 @@ tcTyVar mode name -- Could be a tyvar, a tycon, or a datacon | otherwise = do { (tc_ty, kind) <- instantiateTyN 0 ty tc_kind - ; traceTc "tcTyVar2b" (vcat [ ppr tc <+> dcolon <+> ppr tc_kind - , ppr tc_ty $$ ppr kind ]) + -- tc and tc_ty must not be traced here, because that would + -- force the evaluation of a potentially knot-tied variable (tc), + -- and the typechecker would hang, as per #11708 + ; traceTc "tcTyVar2b" (vcat [ ppr tc_tc <+> dcolon <+> ppr tc_kind + , ppr kind ]) ; return (tc_ty, kind) } where ty = mkNakedTyConApp tc [] |