From c79d882645db49a2ef6dd6f85070c80685ed533c Mon Sep 17 00:00:00 2001 From: Adam Gundry Date: Fri, 30 Dec 2016 02:30:41 +0000 Subject: [PATCH] Avoid find_tycon panic if datacon is not in scope When using TH to splice expressions involving record field construction, the parent datacon may not be in scope. We shouldn't panic about this, because we will be renaming Exact RdrNames which don't require any disambiguation. Reviewers: austin, bgamari Reviewed By: bgamari Differential Revision: https://phabricator.haskell.org/D2321 GHC Trac Issues: #12130 Origin: upstream, https://git.haskell.org/ghc.git/commitdiff/694e0f3a08030 Gbp-Pq: Name find-tycon-panic --- compiler/rename/RnPat.hs | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/compiler/rename/RnPat.hs b/compiler/rename/RnPat.hs index 51ddea95..f1b61e34 100644 --- a/compiler/rename/RnPat.hs +++ b/compiler/rename/RnPat.hs @@ -636,7 +636,7 @@ rnHsRecFields ctxt mk_arg (HsRecFields { rec_flds = flds, rec_dotdot = dotdot }) find_tycon :: GlobalRdrEnv -> Name {- DataCon -} -> Maybe Name {- TyCon -} -- Return the parent *type constructor* of the data constructor -- (that is, the parent of the data constructor), - -- or 'Nothing' if it is a pattern synonym. + -- or 'Nothing' if it is a pattern synonym or not in scope. -- That's the parent to use for looking up record fields. find_tycon env con | Just (AConLike (RealDataCon dc)) <- wiredInNameTyThing_maybe con @@ -648,8 +648,9 @@ rnHsRecFields ctxt mk_arg (HsRecFields { rec_flds = flds, rec_dotdot = dotdot }) ParentIs p -> Just p _ -> Nothing - | otherwise - = pprPanic "find_tycon" (ppr con $$ ppr (lookupGRE_Name env con)) + | otherwise = Nothing + -- This can happen if the datacon is not in scope + -- and we are in a TH splice (Trac #12130) dup_flds :: [[RdrName]] -- Each list represents a RdrName that occurred more than once -- 2.30.2