diff options
Diffstat (limited to 'compiler/typecheck/TcTyClsDecls.hs')
| -rw-r--r-- | compiler/typecheck/TcTyClsDecls.hs | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/compiler/typecheck/TcTyClsDecls.hs b/compiler/typecheck/TcTyClsDecls.hs index 7f4b7c6b6e..8d8f254a3e 100644 --- a/compiler/typecheck/TcTyClsDecls.hs +++ b/compiler/typecheck/TcTyClsDecls.hs @@ -39,7 +39,7 @@ import TcTyDecls import TcClassDcl import {-# SOURCE #-} TcInstDcls( tcInstDecls1 ) import TcDeriv (DerivInfo(..)) -import TcUnify ( unifyKind ) +import TcUnify ( unifyKind, checkTvConstraints ) import TcHsType import ClsInst( AssocInstInfo(..) ) import TcMType @@ -2026,6 +2026,9 @@ tcClassDecl1 roles_info class_name hs_ctxt meths fundeps sigs ats at_defs ; (ctxt, fds, sig_stuff, at_stuff) <- pushTcLevelM_ $ solveEqualities $ + checkTvConstraints skol_info (binderVars binders) $ + -- The checkTvConstraints is needed bring into scope the + -- skolems bound by the class decl header (#17841) do { ctxt <- tcHsContext hs_ctxt ; fds <- mapM (addLocM tc_fundep) fundeps ; sig_stuff <- tcClassSigs class_name sigs meths @@ -2058,6 +2061,7 @@ tcClassDecl1 roles_info class_name hs_ctxt meths fundeps sigs ats at_defs ppr fds) ; return clas } where + skol_info = TyConSkol ClassFlavour class_name tc_fundep (tvs1, tvs2) = do { tvs1' <- mapM (tcLookupTyVar . unLoc) tvs1 ; ; tvs2' <- mapM (tcLookupTyVar . unLoc) tvs2 ; ; return (tvs1', tvs2') } |