[commit: ghc] master: Remove a tcTrace (081f44b)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/ghc

On branch  : master
Link       : http://ghc.haskell.org/trac/ghc/changeset/081f44bf3a2fbd87fe68f946306b836f12b20958/ghc

>---------------------------------------------------------------

commit 081f44bf3a2fbd87fe68f946306b836f12b20958
Author: Simon Peyton Jones <simonpj at microsoft.com>
Date:   Thu Dec 6 14:22:31 2018 +0000

    Remove a tcTrace
    
    This tcTrace, in tcTyFamInstEqn, caused a knot-tying loop, because
    it was printing a type after zonking-to-Type.  Easy solution: don't
    do that.


>---------------------------------------------------------------

081f44bf3a2fbd87fe68f946306b836f12b20958
 compiler/typecheck/TcTyClsDecls.hs | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/compiler/typecheck/TcTyClsDecls.hs b/compiler/typecheck/TcTyClsDecls.hs
index ce7cc83..877166d 100644
--- a/compiler/typecheck/TcTyClsDecls.hs
+++ b/compiler/typecheck/TcTyClsDecls.hs
@@ -1784,7 +1784,8 @@ tcTyFamInstEqn fam_tc mb_clsinfo
                                       imp_vars (mb_expl_bndrs `orElse` [])
                                       hs_pats hs_rhs_ty
 
-       ; traceTc "tcTyFamInstEqn" (ppr fam_tc $$ ppr qtvs $$ ppr pats $$ ppr rhs_ty)
+       -- Don't print results they may be knot-tied
+       -- (tcFamInstEqnGuts zonks to Type)
        ; return (mkCoAxBranch qtvs [] [] pats rhs_ty
                               (map (const Nominal) qtvs)
                               loc) }