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authorSimon Peyton Jones <simon.peytonjones@gmail.com>2022-01-27 10:42:27 +0000
committerMarge Bot <ben+marge-bot@smart-cactus.org>2022-01-31 18:47:23 -0500
commit584f03faed67c59895c90900ededb715a1a62528 (patch)
tree9072a3810bda67d27c5db5463cc822d46d09501f
parent58eccdbc0d46f37cabcb52c3f93b640ff90b24ed (diff)
downloadhaskell-584f03faed67c59895c90900ededb715a1a62528.tar.gz
Make typechecker trace less strict
Fixes #21011
-rw-r--r--compiler/GHC/Tc/Solver/Rewrite.hs6
1 files changed, 4 insertions, 2 deletions
diff --git a/compiler/GHC/Tc/Solver/Rewrite.hs b/compiler/GHC/Tc/Solver/Rewrite.hs
index 3f2f8f35ce..b7573e7f09 100644
--- a/compiler/GHC/Tc/Solver/Rewrite.hs
+++ b/compiler/GHC/Tc/Solver/Rewrite.hs
@@ -865,8 +865,10 @@ rewrite_exact_fam_app tc tys
{ Just (redn, fr@(_, inert_eq_rel))
| fr `eqCanRewriteFR` (flavour, eq_rel) ->
- do { traceRewriteM "rewrite family application with inert"
- (ppr tc <+> ppr xis $$ ppr redn)
+ do { traceRewriteM "rewrite family application with inert" $
+ vcat [ ppr tc <+> ppr xis
+ , ppUnless (flavour == Derived) (ppr redn) ]
+ -- Deriveds have no evidence, so we can't print the reduction
; finish True (homogenise downgraded_redn) }
-- this will sometimes duplicate an inert in the cache,
-- but avoiding doing so had no impact on performance, and