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authorSimon Peyton Jones <simon.peytonjones@gmail.com>2022-01-27 10:42:27 +0000
committerSimon Peyton Jones <simon.peytonjones@gmail.com>2022-01-31 10:47:00 +0000
commitb67c8b573dd8cffcbf321afd21c2902c1504438b (patch)
tree679fdd5bcdd680a84fdbefea148cfab0be48e6ef
parent3531c4784c0a06063dcfc0f084943d5149e64035 (diff)
downloadhaskell-wip/T21011.tar.gz
Make typechecker trace less strictwip/T21011
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