Ignore names introduced "implicitly" in unused-variable warnings (Fix #4404)

[ghc-hetmet.git] / compiler / rename / RnBinds.lhs

diff --git a/compiler/rename/RnBinds.lhs b/compiler/rename/RnBinds.lhs
index 0b10764..6c57cb2 100644 (file)
--- a/compiler/rename/RnBinds.lhs
+++ b/compiler/rename/RnBinds.lhs
@@ -357,7 +357,9 @@ rnLocalValBindsAndThen binds@(ValBindsIn _ sigs) thing_inside
                --      let x = x in 3
                -- should report 'x' unused
        ; let real_uses = findUses dus result_fvs
-       ; warnUnusedLocalBinds bound_names real_uses
+             -- Insert fake uses for variables introduced implicitly by wildcards (#4404)
+             implicit_uses = hsValBindsImplicits binds'
+       ; warnUnusedLocalBinds bound_names (real_uses `unionNameSets` implicit_uses)
 
        ; let
             -- The variables "used" in the val binds are: