fix iterators test

Author: datokrat

tests/lean/run/iterators.lean

@@ -362,28 +362,28 @@ example := positives.toListRev
 example := positives.toArray
 
 /--
-error: failed to synthesize
+error: failed to synthesize instance of type class
   Std.Iterators.Finite (Std.Iterators.RepeatIterator Nat fun x => x + 1) Id
 
-Hint: Additional diagnostic information may be available using the `set_option diagnostics true` command.
+Hint: Type class instance resolution failures can be inspected with the `set_option trace.Meta.synthInstance true` command.
 -/
 #guard_msgs in
 example := positives.ensureTermination.toList
 
 /--
-error: failed to synthesize
+error: failed to synthesize instance of type class
   Std.Iterators.Finite (Std.Iterators.RepeatIterator Nat fun x => x + 1) Id
 
-Hint: Additional diagnostic information may be available using the `set_option diagnostics true` command.
+Hint: Type class instance resolution failures can be inspected with the `set_option trace.Meta.synthInstance true` command.
 -/
 #guard_msgs in
 example := positives.ensureTermination.toListRev
 
 /--
-error: failed to synthesize
+error: failed to synthesize instance of type class
   Std.Iterators.Finite (Std.Iterators.RepeatIterator Nat fun x => x + 1) Id
 
-Hint: Additional diagnostic information may be available using the `set_option diagnostics true` command.
+Hint: Type class instance resolution failures can be inspected with the `set_option trace.Meta.synthInstance true` command.
 -/
 #guard_msgs in
 example := positives.ensureTermination.toArray