t/op/caller.t: Comment magic number

So that when it changes, it is easier to find.

diff --git a/t/op/caller.t b/t/op/caller.t
index 44c5ae5..d08e143 100644 (file)
--- a/t/op/caller.t
+++ b/t/op/caller.t
@@ -108,6 +108,9 @@ sub testwarn {
        $registered = $default;
        vec($registered, $warnings::LAST_BIT/2, 2) = 1;
     }
+
+    # The repetition number must be set to the value of $BYTES in
+    # lib/warnings.pm
     BEGIN { check_bits( ${^WARNING_BITS}, "\0" x 12, 'all bits off via "no warnings"' ) }
     testwarn("\0" x 12, 'no bits');