maint: sc_prohibit_test_empty: add avoidance comment

* cfg.mk: Describe how to avoid the syntax check
in the case of possibly large / binary input.

diff --git a/cfg.mk b/cfg.mk
index 8c10b3b03d4f83ceef12d78e620d8fb979a424df..d5e8f9025d675724d8f252c66aaed3f56b1d581c 100644 (file)
--- a/cfg.mk
+++ b/cfg.mk
@@ -667,6 +667,7 @@ sc_prohibit_test_backticks:
 
 # Ensure that compare is used to check empty files
 # so that the unexpected contents are displayed
+# Use `returns_ 1 test -s ... || fail=1` to avoid this check.
 sc_prohibit_test_empty:
        @prohibit='test -s.*&&' in_vc_files='^tests/'                   \
        halt='use `compare /dev/null ...`, not `test -s ...` in tests/' \