--- a/mercurial/templatekw.py	Fri Mar 16 23:09:21 2018 +0900
+++ b/mercurial/templatekw.py	Fri Mar 16 23:11:55 2018 +0900
@@ -36,6 +36,10 @@
 _showcompatlist = templateutil._showcompatlist
 
 def _showlist(name, values, templ, mapping, plural=None, separator=' '):
+    ui = mapping.get('ui')
+    if ui:
+        ui.deprecwarn("templatekw._showlist() is deprecated, use "
+                      "templateutil._showcompatlist()", '4.6')
     context = templ  # this is actually a template context, not a templater
     return _showcompatlist(context, mapping, name, values, plural, separator)