The expression list in inheritance is not optional. Fixes #960448.
Will backport to 2.3.
diff --git a/Doc/ref/ref7.tex b/Doc/ref/ref7.tex
index 4770dc9..80ddc33 100644
--- a/Doc/ref/ref7.tex
+++ b/Doc/ref/ref7.tex
@@ -412,7 +412,7 @@
              {"class" \token{classname} [\token{inheritance}] ":"
               \token{suite}}
   \production{inheritance}
-             {"(" [\token{expression_list}] ")"}
+             {"(" \token{expression_list} ")"}
   \production{classname}
              {\token{identifier}}
 \end{productionlist}