+Warn if an
+.Sq extern
+declaration is encountered within a function.
+.It Fl Wparentheses
+Warn if parentheses are omitted in certain contexts.
+Warn if an assignment is used as condition, e.g. if\ (x\ =\ 23).
+Warn if && without parentheses is used within ||, e.g. if\ (x\ ||\ y\ &&\ z).
+Warn if it there may be confusion which
+.Sq if Ns
+-statement an
+.Sq else Ns
+-branch belongs to, e.g. if\ (x)\ if\ (y)\ {}\ else\ {}.
+Warn if cascaded comparisons appear which do not have their mathematical meaning, e.g. if\ (23\ <=\ x\ <\ 42).
+Warn if + or - is used as operand of << or >>, e.g. x\ +\ y\ <<\ z.