We add the switch expression to the set of syntactic forms permitted in an expression_statement:

expression_statement
    : statement_expression ';'
    ;

statement_expression
    : switch_expression
    // in addition to all the other forms specified elsewhere
    ;

When a switch expression is used as a statement_expression,

• the expression of each arm of the switch expression is required to be a statement_expression or a throw_expression; and
• the switch expression is not required to have a type.