conversion-function-id: operator conversion-type-id
conversion-type-id: type-specifier-seq conversion-declarator
conversion-declarator: ptr-operator conversion-declarator
ctor-initializer: : mem-initializer-list
mem-initializer-list: mem-initializer ... mem-initializer-list , mem-initializer ...
mem-initializer: mem-initializer-id ( expression-list ) mem-initializer-id braced-init-list
mem-initializer-id: class-or-decltype identifier