규칙 8.25

A parameter declared Ref<T> names the caller’s place, and the call passes it as ref(place): reading the parameter reads that place, and assigning to it, or to a field, component or element of it, writes it, for the call. A Ref<T> parameter belongs to a function declared at the top of the file or of a namespace; an entry, a method, a constructor, an accessor, a local function, a function written as an argument and a generic function take their parameters by value, and Ref<T> written anywhere but on such a parameter (a return type, a field, a local, a module declaration) must be refused. ref(place) takes what a method that changes its object takes as that object (Rule 8.10): a let, a const whose initializer built its value (Rule 6.10), a module variable, an element of a read_write storage binding, this where it may be written, a Ref<T> parameter, or a field or an element of one of those, of exactly the type T; a value parameter, any other const, a read-only binding, a literal, a value nothing holds and a component of a vector must be refused with the edit; a column of a matrix is a place. A Ref<T> parameter the function holds is passed on as itself or as ref of it, and ref(...) written anywhere but as such an argument must be refused. The place is the one the argument names when the call is made: an index is evaluated once, before the body runs, and a write the call makes to it moves nothing. One call must not take two references whose places share a root (the local, module variable or binding they are reached through) when the callee writes either, nor a reference to a module variable or a binding the callee reads or writes by its name when either side is written; a method’s object and a variable a local function writes count as references (Rules 8.10 and 8.17). A local function must not capture a Ref<T> parameter. A reference reaches each target as its own spelling of the parameter the callee writes through: a pointer on WGSL, ptr<AS, T> with &place at the call and one copy of the function for each address space its calls use, an inout parameter on GLSL ES 3.00, and on the CPU a copy in and a store back to the same place on return.