Update with expression in records-wip

proposals/records-wip.md

@@ -89,32 +89,13 @@ A `with` expression allows for "non-destructive mutation", designed to
 produce a copy of the receiver expression with modifications to properties
 listed in the `anonymous_object_initializer`.
 
-A valid `with` expression has a receiver with a non-void type. The receiver type must contain an accessible instance method called `With` with
-the appropriate parameters and return type. It is an error if there are multiple non-override `With` methods. If there are multiple `With` overrides,
-there must be a non-override `With` method, which is the target method. Otherwise, there must be exactly one `With` method.
+A valid `with` expression has a receiver with a non-void type. The receiver type must contain an accessible parameterless instance method called `Clone` whose return type must be the type of the receiver express type, or a base type thereof.
 
 On the right hand side of the `with` expression is an `anonymous_object_initializer` with a
-sequence of assignments with a field or property of the receiver on the left-hand side of the
+sequence of assignments with a compiler-generated record property of the receiver on the left-hand side of the
 assignment, and an arbitrary expression on the right-hand side which is implicitly convertible to the type
 of the left-hand side.
 
-Given a target `With` method, the return type must be the type of the receiver expression type, or a base type thereof. For each parameter of
-the `With` method, there must be an accessible corresponding instance field or readable property on the
-receiver type with the same name and the same type. Each property or field in the right-hand side of the With
-expression must also correspond to a parameter of the same name in the `With` method.
-
-Given a valid `With` method, the evaluation of a `with` expression is equivalent to calling the `With` method with the expressions in the
-`anonymous_object_initializer` substituted for the parameter of the same
-name as the property on the left hand side. If there is no matching property
-for a given parameter in the `anonymous_object_initializer`, the argument
-is the evaluation of the field or property of the same name on the receiver.
-
-The order of evaluation of side effects is as follows, with each expression
-evaluated exactly once:
-
-1. Receiver expression
-
-2. Expressions in the `anonymous_object_initializer`, in lexical order
-
-3. The evaluation of any properties matching the `With` method parameters,
-in order of definition of the `With` method parameters.
+The evaluation of a `with` expression is equivalent to calling the `Clone` method exactly once,
+and then setting the backing field of each record property in the argument list to its corresponding
+expression, in lexical order, using the result of the `Clone` method as the receiver.