Generates copy methods for case classes.
Generates copy methods for case classes. Copy only has defaults on the first parameter list, as of SI-5009.
The parameter types of the copy method need to be exactly the same as the parameter
types of the primary constructor. Just copying the TypeTree is not enough: a type C
might refer to something else *inside* the class (i.e. as parameter type of copy)
than *outside* the class (i.e. in the class parameter list).
One such example is t0054.scala: class A { case class B(x: C) extends A { def copy(x: C = x) = ... } class C {} } (1) (2)
The reference (1) to C is A.this.C. The reference (2) is B.this.C - not the same.
This is fixed with a hack currently. Unapplies.caseClassCopyMeth, which creates the
copy method, uses empty TypeTree() nodes for parameter types.
In Namers.enterDefDef, the copy method gets a special type completer (enterCopyMethod).
Before computing the body type of copy, the class parameter types are assigned the copy
method parameters.
This attachment class stores the copy method parameter ValDefs as an attachment in the ClassDef of the case class.
The apply method corresponding to a case class
The module corresponding to a case class; overrides toString to show the module's name
The unapply method corresponding to a case class
Returns unapply or unapplySeq if available, without further checks.
The apply method corresponding to a case class
Filters out unapplies with multiple (non-implicit) parameter lists, as they cannot be used as extractors