swift234

Make the implicit 'this' argument [byref] rather than
[byref(implicit)], and rely on type coercion for the implicit object
argument to deal with the implicitness. This is one half of
<rdar://problem/11215969>. 

The other half of <rdar://problem/11215969> requires us to invent some
syntax to allow increment/decrement/assignment to operate on lvalues
without requiring one to write '&'. There are two distinct ideas
gaining traction here:

  - Adding an [assignment] attribute to these operators, which tells
    us both that use of the operators is a statement (not an
    expression) and that the byref argument (either on the left, or
    the only argument).

  - Allowing operators to be written as member functions, so that they
    get the same treatment as "a.b".

The former seems like the better option.



Swift SVN r1819