swift234

Let the type checker create implicit DestructorDecls

Improve the type checker to create implicit DestructorDecls, tighten the
assertion in ImplicitReturnLocation::getImplicitReturnLoc(), and add a verifier
check that a class in a type checked AST always has exactly one destructor.

SILGen used to generate a destructor if the class does not have a
DestructorDecl.  SILGen used to put the ClassDecl inside the SILLocation for
the destructor SIL code.  This is not a very clean solution: in this case
ImplicitReturnLocation SILLocations contain ClassDecl, which is surprising.

rdar://14970972 Implicit destructors should have AST nodes


Swift SVN r8498