[Issue 780] New: The assignment of 'this' is allowed

[d-bugmail at puremagic.com]

http://d.puremagic.com/issues/show_bug.cgi?id=780

           Summary: The assignment of 'this' is allowed
           Product: D
           Version: 0.178
          Platform: PC
        OS/Version: Windows
            Status: NEW
          Keywords: accepts-invalid
          Severity: major
          Priority: P2
         Component: DMD
        AssignedTo: bugzilla at digitalmars.com
        ReportedBy: brunodomedeiros+bugz at gmail.com


The compiler allows assignment of the 'this' special reference. Instead 'this'
should be final (i.e., non assignable). In some cases, like in a class
constructor, 'this' is treated as if an inout reference, changing a variable in
another scope:

--------  --------
import std.stdio;

class Foo {
  static bool first = true;

  this() {
    if(first){
      first = false;
      this = new Foo();
      writefln("this= ", cast(void *)this);
    } 
  } 

}


void main(char[][] args) {

        Foo foo = new Foo();
        writefln("foo= ", cast(void *)foo);
}

--------  outputs:  --------
this before= 8B0FE0
this after= 8B0FD0
foo= 8B0FD0


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