DIP66 v1.1 (Multiple) alias this.

[Daniel N via Digitalmars-d]

On Wednesday, 24 December 2014 at 22:09:49 UTC, Andrei 
Alexandrescu wrote:
> Is there a need for explicit overriding, i.e. any inadvertent 
> error people may make without it? -- Andrei

I failed to find any dangerous refactoring sequences, so it might 
be superfluous, however I found another minor issue, see below.

Anyway considering the new ways of working, when using the -dip 
switch for the initial few releases, there is ample time to 
perfect all details.

// Example 1
struct A {int i;alias i this;}
struct Z
{
   A a;
   alias a   this;
}

// A is preferred since it requires only one implicit conversion.
void process(A)   {}
void process(int) {}

// Example 2
struct A {int i;alias i this;}
struct B {int i;alias i this;}
struct Z
{
   A a;
   B b;
   alias a   this;
   alias b   this;
   alias a.i this;
}

// The below is now ambiguous because Z is directly convertible 
to 'int' although we only intended to disambiguate between 
Z->A->int and Z->B->int
void process(A)   {}
void process(int) {}