Move initializers form default ctor to field.

[AviadCo]

Add feature to spartinizer which removes redundant code from c'tors (such as happens in the default c'tor).

P.S. Happy Hanukkah!

[OriRoth]

As I understood, you mean we can give up redundant field initializations in constructors:

int a;
A() {
  this.a = 0;
}

==>

int a;
A() {
}

It is a good idea- actually, this is exactly what we are doing in on-the-spot field initialization:

int a = 0;

==>

int a;

What make things complicated in the constructors' context are:

1. We must initialize final fields

• So we must check fields are not final
• But...

2. Fields may be declared in parent classes

• Hopa! a problem.
• We even have another issue:

3. We should be able to recognize field initializations

• So we can remove the assignment for fields accessed without this expression:

int a;
A() {
  a = 0;
}

==>

int a;
A() {
}

• But... we have the meanings of doing this- simply by checking the name is not a variable declared in the constructor's scope (before the assignment)

[yossigil]

I now work on completing the environment analysis. When this is done, the changed would be easier. I think the algorithm should be:

1. Find all ctors of a class.
2. Find all unconditional initialization of fields, i.e., ones that do not depend on theparameters.
3. If there is a field initialized/uninitialized for which all such assignments are identical, go.

[yossigil]

@orenafek

[yossigil]

@orenafek : For your course. @amirsagiv83 , @michalcohen Try forming a rule for this.

[yossigil]

Similar to #463