Fix a bug that causes a struct field to be initialized twice. (#8619)

We insert field initialization logic at the beginning of every ctor in
`synthesizeCtorBody`, but then immediately inserts another round of
initialization again for explicit ctors in `maybeInsertDefaultInitExpr`,
both called from `SemanticsDeclBodyVisitor::visitAggTypeDecl` right next
to each other.

The fix is to remove `maybeInsertDefaultInitExpr`.

This change also enhances the address aliasing analysis, so that for the
following case:
```
this->member1 = 0;
this->member2 = 0;
this->member1 = param;
```
We can still remove the first assignment to `this->member1` despite
seeing `this->member2=0`, since it is easy to know that `this->member2`
cannot alias with `this->member1`.

Closes #8600.

0 files changed, 0 insertions, 0 deletions