3724 – bug in Expression::arraySyntaxCopy (null pointer dereference on struct->union->struct

In case of code similar to this
struct v {
 union {
 struct { float a, b; }
 struct { float c[2]; }
 }
}
(it is more complicated than just this sample, to trigger this bug.
I can't easly produce small example)
file expression.c
method Expression *StructLiteralExp::semantic(Scope *sc)
performs kind of flatening, and adds member c to array "elements",
but in case on union memberrs it adds them as null:
relevant lines:
line 3373
 if (v->offset < offset)
 { e = NULL;
 sd->hasUnions = 1;
 }
and line 3393
 elements->push(e)
Fix:
In file expression.c line 1477
method Expressions *Expression::arraySyntaxCopy(Expressions *exps)
add condition:
 for (int i = 0; i < a->dim; i++)
 { Expression *e = (Expression *)exps->data[i];
- e = e->syntaxCopy();
+ if (e)
+ e = e->syntaxCopy();
 a->data[i] = e;^M
 }
Without it, optimize.c lines 86-87 will call indirectly this method, when some (last) elemenets of exps is/are nulls, and segfault.

Changeset 348

fixed dmd 1.056 and 2.040