Nullsafe operator
-----
<?php

$a?->b;
$a?->b($c);
new $a?->b;
"{$a?->b}";
"$a?->b";
-----
!!php7
array(
    0: Stmt_Expression(
        expr: Expr_NullsafePropertyFetch(
            var: Expr_Variable(
                name: a
            )
            name: Identifier(
                name: b
            )
        )
    )
    1: Stmt_Expression(
        expr: Expr_NullsafeMethodCall(
            var: Expr_Variable(
                name: a
            )
            name: Identifier(
                name: b
            )
            args: array(
                0: Arg(
                    name: null
                    value: Expr_Variable(
                        name: c
                    )
                    byRef: false
                    unpack: false
                )
            )
        )
    )
    2: Stmt_Expression(
        expr: Expr_New(
            class: Expr_NullsafePropertyFetch(
                var: Expr_Variable(
                    name: a
                )
                name: Identifier(
                    name: b
                )
            )
            args: array(
            )
        )
    )
    3: Stmt_Expression(
        expr: Scalar_Encapsed(
            parts: array(
                0: Expr_NullsafePropertyFetch(
                    var: Expr_Variable(
                        name: a
                    )
                    name: Identifier(
                        name: b
                    )
                )
            )
        )
    )
    4: Stmt_Expression(
        expr: Scalar_Encapsed(
            parts: array(
                0: Expr_Variable(
                    name: a
                )
                1: Scalar_EncapsedStringPart(
                    value: ?->b
                )
            )
        )
    )
)