UVS isset() on temporaries
-----
<?php

isset(([0, 1] + [])[0]);
isset(['a' => 'b']->a);
isset("str"->a);
-----
!!php7
array(
    0: Expr_Isset(
        vars: array(
            0: Expr_ArrayDimFetch(
                var: Expr_BinaryOp_Plus(
                    left: Expr_Array(
                        items: array(
                            0: Expr_ArrayItem(
                                key: null
                                value: Scalar_LNumber(
                                    value: 0
                                )
                                byRef: false
                            )
                            1: Expr_ArrayItem(
                                key: null
                                value: Scalar_LNumber(
                                    value: 1
                                )
                                byRef: false
                            )
                        )
                    )
                    right: Expr_Array(
                        items: array(
                        )
                    )
                )
                dim: Scalar_LNumber(
                    value: 0
                )
            )
        )
    )
    1: Expr_Isset(
        vars: array(
            0: Expr_PropertyFetch(
                var: Expr_Array(
                    items: array(
                        0: Expr_ArrayItem(
                            key: Scalar_String(
                                value: a
                            )
                            value: Scalar_String(
                                value: b
                            )
                            byRef: false
                        )
                    )
                )
                name: a
            )
        )
    )
    2: Expr_Isset(
        vars: array(
            0: Expr_PropertyFetch(
                var: Scalar_String(
                    value: str
                )
                name: a
            )
        )
    )
)