Wrong completion value when switch is part of a statement list

[sunlili]

The bug can be reproduced in ch version 1.11.15.0.
Running following code:

let temp = eval('42;switch (0) { case 0: break; };');
console.log(temp);

Actual results:

42

Expected results:

undefined

According to ecma manual,https://tc39.es/ecma262/#sec-block-runtime-semantics-evaluation, the value of a StatementList is the value of the last value producing item in the StatementList. Switch statement produce value undefined (https://tc39.es/ecma262/#sec-runtime-semantics-caseblockevaluation), so the result should be undefined.

ISec Lab
2019.12.26

[rhuanjl]

Confirmed that this bug repros in master and latest release. AND spidermonkey. Though v8 and JSC handle correctly.

Relates specifically to having a switch statement in a statement list - further investigation needed to determine where the error is, it is likely to be in the bytecode emitter but could also be a parse issue.