ICE on final switch forward referencing its enum

[dkorpel]

This results in a segfault:

enum E
{
    a = 3,
    b = () {
        E e;
        final switch (e)
        {
            case E.a: break;
        }
        return 4;
    } ()
}

src/dmd/statementsem.d:1966 void dmd.statementsem.statementSemanticVisit(dmd.statement.Statement, dmd.dscope.Scope*).visitSwitch(dmd.statement.SwitchStatement) [0x5f403ee2d915]
src/dmd/statement.d:1886 void dmd.statementsem.statementSemanticVisit(dmd.statement.Statement, dmd.dscope.Scope*).visit.VisitStatement(dmd.statement.Statement) [0x5f403ee339c3]
src/dmd/statementsem.d:3685 dmd.statement.Statement dmd.statementsem.statementSemanticVisit(dmd.statement.Statement, dmd.dscope.Scope*) [0x5f403ee2695f]