instance.constructor type narrowing not working in switch

[pushkine]

TypeScript Version: 4.2.0-dev.20201127

Search Terms: switch, narrow, constructor

Code

function foo(o: any) {
    switch (o.constructor) {
        case Array: {
            o // o: any
        }
    }
}
function bar(o: any) {
    if (o.constructor === Array) {
        o // o: any[]
    }
}

Expected behavior: Both functions narrow the value to any[]

Actual behavior: Switch fails to narrow value

Playground Link: playground

Related Issues: #2214 (comment), #32774

[MartinJohns]

Related / duplicate of #28936, #3841. Search terms used: constructor narrow

[pushkine]

The issue is that IfBlocks have a special <var>.constructor === <class> handling that isn't mirrored in switch blocks
The issues mentioned by @MartinJohns are not related to switch blocks

[MartinJohns]

You're right. It's actually a duplicate of #16035.

[typescript-bot]

This issue has been marked as a 'Duplicate' and has seen no recent activity. It has been automatically closed for house-keeping purposes.