Typescript intellisense does not recognize 'delete'd attributes

[mjbvz]

From @Barbiero on August 14, 2018 11:30

Whenever you deletean attribute from an object, I'd expect intellisense to recognize that said attribute was removed.
Example of the problem:

The expected behavior would be for the autocomplete feature to NOT show the date attribute. Furthermore, if I were to call anything over said property(say, example.date.toISOString()) it should warn me of the undefined call. deleteing an attribute from a class/interface that does not define it as an optional attribute should also be an error IMO, though I don't know how feasible that is.

Either way, VSCode(or the typescript language server?) has no support for the side effects of delete atm.

• VSCode Version: 1.26

Does this issue occur when all extensions are disabled?: Yes

Copied from original issue: microsoft/vscode#56340

[RyanCavanaugh]

This isn't a common enough pattern to warrant the complexity needed to support it.

[ghost]

Related: #26549

[ajafff]

As TypeScript won't fix type inference on delete, I wrote a linter rule to disallow delete on required properties: delete-only-optional-property
For a description on how to use it, see https://github.com/fimbullinter/wotan/blob/master/packages/wotan/README.md

[Vanuan]

That would be invalid code.

Deleting non-optional properties should be prohibited.
Delete shouldn't mutate the type of a variable.

[rreeves8]

what if they're optional ?