Infering type from usage does silly import

[jpike88]

TypeScript Version: typescript@3.6.0-dev.20190814

myInterfaceFile.ts

export interface MyExportedInterface {
	something: number
}

another file, when using 'infer type from usage' option in VSCode

export async function someFunction(metricParams: { algebra: import("../../../../../../../../../blaa/bla/myInterfaceFile.ts").MyExportedInterface }) {

}

An 'import' function shouldn't be called.

[DanielRosenwasser]

We should always prefer an import statement at the top of the file.

[andrewbranch]

@jpike88 can you share the contents of that file pre-“infer type from usage” command?

[jpike88]

To reproduce, the file is empty other than the function I've defined, including not having any import statements.

export async function Test(test, user) {

}

Whats weird is this:

if I tell it to infer parameter types, I get this:

export async function Test(test: any, user: any) {

}

Which is correct I guess.

But if the function contains just one line of code, I get this:

export async function getPlantMetric(test: any, user: import("../../../../../../../../../project/some/path//shared/models/User").User) {
	if (!test) throw new Error('whatever!');
}

The second argument attempts to get at an import, but in doing so incorrectly inlines an import() function instead of pulling it in at the top.

[fatcerberus]

How is it even arriving at that type for user if the only thing in the function is just an unconditional throw?

[andrewbranch]

@jpike88 I can’t reproduce this with the info provided. I’m sure it must depend somewhat upon the file that exports some User type, and possibly upon project settings. Can you create or give me access to a repo that exhibits the issue, or describe more details about how to repro? Assume all details are relevant unless you can prove them otherwise.

[jpike88]

Sorry don't have the time, and I guess is an edge case.

But I think that there should be a VSCode setting that disables the import() function from being used at all when these sorts of judgements are being made.

[andrewbranch]

How is it even arriving at that type for user if the only thing in the function is just an unconditional throw?

Somewhere else in the project, something is calling that function with an argument of type User. The code that triggers this issue isn’t shown.