microsoft / microsoft/TypeScript
Have QuickInfo use import types to display type aliases that are not in scope
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Description
Search Terms:
type alias, import, display, quickinfo, intellisense
Code
// @Filename: file1.ts
export type ComplicatedType<T, U> = { [K in Exclude<keyof T, U>]: T[K] } // could be anything here
export declare function getComplicatedType<T, U extends keyof T>(arg: T, exclude: U): ComplicatedType<T, U>
// @Filename: file2.ts
import { getComplicatedType } from "./file1"
interface SomeInterface {
a: string
b<T>(arg: T): T,
c: { c2: string } | { c3: number },
d?: boolean
}
declare const test: SomeInterface
const result = getComplicatedType(test, "a") // quickinfo on result currently displays something like:
/* const result: {
b: <T>(arg: T) => T;
c: {
c2: string;
} | {
c3: number;
};
d: boolean | undefined;
} */
Current behavior:
The quick info type shown for result is a fully expanded anonymous type because ComplicatedType is not in scope in file2. Importing ComplicatedType in file2 makes quick info display const result: ComplicatedType<SomeInterface, "a">, but I don't think it's common to import a type alias purely for the quick info benefit if it isn't actually used anywhere in the file.
While the example above isn't that bad, in some cases (#18754, #23458) the fully expanded types can be so large that they actually cause a performance issue for the language service.
Suggested behavior:
Use import types from #22592 to display an accurate qualified reference to ComplicatedType. So in the example above quick info for result could instead display something like:
const result: import("./file1").ComplicatedType<SomeInterface, "a">
Which, although a little verbose, would be much more readable than many fully expanded types.
Related Issues:
#22592 added import types.
#18754, #23458, #6070, #13095 - Various issues related to the display of types.
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start with the file1.ts/file2.ts repro and the QuickInfo behavior described in the issue; review import types from issue #22592 and the related type-display issues. Done means QuickInfo can show a qualified import-type reference such as import("./file1").ComplicatedType<SomeInterface, "a"> instead of expanding the alias.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- typescript
- Domain
- tooling
- Issue type
- Feature
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 45/100