fix: specify return type in DTS declarations

[43081j]

If we specify the return type in the JSDoc for getRequestEvent, the DTS emit corrects itself and no longer pulls in a missing symbol.

Maybe this means we don't need the generate hack?

Draft for now in case this doesn't fully solve the problem for a reason i'm not aware of.

---

Please don't delete this checklist! Before submitting the PR, please make sure you do the following:

• It's really useful if your PR references an issue where it is discussed ahead of time. In many cases, features are absent for a reason. For large changes, please create an RFC: https://github.com/sveltejs/rfcs
• This message body should clearly illustrate what problems it solves.
• Ideally, include a test that fails without this PR but passes with it.

Tests

• Run the tests with pnpm test and lint the project with pnpm lint and pnpm check

Changesets

• If your PR makes a change that should be noted in one or more packages' changelogs, generate a changeset by running pnpm changeset and following the prompts. Changesets that add features should be minor and those that fix bugs should be patch. Please prefix changeset messages with feat:, fix:, or chore:.

Edits

• Please ensure that 'Allow edits from maintainers' is checked. PRs without this option may be closed.

[changeset-bot]

⚠️ No Changeset found

Latest commit: 31f4b88

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

This PR includes no changesets

When changesets are added to this PR, you'll see the packages that this PR includes changesets for and the associated semver types

Click here to learn what changesets are, and how to add one.

Click here if you're a maintainer who wants to add a changeset to this PR

[43081j]

FYI i think this is entirely because we ts-ignore the symbol being imported:

kit/packages/kit/src/exports/public.d.ts

Lines 21 to 26 in 1164ffa

	import {
	RouteId as AppRouteId,
	LayoutParams as AppLayoutParams,
	ResolvedPathname
	// @ts-ignore
	} from '$app/types';

if this resolved, tsc might have emit the right thing without specifying the return type

isn't it possible we can use declaration merging to provide a "base" $app/types module declaration? and the user's declaration just merges into it. so things that always exist, like LayoutParams are always declared but start off nothing?

// base declaration
declare module '$app/types' {
    export interface LayoutParams {
    }
}

// user declaration
declare module '$app/types' {
    export interface LayoutParams {
        foo: 303;
    }
}

[dummdidumm]

Mhhhm yeah this might work!

[Rich-Harris]

We're mostly dealing with types rather than interfaces, which IIUC can't be merged

[Rich-Harris]

Scratch 'mostly' — everything exported from $app/types is a type https://svelte.dev/docs/kit/$app-types

[43081j]

yup i see

i suppose at least this JSDoc fixes the emit to no longer have a non-existent type

but it does seem we can't do much about app/types in general

[Rich-Harris]

Yeah — @eltigerchino noticed that there's a TypeScript feature called exists that would help us: sveltejs/dts-buddy#110 (comment)

Unfortunately exists doesn't exist!