Enables using `next/font` by adding `@next/font` as a dependency and
reexporting its loaders.
Always generates the `font-loader-manifest` as we can't know beforehand
if the user intends to use `next/font` or not.
Also adds telemetry for `next/font` usage.
The tests are updated to use `next/font`. But `@next/font` is tested in
`test/e2e/next-font/index.test.ts` and `test/e2e/app-dir/next-font` as
well to ensure it doesn't break.
Fixes NEXT-351
## Bug
- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added
- [ ] Errors have a helpful link attached, see
[`contributing.md`](https://github.com/vercel/next.js/blob/canary/contributing.md)
## Feature
- [ ] Implements an existing feature request or RFC. Make sure the
feature request has been accepted for implementation before opening a
PR.
- [ ] Related issues linked using `fixes #number`
- [ ]
[e2e](https://github.com/vercel/next.js/blob/canary/contributing/core/testing.md#writing-tests-for-nextjs)
tests added
- [ ] Documentation added
- [ ] Telemetry added. In case of a feature if it's used or not.
- [ ] Errors have a helpful link attached, see
[`contributing.md`](https://github.com/vercel/next.js/blob/canary/contributing.md)
## Documentation / Examples
- [ ] Make sure the linting passes by running `pnpm build && pnpm lint`
- [ ] The "examples guidelines" are followed from [our contributing
doc](https://github.com/vercel/next.js/blob/canary/contributing/examples/adding-examples.md)
Adds `data-next-font` data attribute to the preload tag if added by
`@next/font`.
```js
// Using `size-adjust` fallback font.
<link data-next-font="size-adjust" rel="preload" href="..." as="font" type="font/woff2" crossorigin="anonymous">
// Not using `size-adjust` fallback font.
<link data-next-font="" rel="preload" href="..." as="font" type="font/woff2" crossorigin="anonymous">
```
If no fonts are preloaded, the tag is added on the preconnect tag.
Fixes NEXT-350
## Bug
- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added
- [ ] Errors have a helpful link attached, see
[`contributing.md`](https://github.com/vercel/next.js/blob/canary/contributing.md)
## Feature
- [ ] Implements an existing feature request or RFC. Make sure the
feature request has been accepted for implementation before opening a
PR.
- [ ] Related issues linked using `fixes #number`
- [ ]
[e2e](https://github.com/vercel/next.js/blob/canary/contributing/core/testing.md#writing-tests-for-nextjs)
tests added
- [ ] Documentation added
- [ ] Telemetry added. In case of a feature if it's used or not.
- [ ] Errors have a helpful link attached, see
[`contributing.md`](https://github.com/vercel/next.js/blob/canary/contributing.md)
## Documentation / Examples
- [ ] Make sure the linting passes by running `pnpm build && pnpm lint`
- [ ] The "examples guidelines" are followed from [our contributing
doc](https://github.com/vercel/next.js/blob/canary/contributing/examples/adding-examples.md)
