next.js: next/font bug when code is instrumented

Verify canary release

I verified that the issue exists in the latest Next.js canary release

Provide environment information

Operating System:
  Platform: darwin
  Arch: arm64
  Version: Darwin Kernel Version 22.2.0: Fri Nov 11 02:03:51 PST 2022; root:xnu-8792.61.2~4/RELEASE_ARM64_T6000
Binaries:
  Node: 18.12.1
  npm: 8.19.2
  Yarn: N/A
  pnpm: N/A
Relevant packages:
  next: 13.1.1
  eslint-config-next: 13.1.1
  react: 18.2.0
  react-dom: 18.2.0

Which area(s) of Next.js are affected? (leave empty if unsure)

Font optimization (@next/font), SWC transpilation

Link to the code that reproduces this issue

https://github.com/frattaro/next-font-repro

To Reproduce

Clone the repo Run npm i Run npm run dev

Describe the Bug

When swc-plugin-coverage-instrument swc plugin is used this error from @next/font is triggered:

Expected Behavior

SWC is expected to be able to build without issue.

Which browser are you using? (if relevant)

No response

How are you deploying your application? (if relevant)

No response

About this issue

Original URL
State: closed
Created 2 years ago
Reactions: 9
Comments: 20 (4 by maintainers)

Most upvoted comments

My colleague (@jch2617) pointed out that setting forceSwcTransforms: true fixes the issue.

EDIT: did not fix in CI

frattaro on Dec 29, 2022

This is neither next.js’s problem or plugin’s, it’s a conflict requirement between 2 features.

next/font requires to have specific scope to call, but coverage wraps calls into paren scope to inject coverage counter. There’s no easy way to detect those 2 conflict detect each other.

Disabling coverage to specific offending line allows to skip coverage attempts to change unexpected scopes to the next/font.

/* istanbul ignore next */
export const lato = Lato({
  subsets: ["latin"],
  weight: ["400", "700"],
  style: ["normal", "italic"]
});

kwonoj on Feb 12, 2024

No change with latest package updates

frattaro on Mar 24, 2023