strange parsing errors since 4.1.0

eslint depends on espree@^4.0.0, which pulls in 4.1.0 on a fresh install. since installing this version, we’ve been getting strange Parsing errors on perfectly normal JSX syntax, e.g. in this build https://circleci.com/gh/Financial-Times/x-dash/1197. the referenced lines aren’t anything weird. our .eslintrc.js includes a few plugins, including eslint-plugin-react, but is otherwise quite minimal.

when running npm install, i did note that it output:

npm ERR! peer dep missing: acorn@^6.0.0, required by acorn-jsx@5.0.0

even though espree includes acorn@^6.0.0 in its dependencies. seems like this might be a cause, if it’s using an incompatible version of acorn from somewhere?

[martijnsenden]

No. We are awaiting. This is npm’s bug and the npm CLI team has a plan to fix the bug by Summer in 2019.

Any news on this?

[mysticatea]

No.

I don’t think the revert makes sense. This causes by acorn’s breaking change. Currently, the npm’s bug appears when there is a older acorn in another dependency. After reverting, it will appear when there is a newer acorn in another dependency. https://github.com/eslint/eslint/issues/11018#issuecomment-438737502