Vscode-eslint: `eslint-plugin-import` rule `import/no-unused-modules` does not work with vscode-eslint.

[ehmicky]

The plugin eslint-plugin-import has a rule import/no-unused-modules that checks (among other things) for exports that are not used in other files.

"import/no-unused-modules": [2, {"unusedExports": true}]

This does not work well with vscode-eslint: files that have not been opened in the editor yet are not taken into account. As a consequence exports are being reported as unused even though they are used.

For example, if I just open a new VSCode Window:

The serialize() exported function is reported, even after saving the file.

Now if I open that other file which imports the serialize() function:

Then go back to the first file and save it, the reporting is now gone:

It seems like only files that are open within VSCode are considered for the import/no-unused-modules rule.

This behavior only seems to happen with VSCode. If I run eslint on the command line, everything works fine.

I've initially opened an issue with eslint-plugin-import but got redirected here by its author.

VSCode: 1.36.1
vscode-eslint: 1.9.0
OS: Ubuntu 19.04
ESLint: 6.0.1
eslint-plugin-import: 2.18.0
Node: 12.6.0

[dbaeumer]

@ehmicky ESLint only validates the open files. This is comparable to running eslint in the terminal for a single file. E.g. eslint folder/file.js. If you do this are the exports reported as well?

There is also a eslint validate task that validates the whole project. It can be enable with "eslint.provideLintTask": true. You can invoke the task using Run Task from the Terminal menu.

[ehmicky]

@dbaeumer thanks for looking into this.

If I understand you correctly, VSCode-ESLint only validates the opened files. This might be an issue with rules like no-unused-modules where linting needs to happen project-wise and not file-wise.

Doing eslint folder/file.js works (i.e. the exports are not reported) because that ESLint rule receives a src option (defaulting to current directory) and manually recurse over it to find out which files are depending on folder/file.js. At least that's what I think the rule does under the hood, I am not completely sure (source code). It just works (outside of VSCode-ESLint).

The eslint.provideLintTask would unfortunately require an explicit action to be triggered, as opposed to linting in realtime.

[dbaeumer]

@ehmicky thanks for the additional information. The problem is that we can't do that on typing since it would not scale parsing all files in a workspace.

What would work is that we auto trigger the lint task on save so that there is not need for a user interaction.

[dbaeumer]

Good opportunity for a PR.

[ehmicky]

@dbaeumer yes triggering the lint task on save would work for me, thanks!

[vscodebot[bot]]

We closed this issue because we don't plan to address it in the foreseeable future. You can find more detailed information about our decision-making process here. If you disagree and feel that this issue is crucial: We are happy to listen and to reconsider.

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Thanks for your understanding and happy coding!

[dbaeumer]

I am still happy to accept a PR if someone wants to work on this.