x/tools/gopls: add a setting to control removal of unused imports, and a quickfix

[findleyr]

We see feedback in survey results that users don't want unused imports to be removed by the organizeImports code action. I myself sometimes get annoyed by this behavior: it can be frustrating to manually type out an import path, save, and have the import disappear.

Surprisingly, I don't think we have an open (or closed) request for this feature, unless my search failed me.

I think we should consider a configuration option removeUnusedImports to control the removal of unused imports, and the default should probably be to not to remove unused imports EDIT: I take that back, the default behavior should not change.

[muirdm]

When do you need to manually type an import?

This would mean after removing the final use of a package and saving, the import wouldn’t be removed automatically by default? When would the unused imports be cleaned up?

[findleyr]

When do you need to manually type an import?

I sometimes do this to improve completion results, actually, which may suggest an alternative solution.

This would mean after removing the final use of a package and saving, the import wouldn’t be removed automatically by default? When would the unused imports be cleaned up?

Err yes these are good points. I filed this issue (rather nearsightedly) based on consistent feedback we see that this is a point of confusion / frustration. But of course the alternative has significant downsides, which you point out, thanks. I think we need more research into whether we can mitigate this pain point by other means, such as improving unimported completion. I've removed the conviction in the original post, and removed this from the milestone.

[skelouse]

@findleyr When trying to improve autocomplete rather than typing it into the imports type it into go get -u github.com/..... This will add it to the auto-import mechanism.

[adonovan]

An unused import generates a compile error, so we shouldn't leave them in as a convenience. If better completions is the motivation for this feature, we should improve the completion algorithm so that it generates candidates from unimported packages.

The only other case I can think of for wanting this is when temporarily commenting out the last use of an imported package, but usually goimports correctly restores the import when the code us uncommented. In any case, if that's not sufficient, I think the fix should be in goimports, not in suppressing the removal in the first place.