x/tools/gopls: allow more formatter options

[yzhou216]

Proposal Details

Currently, in the gopls settings, we only have the option to enable gofumpt. It would be nice if gopls allows the user to set a path to a specific formatter program like how nil implements it, where it supports setting a custom formatter in the config by assigning the path of the formatter to "nil"."formatter"."command" as a String. This would enable the ability to use third party formatters such as golines and golangci-lint fmt with gopls.

[gabyhelp]

Related Issues

• x/tools/gopls: allow enabling gofumpt extra rules #56403

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[adonovan]

Though I don't love the idea of further complicating what should be a simple story ("there is one format and its command is gofmt"), I would support this feature if it meant that gopls could avoid linking in gofumpt, instead being loosely coupled to nonstandard formatters through a common command-line interface. Then gofumpt=true could become a shorthand for formatter=github.com/mvdan/gofumpt.

[yzhou216]

Though I don't love the idea of further complicating what should be a simple story ("there is one format and its command is gofmt")

golines for example, internally calls gofmt anyway, and since gofmt doesn't have any formatting preferences for line wrapping, that means feeding a go source file formatted by golines back to gofmt would not change the format again in any way. Thus, I would like to call that formatters such as golines and gofumpt gofmt compatible formatters, meaning feeding the result of them back to gofmt doesn't change the file again.

I'm guessing when gopls decided to add the option to enable gofumpt, this was part of the consideration, which makes it reasonable to at least add the option for golines. I completely understand and agree with the opinion of only having one formatter, however, I think such compatible formatters should be allowed.