runAnalyzersConfig: export analyzers

[sluongng]

Overview

In order to use golangci-lint in non-trivial use cases, such as Bazel's rules_go's 'nogo' static analysis framework, we would need to make the analysis.Analyzer defined for various different golinters be reuseable outside of golangci-lint.

Export the GetAnalyzers function of runAnalyzersConfig interface as well as adjusting the 2 implementations of that interface: goanalysis.Linter and goanalysis.MetaLinter

This should help enable other packages to be able to consumer golangci-lint analyzers for different use cases.

Technical details

Once this is merged, we can build a solution for issue #1473 by generating a new Go package for each linter in golangci-lint. With each package contains only one file like this:

// Generated code. DO NOT MODIFY.
package nogoGofumpt

import (
	"github.com/golangci/golangci-lint/pkg/golinters"
)

// Assuming that there is only 1 analyzer for each linter
var Analyzer = golinters.NewGofumpt().GetAnalyzers()[0]

Bazel rules_go's nogo static analysis then would be able to consume this package as the documentation stated here https://github.com/bazelbuild/rules_go/blob/master/go/nogo.rst#id8

[boring-cyborg]

Hey, thank you for opening your first Pull Request !

[CLAassistant]

All committers have signed the CLA.

[sluongng]

@ldez is there anything I could do to help unblocking this?

[sluongng]

I discussed with @Helcaraxan updated the PR description with a bit more technical details.

[telus-dvanamst]

Admittedly I have not contributed to golangci-lint in recent times, however @sluongng attracted my attention to this PR as he needs to get it merged to support the work on #1473.

Based on the conversation in that issue, the minor size of this change and the amount of developer value that would be unlocked by it I feel that it's better here to merge and "ask for forgiveness, rather than permission".

[martinbaillie]

Just chiming in as a user to say I'm very keen to see this Bazel nogo enabling work land and happy to help with testing.

[paiyar]

@ldez @Helcaraxan @alexandear Could you please revisit this? There is a lot of interest from the community of Golang & Bazel users and we'd direly like to leverage Golangci-lint in a native way as this paves the way for.

The status of this PR is Blocked.

[sluongng]

Let's just close this stale PR.

Since this PR was opened, I have taken alternative routes to export analyzers from golangci-lint: see nogo-analyzer/golangci-lint and nogo-analyzer/goci-lint.

My understanding of golangci-lint is very out of date since I last looked at this, but I think it's hard to make a systematic export of analyzers from golangci-lint as they are tightly coupled with the configurations framework inside the runner binary. What you gonna get is a set of very slow analyzers as each one of them would need to initialize the configuration of golangci-lint runner.

Instead, in goci-lint, I took the source of these analyzers such as github.com/golangci/gofmt/gofmt or github.com/gordonklaus/ineffassign/pkg/ineffassign and make new, light weighted, standalone analyzer struct out of them. This requires a bit more manual wiring, but they are a lot faster to run in massive monorepo