go1.20 support

[ldez]

This PR adds the support of go1.20.

Note for GitHub Action users: the Go version must be quoted ('1.20') otherwise it is interpreted as a float (1.2).

This PR is to evaluate and prepare golangci-lint to go1.20.

This PR will evolve during the beta and RC phases of go1.20.

Fixes #3420

[ldez]

The behavior of go list has changed between go1.19 and go1.20:

$ go version
go version go1.19.4 linux/amd64

$ go list -e -json=Name,ImportPath,Error,Dir,GoFiles,IgnoredGoFiles,IgnoredOtherFiles,CFiles,CgoFiles,CXXFiles,MF -export=true -- ./test/testdata/notcompiles/typecheck.go 
# command-line-arguments
test/testdata/notcompiles/typecheck.go:4:1: syntax error: non-declaration statement outside function body
{
        "Dir": "/home/ldez/sources/go/src/github.com/golangci/golangci-lint/test/testdata/notcompiles",
        "ImportPath": "command-line-arguments",
        "Name": "testdata",
        "GoFiles": [
                "typecheck.go"
        ]
}

$ go version
go version go1.20rc1 linux/amd64

$ go list -e -json=Name,ImportPath,Error,Dir,GoFiles,IgnoredGoFiles,IgnoredOtherFiles,CFiles,CgoFiles,CXXFiles,MF -export=true -- ./test/testdata/notcompiles/typecheck.go 
{
        "Dir": "/home/ldez/sources/go/src/github.com/golangci/golangci-lint/test/testdata/notcompiles",
        "ImportPath": "command-line-arguments",
        "Name": "testdata",
        "GoFiles": [
                "typecheck.go"
        ],
        "Error": {
                "ImportStack": null,
                "Pos": "",
                "Err": "# command-line-arguments\ntest/testdata/notcompiles/typecheck.go:4:1: syntax error: non-declaration statement outside function body\n"
        }
}

Why this is important? because packages.Load() invokes go list internally.

As the error message has specific content the position is empty ("Pos": "",), so the report of this error is misleading.

Related to:

• cmd/go: go list -export -e outputs errors to stderr and has non-zero exit code golang/go#25842
• https://go-review.googlesource.com/c/go/+/451218
• golang/go@0160412

I created a fix but I think the impact on packages.Load() is an unexpected side effect of golang/go@0160412.

[ldez]

Running golangci-lint (v1.50.1) with go1.20 crashes the shell.
But the version related to my PR works.

The CI crashes because we test the previous version (v1.50.1).

I will fix that. Fixed

[franchb]

Confirm that this version resolves high memory consumption on my Go codebase, Go v1.20rc3

[bouwerp]

I still have the huuuuge memory usage with the 1.51 update... I'm running MacOS Monterey 12.6.3 on an Intel chip.

[ldez]

I'm running MacOS

I guess you are installing golangci-lint with brew, brew uses go1.19 instead of go1.20.
#3565 (comment)

So you have to use either our binaries or our Docker image or build/install golangci-lint with go1.20.

golangci-lint requires to be built with go1.20, without that golangci-lint cannot work with go1.20.

Note the latest version of golangci-lint is v1.51.1.