new custom linters didn't show in "Issue" or "Report" and "fmt.Println" didn't printed

[cuizhiqiang0]

Welcome

• Yes, I'm using a binary release within 2 latest major releases. Only such installations are supported.
• Yes, I've searched similar issues on GitHub and didn't find any.
• Yes, I've included all information below (version, config, etc).
• Yes, I've tried with the standalone linter if available. (https://golangci-lint.run/usage/linters/)

Description of the problem

I add a custom linter to check go projects. And after run that, the output shows that the linter.so was loaded and run in xx us, but the "fmt.Println() " written by the linter did not printed. Also, the custom linter wasn't print in neither "Issue" nor "Report" field of ouput. Why is that?

Version of golangci-lint

$ golangci-lint --version
go version go1.16.5 linux/amd64

Configuration file

run:
  timeout: 5m

output:
  format: json
linters:
  disable-all: true
  enable:
    - my_checker

issues:
  exclude-use-default: false
  exclude-rules:
    - path: ./
      linters:
        - my_checker
#linters-settings:
linters-settings:
  custom:
    my_checker:
      path: /home/xx/my_checker.so
      description: my_checker

Go environment

$ go version && go env
# paste output here

Verbose output of running

$ golangci-lint cache clean
$ export GL_DEBUG=loader,gocritic,env,autogen_exclude,nolint && golangci-lint  -v run -c  my_debug.yml .
INFO [lintersdb] Active 1 linters: [my_checker]
INFO [runner/filename_unadjuster] Pre-built 0 adjustments in 165.727µs
INFO [linters context/goanalysis] analyzers took 18.189µs with top 10 stages: my_checker: 18.189µs
INFO [runner] linters took 1.224164ms with stages: my_checker: 893.899µs

{"Issues":[{"FromLinter":"typecheck","Text":"could not import fmt (Config.Importer.Import(fmt) returned nil but no error)","Severity":"","SourceLines":["\t\"fmt\""],"Replacement":null,"Pos":{"Filename":"main.go","Offset":0,"Line":4,"Column":2},"ExpectNoLint":false,"ExpectedNoLintLinter":""}],"Report":{"Linters":[{"Name":"asciicheck"},{"Name":"bidichk"},{"Name":"bodyclose"},{"Name":"containedctx"},{"Name":"contextcheck"},{"Name":"cyclop"},{"Name":"decorder"},{"Name":"deadcode","EnabledByDefault":true},{"Name":"depguard"},{"Name":"dogsled"},{"Name":"dupl"},{"Name":"durationcheck"},{"Name":"errcheck","EnabledByDefault":true},{"Name":"errchkjson"},{"Name":"errname"},{"Name":"errorlint"},{"Name":"exhaustive"},{"Name":"exhaustivestruct"},{"Name":"exportloopref"},{"Name":"forbidigo"},{"Name":"forcetypeassert"},{"Name":"funlen"},{"Name":"gci"},{"Name":"gochecknoglobals"},{"Name":"gochecknoinits"},{"Name":"gocognit"},{"Name":"goconst"},{"Name":"gocritic"},{"Name":"gocyclo"},{"Name":"godot"},{"Name":"godox"},{"Name":"goerr113"},{"Name":"gofmt"},{"Name":"gofumpt"},{"Name":"goheader"},{"Name":"goimports"},{"Name":"golint"},{"Name":"gomnd"},{"Name":"gomoddirectives"},{"Name":"gomodguard"},{"Name":"goprintffuncname"},{"Name":"gosec"},{"Name":"gosimple","EnabledByDefault":true},{"Name":"govet","EnabledByDefault":true},{"Name":"grouper"},{"Name":"ifshort"},{"Name":"importas"},{"Name":"ineffassign","EnabledByDefault":true},{"Name":"interfacer"},{"Name":"ireturn"},{"Name":"lll"},{"Name":"maintidx"},{"Name":"makezero"},{"Name":"maligned"},{"Name":"misspell"},{"Name":"nakedret"},{"Name":"nestif"},{"Name":"nilerr"},{"Name":"nilnil"},{"Name":"nlreturn"},{"Name":"noctx"},{"Name":"paralleltest"},{"Name":"prealloc"},{"Name":"predeclared"},{"Name":"promlinter"},{"Name":"revive"},{"Name":"rowserrcheck"},{"Name":"scopelint"},{"Name":"sqlclosecheck"},{"Name":"staticcheck","EnabledByDefault":true},{"Name":"structcheck","EnabledByDefault":true},{"Name":"stylecheck"},{"Name":"tagliatelle"},{"Name":"tenv"},{"Name":"testpackage"},{"Name":"thelper"},{"Name":"tparallel"},{"Name":"typecheck","EnabledByDefault":true},{"Name":"unconvert"},{"Name":"unparam"},{"Name":"unused","EnabledByDefault":true},{"Name":"varcheck","EnabledByDefault":true},{"Name":"varnamelen"},{"Name":"wastedassign"},{"Name":"whitespace"},{"Name":"wrapcheck"},{"Name":"wsl"},{"Name":"nolintlint"}]}}

Code example or link to a public repository

package main

import (
	"fmt"
	"go/ast"
	"os"
	"golang.org/x/tools/go/analysis"
)

type analyzerPlugin struct{}

func (*analyzerPlugin) GetAnalyzers() []*analysis.Analyzer {
	return []*analysis.Analyzer{
		My_CHECKERAnalyzer,
	}
}

var AnalyzerPlugin analyzerPlugin

var MY_CHECKERAnalyzer = &analysis.Analyzer{
	Name: "my_checker",
	Doc:  "limit_for_the_use_of_context",
	Run:  run,
}

func run(pass *analysis.Pass) (interface{}, error) {
	fmt.Println(" test args:")
	for _, file := range pass.Files {
		ast.Inspect(file, func(n ast.Node) bool {
			fmt.Fprintf(os.Stderr, "test1: \n")
			msg := "test123"
			pass.Report(analysis.Diagnostic{
				Pos:      n.Pos(),
				End:      n.End(),
				Category: "my_checker",
				Message:  msg,
			})
			
			return true
		})
	}
	return nil, nil
}

[Antonboom]

Please provide using golangci-lint version (there's a typo there now).
P.S. And maybe also to try the latest one?

[HejVkt]

same issue, build by golangci-lint v1.55.1 and use example todo plugin from https://github.com/golangci/example-plugin-linter

[ldez]

This behavior is expected: every data sent to os.Stdout/Stderr (i.e. all the output of functions like fmt.Printxx) by a linter is discarded.
A linter should create reports not display things by itself.

If you want to cancel this discard (which I don't recommend), you should use the following debug key linters_output.

$ GL_DEBUG=linters_output ./golangci-lint run

https://golangci-lint.run/contributing/debug/