feat: auto-detect go version

.golangci.yml

@@ -130,6 +130,7 @@ issues:
 
 run:
   timeout: 5m
+  go: '1.17' # TODO(ldez): we force to use an old Go version for the CI and the tests.
   skip-dirs:
     - test/testdata_etc
     - internal/cache

pkg/commands/run.go

@@ -95,7 +95,7 @@ func initFlagSet(fs *pflag.FlagSet, cfg *config.Config, m *lintersdb.Manager, is
 		"Modules download mode. If not empty, passed as -mod=<mode> to go tools")
 	fs.IntVar(&rc.ExitCodeIfIssuesFound, "issues-exit-code",
 		exitcodes.IssuesFound, wh("Exit code when issues were found"))
-	fs.StringVar(&rc.Go, "go", "1.17", wh("Targeted Go version"))
+	fs.StringVar(&rc.Go, "go", "", wh("Targeted Go version"))
 	fs.StringSliceVar(&rc.BuildTags, "build-tags", nil, wh("Build tags"))
 
 	fs.DurationVar(&rc.Timeout, "deadline", defaultTimeout, wh("Deadline for total work"))

pkg/lint/lintersdb/manager.go

@@ -5,6 +5,7 @@ import (
 	"path/filepath"
 	"plugin"
 
+	"github.com/ldez/gomoddirectives"
 	"github.com/spf13/viper"
 	"golang.org/x/tools/go/analysis"
 
@@ -164,6 +165,19 @@ func (m Manager) GetAllSupportedLinterConfigs() []*linter.Config {
 		unusedCfg = &m.cfg.LintersSettings.Unused
 		varnamelenCfg = &m.cfg.LintersSettings.Varnamelen
 		wrapcheckCfg = &m.cfg.LintersSettings.Wrapcheck
+
+		if m.cfg.Run.Go == "" {
+			file, err := gomoddirectives.GetModuleFile()
+			if err != nil {
+				m.log.Warnf("unable to find go.mod file: %v", err)
+			}
+
+			if file != nil && file.Go != nil {
+				m.cfg.Run.Go = file.Go.Version
+			} else {
+				m.cfg.Run.Go = "1.17"
+			}
+		}
 	}
 
 	const megacheckName = "megacheck"