fix: improve Go version detection inside workspace (#5179)

Author: ldez

go.mod

@@ -67,6 +67,7 @@ require (
 	github.com/kyoh86/exportloopref v0.1.11
 	github.com/lasiar/canonicalheader v1.1.2
 	github.com/ldez/gomoddirectives v0.4.2
+	github.com/ldez/grignotin v0.6.0
 	github.com/ldez/tagliatelle v0.6.0
 	github.com/ldez/usetesting v0.2.0
 	github.com/leonklingele/grouper v1.1.2
@@ -128,6 +129,7 @@ require (
 	go-simpler.org/sloglint v0.7.2
 	go.uber.org/automaxprocs v1.6.0
 	golang.org/x/exp v0.0.0-20240909161429-701f63a606c0
+	golang.org/x/mod v0.22.0
 	golang.org/x/sys v0.27.0
 	golang.org/x/tools v0.27.0
 	gopkg.in/yaml.v3 v3.0.1
@@ -164,7 +166,6 @@ require (
 	github.com/hashicorp/golang-lru/v2 v2.0.7 // indirect
 	github.com/hashicorp/hcl v1.0.0 // indirect
 	github.com/inconshreveable/mousetrap v1.1.0 // indirect
-	github.com/ldez/grignotin v0.6.0 // indirect
 	github.com/lufia/plan9stats v0.0.0-20211012122336-39d0f177ccd0 // indirect
 	github.com/magiconair/properties v1.8.6 // indirect
 	github.com/mattn/go-isatty v0.0.20 // indirect
@@ -197,7 +198,6 @@ require (
 	go.uber.org/multierr v1.6.0 // indirect
 	go.uber.org/zap v1.24.0 // indirect
 	golang.org/x/exp/typeparams v0.0.0-20241108190413-2d47ceb2692f // indirect
-	golang.org/x/mod v0.22.0 // indirect
 	golang.org/x/sync v0.9.0 // indirect
 	golang.org/x/text v0.18.0 // indirect
 	google.golang.org/protobuf v1.34.2 // indirect

pkg/config/config.go

@@ -1,11 +1,16 @@
 package config
 
 import (
+	"cmp"
+	"fmt"
 	"os"
+	"path/filepath"
+	"slices"
 	"strings"
 
 	hcversion "github.com/hashicorp/go-version"
-	"github.com/ldez/gomoddirectives"
+	"github.com/ldez/grignotin/gomod"
+	"golang.org/x/mod/modfile"
 )
 
 // Config encapsulates the config data specified in the golangci-lint YAML config file.
@@ -93,8 +98,33 @@ func detectGoVersion() string {
 // else it returns `go` version if present,
 // else it returns empty.
 func detectGoVersionFromGoMod() string {
-	file, _ := gomoddirectives.GetModuleFile()
-	if file == nil {
+	info, err := gomod.GetModuleInfo()
+	if err != nil {
+		return ""
+	}
+
+	wd, err := os.Getwd()
+	if err != nil {
+		return ""
+	}
+
+	slices.SortFunc(info, func(a, b gomod.ModInfo) int {
+		return cmp.Compare(len(b.Path), len(a.Path))
+	})
+
+	goMod := info[0]
+	for _, m := range info {
+		if !strings.HasPrefix(wd, m.Dir) {
+			continue
+		}
+
+		goMod = m
+
+		break
+	}
+
+	file, err := parseGoMod(goMod.GoMod)
+	if err != nil {
 		return ""
 	}
 
@@ -110,3 +140,12 @@ func detectGoVersionFromGoMod() string {
 
 	return ""
 }
+
+func parseGoMod(goMod string) (*modfile.File, error) {
+	raw, err := os.ReadFile(filepath.Clean(goMod))
+	if err != nil {
+		return nil, fmt.Errorf("reading go.mod file: %w", err)
+	}
+
+	return modfile.Parse("go.mod", raw, nil)
+}

pkg/golinters/gomodguard/testdata/go.mod

@@ -0,0 +1,8 @@
+module gomodguard
+
+go 1.22.0
+
+require (
+	golang.org/x/mod v0.22.0
+	gopkg.in/yaml.v3 v3.0.1
+)

pkg/golinters/gomodguard/testdata/go.sum

@@ -1,8 +1,8 @@
 linters-settings:
   gomodguard:
     allowed:
-      modules:                                                    # List of allowed modules
-        - golang.org/x/mod/modfile
+      modules:                                                      # List of allowed modules
+        - golang.org/x/mod
     blocked:
       modules:                                                      # List of blocked modules
         - gopkg.in/yaml.v3:                                         # Blocked module