Add support for the new implementation of for loop variables in go 1.22. (#993)

* Add support for the new behaviour of for loops in go 1.22.

Go 1.22 has changed the behaviour of for loops. Every iteration
makes new loop variables. It is now safe to take their addresses
because they are guaranteed to be unique. Similarly, it is now
safe to capture loop variables in functions.

* adds documentation for public function

---------

Co-authored-by: chavacava <salvadorcavadini+github@gmail.com>

lint/linter.go

@@ -3,12 +3,18 @@ package lint
 import (
 	"bufio"
 	"bytes"
+	"encoding/json"
 	"fmt"
 	"go/token"
 	"os"
+	"os/exec"
+	"path/filepath"
 	"regexp"
 	"strconv"
+	"strings"
 	"sync"
+
+	goversion "github.com/hashicorp/go-version"
 )
 
 // ReadFile defines an abstraction for reading files.
@@ -78,9 +84,19 @@ func (l *Linter) Lint(packages [][]string, ruleSet []Rule, config Config) (<-cha
 }
 
 func (l *Linter) lintPackage(filenames []string, ruleSet []Rule, config Config, failures chan Failure) error {
+	if len(filenames) == 0 {
+		return nil
+	}
+
+	goVersion, err := detectGoVersion(filepath.Dir(filenames[0]))
+	if err != nil {
+		return err
+	}
+
 	pkg := &Package{
-		fset:  token.NewFileSet(),
-		files: map[string]*File{},
+		fset:      token.NewFileSet(),
+		files:     map[string]*File{},
+		goVersion: goVersion,
 	}
 	for _, filename := range filenames {
 		content, err := l.readFile(filename)
@@ -108,6 +124,39 @@ func (l *Linter) lintPackage(filenames []string, ruleSet []Rule, config Config,
 	return nil
 }
 
+func detectGoVersion(dir string) (ver *goversion.Version, err error) {
+	// https://github.com/golang/go/issues/44753#issuecomment-790089020
+	cmd := exec.Command("go", "list", "-m", "-json")
+	cmd.Dir = dir
+
+	raw, err := cmd.Output()
+	if err != nil {
+		return nil, fmt.Errorf("command go list: %w", err)
+	}
+
+	var v struct {
+		GoMod     string `json:"GoMod"`
+		GoVersion string `json:"GoVersion"`
+	}
+	if err = json.Unmarshal(raw, &v); err != nil {
+		return nil, fmt.Errorf("can't parse the output of go list: %w", err)
+	}
+
+	if v.GoMod == "" {
+		// this package is outside a module, so assume
+		// an old-style source directory
+
+		if v := os.Getenv("GOVERSION"); v != "" {
+			return goversion.NewVersion(strings.TrimPrefix(v, "go"))
+		}
+
+		// assume the last version that does not have generics
+		return goversion.Must(goversion.NewVersion("1.17")), nil
+	}
+
+	return goversion.NewVersion(strings.TrimPrefix(v.GoVersion, "go"))
+}
+
 // isGenerated reports whether the source file is generated code
 // according the rules from https://golang.org/s/generatedcode.
 // This is inherited from the original go lint.