refactor gofumpt to get rid of shazow/go-diff dep

Author: SVilgelm

go.mod

@@ -71,7 +71,6 @@ require (
 	github.com/ryanrolds/sqlclosecheck v0.3.0
 	github.com/sanposhiho/wastedassign/v2 v2.0.6
 	github.com/securego/gosec/v2 v2.9.6
-	github.com/shazow/go-diff v0.0.0-20160112020656-b6b7b6733b8c
 	github.com/shirou/gopsutil/v3 v3.22.1
 	github.com/sirupsen/logrus v1.8.1
 	github.com/sivchari/containedctx v1.0.1

go.sum

@@ -90,7 +90,6 @@ func createPatchAndExtractIssues(lintCtx *linter.Context, linterName, filename s
 		B:       difflib.SplitLines(string(dst)),
 		Context: 3,
 	}
-
 	if err := difflib.WriteUnifiedDiff(&out, d); err != nil {
 		return nil, errors.Wrap(err, "can't create diff")
 	}

pkg/golinters/goanalysis/suggested_fixes.go

@@ -7,7 +7,7 @@ import (
 	"sync"
 
 	"github.com/pkg/errors"
-	"github.com/shazow/go-diff/difflib"
+	"github.com/pmezard/go-difflib/difflib"
 	"golang.org/x/tools/go/analysis"
 	"mvdan.cc/gofumpt/format"
 
@@ -29,7 +29,6 @@ func NewGofumpt() *goanalysis.Linter {
 
 	var mu sync.Mutex
 	var resIssues []goanalysis.Issue
-	differ := difflib.New()
 
 	analyzer := &analysis.Analyzer{
 		Name: gofumptName,
@@ -75,9 +74,13 @@ func NewGofumpt() *goanalysis.Linter {
 						return nil, fmt.Errorf("error while running gofumpt: %w", err)
 					}
 
-					err = differ.Diff(&out, bytes.NewReader(input), bytes.NewReader(output))
-					if err != nil {
-						return nil, fmt.Errorf("error while running gofumpt: %w", err)
+					d := difflib.UnifiedDiff{
+						A:       difflib.SplitLines(string(input)),
+						B:       difflib.SplitLines(string(output)),
+						Context: 3,
+					}
+					if err := difflib.WriteUnifiedDiff(&out, d); err != nil {
+						return nil, errors.Wrap(err, "can't create diff")
 					}
 
 					diff := out.String()