Add more linters to improve code readability (#19989)

Add nakedret, unconvert, wastedassign, stylecheck and nolintlint linters to improve code readability

- nakedret - https://github.com/alexkohler/nakedret - nakedret is a Go static analysis tool to find naked returns in functions greater than a specified function length.
- unconvert - https://github.com/mdempsky/unconvert - Remove unnecessary type conversions
- wastedassign - https://github.com/sanposhiho/wastedassign -  wastedassign finds wasted assignment statements.
- notlintlint -  Reports ill-formed or insufficient nolint directives
- stylecheck - https://staticcheck.io/docs/checks/#ST - keep style consistent
  - excluded: [ST1003 - Poorly chosen identifier](https://staticcheck.io/docs/checks/#ST1003) and [ST1005 - Incorrectly formatted error string](https://staticcheck.io/docs/checks/#ST1005)

modules/git/batch_reader.go

@@ -176,12 +176,12 @@ func ReadBatchLine(rd *bufio.Reader) (sha []byte, typ string, size int64, err er
 	typ = typ[:idx]
 
 	size, err = strconv.ParseInt(sizeStr, 10, 64)
-	return
+	return sha, typ, size, err
 }
 
 // ReadTagObjectID reads a tag object ID hash from a cat-file --batch stream, throwing away the rest of the stream.
 func ReadTagObjectID(rd *bufio.Reader, size int64) (string, error) {
-	id := ""
+	var id string
 	var n int64
 headerLoop:
 	for {
@@ -216,7 +216,7 @@ headerLoop:
 
 // ReadTreeID reads a tree ID from a cat-file --batch stream, throwing away the rest of the stream.
 func ReadTreeID(rd *bufio.Reader, size int64) (string, error) {
-	id := ""
+	var id string
 	var n int64
 headerLoop:
 	for {
@@ -328,7 +328,7 @@ func ParseTreeLine(rd *bufio.Reader, modeBuf, fnameBuf, shaBuf []byte) (mode, fn
 	// Deal with the 20-byte SHA
 	idx = 0
 	for idx < 20 {
-		read := 0
+		var read int
 		read, err = rd.Read(shaBuf[idx:20])
 		n += read
 		if err != nil {
@@ -337,7 +337,7 @@ func ParseTreeLine(rd *bufio.Reader, modeBuf, fnameBuf, shaBuf []byte) (mode, fn
 		idx += read
 	}
 	sha = shaBuf
-	return
+	return mode, fname, sha, n, err
 }
 
 var callerPrefix string

modules/git/blob_nogogit.go

@@ -99,7 +99,7 @@ func (b *blobReader) Read(p []byte) (n int, err error) {
 	}
 	n, err = b.rd.Read(p)
 	b.n -= int64(n)
-	return
+	return n, err
 }
 
 // Close implements io.Closer

modules/git/commit.go

@@ -418,7 +418,7 @@ func (c *Commit) LoadBranchName() (err error) {
 	}
 
 	c.Branch, err = c.GetBranchName()
-	return
+	return err
 }
 
 // GetTagName gets the current tag name for given commit

modules/git/commit_info_nogogit.go

@@ -157,7 +157,7 @@ func GetLastCommitForPaths(ctx context.Context, cache *LastCommitCache, commit *
 		if typ != "commit" {
 			return nil, fmt.Errorf("unexpected type: %s for commit id: %s", typ, commitID)
 		}
-		c, err = CommitFromReader(commit.repo, MustIDFromString(string(commitID)), io.LimitReader(batchReader, int64(size)))
+		c, err = CommitFromReader(commit.repo, MustIDFromString(commitID), io.LimitReader(batchReader, size))
 		if err != nil {
 			return nil, err
 		}

modules/git/diff.go

@@ -115,7 +115,7 @@ func ParseDiffHunkString(diffhunk string) (leftLine, leftHunk, rightLine, righHu
 		rightLine = leftLine
 		righHunk = leftHunk
 	}
-	return
+	return leftLine, leftHunk, rightLine, righHunk
 }
 
 // Example: @@ -1,8 +1,9 @@ => [..., 1, 8, 1, 9]

modules/git/pipeline/lfs_nogogit.go

@@ -116,7 +116,7 @@ func FindLFSFile(repo *git.Repository, hash git.SHA1) ([]*LFSResult, error) {
 				continue
 			case "commit":
 				// Read in the commit to get its tree and in case this is one of the last used commits
-				curCommit, err = git.CommitFromReader(repo, git.MustIDFromString(string(commitID)), io.LimitReader(batchReader, int64(size)))
+				curCommit, err = git.CommitFromReader(repo, git.MustIDFromString(string(commitID)), io.LimitReader(batchReader, size))
 				if err != nil {
 					return nil, err
 				}

modules/git/repo_attribute.go

@@ -334,7 +334,7 @@ func (wr *lineSeparatedAttributeWriter) Write(p []byte) (n int, err error) {
 						wr.tmp = []byte(remaining[3:])
 						break
 					}
-					return l, fmt.Errorf("unexpected tail %s", string(remaining))
+					return l, fmt.Errorf("unexpected tail %s", remaining)
 				}
 				_, _ = sb.WriteRune(rn)
 				remaining = tail

modules/git/repo_base_nogogit.go

@@ -101,5 +101,5 @@ func (repo *Repository) Close() (err error) {
 		repo.checkReader = nil
 		repo.checkWriter = nil
 	}
-	return
+	return err
 }

modules/git/repo_branch_nogogit.go

@@ -95,7 +95,7 @@ func callShowRef(ctx context.Context, repoPath, prefix, arg string, skip, limit
 
 		return nil
 	})
-	return
+	return branchNames, countAll, err
 }
 
 func walkShowRef(ctx context.Context, repoPath, arg string, skip, limit int, walkfn func(sha1, refname string) error) (countAll int, err error) {

modules/git/repo_compare.go

@@ -132,7 +132,7 @@ type lineCountWriter struct {
 func (l *lineCountWriter) Write(p []byte) (n int, err error) {
 	n = len(p)
 	l.numLines += bytes.Count(p, []byte{'\000'})
-	return
+	return n, err
 }
 
 // GetDiffNumChangedFiles counts the number of changed files
@@ -177,7 +177,7 @@ func (repo *Repository) GetDiffShortStat(base, head string) (numFiles, totalAddi
 	if err != nil && strings.Contains(err.Error(), "no merge base") {
 		return GetDiffShortStat(repo.Ctx, repo.Path, base, head)
 	}
-	return
+	return numFiles, totalAdditions, totalDeletions, err
 }
 
 // GetDiffShortStat counts number of changed files, number of additions and deletions
@@ -231,7 +231,7 @@ func parseDiffStat(stdout string) (numFiles, totalAdditions, totalDeletions int,
 			return 0, 0, 0, fmt.Errorf("unable to parse shortstat: %s. Error parsing NumDeletions %v", stdout, err)
 		}
 	}
-	return
+	return numFiles, totalAdditions, totalDeletions, err
 }
 
 // GetDiffOrPatch generates either diff or formatted patch data between given revisions

modules/git/repo_compare_test.go

@@ -117,8 +117,8 @@ func TestReadWritePullHead(t *testing.T) {
 		return
 	}
 
-	assert.Len(t, string(headContents), 40)
-	assert.True(t, string(headContents) == newCommit)
+	assert.Len(t, headContents, 40)
+	assert.True(t, headContents == newCommit)
 
 	// Remove file after the test
 	err = repo.RemoveReference(PullPrefix + "1/head")

modules/git/repo_index.go

@@ -64,7 +64,7 @@ func (repo *Repository) ReadTreeToTemporaryIndex(treeish string) (filename, tmpD
 		defer cancel()
 		return "", "", func() {}, err
 	}
-	return
+	return filename, tmpDir, cancel, err
 }
 
 // EmptyIndex empties the index

modules/git/repo_tag_nogogit.go

@@ -27,7 +27,7 @@ func (repo *Repository) IsTagExist(name string) bool {
 // returning at most limit tags, or all if limit is 0.
 func (repo *Repository) GetTags(skip, limit int) (tags []string, err error) {
 	tags, _, err = callShowRef(repo.Ctx, repo.Path, TagPrefix, "--tags", skip, limit)
-	return
+	return tags, err
 }
 
 // GetTagType gets the type of the tag, either commit (simple) or tag (annotated)

modules/git/sha1_nogogit.go

@@ -58,5 +58,5 @@ func NewHasher(t ObjectType, size int64) Hasher {
 // Sum generates a SHA1 for the provided hash
 func (h Hasher) Sum() (sha1 SHA1) {
 	copy(sha1[:], h.Hash.Sum(nil))
-	return
+	return sha1
 }

modules/git/signature_nogogit.go

@@ -91,5 +91,5 @@ func newSignatureFromCommitline(line []byte) (sig *Signature, err error) {
 			return
 		}
 	}
-	return
+	return sig, err
 }

modules/git/utils.go

@@ -163,7 +163,7 @@ func (l *LimitedReaderCloser) Read(p []byte) (n int, err error) {
 	}
 	n, err = l.R.Read(p)
 	l.N -= int64(n)
-	return
+	return n, err
 }
 
 // Close implements io.Closer