optimize code and fix error offset in golangci-lint mode

Author: 4meepo

tagalign.go

@@ -211,25 +211,28 @@ func (w *Helper) Process(pass *analysis.Pass) { //nolint:gocognit
 			}
 			uniqueKeys = append(uniqueKeys, k)
 		}
-		mark := make(map[int]struct{})
 
-		for i, field := range fields {
+		for i := 0; i < len(fields); {
+			field := fields[i]
 			column := pass.Fset.Position(field.Tag.Pos()).Column - 1
+			offsets[i] = column
+
 			tag, err := strconv.Unquote(field.Tag.Value)
 			if err != nil {
-				mark[i] = struct{}{}
+				// if tag value is not a valid string, report it directly
 				w.report(pass, field, column, errTagValueSyntax, field.Tag.Value)
+				fields = append(fields[:i], fields[i+1:]...)
 				continue
 			}
 
 			tags, err := structtag.Parse(tag)
 			if err != nil {
-				mark[i] = struct{}{}
+				// if tag value is not a valid struct tag, report it directly
 				w.report(pass, field, column, err.Error(), field.Tag.Value)
+				fields = append(fields[:i], fields[i+1:]...)
 				continue
 			}
 
-			offsets = append(offsets, column)
 			maxTagNum = max(maxTagNum, tags.Len())
 
 			if w.sort {
@@ -244,18 +247,9 @@ func (w *Helper) Process(pass *analysis.Pass) { //nolint:gocognit
 				addKey(t.Key)
 			}
 			tagsGroup = append(tagsGroup, tags.Tags())
-		}
-
-		offset := 0
-		for i := range fields {
-			if _, exist := mark[i]; exist {
-				continue
-			}
 
-			fields[offset] = fields[i]
-			offset++
+			i++
 		}
-		fields = fields[:offset]
 
 		if w.sort && StrictStyle == w.style {
 			sortAllKeys(w.fixedTagOrder, uniqueKeys)

tagalign_test.go

@@ -74,10 +74,10 @@ func Test_alignSingleField(t *testing.T) {
 	analysistest.Run(t, unsort, a)
 }
 
-func Test_issues6(t *testing.T) {
+func Test_badSyntaxTag(t *testing.T) {
 	// only align
 	a := NewAnalyzer()
-	unsort, err := filepath.Abs("testdata/issues6")
+	unsort, err := filepath.Abs("testdata/bad_syntax_tag")
 	assert.NoError(t, err)
 	analysistest.Run(t, unsort, a)
 }

testdata/issues6/example.go renamed to testdata/bad_syntax_tag/example.go

@@ -6,3 +6,12 @@ type FooBar struct {
 	FooFoo int8   `json:"foo_foo" validate:"required"`
 	BarBar int    `json:"bar_bar" validate:"required"`
 }
+
+type FooBar2 struct {
+	Foo int `json:"foo" validate:"required"`
+
+	Bar string `json:bar` // want `bad syntax for struct tag value`
+
+	FooFoo int8 `json:"foo_foo"`
+	BarBar int  `json:"bar_bar" validate:"required"`
+}