Merge pull request #5 from karamaru-alpha/feat/karamaru/ignore-alias

feat: ignore-alias option

cmd/copyloopvar/main.go

@@ -1,9 +1,9 @@
 package main
 
 import (
-	"golang.org/x/tools/go/analysis/unitchecker"
+	"golang.org/x/tools/go/analysis/singlechecker"
 
 	"github.com/karamaru-alpha/copyloopvar"
 )
 
-func main() { unitchecker.Main(copyloopvar.Analyzer) }
+func main() { singlechecker.Main(copyloopvar.Analyzer) }

copyloopvar.go

@@ -19,6 +19,14 @@ var Analyzer = &analysis.Analyzer{
 	},
 }
 
+var (
+	ignoreAlias bool
+)
+
+func init() {
+	Analyzer.Flags.BoolVar(&ignoreAlias, "ignore-alias", false, "ignore aliasing of loop variables")
+}
+
 func run(pass *analysis.Pass) (any, error) {
 	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
 
@@ -56,14 +64,23 @@ func checkRangeStmt(pass *analysis.Pass, rangeStmt *ast.RangeStmt) {
 		if assignStmt.Tok != token.DEFINE {
 			continue
 		}
-		for _, rh := range assignStmt.Rhs {
+		for i, rh := range assignStmt.Rhs {
 			right, ok := rh.(*ast.Ident)
 			if !ok {
 				continue
 			}
 			if right.Name != key.Name && (value != nil && right.Name != value.Name) {
 				continue
 			}
+			if ignoreAlias {
+				left, ok := assignStmt.Lhs[i].(*ast.Ident)
+				if !ok {
+					continue
+				}
+				if left.Name != right.Name {
+					continue
+				}
+			}
 			pass.Report(analysis.Diagnostic{
 				Pos:     assignStmt.Pos(),
 				Message: fmt.Sprintf(`The copy of the 'for' variable "%s" can be deleted (Go 1.22+)`, right.Name),
@@ -94,14 +111,23 @@ func checkForStmt(pass *analysis.Pass, forStmt *ast.ForStmt) {
 		if assignStmt.Tok != token.DEFINE {
 			continue
 		}
-		for _, rh := range assignStmt.Rhs {
+		for i, rh := range assignStmt.Rhs {
 			right, ok := rh.(*ast.Ident)
 			if !ok {
 				continue
 			}
 			if _, ok := initVarNameMap[right.Name]; !ok {
 				continue
 			}
+			if ignoreAlias {
+				left, ok := assignStmt.Lhs[i].(*ast.Ident)
+				if !ok {
+					continue
+				}
+				if left.Name != right.Name {
+					continue
+				}
+			}
 			pass.Report(analysis.Diagnostic{
 				Pos:     assignStmt.Pos(),
 				Message: fmt.Sprintf(`The copy of the 'for' variable "%s" can be deleted (Go 1.22+)`, right.Name),

copyloopvar_test.go

@@ -8,6 +8,17 @@ import (
 )
 
 func TestAnalyzer(t *testing.T) {
-	testdata := testutil.WithModules(t, analysistest.TestData(), nil)
-	analysistest.Run(t, testdata, Analyzer, "a")
+	t.Run("basic", func(t *testing.T) {
+		testdata := testutil.WithModules(t, analysistest.TestData(), nil)
+		analysistest.Run(t, testdata, Analyzer, "basic")
+	})
+
+	t.Run("ignore-alias", func(t *testing.T) {
+		err := Analyzer.Flags.Set("ignore-alias", "true")
+		if err != nil {
+			t.Error(err)
+		}
+		testdata := testutil.WithModules(t, analysistest.TestData(), nil)
+		analysistest.Run(t, testdata, Analyzer, "ignorealias")
+	})
 }

testdata/src/basic/go.mod

@@ -0,0 +1,3 @@
+module basic
+
+go 1.21

testdata/src/basic/main.go

@@ -0,0 +1,23 @@
+package main
+
+func main() {
+	for i, v := range []int{1, 2, 3} {
+		i := i       // want `The copy of the 'for' variable "i" can be deleted \(Go 1\.22\+\)`
+		_i := i      // want `The copy of the 'for' variable "i" can be deleted \(Go 1\.22\+\)`
+		v := v       // want `The copy of the 'for' variable "v" can be deleted \(Go 1\.22\+\)`
+		_v := v      // want `The copy of the 'for' variable "v" can be deleted \(Go 1\.22\+\)`
+		a, b := 1, i // want `The copy of the 'for' variable "i" can be deleted \(Go 1\.22\+\)`
+		c, d := 1, v // want `The copy of the 'for' variable "v" can be deleted \(Go 1\.22\+\)`
+		_, _, _, _, _, _, _, _ = i, _i, v, _v, a, b, c, d
+	}
+
+	for i, j := 1, 1; i+j <= 3; i++ {
+		i := i       // want `The copy of the 'for' variable "i" can be deleted \(Go 1\.22\+\)`
+		_i := i      // want `The copy of the 'for' variable "i" can be deleted \(Go 1\.22\+\)`
+		j := j       // want `The copy of the 'for' variable "j" can be deleted \(Go 1\.22\+\)`
+		_j := j      // want `The copy of the 'for' variable "j" can be deleted \(Go 1\.22\+\)`
+		a, b := 1, i // want `The copy of the 'for' variable "i" can be deleted \(Go 1\.22\+\)`
+		c, d := 1, j // want `The copy of the 'for' variable "j" can be deleted \(Go 1\.22\+\)`
+		_, _, _, _, _, _, _, _ = i, _i, j, _j, a, b, c, d
+	}
+}

testdata/src/ignorealias/go.mod

@@ -0,0 +1,3 @@
+module ignorealias
+
+go 1.21

testdata/src/ignorealias/main.go

@@ -0,0 +1,23 @@
+package main
+
+func main() {
+	for i, v := range []int{1, 2, 3} {
+		i := i // want `The copy of the 'for' variable "i" can be deleted \(Go 1\.22\+\)`
+		_i := i
+		v := v // want `The copy of the 'for' variable "v" can be deleted \(Go 1\.22\+\)`
+		_v := v
+		a, b := 1, i
+		c, d := 1, v
+		_, _, _, _, _, _, _, _ = i, _i, v, _v, a, b, c, d
+	}
+
+	for i, j := 1, 1; i+j <= 3; i++ {
+		i := i // want `The copy of the 'for' variable "i" can be deleted \(Go 1\.22\+\)`
+		_i := i
+		j := j // want `The copy of the 'for' variable "j" can be deleted \(Go 1\.22\+\)`
+		_j := j
+		a, b := 1, i
+		c, d := 1, j
+		_, _, _, _, _, _, _, _ = i, _i, j, _j, a, b, c, d
+	}
+}