Add astutil.Root and migrate two linters to Cursor traversal

Co-authored-by: pelikhan <4175913+pelikhan@users.noreply.github.com>

Author: Copilot

pkg/linters/httpstatuscode/httpstatuscode.go

@@ -91,34 +91,29 @@ var httpStatusNames = map[int]string{
 }
 
 func run(pass *analysis.Pass) (any, error) {
-	insp, err := astutil.Inspector(pass)
+	root, err := astutil.Root(pass)
 	if err != nil {
 		return nil, err
 	}
 	noLintLinesByFile := nolint.BuildLineIndex(pass, "httpstatuscode")
 
-	nodeFilter := []ast.Node{
-		(*ast.BinaryExpr)(nil),
-		(*ast.SwitchStmt)(nil),
-	}
-
-	insp.Preorder(nodeFilter, func(n ast.Node) {
-		switch node := n.(type) {
+	for cur := range root.Preorder((*ast.BinaryExpr)(nil), (*ast.SwitchStmt)(nil)) {
+		switch node := cur.Node().(type) {
 		case *ast.BinaryExpr:
 			if node.Op != token.EQL && node.Op != token.NEQ {
-				return
+				continue
 			}
 			lit, other := extractStatusLiteral(node)
 			if lit == nil {
-				return
+				continue
 			}
 			if !isHTTPStatusContext(pass, other) {
-				return
+				continue
 			}
 			checkAndReport(pass, lit, noLintLinesByFile)
 		case *ast.SwitchStmt:
 			if node.Tag == nil || !isHTTPStatusContext(pass, node.Tag) {
-				return
+				continue
 			}
 			for _, s := range node.Body.List {
 				cc, ok := s.(*ast.CaseClause)
@@ -134,7 +129,7 @@ func run(pass *analysis.Pass) (any, error) {
 				}
 			}
 		}
-	})
+	}
 
 	return nil, nil
 }

pkg/linters/internal/astutil/astutil.go

@@ -103,6 +103,16 @@ func Inspector(pass *analysis.Pass) (*inspector.Inspector, error) {
 	return insp, nil
 }
 
+// Root extracts the inspector root cursor from pass.ResultOf.
+// It returns an error if the inspect result has an unexpected type.
+func Root(pass *analysis.Pass) (inspector.Cursor, error) {
+	insp, err := Inspector(pass)
+	if err != nil {
+		return inspector.Cursor{}, err
+	}
+	return insp.Root(), nil
+}
+
 // NodeText formats node as Go source text using go/printer.
 func NodeText(fset *token.FileSet, node ast.Node) string {
 	var buf bytes.Buffer

pkg/linters/sortslice/sortslice.go

@@ -25,47 +25,45 @@ var Analyzer = &analysis.Analyzer{
 }
 
 func run(pass *analysis.Pass) (any, error) {
-	insp, err := astutil.Inspector(pass)
+	root, err := astutil.Root(pass)
 	if err != nil {
 		return nil, err
 	}
 	noLintLinesByFile := nolint.BuildLineIndex(pass, "sortslice")
 
-	nodeFilter := []ast.Node{(*ast.CallExpr)(nil)}
-
-	insp.Preorder(nodeFilter, func(n ast.Node) {
-		call, ok := n.(*ast.CallExpr)
+	for cur := range root.Preorder((*ast.CallExpr)(nil)) {
+		call, ok := cur.Node().(*ast.CallExpr)
 		if !ok {
-			return
+			continue
 		}
 
 		pos := pass.Fset.PositionFor(call.Pos(), false)
 		if filecheck.IsTestFile(pos.Filename) {
-			return
+			continue
 		}
 		if nolint.HasDirective(pos, noLintLinesByFile) {
-			return
+			continue
 		}
 
 		sel, ok := call.Fun.(*ast.SelectorExpr)
 		if !ok {
-			return
+			continue
 		}
 		pkgIdent, ok := sel.X.(*ast.Ident)
 		if !ok {
-			return
+			continue
 		}
 		if pass.TypesInfo == nil {
-			return
+			continue
 		}
 		obj := pass.TypesInfo.ObjectOf(pkgIdent)
 		// ObjectOf can be nil when type information is incomplete.
 		if obj == nil {
-			return
+			continue
 		}
 		pkgName, ok := obj.(*types.PkgName)
 		if !ok || pkgName.Imported().Path() != "sort" {
-			return
+			continue
 		}
 
 		switch sel.Sel.Name {
@@ -75,7 +73,7 @@ func run(pass *analysis.Pass) (any, error) {
 		case "SliceStable":
 			pass.ReportRangef(call, "sort.SliceStable is not type-safe; use slices.SortStableFunc instead")
 		}
-	})
+	}
 
 	return nil, nil
 }