+++ /dev/null
-// Copyright 2020 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// Package unusedparams defines an analyzer that checks for unused
-// parameters of functions.
-package unusedparams
-
-import (
- "fmt"
- "go/ast"
- "go/types"
- "strings"
-
- "golang.org/x/tools/go/analysis"
- "golang.org/x/tools/go/analysis/passes/inspect"
- "golang.org/x/tools/go/ast/inspector"
-)
-
-const Doc = `check for unused parameters of functions
-
-The unusedparams analyzer checks functions to see if there are
-any parameters that are not being used.
-
-To reduce false positives it ignores:
-- methods
-- parameters that do not have a name or are underscored
-- functions in test files
-- functions with empty bodies or those with just a return stmt`
-
-var Analyzer = &analysis.Analyzer{
- Name: "unusedparams",
- Doc: Doc,
- Requires: []*analysis.Analyzer{inspect.Analyzer},
- Run: run,
-}
-
-type paramData struct {
- field *ast.Field
- ident *ast.Ident
- typObj types.Object
-}
-
-func run(pass *analysis.Pass) (interface{}, error) {
- inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
- nodeFilter := []ast.Node{
- (*ast.FuncDecl)(nil),
- (*ast.FuncLit)(nil),
- }
-
- inspect.Preorder(nodeFilter, func(n ast.Node) {
- var fieldList *ast.FieldList
- var body *ast.BlockStmt
-
- // Get the fieldList and body from the function node.
- switch f := n.(type) {
- case *ast.FuncDecl:
- fieldList, body = f.Type.Params, f.Body
- // TODO(golang/go#36602): add better handling for methods, if we enable methods
- // we will get false positives if a struct is potentially implementing
- // an interface.
- if f.Recv != nil {
- return
- }
- // Ignore functions in _test.go files to reduce false positives.
- if file := pass.Fset.File(n.Pos()); file != nil && strings.HasSuffix(file.Name(), "_test.go") {
- return
- }
- case *ast.FuncLit:
- fieldList, body = f.Type.Params, f.Body
- }
- // If there are no arguments or the function is empty, then return.
- if fieldList.NumFields() == 0 || len(body.List) == 0 {
- return
- }
-
- switch expr := body.List[0].(type) {
- case *ast.ReturnStmt:
- // Ignore functions that only contain a return statement to reduce false positives.
- return
- case *ast.ExprStmt:
- callExpr, ok := expr.X.(*ast.CallExpr)
- if !ok || len(body.List) > 1 {
- break
- }
- // Ignore functions that only contain a panic statement to reduce false positives.
- if fun, ok := callExpr.Fun.(*ast.Ident); ok && fun.Name == "panic" {
- return
- }
- }
-
- // Get the useful data from each field.
- params := make(map[string]*paramData)
- unused := make(map[*paramData]bool)
- for _, f := range fieldList.List {
- for _, i := range f.Names {
- if i.Name == "_" {
- continue
- }
- params[i.Name] = ¶mData{
- field: f,
- ident: i,
- typObj: pass.TypesInfo.ObjectOf(i),
- }
- unused[params[i.Name]] = true
- }
- }
-
- // Traverse through the body of the function and
- // check to see which parameters are unused.
- ast.Inspect(body, func(node ast.Node) bool {
- n, ok := node.(*ast.Ident)
- if !ok {
- return true
- }
- param, ok := params[n.Name]
- if !ok {
- return false
- }
- if nObj := pass.TypesInfo.ObjectOf(n); nObj != param.typObj {
- return false
- }
- delete(unused, param)
- return false
- })
-
- // Create the reports for the unused parameters.
- for u := range unused {
- start, end := u.field.Pos(), u.field.End()
- if len(u.field.Names) > 1 {
- start, end = u.ident.Pos(), u.ident.End()
- }
- // TODO(golang/go#36602): Add suggested fixes to automatically
- // remove the unused parameter. To start, just remove it from the
- // function declaration. Later, remove it from every use of this
- // function.
- pass.Report(analysis.Diagnostic{
- Pos: start,
- End: end,
- Message: fmt.Sprintf("potentially unused parameter: '%s'", u.ident.Name),
- })
- }
- })
- return nil, nil
-}
projects / dotfiles / .git / blobdiff