go/analysis/passes/unusedresult: split out of vet
Change-Id: I4bdba827ab0a518d62dda85cfc66875a54aeda24 Reviewed-on: https://go-review.googlesource.com/c/140760 Reviewed-by: Michael Matloob <matloob@golang.org> Run-TryBot: Michael Matloob <matloob@golang.org>
This commit is contained in:
Alan Donovan
parent
dd8190d4c7
commit
088df9ca28
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@ -0,0 +1,27 @@
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// Copyright 2015 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package a
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import (
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"bytes"
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"errors"
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"fmt"
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)
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func _() {
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fmt.Errorf("") // want "result of fmt.Errorf call not used"
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_ = fmt.Errorf("")
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errors.New("") // want "result of errors.New call not used"
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err := errors.New("")
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err.Error() // want `result of \(error\).Error call not used`
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var buf bytes.Buffer
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buf.String() // want `result of \(bytes.Buffer\).String call not used`
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fmt.Sprint("") // want "result of fmt.Sprint call not used"
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fmt.Sprintf("") // want "result of fmt.Sprintf call not used"
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}
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@ -0,0 +1,129 @@
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// Copyright 2015 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Package unusedresult defines an analyer that checks for unused
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// results of calls to certain pure functions.
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package unusedresult
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import (
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"go/ast"
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"go/token"
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"go/types"
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"sort"
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"strings"
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"golang.org/x/tools/go/analysis"
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"golang.org/x/tools/go/analysis/passes/inspect"
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"golang.org/x/tools/go/analysis/passes/internal/analysisutil"
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"golang.org/x/tools/go/ast/inspector"
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)
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// TODO(adonovan): make this analysis modular: export a mustUseResult
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// fact for each function that tail-calls one of the functions that we
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// check, and check those functions too.
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var Analyzer = &analysis.Analyzer{
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Name: "unusedresult",
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Doc: `check for unused results of calls to some functions
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Some functions like fmt.Errorf return a result and have no side effects,
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so it is always a mistake to discard the result. This analyzer reports
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calls to certain functions in which the result of the call is ignored.
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The set of functions may be controlled using flags.`,
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Requires: []*analysis.Analyzer{inspect.Analyzer},
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Run: run,
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}
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// flags
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var funcs, stringMethods stringSetFlag
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func init() {
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// TODO(adonovan): provide a comment syntax to allow users to
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// add their functions to this set using facts.
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funcs.Set("errors.New,fmt.Errorf,fmt.Sprintf,fmt.Sprint,sort.Reverse")
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Analyzer.Flags.Var(&funcs, "funcs",
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"comma-separated list of functions whose results must be used")
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stringMethods.Set("Error,String")
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Analyzer.Flags.Var(&stringMethods, "stringmethods",
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"comma-separated list of names of methods of type func() string whose results must be used")
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}
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func run(pass *analysis.Pass) (interface{}, error) {
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inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
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nodeFilter := []ast.Node{
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(*ast.ExprStmt)(nil),
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}
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inspect.Preorder(nodeFilter, func(n ast.Node) {
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call, ok := analysisutil.Unparen(n.(*ast.ExprStmt).X).(*ast.CallExpr)
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if !ok {
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return // not a call statement
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}
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fun := analysisutil.Unparen(call.Fun)
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if pass.TypesInfo.Types[fun].IsType() {
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return // a conversion, not a call
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}
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selector, ok := fun.(*ast.SelectorExpr)
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if !ok {
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return // neither a method call nor a qualified ident
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}
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sel, ok := pass.TypesInfo.Selections[selector]
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if ok && sel.Kind() == types.MethodVal {
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// method (e.g. foo.String())
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obj := sel.Obj().(*types.Func)
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sig := sel.Type().(*types.Signature)
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if types.Identical(sig, sigNoArgsStringResult) {
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if stringMethods[obj.Name()] {
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pass.Reportf(call.Lparen, "result of (%s).%s call not used",
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sig.Recv().Type(), obj.Name())
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}
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}
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} else if !ok {
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// package-qualified function (e.g. fmt.Errorf)
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obj := pass.TypesInfo.Uses[selector.Sel]
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if obj, ok := obj.(*types.Func); ok {
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qname := obj.Pkg().Path() + "." + obj.Name()
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if funcs[qname] {
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pass.Reportf(call.Lparen, "result of %v call not used", qname)
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}
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}
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}
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})
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return nil, nil
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}
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// func() string
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var sigNoArgsStringResult = types.NewSignature(nil, nil,
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types.NewTuple(types.NewVar(token.NoPos, nil, "", types.Typ[types.String])),
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false)
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type stringSetFlag map[string]bool
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func (ss *stringSetFlag) String() string {
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var items []string
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for item := range *ss {
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items = append(items, item)
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}
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sort.Strings(items)
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return strings.Join(items, ",")
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}
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func (ss *stringSetFlag) Set(s string) error {
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m := make(map[string]bool) // clobber previous value
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if s != "" {
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for _, name := range strings.Split(s, ",") {
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if name == "" {
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continue // TODO: report error? proceed?
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}
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m[name] = true
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}
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}
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*ss = m
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return nil
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}
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@ -0,0 +1,13 @@
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package unusedresult_test
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import (
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"testing"
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"golang.org/x/tools/go/analysis/analysistest"
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"golang.org/x/tools/go/analysis/passes/unusedresult"
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)
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func Test(t *testing.T) {
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testdata := analysistest.TestData()
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analysistest.Run(t, testdata, unusedresult.Analyzer, "a")
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}
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@ -1,29 +0,0 @@
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// Copyright 2015 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// This file contains tests for the unusedresult checker.
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package testdata
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import (
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"bytes"
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"errors"
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"fmt"
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)
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func _() {
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fmt.Errorf("") // ERROR "result of fmt.Errorf call not used"
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_ = fmt.Errorf("")
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errors.New("") // ERROR "result of errors.New call not used"
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err := errors.New("")
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err.Error() // ERROR "result of \(error\).Error call not used"
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var buf bytes.Buffer
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buf.String() // ERROR "result of \(bytes.Buffer\).String call not used"
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fmt.Sprint("") // ERROR "result of fmt.Sprint call not used"
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fmt.Sprintf("") // ERROR "result of fmt.Sprintf call not used"
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}
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@ -1,95 +0,0 @@
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// +build ignore
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// Copyright 2015 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// This file defines the check for unused results of calls to certain
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// pure functions.
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package main
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import (
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"flag"
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"go/ast"
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"go/token"
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"go/types"
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"strings"
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)
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var unusedFuncsFlag = flag.String("unusedfuncs",
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"errors.New,fmt.Errorf,fmt.Sprintf,fmt.Sprint,sort.Reverse",
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"comma-separated list of functions whose results must be used")
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var unusedStringMethodsFlag = flag.String("unusedstringmethods",
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"Error,String",
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"comma-separated list of names of methods of type func() string whose results must be used")
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func init() {
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register("unusedresult",
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"check for unused result of calls to functions in -unusedfuncs list and methods in -unusedstringmethods list",
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checkUnusedResult,
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exprStmt)
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}
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// func() string
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var sigNoArgsStringResult = types.NewSignature(nil, nil,
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types.NewTuple(types.NewVar(token.NoPos, nil, "", types.Typ[types.String])),
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false)
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var unusedFuncs = make(map[string]bool)
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var unusedStringMethods = make(map[string]bool)
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func initUnusedFlags() {
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commaSplit := func(s string, m map[string]bool) {
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if s != "" {
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for _, name := range strings.Split(s, ",") {
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if len(name) == 0 {
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flag.Usage()
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}
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m[name] = true
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}
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}
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}
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commaSplit(*unusedFuncsFlag, unusedFuncs)
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commaSplit(*unusedStringMethodsFlag, unusedStringMethods)
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}
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func checkUnusedResult(f *File, n ast.Node) {
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call, ok := unparen(n.(*ast.ExprStmt).X).(*ast.CallExpr)
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if !ok {
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return // not a call statement
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}
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fun := unparen(call.Fun)
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if f.pkg.types[fun].IsType() {
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return // a conversion, not a call
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}
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selector, ok := fun.(*ast.SelectorExpr)
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if !ok {
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return // neither a method call nor a qualified ident
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}
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sel, ok := f.pkg.selectors[selector]
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if ok && sel.Kind() == types.MethodVal {
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// method (e.g. foo.String())
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obj := sel.Obj().(*types.Func)
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sig := sel.Type().(*types.Signature)
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if types.Identical(sig, sigNoArgsStringResult) {
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if unusedStringMethods[obj.Name()] {
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f.Badf(call.Lparen, "result of (%s).%s call not used",
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sig.Recv().Type(), obj.Name())
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}
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}
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} else if !ok {
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// package-qualified function (e.g. fmt.Errorf)
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obj := f.pkg.uses[selector.Sel]
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if obj, ok := obj.(*types.Func); ok {
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qname := obj.Pkg().Path() + "." + obj.Name()
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if unusedFuncs[qname] {
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f.Badf(call.Lparen, "result of %v call not used", qname)
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}
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}
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}
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}
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