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// Copyright 2018 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 findcall defines an Analyzer that serves as a trivial
// example and test of the Analysis API. It reports a diagnostic for
// every call to a function or method of the name specified by its
// -name flag. It also exports a fact for each declaration that
// matches the name, plus a package-level fact if the package contained
// one or more such declarations.
package findcall
import (
const Doc = `find calls to a particular function
The findcall analysis reports calls to functions or methods
of a particular name.`
var Analyzer = &analysis.Analyzer{
Name: "findcall",
Doc: Doc,
URL: "",
Run: run,
RunDespiteErrors: true,
FactTypes: []analysis.Fact{new(foundFact)},
var name string // -name flag
func init() {
Analyzer.Flags.StringVar(&name, "name", name, "name of the function to find")
func run(pass *analysis.Pass) (interface{}, error) {
for _, f := range pass.Files {
ast.Inspect(f, func(n ast.Node) bool {
if call, ok := n.(*ast.CallExpr); ok {
var id *ast.Ident
switch fun := call.Fun.(type) {
case *ast.Ident:
id = fun
case *ast.SelectorExpr:
id = fun.Sel
if id != nil && !pass.TypesInfo.Types[id].IsType() && id.Name == name {
Pos: call.Lparen,
Message: fmt.Sprintf("call of %s(...)", id.Name),
SuggestedFixes: []analysis.SuggestedFix{{
Message: fmt.Sprintf("Add '_TEST_'"),
TextEdits: []analysis.TextEdit{{
Pos: call.Lparen,
End: call.Lparen,
NewText: []byte("_TEST_"),
return true
// Export a fact for each matching function.
// These facts are produced only to test the testing
// infrastructure in the analysistest package.
// They are not consumed by the findcall Analyzer
// itself, as would happen in a more realistic example.
for _, f := range pass.Files {
for _, decl := range f.Decls {
if decl, ok := decl.(*ast.FuncDecl); ok && decl.Name.Name == name {
if obj, ok := pass.TypesInfo.Defs[decl.Name].(*types.Func); ok {
pass.ExportObjectFact(obj, new(foundFact))
if len(pass.AllObjectFacts()) > 0 {
return nil, nil
// foundFact is a fact associated with functions that match -name.
// We use it to exercise the fact machinery in tests.
type foundFact struct{}
func (*foundFact) String() string { return "found" }
func (*foundFact) AFact() {}