| // 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 noresultvalues defines an Analyzer that applies suggested fixes |
| // to errors of the type "no result values expected". |
| package noresultvalues |
| |
| import ( |
| "bytes" |
| "go/ast" |
| "go/format" |
| "strings" |
| |
| "golang.org/x/tools/go/analysis" |
| "golang.org/x/tools/go/analysis/passes/inspect" |
| "golang.org/x/tools/go/ast/inspector" |
| "golang.org/x/tools/internal/analysisinternal" |
| ) |
| |
| const Doc = `suggested fixes for unexpected return values |
| |
| This checker provides suggested fixes for type errors of the |
| type "no result values expected" or "too many return values". |
| For example: |
| func z() { return nil } |
| will turn into |
| func z() { return } |
| ` |
| |
| var Analyzer = &analysis.Analyzer{ |
| Name: string(analysisinternal.NoResultValues), |
| Doc: Doc, |
| Requires: []*analysis.Analyzer{inspect.Analyzer}, |
| Run: run, |
| RunDespiteErrors: true, |
| } |
| |
| func run(pass *analysis.Pass) (interface{}, error) { |
| inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector) |
| errors := analysisinternal.GetTypeErrors(pass) |
| |
| nodeFilter := []ast.Node{(*ast.ReturnStmt)(nil)} |
| inspect.Preorder(nodeFilter, func(n ast.Node) { |
| retStmt, _ := n.(*ast.ReturnStmt) |
| |
| var file *ast.File |
| for _, f := range pass.Files { |
| if f.Pos() <= retStmt.Pos() && retStmt.Pos() < f.End() { |
| file = f |
| break |
| } |
| } |
| if file == nil { |
| return |
| } |
| |
| for _, err := range errors { |
| if !FixesError(err.Msg) { |
| continue |
| } |
| if retStmt.Pos() >= err.Pos || err.Pos >= retStmt.End() { |
| continue |
| } |
| var buf bytes.Buffer |
| if err := format.Node(&buf, pass.Fset, file); err != nil { |
| continue |
| } |
| pass.Report(analysis.Diagnostic{ |
| Pos: err.Pos, |
| End: analysisinternal.TypeErrorEndPos(pass.Fset, buf.Bytes(), err.Pos), |
| Message: err.Msg, |
| SuggestedFixes: []analysis.SuggestedFix{{ |
| Message: "Delete return values", |
| TextEdits: []analysis.TextEdit{{ |
| Pos: retStmt.Pos(), |
| End: retStmt.End(), |
| NewText: []byte("return"), |
| }}, |
| }}, |
| }) |
| } |
| }) |
| return nil, nil |
| } |
| |
| func FixesError(msg string) bool { |
| return msg == "no result values expected" || |
| strings.HasPrefix(msg, "too many return values") && strings.Contains(msg, "want ()") |
| } |