.config/coc/extensions/coc-go-data/tools/pkg/mod/golang.org/x/tools@v0.0.0-20201028153306-37f0764111ff/internal/lsp/analysis/noresultvalues/noresultvalues.go

   1 // Copyright 2020 The Go Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE file.
   4
   5 // Package noresultvalues defines an Analyzer that applies suggested fixes
   6 // to errors of the type "no result values expected".
   7 package noresultvalues
   8
   9 import (
  10         "bytes"
  11         "go/ast"
  12         "go/format"
  13
  14         "golang.org/x/tools/go/analysis"
  15         "golang.org/x/tools/go/analysis/passes/inspect"
  16         "golang.org/x/tools/go/ast/inspector"
  17         "golang.org/x/tools/internal/analysisinternal"
  18 )
  19
  20 const Doc = `suggested fixes for "no result values expected"
  21
  22 This checker provides suggested fixes for type errors of the
  23 type "no result values expected". For example:
  24         func z() { return nil }
  25 will turn into
  26         func z() { return }
  27 `
  28
  29 var Analyzer = &analysis.Analyzer{
  30         Name:             string(analysisinternal.NoResultValues),
  31         Doc:              Doc,
  32         Requires:         []*analysis.Analyzer{inspect.Analyzer},
  33         Run:              run,
  34         RunDespiteErrors: true,
  35 }
  36
  37 func run(pass *analysis.Pass) (interface{}, error) {
  38         inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
  39         errors := analysisinternal.GetTypeErrors(pass)
  40
  41         nodeFilter := []ast.Node{(*ast.ReturnStmt)(nil)}
  42         inspect.Preorder(nodeFilter, func(n ast.Node) {
  43                 retStmt, _ := n.(*ast.ReturnStmt)
  44
  45                 var file *ast.File
  46                 for _, f := range pass.Files {
  47                         if f.Pos() <= retStmt.Pos() && retStmt.Pos() < f.End() {
  48                                 file = f
  49                                 break
  50                         }
  51                 }
  52                 if file == nil {
  53                         return
  54                 }
  55
  56                 for _, err := range errors {
  57                         if !FixesError(err.Msg) {
  58                                 continue
  59                         }
  60                         if retStmt.Pos() >= err.Pos || err.Pos >= retStmt.End() {
  61                                 continue
  62                         }
  63                         var buf bytes.Buffer
  64                         if err := format.Node(&buf, pass.Fset, file); err != nil {
  65                                 continue
  66                         }
  67                         pass.Report(analysis.Diagnostic{
  68                                 Pos:     err.Pos,
  69                                 End:     analysisinternal.TypeErrorEndPos(pass.Fset, buf.Bytes(), err.Pos),
  70                                 Message: err.Msg,
  71                                 SuggestedFixes: []analysis.SuggestedFix{{
  72                                         Message: "Delete return values",
  73                                         TextEdits: []analysis.TextEdit{{
  74                                                 Pos:     retStmt.Pos(),
  75                                                 End:     retStmt.End(),
  76                                                 NewText: []byte("return"),
  77                                         }},
  78                                 }},
  79                         })
  80                 }
  81         })
  82         return nil, nil
  83 }
  84
  85 func FixesError(msg string) bool {
  86         return msg == "no result values expected"
  87 }