.config/coc/extensions/coc-go-data/tools/pkg/mod/golang.org/x/tools@v0.0.0-20201028153306-37f0764111ff/internal/lsp/analysis/nonewvars/nonewvars.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 nonewvars defines an Analyzer that applies suggested fixes
   6 // to errors of the type "no new variables on left side of :=".
   7 package nonewvars
   8
   9 import (
  10         "bytes"
  11         "go/ast"
  12         "go/format"
  13         "go/token"
  14
  15         "golang.org/x/tools/go/analysis"
  16         "golang.org/x/tools/go/analysis/passes/inspect"
  17         "golang.org/x/tools/go/ast/inspector"
  18         "golang.org/x/tools/internal/analysisinternal"
  19 )
  20
  21 const Doc = `suggested fixes for "no new vars on left side of :="
  22
  23 This checker provides suggested fixes for type errors of the
  24 type "no new vars on left side of :=". For example:
  25         z := 1
  26         z := 2
  27 will turn into
  28         z := 1
  29         z = 2
  30 `
  31
  32 var Analyzer = &analysis.Analyzer{
  33         Name:             string(analysisinternal.NoNewVars),
  34         Doc:              Doc,
  35         Requires:         []*analysis.Analyzer{inspect.Analyzer},
  36         Run:              run,
  37         RunDespiteErrors: true,
  38 }
  39
  40 func run(pass *analysis.Pass) (interface{}, error) {
  41         inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
  42         errors := analysisinternal.GetTypeErrors(pass)
  43
  44         nodeFilter := []ast.Node{(*ast.AssignStmt)(nil)}
  45         inspect.Preorder(nodeFilter, func(n ast.Node) {
  46                 assignStmt, _ := n.(*ast.AssignStmt)
  47                 // We only care about ":=".
  48                 if assignStmt.Tok != token.DEFINE {
  49                         return
  50                 }
  51
  52                 var file *ast.File
  53                 for _, f := range pass.Files {
  54                         if f.Pos() <= assignStmt.Pos() && assignStmt.Pos() < f.End() {
  55                                 file = f
  56                                 break
  57                         }
  58                 }
  59                 if file == nil {
  60                         return
  61                 }
  62
  63                 for _, err := range errors {
  64                         if !FixesError(err.Msg) {
  65                                 continue
  66                         }
  67                         if assignStmt.Pos() > err.Pos || err.Pos >= assignStmt.End() {
  68                                 continue
  69                         }
  70                         var buf bytes.Buffer
  71                         if err := format.Node(&buf, pass.Fset, file); err != nil {
  72                                 continue
  73                         }
  74                         pass.Report(analysis.Diagnostic{
  75                                 Pos:     err.Pos,
  76                                 End:     analysisinternal.TypeErrorEndPos(pass.Fset, buf.Bytes(), err.Pos),
  77                                 Message: err.Msg,
  78                                 SuggestedFixes: []analysis.SuggestedFix{{
  79                                         Message: "Change ':=' to '='",
  80                                         TextEdits: []analysis.TextEdit{{
  81                                                 Pos: err.Pos,
  82                                                 End: err.Pos + 1,
  83                                         }},
  84                                 }},
  85                         })
  86                 }
  87         })
  88         return nil, nil
  89 }
  90
  91 func FixesError(msg string) bool {
  92         return msg == "no new variables on left side of :="
  93 }