github.com/v2fly/tools@v0.100.0/internal/lsp/analysis/noresultvalues/noresultvalues.go (about)

     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  	"github.com/v2fly/tools/go/analysis"
    15  	"github.com/v2fly/tools/go/analysis/passes/inspect"
    16  	"github.com/v2fly/tools/go/ast/inspector"
    17  	"github.com/v2fly/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  }