timeformat.go

Documentation: golang.org/x/tools/go/analysis/passes/timeformat

     1  // Copyright 2022 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 timeformat defines an Analyzer that checks for the use
     6  // of time.Format or time.Parse calls with a bad format.
     7  package timeformat
     8  
     9  import (
    10  	_ "embed"
    11  	"go/ast"
    12  	"go/constant"
    13  	"go/token"
    14  	"go/types"
    15  	"strings"
    16  
    17  	"golang.org/x/tools/go/analysis"
    18  	"golang.org/x/tools/go/analysis/passes/inspect"
    19  	"golang.org/x/tools/go/analysis/passes/internal/analysisutil"
    20  	"golang.org/x/tools/go/ast/inspector"
    21  	"golang.org/x/tools/go/types/typeutil"
    22  )
    23  
    24  const badFormat = "2006-02-01"
    25  const goodFormat = "2006-01-02"
    26  
    27  //go:embed doc.go
    28  var doc string
    29  
    30  var Analyzer = &analysis.Analyzer{
    31  	Name:     "timeformat",
    32  	Doc:      analysisutil.MustExtractDoc(doc, "timeformat"),
    33  	URL:      "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/timeformat",
    34  	Requires: []*analysis.Analyzer{inspect.Analyzer},
    35  	Run:      run,
    36  }
    37  
    38  func run(pass *analysis.Pass) (interface{}, error) {
    39  	// Note: (time.Time).Format is a method and can be a typeutil.Callee
    40  	// without directly importing "time". So we cannot just skip this package
    41  	// when !analysisutil.Imports(pass.Pkg, "time").
    42  	// TODO(taking): Consider using a prepass to collect typeutil.Callees.
    43  
    44  	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
    45  
    46  	nodeFilter := []ast.Node{
    47  		(*ast.CallExpr)(nil),
    48  	}
    49  	inspect.Preorder(nodeFilter, func(n ast.Node) {
    50  		call := n.(*ast.CallExpr)
    51  		fn, ok := typeutil.Callee(pass.TypesInfo, call).(*types.Func)
    52  		if !ok {
    53  			return
    54  		}
    55  		if !isTimeDotFormat(fn) && !isTimeDotParse(fn) {
    56  			return
    57  		}
    58  		if len(call.Args) > 0 {
    59  			arg := call.Args[0]
    60  			badAt := badFormatAt(pass.TypesInfo, arg)
    61  
    62  			if badAt > -1 {
    63  				// Check if it's a literal string, otherwise we can't suggest a fix.
    64  				if _, ok := arg.(*ast.BasicLit); ok {
    65  					pos := int(arg.Pos()) + badAt + 1 // +1 to skip the " or `
    66  					end := pos + len(badFormat)
    67  
    68  					pass.Report(analysis.Diagnostic{
    69  						Pos:     token.Pos(pos),
    70  						End:     token.Pos(end),
    71  						Message: badFormat + " should be " + goodFormat,
    72  						SuggestedFixes: []analysis.SuggestedFix{{
    73  							Message: "Replace " + badFormat + " with " + goodFormat,
    74  							TextEdits: []analysis.TextEdit{{
    75  								Pos:     token.Pos(pos),
    76  								End:     token.Pos(end),
    77  								NewText: []byte(goodFormat),
    78  							}},
    79  						}},
    80  					})
    81  				} else {
    82  					pass.Reportf(arg.Pos(), badFormat+" should be "+goodFormat)
    83  				}
    84  			}
    85  		}
    86  	})
    87  	return nil, nil
    88  }
    89  
    90  func isTimeDotFormat(f *types.Func) bool {
    91  	if f.Name() != "Format" || f.Pkg() == nil || f.Pkg().Path() != "time" {
    92  		return false
    93  	}
    94  	// Verify that the receiver is time.Time.
    95  	recv := f.Type().(*types.Signature).Recv()
    96  	return recv != nil && analysisutil.IsNamedType(recv.Type(), "time", "Time")
    97  }
    98  
    99  func isTimeDotParse(f *types.Func) bool {
   100  	return analysisutil.IsFunctionNamed(f, "time", "Parse")
   101  }
   102  
   103  // badFormatAt return the start of a bad format in e or -1 if no bad format is found.
   104  func badFormatAt(info *types.Info, e ast.Expr) int {
   105  	tv, ok := info.Types[e]
   106  	if !ok { // no type info, assume good
   107  		return -1
   108  	}
   109  
   110  	t, ok := tv.Type.(*types.Basic) // sic, no unalias
   111  	if !ok || t.Info()&types.IsString == 0 {
   112  		return -1
   113  	}
   114  
   115  	if tv.Value == nil {
   116  		return -1
   117  	}
   118  
   119  	return strings.Index(constant.StringVal(tv.Value), badFormat)
   120  }
   121
View as plain text