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  	"go/ast"
    11  	"go/constant"
    12  	"go/token"
    13  	"go/types"
    14  	"strings"
    15  
    16  	"golang.org/x/tools/go/analysis"
    17  	"golang.org/x/tools/go/analysis/passes/inspect"
    18  	"golang.org/x/tools/go/ast/inspector"
    19  	"golang.org/x/tools/go/types/typeutil"
    20  )
    21  
    22  const badFormat = "2006-02-01"
    23  const goodFormat = "2006-01-02"
    24  
    25  const Doc = `check for calls of (time.Time).Format or time.Parse with 2006-02-01
    26  
    27  The timeformat checker looks for time formats with the 2006-02-01 (yyyy-dd-mm)
    28  format. Internationally, "yyyy-dd-mm" does not occur in common calendar date
    29  standards, and so it is more likely that 2006-01-02 (yyyy-mm-dd) was intended.
    30  `
    31  
    32  var Analyzer = &analysis.Analyzer{
    33  	Name:     "timeformat",
    34  	Doc:      Doc,
    35  	Requires: []*analysis.Analyzer{inspect.Analyzer},
    36  	Run:      run,
    37  }
    38  
    39  func run(pass *analysis.Pass) (interface{}, error) {
    40  	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
    41  
    42  	nodeFilter := []ast.Node{
    43  		(*ast.CallExpr)(nil),
    44  	}
    45  	inspect.Preorder(nodeFilter, func(n ast.Node) {
    46  		call := n.(*ast.CallExpr)
    47  		fn, ok := typeutil.Callee(pass.TypesInfo, call).(*types.Func)
    48  		if !ok {
    49  			return
    50  		}
    51  		if !isTimeDotFormat(fn) && !isTimeDotParse(fn) {
    52  			return
    53  		}
    54  		if len(call.Args) > 0 {
    55  			arg := call.Args[0]
    56  			badAt := badFormatAt(pass.TypesInfo, arg)
    57  
    58  			if badAt > -1 {
    59  				// Check if it's a literal string, otherwise we can't suggest a fix.
    60  				if _, ok := arg.(*ast.BasicLit); ok {
    61  					pos := int(arg.Pos()) + badAt + 1 // +1 to skip the " or `
    62  					end := pos + len(badFormat)
    63  
    64  					pass.Report(analysis.Diagnostic{
    65  						Pos:     token.Pos(pos),
    66  						End:     token.Pos(end),
    67  						Message: badFormat + " should be " + goodFormat,
    68  						SuggestedFixes: []analysis.SuggestedFix{{
    69  							Message: "Replace " + badFormat + " with " + goodFormat,
    70  							TextEdits: []analysis.TextEdit{{
    71  								Pos:     token.Pos(pos),
    72  								End:     token.Pos(end),
    73  								NewText: []byte(goodFormat),
    74  							}},
    75  						}},
    76  					})
    77  				} else {
    78  					pass.Reportf(arg.Pos(), badFormat+" should be "+goodFormat)
    79  				}
    80  			}
    81  		}
    82  	})
    83  	return nil, nil
    84  }
    85  
    86  func isTimeDotFormat(f *types.Func) bool {
    87  	if f.Name() != "Format" || f.Pkg().Path() != "time" {
    88  		return false
    89  	}
    90  	sig, ok := f.Type().(*types.Signature)
    91  	if !ok {
    92  		return false
    93  	}
    94  	// Verify that the receiver is time.Time.
    95  	recv := sig.Recv()
    96  	if recv == nil {
    97  		return false
    98  	}
    99  	named, ok := recv.Type().(*types.Named)
   100  	return ok && named.Obj().Name() == "Time"
   101  }
   102  
   103  func isTimeDotParse(f *types.Func) bool {
   104  	if f.Name() != "Parse" || f.Pkg().Path() != "time" {
   105  		return false
   106  	}
   107  	// Verify that there is no receiver.
   108  	sig, ok := f.Type().(*types.Signature)
   109  	return ok && sig.Recv() == nil
   110  }
   111  
   112  // badFormatAt return the start of a bad format in e or -1 if no bad format is found.
   113  func badFormatAt(info *types.Info, e ast.Expr) int {
   114  	tv, ok := info.Types[e]
   115  	if !ok { // no type info, assume good
   116  		return -1
   117  	}
   118  
   119  	t, ok := tv.Type.(*types.Basic)
   120  	if !ok || t.Info()&types.IsString == 0 {
   121  		return -1
   122  	}
   123  
   124  	if tv.Value == nil {
   125  		return -1
   126  	}
   127  
   128  	return strings.Index(constant.StringVal(tv.Value), badFormat)
   129  }
   130
View as plain text