Source file src/cmd/vendor/golang.org/x/mod/modfile/rule.go

     1  // Copyright 2018 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 modfile implements a parser and formatter for go.mod files.
     6  //
     7  // The go.mod syntax is described in
     8  // https://pkg.go.dev/cmd/go/#hdr-The_go_mod_file.
     9  //
    10  // The [Parse] and [ParseLax] functions both parse a go.mod file and return an
    11  // abstract syntax tree. ParseLax ignores unknown statements and may be used to
    12  // parse go.mod files that may have been developed with newer versions of Go.
    13  //
    14  // The [File] struct returned by Parse and ParseLax represent an abstract
    15  // go.mod file. File has several methods like [File.AddNewRequire] and
    16  // [File.DropReplace] that can be used to programmatically edit a file.
    17  //
    18  // The [Format] function formats a File back to a byte slice which can be
    19  // written to a file.
    20  package modfile
    21  
    22  import (
    23  	"cmp"
    24  	"errors"
    25  	"fmt"
    26  	"path/filepath"
    27  	"slices"
    28  	"strconv"
    29  	"strings"
    30  	"unicode"
    31  
    32  	"golang.org/x/mod/internal/lazyregexp"
    33  	"golang.org/x/mod/module"
    34  	"golang.org/x/mod/semver"
    35  )
    36  
    37  // A File is the parsed, interpreted form of a go.mod file.
    38  type File struct {
    39  	Module    *Module
    40  	Go        *Go
    41  	Toolchain *Toolchain
    42  	Godebug   []*Godebug
    43  	Require   []*Require
    44  	Exclude   []*Exclude
    45  	Replace   []*Replace
    46  	Retract   []*Retract
    47  	Tool      []*Tool
    48  	Ignore    []*Ignore
    49  
    50  	Syntax *FileSyntax
    51  }
    52  
    53  // A Module is the module statement.
    54  type Module struct {
    55  	Mod        module.Version
    56  	Deprecated string
    57  	Syntax     *Line
    58  }
    59  
    60  // A Go is the go statement.
    61  type Go struct {
    62  	Version string // "1.23"
    63  	Syntax  *Line
    64  }
    65  
    66  // A Toolchain is the toolchain statement.
    67  type Toolchain struct {
    68  	Name   string // "go1.21rc1"
    69  	Syntax *Line
    70  }
    71  
    72  // A Godebug is a single godebug key=value statement.
    73  type Godebug struct {
    74  	Key    string
    75  	Value  string
    76  	Syntax *Line
    77  }
    78  
    79  // An Exclude is a single exclude statement.
    80  type Exclude struct {
    81  	Mod    module.Version
    82  	Syntax *Line
    83  }
    84  
    85  // A Replace is a single replace statement.
    86  type Replace struct {
    87  	Old    module.Version
    88  	New    module.Version
    89  	Syntax *Line
    90  }
    91  
    92  // A Retract is a single retract statement.
    93  type Retract struct {
    94  	VersionInterval
    95  	Rationale string
    96  	Syntax    *Line
    97  }
    98  
    99  // A Tool is a single tool statement.
   100  type Tool struct {
   101  	Path   string
   102  	Syntax *Line
   103  }
   104  
   105  // An Ignore is a single ignore statement.
   106  type Ignore struct {
   107  	Path   string
   108  	Syntax *Line
   109  }
   110  
   111  // A VersionInterval represents a range of versions with upper and lower bounds.
   112  // Intervals are closed: both bounds are included. When Low is equal to High,
   113  // the interval may refer to a single version ('v1.2.3') or an interval
   114  // ('[v1.2.3, v1.2.3]'); both have the same representation.
   115  type VersionInterval struct {
   116  	Low, High string
   117  }
   118  
   119  // A Require is a single require statement.
   120  type Require struct {
   121  	Mod      module.Version
   122  	Indirect bool // has "// indirect" comment
   123  	Syntax   *Line
   124  }
   125  
   126  func (r *Require) markRemoved() {
   127  	r.Syntax.markRemoved()
   128  	*r = Require{}
   129  }
   130  
   131  func (r *Require) setVersion(v string) {
   132  	r.Mod.Version = v
   133  
   134  	if line := r.Syntax; len(line.Token) > 0 {
   135  		if line.InBlock {
   136  			// If the line is preceded by an empty line, remove it; see
   137  			// https://golang.org/issue/33779.
   138  			if len(line.Comments.Before) == 1 && len(line.Comments.Before[0].Token) == 0 {
   139  				line.Comments.Before = line.Comments.Before[:0]
   140  			}
   141  			if len(line.Token) >= 2 { // example.com v1.2.3
   142  				line.Token[1] = v
   143  			}
   144  		} else {
   145  			if len(line.Token) >= 3 { // require example.com v1.2.3
   146  				line.Token[2] = v
   147  			}
   148  		}
   149  	}
   150  }
   151  
   152  // setIndirect sets line to have (or not have) a "// indirect" comment.
   153  func (r *Require) setIndirect(indirect bool) {
   154  	r.Indirect = indirect
   155  	line := r.Syntax
   156  	if isIndirect(line) == indirect {
   157  		return
   158  	}
   159  	if indirect {
   160  		// Adding comment.
   161  		if len(line.Suffix) == 0 {
   162  			// New comment.
   163  			line.Suffix = []Comment{{Token: "// indirect", Suffix: true}}
   164  			return
   165  		}
   166  
   167  		com := &line.Suffix[0]
   168  		text := strings.TrimSpace(strings.TrimPrefix(com.Token, string(slashSlash)))
   169  		if text == "" {
   170  			// Empty comment.
   171  			com.Token = "// indirect"
   172  			return
   173  		}
   174  
   175  		// Insert at beginning of existing comment.
   176  		com.Token = "// indirect; " + text
   177  		return
   178  	}
   179  
   180  	// Removing comment.
   181  	f := strings.TrimSpace(strings.TrimPrefix(line.Suffix[0].Token, string(slashSlash)))
   182  	if f == "indirect" {
   183  		// Remove whole comment.
   184  		line.Suffix = nil
   185  		return
   186  	}
   187  
   188  	// Remove comment prefix.
   189  	com := &line.Suffix[0]
   190  	i := strings.Index(com.Token, "indirect;")
   191  	com.Token = "//" + com.Token[i+len("indirect;"):]
   192  }
   193  
   194  // isIndirect reports whether line has a "// indirect" comment,
   195  // meaning it is in go.mod only for its effect on indirect dependencies,
   196  // so that it can be dropped entirely once the effective version of the
   197  // indirect dependency reaches the given minimum version.
   198  func isIndirect(line *Line) bool {
   199  	if len(line.Suffix) == 0 {
   200  		return false
   201  	}
   202  	f := strings.Fields(strings.TrimPrefix(line.Suffix[0].Token, string(slashSlash)))
   203  	return (len(f) == 1 && f[0] == "indirect" || len(f) > 1 && f[0] == "indirect;")
   204  }
   205  
   206  func (f *File) AddModuleStmt(path string) error {
   207  	if f.Syntax == nil {
   208  		f.Syntax = new(FileSyntax)
   209  	}
   210  	if f.Module == nil {
   211  		f.Module = &Module{
   212  			Mod:    module.Version{Path: path},
   213  			Syntax: f.Syntax.addLine(nil, "module", AutoQuote(path)),
   214  		}
   215  	} else {
   216  		f.Module.Mod.Path = path
   217  		f.Syntax.updateLine(f.Module.Syntax, "module", AutoQuote(path))
   218  	}
   219  	return nil
   220  }
   221  
   222  func (f *File) AddComment(text string) {
   223  	if f.Syntax == nil {
   224  		f.Syntax = new(FileSyntax)
   225  	}
   226  	f.Syntax.Stmt = append(f.Syntax.Stmt, &CommentBlock{
   227  		Comments: Comments{
   228  			Before: []Comment{
   229  				{
   230  					Token: text,
   231  				},
   232  			},
   233  		},
   234  	})
   235  }
   236  
   237  type VersionFixer func(path, version string) (string, error)
   238  
   239  // errDontFix is returned by a VersionFixer to indicate the version should be
   240  // left alone, even if it's not canonical.
   241  var dontFixRetract VersionFixer = func(_, vers string) (string, error) {
   242  	return vers, nil
   243  }
   244  
   245  // Parse parses and returns a go.mod file.
   246  //
   247  // file is the name of the file, used in positions and errors.
   248  //
   249  // data is the content of the file.
   250  //
   251  // fix is an optional function that canonicalizes module versions.
   252  // If fix is nil, all module versions must be canonical ([module.CanonicalVersion]
   253  // must return the same string).
   254  func Parse(file string, data []byte, fix VersionFixer) (*File, error) {
   255  	return parseToFile(file, data, fix, true)
   256  }
   257  
   258  // ParseLax is like Parse but ignores unknown statements.
   259  // It is used when parsing go.mod files other than the main module,
   260  // under the theory that most statement types we add in the future will
   261  // only apply in the main module, like exclude and replace,
   262  // and so we get better gradual deployments if old go commands
   263  // simply ignore those statements when found in go.mod files
   264  // in dependencies.
   265  func ParseLax(file string, data []byte, fix VersionFixer) (*File, error) {
   266  	return parseToFile(file, data, fix, false)
   267  }
   268  
   269  func parseToFile(file string, data []byte, fix VersionFixer, strict bool) (parsed *File, err error) {
   270  	fs, err := parse(file, data)
   271  	if err != nil {
   272  		return nil, err
   273  	}
   274  	f := &File{
   275  		Syntax: fs,
   276  	}
   277  	var errs ErrorList
   278  
   279  	// fix versions in retract directives after the file is parsed.
   280  	// We need the module path to fix versions, and it might be at the end.
   281  	defer func() {
   282  		oldLen := len(errs)
   283  		f.fixRetract(fix, &errs)
   284  		if len(errs) > oldLen {
   285  			parsed, err = nil, errs
   286  		}
   287  	}()
   288  
   289  	for _, x := range fs.Stmt {
   290  		switch x := x.(type) {
   291  		case *Line:
   292  			f.add(&errs, nil, x, x.Token[0], x.Token[1:], fix, strict)
   293  
   294  		case *LineBlock:
   295  			if len(x.Token) > 1 {
   296  				if strict {
   297  					errs = append(errs, Error{
   298  						Filename: file,
   299  						Pos:      x.Start,
   300  						Err:      fmt.Errorf("unknown block type: %s", strings.Join(x.Token, " ")),
   301  					})
   302  				}
   303  				continue
   304  			}
   305  			switch x.Token[0] {
   306  			default:
   307  				if strict {
   308  					errs = append(errs, Error{
   309  						Filename: file,
   310  						Pos:      x.Start,
   311  						Err:      fmt.Errorf("unknown block type: %s", strings.Join(x.Token, " ")),
   312  					})
   313  				}
   314  				continue
   315  			case "module", "godebug", "require", "exclude", "replace", "retract", "tool", "ignore":
   316  				for _, l := range x.Line {
   317  					f.add(&errs, x, l, x.Token[0], l.Token, fix, strict)
   318  				}
   319  			}
   320  		}
   321  	}
   322  
   323  	if len(errs) > 0 {
   324  		return nil, errs
   325  	}
   326  	return f, nil
   327  }
   328  
   329  var GoVersionRE = lazyregexp.New(`^([1-9][0-9]*)\.(0|[1-9][0-9]*)(\.(0|[1-9][0-9]*))?([a-z]+[0-9]+)?$`)
   330  var laxGoVersionRE = lazyregexp.New(`^v?(([1-9][0-9]*)\.(0|[1-9][0-9]*))([^0-9].*)$`)
   331  
   332  // Toolchains must be named beginning with `go1`,
   333  // like "go1.20.3" or "go1.20.3-gccgo". As a special case, "default" is also permitted.
   334  // Note that this regexp is a much looser condition than go/version.IsValid,
   335  // for forward compatibility.
   336  // (This code has to be work to identify new toolchains even if we tweak the syntax in the future.)
   337  var ToolchainRE = lazyregexp.New(`^default$|^go1($|\.)`)
   338  
   339  func (f *File) add(errs *ErrorList, block *LineBlock, line *Line, verb string, args []string, fix VersionFixer, strict bool) {
   340  	// If strict is false, this module is a dependency.
   341  	// We ignore all unknown directives as well as main-module-only
   342  	// directives like replace and exclude. It will work better for
   343  	// forward compatibility if we can depend on modules that have unknown
   344  	// statements (presumed relevant only when acting as the main module)
   345  	// and simply ignore those statements.
   346  	if !strict {
   347  		switch verb {
   348  		case "go", "module", "retract", "require", "ignore":
   349  			// want these even for dependency go.mods
   350  		default:
   351  			return
   352  		}
   353  	}
   354  
   355  	wrapModPathError := func(modPath string, err error) {
   356  		*errs = append(*errs, Error{
   357  			Filename: f.Syntax.Name,
   358  			Pos:      line.Start,
   359  			ModPath:  modPath,
   360  			Verb:     verb,
   361  			Err:      err,
   362  		})
   363  	}
   364  	wrapError := func(err error) {
   365  		*errs = append(*errs, Error{
   366  			Filename: f.Syntax.Name,
   367  			Pos:      line.Start,
   368  			Err:      err,
   369  		})
   370  	}
   371  	errorf := func(format string, args ...interface{}) {
   372  		wrapError(fmt.Errorf(format, args...))
   373  	}
   374  
   375  	switch verb {
   376  	default:
   377  		errorf("unknown directive: %s", verb)
   378  
   379  	case "go":
   380  		if f.Go != nil {
   381  			errorf("repeated go statement")
   382  			return
   383  		}
   384  		if len(args) != 1 {
   385  			errorf("go directive expects exactly one argument")
   386  			return
   387  		} else if !GoVersionRE.MatchString(args[0]) {
   388  			fixed := false
   389  			if !strict {
   390  				if m := laxGoVersionRE.FindStringSubmatch(args[0]); m != nil {
   391  					args[0] = m[1]
   392  					fixed = true
   393  				}
   394  			}
   395  			if !fixed {
   396  				errorf("invalid go version '%s': must match format 1.23.0", args[0])
   397  				return
   398  			}
   399  		}
   400  
   401  		f.Go = &Go{Syntax: line}
   402  		f.Go.Version = args[0]
   403  
   404  	case "toolchain":
   405  		if f.Toolchain != nil {
   406  			errorf("repeated toolchain statement")
   407  			return
   408  		}
   409  		if len(args) != 1 {
   410  			errorf("toolchain directive expects exactly one argument")
   411  			return
   412  		} else if !ToolchainRE.MatchString(args[0]) {
   413  			errorf("invalid toolchain version '%s': must match format go1.23.0 or default", args[0])
   414  			return
   415  		}
   416  		f.Toolchain = &Toolchain{Syntax: line}
   417  		f.Toolchain.Name = args[0]
   418  
   419  	case "module":
   420  		if f.Module != nil {
   421  			errorf("repeated module statement")
   422  			return
   423  		}
   424  		deprecated := parseDeprecation(block, line)
   425  		f.Module = &Module{
   426  			Syntax:     line,
   427  			Deprecated: deprecated,
   428  		}
   429  		if len(args) != 1 {
   430  			errorf("usage: module module/path")
   431  			return
   432  		}
   433  		s, err := parseString(&args[0])
   434  		if err != nil {
   435  			errorf("invalid quoted string: %v", err)
   436  			return
   437  		}
   438  		f.Module.Mod = module.Version{Path: s}
   439  
   440  	case "godebug":
   441  		if len(args) != 1 || strings.ContainsAny(args[0], "\"`',") {
   442  			errorf("usage: godebug key=value")
   443  			return
   444  		}
   445  		key, value, ok := strings.Cut(args[0], "=")
   446  		if !ok {
   447  			errorf("usage: godebug key=value")
   448  			return
   449  		}
   450  		f.Godebug = append(f.Godebug, &Godebug{
   451  			Key:    key,
   452  			Value:  value,
   453  			Syntax: line,
   454  		})
   455  
   456  	case "require", "exclude":
   457  		if len(args) != 2 {
   458  			errorf("usage: %s module/path v1.2.3", verb)
   459  			return
   460  		}
   461  		s, err := parseString(&args[0])
   462  		if err != nil {
   463  			errorf("invalid quoted string: %v", err)
   464  			return
   465  		}
   466  		v, err := parseVersion(verb, s, &args[1], fix)
   467  		if err != nil {
   468  			wrapError(err)
   469  			return
   470  		}
   471  		pathMajor, err := modulePathMajor(s)
   472  		if err != nil {
   473  			wrapError(err)
   474  			return
   475  		}
   476  		if err := module.CheckPathMajor(v, pathMajor); err != nil {
   477  			wrapModPathError(s, err)
   478  			return
   479  		}
   480  		if verb == "require" {
   481  			f.Require = append(f.Require, &Require{
   482  				Mod:      module.Version{Path: s, Version: v},
   483  				Syntax:   line,
   484  				Indirect: isIndirect(line),
   485  			})
   486  		} else {
   487  			f.Exclude = append(f.Exclude, &Exclude{
   488  				Mod:    module.Version{Path: s, Version: v},
   489  				Syntax: line,
   490  			})
   491  		}
   492  
   493  	case "replace":
   494  		replace, wrappederr := parseReplace(f.Syntax.Name, line, verb, args, fix)
   495  		if wrappederr != nil {
   496  			*errs = append(*errs, *wrappederr)
   497  			return
   498  		}
   499  		f.Replace = append(f.Replace, replace)
   500  
   501  	case "retract":
   502  		rationale := parseDirectiveComment(block, line)
   503  		vi, err := parseVersionInterval(verb, "", &args, dontFixRetract)
   504  		if err != nil {
   505  			if strict {
   506  				wrapError(err)
   507  				return
   508  			} else {
   509  				// Only report errors parsing intervals in the main module. We may
   510  				// support additional syntax in the future, such as open and half-open
   511  				// intervals. Those can't be supported now, because they break the
   512  				// go.mod parser, even in lax mode.
   513  				return
   514  			}
   515  		}
   516  		if len(args) > 0 && strict {
   517  			// In the future, there may be additional information after the version.
   518  			errorf("unexpected token after version: %q", args[0])
   519  			return
   520  		}
   521  		retract := &Retract{
   522  			VersionInterval: vi,
   523  			Rationale:       rationale,
   524  			Syntax:          line,
   525  		}
   526  		f.Retract = append(f.Retract, retract)
   527  
   528  	case "tool":
   529  		if len(args) != 1 {
   530  			errorf("tool directive expects exactly one argument")
   531  			return
   532  		}
   533  		s, err := parseString(&args[0])
   534  		if err != nil {
   535  			errorf("invalid quoted string: %v", err)
   536  			return
   537  		}
   538  		f.Tool = append(f.Tool, &Tool{
   539  			Path:   s,
   540  			Syntax: line,
   541  		})
   542  
   543  	case "ignore":
   544  		if len(args) != 1 {
   545  			errorf("ignore directive expects exactly one argument")
   546  			return
   547  		}
   548  		s, err := parseString(&args[0])
   549  		if err != nil {
   550  			errorf("invalid quoted string: %v", err)
   551  			return
   552  		}
   553  		f.Ignore = append(f.Ignore, &Ignore{
   554  			Path:   s,
   555  			Syntax: line,
   556  		})
   557  	}
   558  }
   559  
   560  func parseReplace(filename string, line *Line, verb string, args []string, fix VersionFixer) (*Replace, *Error) {
   561  	wrapModPathError := func(modPath string, err error) *Error {
   562  		return &Error{
   563  			Filename: filename,
   564  			Pos:      line.Start,
   565  			ModPath:  modPath,
   566  			Verb:     verb,
   567  			Err:      err,
   568  		}
   569  	}
   570  	wrapError := func(err error) *Error {
   571  		return &Error{
   572  			Filename: filename,
   573  			Pos:      line.Start,
   574  			Err:      err,
   575  		}
   576  	}
   577  	errorf := func(format string, args ...interface{}) *Error {
   578  		return wrapError(fmt.Errorf(format, args...))
   579  	}
   580  
   581  	arrow := 2
   582  	if len(args) >= 2 && args[1] == "=>" {
   583  		arrow = 1
   584  	}
   585  	if len(args) < arrow+2 || len(args) > arrow+3 || args[arrow] != "=>" {
   586  		return nil, errorf("usage: %s module/path [v1.2.3] => other/module v1.4\n\t or %s module/path [v1.2.3] => ../local/directory", verb, verb)
   587  	}
   588  	s, err := parseString(&args[0])
   589  	if err != nil {
   590  		return nil, errorf("invalid quoted string: %v", err)
   591  	}
   592  	pathMajor, err := modulePathMajor(s)
   593  	if err != nil {
   594  		return nil, wrapModPathError(s, err)
   595  
   596  	}
   597  	var v string
   598  	if arrow == 2 {
   599  		v, err = parseVersion(verb, s, &args[1], fix)
   600  		if err != nil {
   601  			return nil, wrapError(err)
   602  		}
   603  		if err := module.CheckPathMajor(v, pathMajor); err != nil {
   604  			return nil, wrapModPathError(s, err)
   605  		}
   606  	}
   607  	ns, err := parseString(&args[arrow+1])
   608  	if err != nil {
   609  		return nil, errorf("invalid quoted string: %v", err)
   610  	}
   611  	nv := ""
   612  	if len(args) == arrow+2 {
   613  		if !IsDirectoryPath(ns) {
   614  			if strings.Contains(ns, "@") {
   615  				return nil, errorf("replacement module must match format 'path version', not 'path@version'")
   616  			}
   617  			return nil, errorf("replacement module without version must be directory path (rooted or starting with . or ..)")
   618  		}
   619  		if filepath.Separator == '/' && strings.Contains(ns, `\`) {
   620  			return nil, errorf("replacement directory appears to be Windows path (on a non-windows system)")
   621  		}
   622  	}
   623  	if len(args) == arrow+3 {
   624  		nv, err = parseVersion(verb, ns, &args[arrow+2], fix)
   625  		if err != nil {
   626  			return nil, wrapError(err)
   627  		}
   628  		if IsDirectoryPath(ns) {
   629  			return nil, errorf("replacement module directory path %q cannot have version", ns)
   630  		}
   631  	}
   632  	return &Replace{
   633  		Old:    module.Version{Path: s, Version: v},
   634  		New:    module.Version{Path: ns, Version: nv},
   635  		Syntax: line,
   636  	}, nil
   637  }
   638  
   639  // fixRetract applies fix to each retract directive in f, appending any errors
   640  // to errs.
   641  //
   642  // Most versions are fixed as we parse the file, but for retract directives,
   643  // the relevant module path is the one specified with the module directive,
   644  // and that might appear at the end of the file (or not at all).
   645  func (f *File) fixRetract(fix VersionFixer, errs *ErrorList) {
   646  	if fix == nil {
   647  		return
   648  	}
   649  	path := ""
   650  	if f.Module != nil {
   651  		path = f.Module.Mod.Path
   652  	}
   653  	var r *Retract
   654  	wrapError := func(err error) {
   655  		*errs = append(*errs, Error{
   656  			Filename: f.Syntax.Name,
   657  			Pos:      r.Syntax.Start,
   658  			Err:      err,
   659  		})
   660  	}
   661  
   662  	for _, r = range f.Retract {
   663  		if path == "" {
   664  			wrapError(errors.New("no module directive found, so retract cannot be used"))
   665  			return // only print the first one of these
   666  		}
   667  
   668  		args := r.Syntax.Token
   669  		if args[0] == "retract" {
   670  			args = args[1:]
   671  		}
   672  		vi, err := parseVersionInterval("retract", path, &args, fix)
   673  		if err != nil {
   674  			wrapError(err)
   675  		}
   676  		r.VersionInterval = vi
   677  	}
   678  }
   679  
   680  func (f *WorkFile) add(errs *ErrorList, line *Line, verb string, args []string, fix VersionFixer) {
   681  	wrapError := func(err error) {
   682  		*errs = append(*errs, Error{
   683  			Filename: f.Syntax.Name,
   684  			Pos:      line.Start,
   685  			Err:      err,
   686  		})
   687  	}
   688  	errorf := func(format string, args ...interface{}) {
   689  		wrapError(fmt.Errorf(format, args...))
   690  	}
   691  
   692  	switch verb {
   693  	default:
   694  		errorf("unknown directive: %s", verb)
   695  
   696  	case "go":
   697  		if f.Go != nil {
   698  			errorf("repeated go statement")
   699  			return
   700  		}
   701  		if len(args) != 1 {
   702  			errorf("go directive expects exactly one argument")
   703  			return
   704  		} else if !GoVersionRE.MatchString(args[0]) {
   705  			errorf("invalid go version '%s': must match format 1.23.0", args[0])
   706  			return
   707  		}
   708  
   709  		f.Go = &Go{Syntax: line}
   710  		f.Go.Version = args[0]
   711  
   712  	case "toolchain":
   713  		if f.Toolchain != nil {
   714  			errorf("repeated toolchain statement")
   715  			return
   716  		}
   717  		if len(args) != 1 {
   718  			errorf("toolchain directive expects exactly one argument")
   719  			return
   720  		} else if !ToolchainRE.MatchString(args[0]) {
   721  			errorf("invalid toolchain version '%s': must match format go1.23.0 or default", args[0])
   722  			return
   723  		}
   724  
   725  		f.Toolchain = &Toolchain{Syntax: line}
   726  		f.Toolchain.Name = args[0]
   727  
   728  	case "godebug":
   729  		if len(args) != 1 || strings.ContainsAny(args[0], "\"`',") {
   730  			errorf("usage: godebug key=value")
   731  			return
   732  		}
   733  		key, value, ok := strings.Cut(args[0], "=")
   734  		if !ok {
   735  			errorf("usage: godebug key=value")
   736  			return
   737  		}
   738  		f.Godebug = append(f.Godebug, &Godebug{
   739  			Key:    key,
   740  			Value:  value,
   741  			Syntax: line,
   742  		})
   743  
   744  	case "use":
   745  		if len(args) != 1 {
   746  			errorf("usage: %s local/dir", verb)
   747  			return
   748  		}
   749  		s, err := parseString(&args[0])
   750  		if err != nil {
   751  			errorf("invalid quoted string: %v", err)
   752  			return
   753  		}
   754  		f.Use = append(f.Use, &Use{
   755  			Path:   s,
   756  			Syntax: line,
   757  		})
   758  
   759  	case "replace":
   760  		replace, wrappederr := parseReplace(f.Syntax.Name, line, verb, args, fix)
   761  		if wrappederr != nil {
   762  			*errs = append(*errs, *wrappederr)
   763  			return
   764  		}
   765  		f.Replace = append(f.Replace, replace)
   766  	}
   767  }
   768  
   769  // IsDirectoryPath reports whether the given path should be interpreted as a directory path.
   770  // Just like on the go command line, relative paths starting with a '.' or '..' path component
   771  // and rooted paths are directory paths; the rest are module paths.
   772  func IsDirectoryPath(ns string) bool {
   773  	// Because go.mod files can move from one system to another,
   774  	// we check all known path syntaxes, both Unix and Windows.
   775  	return ns == "." || strings.HasPrefix(ns, "./") || strings.HasPrefix(ns, `.\`) ||
   776  		ns == ".." || strings.HasPrefix(ns, "../") || strings.HasPrefix(ns, `..\`) ||
   777  		strings.HasPrefix(ns, "/") || strings.HasPrefix(ns, `\`) ||
   778  		len(ns) >= 2 && ('A' <= ns[0] && ns[0] <= 'Z' || 'a' <= ns[0] && ns[0] <= 'z') && ns[1] == ':'
   779  }
   780  
   781  // MustQuote reports whether s must be quoted in order to appear as
   782  // a single token in a go.mod line.
   783  func MustQuote(s string) bool {
   784  	for _, r := range s {
   785  		switch r {
   786  		case ' ', '"', '\'', '`':
   787  			return true
   788  
   789  		case '(', ')', '[', ']', '{', '}', ',':
   790  			if len(s) > 1 {
   791  				return true
   792  			}
   793  
   794  		default:
   795  			if !unicode.IsPrint(r) {
   796  				return true
   797  			}
   798  		}
   799  	}
   800  	return s == "" || strings.Contains(s, "//") || strings.Contains(s, "/*")
   801  }
   802  
   803  // AutoQuote returns s or, if quoting is required for s to appear in a go.mod,
   804  // the quotation of s.
   805  func AutoQuote(s string) string {
   806  	if MustQuote(s) {
   807  		return strconv.Quote(s)
   808  	}
   809  	return s
   810  }
   811  
   812  func parseVersionInterval(verb string, path string, args *[]string, fix VersionFixer) (VersionInterval, error) {
   813  	toks := *args
   814  	if len(toks) == 0 || toks[0] == "(" {
   815  		return VersionInterval{}, fmt.Errorf("expected '[' or version")
   816  	}
   817  	if toks[0] != "[" {
   818  		v, err := parseVersion(verb, path, &toks[0], fix)
   819  		if err != nil {
   820  			return VersionInterval{}, err
   821  		}
   822  		*args = toks[1:]
   823  		return VersionInterval{Low: v, High: v}, nil
   824  	}
   825  	toks = toks[1:]
   826  
   827  	if len(toks) == 0 {
   828  		return VersionInterval{}, fmt.Errorf("expected version after '['")
   829  	}
   830  	low, err := parseVersion(verb, path, &toks[0], fix)
   831  	if err != nil {
   832  		return VersionInterval{}, err
   833  	}
   834  	toks = toks[1:]
   835  
   836  	if len(toks) == 0 || toks[0] != "," {
   837  		return VersionInterval{}, fmt.Errorf("expected ',' after version")
   838  	}
   839  	toks = toks[1:]
   840  
   841  	if len(toks) == 0 {
   842  		return VersionInterval{}, fmt.Errorf("expected version after ','")
   843  	}
   844  	high, err := parseVersion(verb, path, &toks[0], fix)
   845  	if err != nil {
   846  		return VersionInterval{}, err
   847  	}
   848  	toks = toks[1:]
   849  
   850  	if len(toks) == 0 || toks[0] != "]" {
   851  		return VersionInterval{}, fmt.Errorf("expected ']' after version")
   852  	}
   853  	toks = toks[1:]
   854  
   855  	*args = toks
   856  	return VersionInterval{Low: low, High: high}, nil
   857  }
   858  
   859  func parseString(s *string) (string, error) {
   860  	t := *s
   861  	if strings.HasPrefix(t, `"`) {
   862  		var err error
   863  		if t, err = strconv.Unquote(t); err != nil {
   864  			return "", err
   865  		}
   866  	} else if strings.ContainsAny(t, "\"'`") {
   867  		// Other quotes are reserved both for possible future expansion
   868  		// and to avoid confusion. For example if someone types 'x'
   869  		// we want that to be a syntax error and not a literal x in literal quotation marks.
   870  		return "", fmt.Errorf("unquoted string cannot contain quote")
   871  	}
   872  	*s = AutoQuote(t)
   873  	return t, nil
   874  }
   875  
   876  var deprecatedRE = lazyregexp.New(`(?s)(?:^|\n\n)Deprecated: *(.*?)(?:$|\n\n)`)
   877  
   878  // parseDeprecation extracts the text of comments on a "module" directive and
   879  // extracts a deprecation message from that.
   880  //
   881  // A deprecation message is contained in a paragraph within a block of comments
   882  // that starts with "Deprecated:" (case sensitive). The message runs until the
   883  // end of the paragraph and does not include the "Deprecated:" prefix. If the
   884  // comment block has multiple paragraphs that start with "Deprecated:",
   885  // parseDeprecation returns the message from the first.
   886  func parseDeprecation(block *LineBlock, line *Line) string {
   887  	text := parseDirectiveComment(block, line)
   888  	m := deprecatedRE.FindStringSubmatch(text)
   889  	if m == nil {
   890  		return ""
   891  	}
   892  	return m[1]
   893  }
   894  
   895  // parseDirectiveComment extracts the text of comments on a directive.
   896  // If the directive's line does not have comments and is part of a block that
   897  // does have comments, the block's comments are used.
   898  func parseDirectiveComment(block *LineBlock, line *Line) string {
   899  	comments := line.Comment()
   900  	if block != nil && len(comments.Before) == 0 && len(comments.Suffix) == 0 {
   901  		comments = block.Comment()
   902  	}
   903  	groups := [][]Comment{comments.Before, comments.Suffix}
   904  	var lines []string
   905  	for _, g := range groups {
   906  		for _, c := range g {
   907  			if !strings.HasPrefix(c.Token, "//") {
   908  				continue // blank line
   909  			}
   910  			lines = append(lines, strings.TrimSpace(strings.TrimPrefix(c.Token, "//")))
   911  		}
   912  	}
   913  	return strings.Join(lines, "\n")
   914  }
   915  
   916  type ErrorList []Error
   917  
   918  func (e ErrorList) Error() string {
   919  	errStrs := make([]string, len(e))
   920  	for i, err := range e {
   921  		errStrs[i] = err.Error()
   922  	}
   923  	return strings.Join(errStrs, "\n")
   924  }
   925  
   926  type Error struct {
   927  	Filename string
   928  	Pos      Position
   929  	Verb     string
   930  	ModPath  string
   931  	Err      error
   932  }
   933  
   934  func (e *Error) Error() string {
   935  	var pos string
   936  	if e.Pos.LineRune > 1 {
   937  		// Don't print LineRune if it's 1 (beginning of line).
   938  		// It's always 1 except in scanner errors, which are rare.
   939  		pos = fmt.Sprintf("%s:%d:%d: ", e.Filename, e.Pos.Line, e.Pos.LineRune)
   940  	} else if e.Pos.Line > 0 {
   941  		pos = fmt.Sprintf("%s:%d: ", e.Filename, e.Pos.Line)
   942  	} else if e.Filename != "" {
   943  		pos = fmt.Sprintf("%s: ", e.Filename)
   944  	}
   945  
   946  	var directive string
   947  	if e.ModPath != "" {
   948  		directive = fmt.Sprintf("%s %s: ", e.Verb, e.ModPath)
   949  	} else if e.Verb != "" {
   950  		directive = fmt.Sprintf("%s: ", e.Verb)
   951  	}
   952  
   953  	return pos + directive + e.Err.Error()
   954  }
   955  
   956  func (e *Error) Unwrap() error { return e.Err }
   957  
   958  func parseVersion(verb string, path string, s *string, fix VersionFixer) (string, error) {
   959  	t, err := parseString(s)
   960  	if err != nil {
   961  		return "", &Error{
   962  			Verb:    verb,
   963  			ModPath: path,
   964  			Err: &module.InvalidVersionError{
   965  				Version: *s,
   966  				Err:     err,
   967  			},
   968  		}
   969  	}
   970  	if fix != nil {
   971  		fixed, err := fix(path, t)
   972  		if err != nil {
   973  			if err, ok := err.(*module.ModuleError); ok {
   974  				return "", &Error{
   975  					Verb:    verb,
   976  					ModPath: path,
   977  					Err:     err.Err,
   978  				}
   979  			}
   980  			return "", err
   981  		}
   982  		t = fixed
   983  	} else {
   984  		cv := module.CanonicalVersion(t)
   985  		if cv == "" {
   986  			return "", &Error{
   987  				Verb:    verb,
   988  				ModPath: path,
   989  				Err: &module.InvalidVersionError{
   990  					Version: t,
   991  					Err:     errors.New("must be of the form v1.2.3"),
   992  				},
   993  			}
   994  		}
   995  		t = cv
   996  	}
   997  	*s = t
   998  	return *s, nil
   999  }
  1000  
  1001  func modulePathMajor(path string) (string, error) {
  1002  	_, major, ok := module.SplitPathVersion(path)
  1003  	if !ok {
  1004  		return "", fmt.Errorf("invalid module path")
  1005  	}
  1006  	return major, nil
  1007  }
  1008  
  1009  func (f *File) Format() ([]byte, error) {
  1010  	return Format(f.Syntax), nil
  1011  }
  1012  
  1013  // Cleanup cleans up the file f after any edit operations.
  1014  // To avoid quadratic behavior, modifications like [File.DropRequire]
  1015  // clear the entry but do not remove it from the slice.
  1016  // Cleanup cleans out all the cleared entries.
  1017  func (f *File) Cleanup() {
  1018  	w := 0
  1019  	for _, g := range f.Godebug {
  1020  		if g.Key != "" {
  1021  			f.Godebug[w] = g
  1022  			w++
  1023  		}
  1024  	}
  1025  	f.Godebug = f.Godebug[:w]
  1026  
  1027  	w = 0
  1028  	for _, r := range f.Require {
  1029  		if r.Mod.Path != "" {
  1030  			f.Require[w] = r
  1031  			w++
  1032  		}
  1033  	}
  1034  	f.Require = f.Require[:w]
  1035  
  1036  	w = 0
  1037  	for _, x := range f.Exclude {
  1038  		if x.Mod.Path != "" {
  1039  			f.Exclude[w] = x
  1040  			w++
  1041  		}
  1042  	}
  1043  	f.Exclude = f.Exclude[:w]
  1044  
  1045  	w = 0
  1046  	for _, r := range f.Replace {
  1047  		if r.Old.Path != "" {
  1048  			f.Replace[w] = r
  1049  			w++
  1050  		}
  1051  	}
  1052  	f.Replace = f.Replace[:w]
  1053  
  1054  	w = 0
  1055  	for _, r := range f.Retract {
  1056  		if r.Low != "" || r.High != "" {
  1057  			f.Retract[w] = r
  1058  			w++
  1059  		}
  1060  	}
  1061  	f.Retract = f.Retract[:w]
  1062  
  1063  	f.Syntax.Cleanup()
  1064  }
  1065  
  1066  func (f *File) AddGoStmt(version string) error {
  1067  	if !GoVersionRE.MatchString(version) {
  1068  		return fmt.Errorf("invalid language version %q", version)
  1069  	}
  1070  	if f.Go == nil {
  1071  		var hint Expr
  1072  		if f.Module != nil && f.Module.Syntax != nil {
  1073  			hint = f.Module.Syntax
  1074  		} else if f.Syntax == nil {
  1075  			f.Syntax = new(FileSyntax)
  1076  		}
  1077  		f.Go = &Go{
  1078  			Version: version,
  1079  			Syntax:  f.Syntax.addLine(hint, "go", version),
  1080  		}
  1081  	} else {
  1082  		f.Go.Version = version
  1083  		f.Syntax.updateLine(f.Go.Syntax, "go", version)
  1084  	}
  1085  	return nil
  1086  }
  1087  
  1088  // DropGoStmt deletes the go statement from the file.
  1089  func (f *File) DropGoStmt() {
  1090  	if f.Go != nil {
  1091  		f.Go.Syntax.markRemoved()
  1092  		f.Go = nil
  1093  	}
  1094  }
  1095  
  1096  // DropToolchainStmt deletes the toolchain statement from the file.
  1097  func (f *File) DropToolchainStmt() {
  1098  	if f.Toolchain != nil {
  1099  		f.Toolchain.Syntax.markRemoved()
  1100  		f.Toolchain = nil
  1101  	}
  1102  }
  1103  
  1104  func (f *File) AddToolchainStmt(name string) error {
  1105  	if !ToolchainRE.MatchString(name) {
  1106  		return fmt.Errorf("invalid toolchain name %q", name)
  1107  	}
  1108  	if f.Toolchain == nil {
  1109  		var hint Expr
  1110  		if f.Go != nil && f.Go.Syntax != nil {
  1111  			hint = f.Go.Syntax
  1112  		} else if f.Module != nil && f.Module.Syntax != nil {
  1113  			hint = f.Module.Syntax
  1114  		}
  1115  		f.Toolchain = &Toolchain{
  1116  			Name:   name,
  1117  			Syntax: f.Syntax.addLine(hint, "toolchain", name),
  1118  		}
  1119  	} else {
  1120  		f.Toolchain.Name = name
  1121  		f.Syntax.updateLine(f.Toolchain.Syntax, "toolchain", name)
  1122  	}
  1123  	return nil
  1124  }
  1125  
  1126  // AddGodebug sets the first godebug line for key to value,
  1127  // preserving any existing comments for that line and removing all
  1128  // other godebug lines for key.
  1129  //
  1130  // If no line currently exists for key, AddGodebug adds a new line
  1131  // at the end of the last godebug block.
  1132  func (f *File) AddGodebug(key, value string) error {
  1133  	need := true
  1134  	for _, g := range f.Godebug {
  1135  		if g.Key == key {
  1136  			if need {
  1137  				g.Value = value
  1138  				f.Syntax.updateLine(g.Syntax, "godebug", key+"="+value)
  1139  				need = false
  1140  			} else {
  1141  				g.Syntax.markRemoved()
  1142  				*g = Godebug{}
  1143  			}
  1144  		}
  1145  	}
  1146  
  1147  	if need {
  1148  		f.addNewGodebug(key, value)
  1149  	}
  1150  	return nil
  1151  }
  1152  
  1153  // addNewGodebug adds a new godebug key=value line at the end
  1154  // of the last godebug block, regardless of any existing godebug lines for key.
  1155  func (f *File) addNewGodebug(key, value string) {
  1156  	line := f.Syntax.addLine(nil, "godebug", key+"="+value)
  1157  	g := &Godebug{
  1158  		Key:    key,
  1159  		Value:  value,
  1160  		Syntax: line,
  1161  	}
  1162  	f.Godebug = append(f.Godebug, g)
  1163  }
  1164  
  1165  // AddRequire sets the first require line for path to version vers,
  1166  // preserving any existing comments for that line and removing all
  1167  // other lines for path.
  1168  //
  1169  // If no line currently exists for path, AddRequire adds a new line
  1170  // at the end of the last require block.
  1171  func (f *File) AddRequire(path, vers string) error {
  1172  	need := true
  1173  	for _, r := range f.Require {
  1174  		if r.Mod.Path == path {
  1175  			if need {
  1176  				r.Mod.Version = vers
  1177  				f.Syntax.updateLine(r.Syntax, "require", AutoQuote(path), vers)
  1178  				need = false
  1179  			} else {
  1180  				r.Syntax.markRemoved()
  1181  				*r = Require{}
  1182  			}
  1183  		}
  1184  	}
  1185  
  1186  	if need {
  1187  		f.AddNewRequire(path, vers, false)
  1188  	}
  1189  	return nil
  1190  }
  1191  
  1192  // AddNewRequire adds a new require line for path at version vers at the end of
  1193  // the last require block, regardless of any existing require lines for path.
  1194  func (f *File) AddNewRequire(path, vers string, indirect bool) {
  1195  	line := f.Syntax.addLine(nil, "require", AutoQuote(path), vers)
  1196  	r := &Require{
  1197  		Mod:    module.Version{Path: path, Version: vers},
  1198  		Syntax: line,
  1199  	}
  1200  	r.setIndirect(indirect)
  1201  	f.Require = append(f.Require, r)
  1202  }
  1203  
  1204  // SetRequire updates the requirements of f to contain exactly req, preserving
  1205  // the existing block structure and line comment contents (except for 'indirect'
  1206  // markings) for the first requirement on each named module path.
  1207  //
  1208  // The Syntax field is ignored for the requirements in req.
  1209  //
  1210  // Any requirements not already present in the file are added to the block
  1211  // containing the last require line.
  1212  //
  1213  // The requirements in req must specify at most one distinct version for each
  1214  // module path.
  1215  //
  1216  // If any existing requirements may be removed, the caller should call
  1217  // [File.Cleanup] after all edits are complete.
  1218  func (f *File) SetRequire(req []*Require) {
  1219  	type elem struct {
  1220  		version  string
  1221  		indirect bool
  1222  	}
  1223  	need := make(map[string]elem)
  1224  	for _, r := range req {
  1225  		if prev, dup := need[r.Mod.Path]; dup && prev.version != r.Mod.Version {
  1226  			panic(fmt.Errorf("SetRequire called with conflicting versions for path %s (%s and %s)", r.Mod.Path, prev.version, r.Mod.Version))
  1227  		}
  1228  		need[r.Mod.Path] = elem{r.Mod.Version, r.Indirect}
  1229  	}
  1230  
  1231  	// Update or delete the existing Require entries to preserve
  1232  	// only the first for each module path in req.
  1233  	for _, r := range f.Require {
  1234  		e, ok := need[r.Mod.Path]
  1235  		if ok {
  1236  			r.setVersion(e.version)
  1237  			r.setIndirect(e.indirect)
  1238  		} else {
  1239  			r.markRemoved()
  1240  		}
  1241  		delete(need, r.Mod.Path)
  1242  	}
  1243  
  1244  	// Add new entries in the last block of the file for any paths that weren't
  1245  	// already present.
  1246  	//
  1247  	// This step is nondeterministic, but the final result will be deterministic
  1248  	// because we will sort the block.
  1249  	for path, e := range need {
  1250  		f.AddNewRequire(path, e.version, e.indirect)
  1251  	}
  1252  
  1253  	f.SortBlocks()
  1254  }
  1255  
  1256  // SetRequireSeparateIndirect updates the requirements of f to contain the given
  1257  // requirements. Comment contents (except for 'indirect' markings) are retained
  1258  // from the first existing requirement for each module path. Like SetRequire,
  1259  // SetRequireSeparateIndirect adds requirements for new paths in req,
  1260  // updates the version and "// indirect" comment on existing requirements,
  1261  // and deletes requirements on paths not in req. Existing duplicate requirements
  1262  // are deleted.
  1263  //
  1264  // As its name suggests, SetRequireSeparateIndirect puts direct and indirect
  1265  // requirements into two separate blocks, one containing only direct
  1266  // requirements, and the other containing only indirect requirements.
  1267  // SetRequireSeparateIndirect may move requirements between these two blocks
  1268  // when their indirect markings change. However, SetRequireSeparateIndirect
  1269  // won't move requirements from other blocks, especially blocks with comments.
  1270  //
  1271  // If the file initially has one uncommented block of requirements,
  1272  // SetRequireSeparateIndirect will split it into a direct-only and indirect-only
  1273  // block. This aids in the transition to separate blocks.
  1274  func (f *File) SetRequireSeparateIndirect(req []*Require) {
  1275  	// hasComments returns whether a line or block has comments
  1276  	// other than "indirect".
  1277  	hasComments := func(c Comments) bool {
  1278  		return len(c.Before) > 0 || len(c.After) > 0 || len(c.Suffix) > 1 ||
  1279  			(len(c.Suffix) == 1 &&
  1280  				strings.TrimSpace(strings.TrimPrefix(c.Suffix[0].Token, string(slashSlash))) != "indirect")
  1281  	}
  1282  
  1283  	// moveReq adds r to block. If r was in another block, moveReq deletes
  1284  	// it from that block and transfers its comments.
  1285  	moveReq := func(r *Require, block *LineBlock) {
  1286  		var line *Line
  1287  		if r.Syntax == nil {
  1288  			line = &Line{Token: []string{AutoQuote(r.Mod.Path), r.Mod.Version}}
  1289  			r.Syntax = line
  1290  			if r.Indirect {
  1291  				r.setIndirect(true)
  1292  			}
  1293  		} else {
  1294  			line = new(Line)
  1295  			*line = *r.Syntax
  1296  			if !line.InBlock && len(line.Token) > 0 && line.Token[0] == "require" {
  1297  				line.Token = line.Token[1:]
  1298  			}
  1299  			r.Syntax.Token = nil // Cleanup will delete the old line.
  1300  			r.Syntax = line
  1301  		}
  1302  		line.InBlock = true
  1303  		block.Line = append(block.Line, line)
  1304  	}
  1305  
  1306  	// Examine existing require lines and blocks.
  1307  	var (
  1308  		// We may insert new requirements into the last uncommented
  1309  		// direct-only and indirect-only blocks. We may also move requirements
  1310  		// to the opposite block if their indirect markings change.
  1311  		lastDirectIndex   = -1
  1312  		lastIndirectIndex = -1
  1313  
  1314  		// If there are no direct-only or indirect-only blocks, a new block may
  1315  		// be inserted after the last require line or block.
  1316  		lastRequireIndex = -1
  1317  
  1318  		// If there's only one require line or block, and it's uncommented,
  1319  		// we'll move its requirements to the direct-only or indirect-only blocks.
  1320  		requireLineOrBlockCount = 0
  1321  
  1322  		// Track the block each requirement belongs to (if any) so we can
  1323  		// move them later.
  1324  		lineToBlock = make(map[*Line]*LineBlock)
  1325  	)
  1326  	for i, stmt := range f.Syntax.Stmt {
  1327  		switch stmt := stmt.(type) {
  1328  		case *Line:
  1329  			if len(stmt.Token) == 0 || stmt.Token[0] != "require" {
  1330  				continue
  1331  			}
  1332  			lastRequireIndex = i
  1333  			requireLineOrBlockCount++
  1334  			if !hasComments(stmt.Comments) {
  1335  				if isIndirect(stmt) {
  1336  					lastIndirectIndex = i
  1337  				} else {
  1338  					lastDirectIndex = i
  1339  				}
  1340  			}
  1341  
  1342  		case *LineBlock:
  1343  			if len(stmt.Token) == 0 || stmt.Token[0] != "require" {
  1344  				continue
  1345  			}
  1346  			lastRequireIndex = i
  1347  			requireLineOrBlockCount++
  1348  			allDirect := len(stmt.Line) > 0 && !hasComments(stmt.Comments)
  1349  			allIndirect := len(stmt.Line) > 0 && !hasComments(stmt.Comments)
  1350  			for _, line := range stmt.Line {
  1351  				lineToBlock[line] = stmt
  1352  				if hasComments(line.Comments) {
  1353  					allDirect = false
  1354  					allIndirect = false
  1355  				} else if isIndirect(line) {
  1356  					allDirect = false
  1357  				} else {
  1358  					allIndirect = false
  1359  				}
  1360  			}
  1361  			if allDirect {
  1362  				lastDirectIndex = i
  1363  			}
  1364  			if allIndirect {
  1365  				lastIndirectIndex = i
  1366  			}
  1367  		}
  1368  	}
  1369  
  1370  	oneFlatUncommentedBlock := requireLineOrBlockCount == 1 &&
  1371  		!hasComments(*f.Syntax.Stmt[lastRequireIndex].Comment())
  1372  
  1373  	// Create direct and indirect blocks if needed. Convert lines into blocks
  1374  	// if needed. If we end up with an empty block or a one-line block,
  1375  	// Cleanup will delete it or convert it to a line later.
  1376  	insertBlock := func(i int) *LineBlock {
  1377  		block := &LineBlock{Token: []string{"require"}}
  1378  		f.Syntax.Stmt = append(f.Syntax.Stmt, nil)
  1379  		copy(f.Syntax.Stmt[i+1:], f.Syntax.Stmt[i:])
  1380  		f.Syntax.Stmt[i] = block
  1381  		return block
  1382  	}
  1383  
  1384  	ensureBlock := func(i int) *LineBlock {
  1385  		switch stmt := f.Syntax.Stmt[i].(type) {
  1386  		case *LineBlock:
  1387  			return stmt
  1388  		case *Line:
  1389  			block := &LineBlock{
  1390  				Token: []string{"require"},
  1391  				Line:  []*Line{stmt},
  1392  			}
  1393  			stmt.Token = stmt.Token[1:] // remove "require"
  1394  			stmt.InBlock = true
  1395  			f.Syntax.Stmt[i] = block
  1396  			return block
  1397  		default:
  1398  			panic(fmt.Sprintf("unexpected statement: %v", stmt))
  1399  		}
  1400  	}
  1401  
  1402  	var lastDirectBlock *LineBlock
  1403  	if lastDirectIndex < 0 {
  1404  		if lastIndirectIndex >= 0 {
  1405  			lastDirectIndex = lastIndirectIndex
  1406  			lastIndirectIndex++
  1407  		} else if lastRequireIndex >= 0 {
  1408  			lastDirectIndex = lastRequireIndex + 1
  1409  		} else {
  1410  			lastDirectIndex = len(f.Syntax.Stmt)
  1411  		}
  1412  		lastDirectBlock = insertBlock(lastDirectIndex)
  1413  	} else {
  1414  		lastDirectBlock = ensureBlock(lastDirectIndex)
  1415  	}
  1416  
  1417  	var lastIndirectBlock *LineBlock
  1418  	if lastIndirectIndex < 0 {
  1419  		lastIndirectIndex = lastDirectIndex + 1
  1420  		lastIndirectBlock = insertBlock(lastIndirectIndex)
  1421  	} else {
  1422  		lastIndirectBlock = ensureBlock(lastIndirectIndex)
  1423  	}
  1424  
  1425  	// Delete requirements we don't want anymore.
  1426  	// Update versions and indirect comments on requirements we want to keep.
  1427  	// If a requirement is in last{Direct,Indirect}Block with the wrong
  1428  	// indirect marking after this, or if the requirement is in an single
  1429  	// uncommented mixed block (oneFlatUncommentedBlock), move it to the
  1430  	// correct block.
  1431  	//
  1432  	// Some blocks may be empty after this. Cleanup will remove them.
  1433  	need := make(map[string]*Require)
  1434  	for _, r := range req {
  1435  		need[r.Mod.Path] = r
  1436  	}
  1437  	have := make(map[string]*Require)
  1438  	for _, r := range f.Require {
  1439  		path := r.Mod.Path
  1440  		if need[path] == nil || have[path] != nil {
  1441  			// Requirement not needed, or duplicate requirement. Delete.
  1442  			r.markRemoved()
  1443  			continue
  1444  		}
  1445  		have[r.Mod.Path] = r
  1446  		r.setVersion(need[path].Mod.Version)
  1447  		r.setIndirect(need[path].Indirect)
  1448  		if need[path].Indirect &&
  1449  			(oneFlatUncommentedBlock || lineToBlock[r.Syntax] == lastDirectBlock) {
  1450  			moveReq(r, lastIndirectBlock)
  1451  		} else if !need[path].Indirect &&
  1452  			(oneFlatUncommentedBlock || lineToBlock[r.Syntax] == lastIndirectBlock) {
  1453  			moveReq(r, lastDirectBlock)
  1454  		}
  1455  	}
  1456  
  1457  	// Add new requirements.
  1458  	for path, r := range need {
  1459  		if have[path] == nil {
  1460  			if r.Indirect {
  1461  				moveReq(r, lastIndirectBlock)
  1462  			} else {
  1463  				moveReq(r, lastDirectBlock)
  1464  			}
  1465  			f.Require = append(f.Require, r)
  1466  		}
  1467  	}
  1468  
  1469  	f.SortBlocks()
  1470  }
  1471  
  1472  func (f *File) DropGodebug(key string) error {
  1473  	for _, g := range f.Godebug {
  1474  		if g.Key == key {
  1475  			g.Syntax.markRemoved()
  1476  			*g = Godebug{}
  1477  		}
  1478  	}
  1479  	return nil
  1480  }
  1481  
  1482  func (f *File) DropRequire(path string) error {
  1483  	for _, r := range f.Require {
  1484  		if r.Mod.Path == path {
  1485  			r.Syntax.markRemoved()
  1486  			*r = Require{}
  1487  		}
  1488  	}
  1489  	return nil
  1490  }
  1491  
  1492  // AddExclude adds a exclude statement to the mod file. Errors if the provided
  1493  // version is not a canonical version string
  1494  func (f *File) AddExclude(path, vers string) error {
  1495  	if err := checkCanonicalVersion(path, vers); err != nil {
  1496  		return err
  1497  	}
  1498  
  1499  	var hint *Line
  1500  	for _, x := range f.Exclude {
  1501  		if x.Mod.Path == path && x.Mod.Version == vers {
  1502  			return nil
  1503  		}
  1504  		if x.Mod.Path == path {
  1505  			hint = x.Syntax
  1506  		}
  1507  	}
  1508  
  1509  	f.Exclude = append(f.Exclude, &Exclude{Mod: module.Version{Path: path, Version: vers}, Syntax: f.Syntax.addLine(hint, "exclude", AutoQuote(path), vers)})
  1510  	return nil
  1511  }
  1512  
  1513  func (f *File) DropExclude(path, vers string) error {
  1514  	for _, x := range f.Exclude {
  1515  		if x.Mod.Path == path && x.Mod.Version == vers {
  1516  			x.Syntax.markRemoved()
  1517  			*x = Exclude{}
  1518  		}
  1519  	}
  1520  	return nil
  1521  }
  1522  
  1523  func (f *File) AddReplace(oldPath, oldVers, newPath, newVers string) error {
  1524  	return addReplace(f.Syntax, &f.Replace, oldPath, oldVers, newPath, newVers)
  1525  }
  1526  
  1527  func addReplace(syntax *FileSyntax, replace *[]*Replace, oldPath, oldVers, newPath, newVers string) error {
  1528  	need := true
  1529  	old := module.Version{Path: oldPath, Version: oldVers}
  1530  	new := module.Version{Path: newPath, Version: newVers}
  1531  	tokens := []string{"replace", AutoQuote(oldPath)}
  1532  	if oldVers != "" {
  1533  		tokens = append(tokens, oldVers)
  1534  	}
  1535  	tokens = append(tokens, "=>", AutoQuote(newPath))
  1536  	if newVers != "" {
  1537  		tokens = append(tokens, newVers)
  1538  	}
  1539  
  1540  	var hint *Line
  1541  	for _, r := range *replace {
  1542  		if r.Old.Path == oldPath && (oldVers == "" || r.Old.Version == oldVers) {
  1543  			if need {
  1544  				// Found replacement for old; update to use new.
  1545  				r.New = new
  1546  				syntax.updateLine(r.Syntax, tokens...)
  1547  				need = false
  1548  				continue
  1549  			}
  1550  			// Already added; delete other replacements for same.
  1551  			r.Syntax.markRemoved()
  1552  			*r = Replace{}
  1553  		}
  1554  		if r.Old.Path == oldPath {
  1555  			hint = r.Syntax
  1556  		}
  1557  	}
  1558  	if need {
  1559  		*replace = append(*replace, &Replace{Old: old, New: new, Syntax: syntax.addLine(hint, tokens...)})
  1560  	}
  1561  	return nil
  1562  }
  1563  
  1564  func (f *File) DropReplace(oldPath, oldVers string) error {
  1565  	for _, r := range f.Replace {
  1566  		if r.Old.Path == oldPath && r.Old.Version == oldVers {
  1567  			r.Syntax.markRemoved()
  1568  			*r = Replace{}
  1569  		}
  1570  	}
  1571  	return nil
  1572  }
  1573  
  1574  // AddRetract adds a retract statement to the mod file. Errors if the provided
  1575  // version interval does not consist of canonical version strings
  1576  func (f *File) AddRetract(vi VersionInterval, rationale string) error {
  1577  	var path string
  1578  	if f.Module != nil {
  1579  		path = f.Module.Mod.Path
  1580  	}
  1581  	if err := checkCanonicalVersion(path, vi.High); err != nil {
  1582  		return err
  1583  	}
  1584  	if err := checkCanonicalVersion(path, vi.Low); err != nil {
  1585  		return err
  1586  	}
  1587  
  1588  	r := &Retract{
  1589  		VersionInterval: vi,
  1590  	}
  1591  	if vi.Low == vi.High {
  1592  		r.Syntax = f.Syntax.addLine(nil, "retract", AutoQuote(vi.Low))
  1593  	} else {
  1594  		r.Syntax = f.Syntax.addLine(nil, "retract", "[", AutoQuote(vi.Low), ",", AutoQuote(vi.High), "]")
  1595  	}
  1596  	if rationale != "" {
  1597  		for _, line := range strings.Split(rationale, "\n") {
  1598  			com := Comment{Token: "// " + line}
  1599  			r.Syntax.Comment().Before = append(r.Syntax.Comment().Before, com)
  1600  		}
  1601  	}
  1602  	return nil
  1603  }
  1604  
  1605  func (f *File) DropRetract(vi VersionInterval) error {
  1606  	for _, r := range f.Retract {
  1607  		if r.VersionInterval == vi {
  1608  			r.Syntax.markRemoved()
  1609  			*r = Retract{}
  1610  		}
  1611  	}
  1612  	return nil
  1613  }
  1614  
  1615  // AddTool adds a new tool directive with the given path.
  1616  // It does nothing if the tool line already exists.
  1617  func (f *File) AddTool(path string) error {
  1618  	for _, t := range f.Tool {
  1619  		if t.Path == path {
  1620  			return nil
  1621  		}
  1622  	}
  1623  
  1624  	f.Tool = append(f.Tool, &Tool{
  1625  		Path:   path,
  1626  		Syntax: f.Syntax.addLine(nil, "tool", path),
  1627  	})
  1628  
  1629  	f.SortBlocks()
  1630  	return nil
  1631  }
  1632  
  1633  // RemoveTool removes a tool directive with the given path.
  1634  // It does nothing if no such tool directive exists.
  1635  func (f *File) DropTool(path string) error {
  1636  	for _, t := range f.Tool {
  1637  		if t.Path == path {
  1638  			t.Syntax.markRemoved()
  1639  			*t = Tool{}
  1640  		}
  1641  	}
  1642  	return nil
  1643  }
  1644  
  1645  // AddIgnore adds a new ignore directive with the given path.
  1646  // It does nothing if the ignore line already exists.
  1647  func (f *File) AddIgnore(path string) error {
  1648  	for _, t := range f.Ignore {
  1649  		if t.Path == path {
  1650  			return nil
  1651  		}
  1652  	}
  1653  
  1654  	f.Ignore = append(f.Ignore, &Ignore{
  1655  		Path:   path,
  1656  		Syntax: f.Syntax.addLine(nil, "ignore", path),
  1657  	})
  1658  
  1659  	f.SortBlocks()
  1660  	return nil
  1661  }
  1662  
  1663  // DropIgnore removes a ignore directive with the given path.
  1664  // It does nothing if no such ignore directive exists.
  1665  func (f *File) DropIgnore(path string) error {
  1666  	for _, t := range f.Ignore {
  1667  		if t.Path == path {
  1668  			t.Syntax.markRemoved()
  1669  			*t = Ignore{}
  1670  		}
  1671  	}
  1672  	return nil
  1673  }
  1674  
  1675  func (f *File) SortBlocks() {
  1676  	f.removeDups() // otherwise sorting is unsafe
  1677  
  1678  	// semanticSortForExcludeVersionV is the Go version (plus leading "v") at which
  1679  	// lines in exclude blocks start to use semantic sort instead of lexicographic sort.
  1680  	// See go.dev/issue/60028.
  1681  	const semanticSortForExcludeVersionV = "v1.21"
  1682  	useSemanticSortForExclude := f.Go != nil && semver.Compare("v"+f.Go.Version, semanticSortForExcludeVersionV) >= 0
  1683  
  1684  	for _, stmt := range f.Syntax.Stmt {
  1685  		block, ok := stmt.(*LineBlock)
  1686  		if !ok {
  1687  			continue
  1688  		}
  1689  		less := compareLine
  1690  		if block.Token[0] == "exclude" && useSemanticSortForExclude {
  1691  			less = compareLineExclude
  1692  		} else if block.Token[0] == "retract" {
  1693  			less = compareLineRetract
  1694  		}
  1695  		slices.SortStableFunc(block.Line, less)
  1696  	}
  1697  }
  1698  
  1699  // removeDups removes duplicate exclude, replace and tool directives.
  1700  //
  1701  // Earlier exclude and tool directives take priority.
  1702  //
  1703  // Later replace directives take priority.
  1704  //
  1705  // require directives are not de-duplicated. That's left up to higher-level
  1706  // logic (MVS).
  1707  //
  1708  // retract directives are not de-duplicated since comments are
  1709  // meaningful, and versions may be retracted multiple times.
  1710  func (f *File) removeDups() {
  1711  	removeDups(f.Syntax, &f.Exclude, &f.Replace, &f.Tool, &f.Ignore)
  1712  }
  1713  
  1714  func removeDups(syntax *FileSyntax, exclude *[]*Exclude, replace *[]*Replace, tool *[]*Tool, ignore *[]*Ignore) {
  1715  	kill := make(map[*Line]bool)
  1716  
  1717  	// Remove duplicate excludes.
  1718  	if exclude != nil {
  1719  		haveExclude := make(map[module.Version]bool)
  1720  		for _, x := range *exclude {
  1721  			if haveExclude[x.Mod] {
  1722  				kill[x.Syntax] = true
  1723  				continue
  1724  			}
  1725  			haveExclude[x.Mod] = true
  1726  		}
  1727  		var excl []*Exclude
  1728  		for _, x := range *exclude {
  1729  			if !kill[x.Syntax] {
  1730  				excl = append(excl, x)
  1731  			}
  1732  		}
  1733  		*exclude = excl
  1734  	}
  1735  
  1736  	// Remove duplicate replacements.
  1737  	// Later replacements take priority over earlier ones.
  1738  	haveReplace := make(map[module.Version]bool)
  1739  	for i := len(*replace) - 1; i >= 0; i-- {
  1740  		x := (*replace)[i]
  1741  		if haveReplace[x.Old] {
  1742  			kill[x.Syntax] = true
  1743  			continue
  1744  		}
  1745  		haveReplace[x.Old] = true
  1746  	}
  1747  	var repl []*Replace
  1748  	for _, x := range *replace {
  1749  		if !kill[x.Syntax] {
  1750  			repl = append(repl, x)
  1751  		}
  1752  	}
  1753  	*replace = repl
  1754  
  1755  	if tool != nil {
  1756  		haveTool := make(map[string]bool)
  1757  		for _, t := range *tool {
  1758  			if haveTool[t.Path] {
  1759  				kill[t.Syntax] = true
  1760  				continue
  1761  			}
  1762  			haveTool[t.Path] = true
  1763  		}
  1764  		var newTool []*Tool
  1765  		for _, t := range *tool {
  1766  			if !kill[t.Syntax] {
  1767  				newTool = append(newTool, t)
  1768  			}
  1769  		}
  1770  		*tool = newTool
  1771  	}
  1772  
  1773  	if ignore != nil {
  1774  		haveIgnore := make(map[string]bool)
  1775  		for _, i := range *ignore {
  1776  			if haveIgnore[i.Path] {
  1777  				kill[i.Syntax] = true
  1778  				continue
  1779  			}
  1780  			haveIgnore[i.Path] = true
  1781  		}
  1782  		var newIgnore []*Ignore
  1783  		for _, i := range *ignore {
  1784  			if !kill[i.Syntax] {
  1785  				newIgnore = append(newIgnore, i)
  1786  			}
  1787  		}
  1788  		*ignore = newIgnore
  1789  	}
  1790  
  1791  	// Duplicate require and retract directives are not removed.
  1792  
  1793  	// Drop killed statements from the syntax tree.
  1794  	var stmts []Expr
  1795  	for _, stmt := range syntax.Stmt {
  1796  		switch stmt := stmt.(type) {
  1797  		case *Line:
  1798  			if kill[stmt] {
  1799  				continue
  1800  			}
  1801  		case *LineBlock:
  1802  			var lines []*Line
  1803  			for _, line := range stmt.Line {
  1804  				if !kill[line] {
  1805  					lines = append(lines, line)
  1806  				}
  1807  			}
  1808  			stmt.Line = lines
  1809  			if len(lines) == 0 {
  1810  				continue
  1811  			}
  1812  		}
  1813  		stmts = append(stmts, stmt)
  1814  	}
  1815  	syntax.Stmt = stmts
  1816  }
  1817  
  1818  // compareLine compares li and lj. It sorts lexicographically without assigning
  1819  // any special meaning to tokens.
  1820  func compareLine(li, lj *Line) int {
  1821  	for k := 0; k < len(li.Token) && k < len(lj.Token); k++ {
  1822  		if li.Token[k] != lj.Token[k] {
  1823  			return cmp.Compare(li.Token[k], lj.Token[k])
  1824  		}
  1825  	}
  1826  	return cmp.Compare(len(li.Token), len(lj.Token))
  1827  }
  1828  
  1829  // compareLineExclude compares li and lj for lines in an "exclude" block.
  1830  func compareLineExclude(li, lj *Line) int {
  1831  	if len(li.Token) != 2 || len(lj.Token) != 2 {
  1832  		// Not a known exclude specification.
  1833  		// Fall back to sorting lexicographically.
  1834  		return compareLine(li, lj)
  1835  	}
  1836  	// An exclude specification has two tokens: ModulePath and Version.
  1837  	// Compare module path by string order and version by semver rules.
  1838  	if pi, pj := li.Token[0], lj.Token[0]; pi != pj {
  1839  		return cmp.Compare(pi, pj)
  1840  	}
  1841  	return semver.Compare(li.Token[1], lj.Token[1])
  1842  }
  1843  
  1844  // compareLineRetract compares li and lj for lines in a "retract" block.
  1845  // It treats each line as a version interval. Single versions are compared as
  1846  // if they were intervals with the same low and high version.
  1847  // Intervals are sorted in descending order, first by low version, then by
  1848  // high version, using [semver.Compare].
  1849  func compareLineRetract(li, lj *Line) int {
  1850  	interval := func(l *Line) VersionInterval {
  1851  		if len(l.Token) == 1 {
  1852  			return VersionInterval{Low: l.Token[0], High: l.Token[0]}
  1853  		} else if len(l.Token) == 5 && l.Token[0] == "[" && l.Token[2] == "," && l.Token[4] == "]" {
  1854  			return VersionInterval{Low: l.Token[1], High: l.Token[3]}
  1855  		} else {
  1856  			// Line in unknown format. Treat as an invalid version.
  1857  			return VersionInterval{}
  1858  		}
  1859  	}
  1860  	vii := interval(li)
  1861  	vij := interval(lj)
  1862  	if cmp := semver.Compare(vii.Low, vij.Low); cmp != 0 {
  1863  		return -cmp
  1864  	}
  1865  	return -semver.Compare(vii.High, vij.High)
  1866  }
  1867  
  1868  // checkCanonicalVersion returns a non-nil error if vers is not a canonical
  1869  // version string or does not match the major version of path.
  1870  //
  1871  // If path is non-empty, the error text suggests a format with a major version
  1872  // corresponding to the path.
  1873  func checkCanonicalVersion(path, vers string) error {
  1874  	_, pathMajor, pathMajorOk := module.SplitPathVersion(path)
  1875  
  1876  	if vers == "" || vers != module.CanonicalVersion(vers) {
  1877  		if pathMajor == "" {
  1878  			return &module.InvalidVersionError{
  1879  				Version: vers,
  1880  				Err:     fmt.Errorf("must be of the form v1.2.3"),
  1881  			}
  1882  		}
  1883  		return &module.InvalidVersionError{
  1884  			Version: vers,
  1885  			Err:     fmt.Errorf("must be of the form %s.2.3", module.PathMajorPrefix(pathMajor)),
  1886  		}
  1887  	}
  1888  
  1889  	if pathMajorOk {
  1890  		if err := module.CheckPathMajor(vers, pathMajor); err != nil {
  1891  			if pathMajor == "" {
  1892  				// In this context, the user probably wrote "v2.3.4" when they meant
  1893  				// "v2.3.4+incompatible". Suggest that instead of "v0 or v1".
  1894  				return &module.InvalidVersionError{
  1895  					Version: vers,
  1896  					Err:     fmt.Errorf("should be %s+incompatible (or module %s/%v)", vers, path, semver.Major(vers)),
  1897  				}
  1898  			}
  1899  			return err
  1900  		}
  1901  	}
  1902  
  1903  	return nil
  1904  }
  1905  

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