Source file src/cmd/go/internal/load/pkg.go

     1  // Copyright 2011 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 load loads packages.
     6  package load
     7  
     8  import (
     9  	"bytes"
    10  	"context"
    11  	"crypto/sha256"
    12  	"encoding/json"
    13  	"errors"
    14  	"fmt"
    15  	"go/build"
    16  	"go/scanner"
    17  	"go/token"
    18  	"internal/platform"
    19  	"io/fs"
    20  	"os"
    21  	pathpkg "path"
    22  	"path/filepath"
    23  	"runtime"
    24  	"runtime/debug"
    25  	"slices"
    26  	"sort"
    27  	"strconv"
    28  	"strings"
    29  	"time"
    30  	"unicode"
    31  	"unicode/utf8"
    32  
    33  	"cmd/go/internal/base"
    34  	"cmd/go/internal/cfg"
    35  	"cmd/go/internal/fips140"
    36  	"cmd/go/internal/fsys"
    37  	"cmd/go/internal/gover"
    38  	"cmd/go/internal/imports"
    39  	"cmd/go/internal/modfetch"
    40  	"cmd/go/internal/modindex"
    41  	"cmd/go/internal/modinfo"
    42  	"cmd/go/internal/modload"
    43  	"cmd/go/internal/search"
    44  	"cmd/go/internal/str"
    45  	"cmd/go/internal/trace"
    46  	"cmd/go/internal/vcs"
    47  	"cmd/internal/par"
    48  	"cmd/internal/pathcache"
    49  	"cmd/internal/pkgpattern"
    50  
    51  	"golang.org/x/mod/modfile"
    52  	"golang.org/x/mod/module"
    53  )
    54  
    55  // A Package describes a single package found in a directory.
    56  type Package struct {
    57  	PackagePublic                 // visible in 'go list'
    58  	Internal      PackageInternal // for use inside go command only
    59  }
    60  
    61  type PackagePublic struct {
    62  	// Note: These fields are part of the go command's public API.
    63  	// See list.go. It is okay to add fields, but not to change or
    64  	// remove existing ones. Keep in sync with ../list/list.go
    65  	Dir           string                `json:",omitempty"` // directory containing package sources
    66  	ImportPath    string                `json:",omitempty"` // import path of package in dir
    67  	ImportComment string                `json:",omitempty"` // path in import comment on package statement
    68  	Name          string                `json:",omitempty"` // package name
    69  	Doc           string                `json:",omitempty"` // package documentation string
    70  	Target        string                `json:",omitempty"` // installed target for this package (may be executable)
    71  	Shlib         string                `json:",omitempty"` // the shared library that contains this package (only set when -linkshared)
    72  	Root          string                `json:",omitempty"` // Go root, Go path dir, or module root dir containing this package
    73  	ConflictDir   string                `json:",omitempty"` // Dir is hidden by this other directory
    74  	ForTest       string                `json:",omitempty"` // package is only for use in named test
    75  	Export        string                `json:",omitempty"` // file containing export data (set by go list -export)
    76  	BuildID       string                `json:",omitempty"` // build ID of the compiled package (set by go list -export)
    77  	Module        *modinfo.ModulePublic `json:",omitempty"` // info about package's module, if any
    78  	Match         []string              `json:",omitempty"` // command-line patterns matching this package
    79  	Goroot        bool                  `json:",omitempty"` // is this package found in the Go root?
    80  	Standard      bool                  `json:",omitempty"` // is this package part of the standard Go library?
    81  	DepOnly       bool                  `json:",omitempty"` // package is only as a dependency, not explicitly listed
    82  	BinaryOnly    bool                  `json:",omitempty"` // package cannot be recompiled
    83  	Incomplete    bool                  `json:",omitempty"` // was there an error loading this package or dependencies?
    84  
    85  	DefaultGODEBUG string `json:",omitempty"` // default GODEBUG setting (only for Name=="main")
    86  
    87  	// Stale and StaleReason remain here *only* for the list command.
    88  	// They are only initialized in preparation for list execution.
    89  	// The regular build determines staleness on the fly during action execution.
    90  	Stale       bool   `json:",omitempty"` // would 'go install' do anything for this package?
    91  	StaleReason string `json:",omitempty"` // why is Stale true?
    92  
    93  	// Source files
    94  	// If you add to this list you MUST add to p.AllFiles (below) too.
    95  	// Otherwise file name security lists will not apply to any new additions.
    96  	GoFiles           []string `json:",omitempty"` // .go source files (excluding CgoFiles, TestGoFiles, XTestGoFiles)
    97  	CgoFiles          []string `json:",omitempty"` // .go source files that import "C"
    98  	CompiledGoFiles   []string `json:",omitempty"` // .go output from running cgo on CgoFiles
    99  	IgnoredGoFiles    []string `json:",omitempty"` // .go source files ignored due to build constraints
   100  	InvalidGoFiles    []string `json:",omitempty"` // .go source files with detected problems (parse error, wrong package name, and so on)
   101  	IgnoredOtherFiles []string `json:",omitempty"` // non-.go source files ignored due to build constraints
   102  	CFiles            []string `json:",omitempty"` // .c source files
   103  	CXXFiles          []string `json:",omitempty"` // .cc, .cpp and .cxx source files
   104  	MFiles            []string `json:",omitempty"` // .m source files
   105  	HFiles            []string `json:",omitempty"` // .h, .hh, .hpp and .hxx source files
   106  	FFiles            []string `json:",omitempty"` // .f, .F, .for and .f90 Fortran source files
   107  	SFiles            []string `json:",omitempty"` // .s source files
   108  	SwigFiles         []string `json:",omitempty"` // .swig files
   109  	SwigCXXFiles      []string `json:",omitempty"` // .swigcxx files
   110  	SysoFiles         []string `json:",omitempty"` // .syso system object files added to package
   111  
   112  	// Embedded files
   113  	EmbedPatterns []string `json:",omitempty"` // //go:embed patterns
   114  	EmbedFiles    []string `json:",omitempty"` // files matched by EmbedPatterns
   115  
   116  	// Cgo directives
   117  	CgoCFLAGS    []string `json:",omitempty"` // cgo: flags for C compiler
   118  	CgoCPPFLAGS  []string `json:",omitempty"` // cgo: flags for C preprocessor
   119  	CgoCXXFLAGS  []string `json:",omitempty"` // cgo: flags for C++ compiler
   120  	CgoFFLAGS    []string `json:",omitempty"` // cgo: flags for Fortran compiler
   121  	CgoLDFLAGS   []string `json:",omitempty"` // cgo: flags for linker
   122  	CgoPkgConfig []string `json:",omitempty"` // cgo: pkg-config names
   123  
   124  	// Dependency information
   125  	Imports   []string          `json:",omitempty"` // import paths used by this package
   126  	ImportMap map[string]string `json:",omitempty"` // map from source import to ImportPath (identity entries omitted)
   127  	Deps      []string          `json:",omitempty"` // all (recursively) imported dependencies
   128  
   129  	// Error information
   130  	// Incomplete is above, packed into the other bools
   131  	Error      *PackageError   `json:",omitempty"` // error loading this package (not dependencies)
   132  	DepsErrors []*PackageError `json:",omitempty"` // errors loading dependencies, collected by go list before output
   133  
   134  	// Test information
   135  	// If you add to this list you MUST add to p.AllFiles (below) too.
   136  	// Otherwise file name security lists will not apply to any new additions.
   137  	TestGoFiles        []string `json:",omitempty"` // _test.go files in package
   138  	TestImports        []string `json:",omitempty"` // imports from TestGoFiles
   139  	TestEmbedPatterns  []string `json:",omitempty"` // //go:embed patterns
   140  	TestEmbedFiles     []string `json:",omitempty"` // files matched by TestEmbedPatterns
   141  	XTestGoFiles       []string `json:",omitempty"` // _test.go files outside package
   142  	XTestImports       []string `json:",omitempty"` // imports from XTestGoFiles
   143  	XTestEmbedPatterns []string `json:",omitempty"` // //go:embed patterns
   144  	XTestEmbedFiles    []string `json:",omitempty"` // files matched by XTestEmbedPatterns
   145  }
   146  
   147  // AllFiles returns the names of all the files considered for the package.
   148  // This is used for sanity and security checks, so we include all files,
   149  // even IgnoredGoFiles, because some subcommands consider them.
   150  // The go/build package filtered others out (like foo_wrongGOARCH.s)
   151  // and that's OK.
   152  func (p *Package) AllFiles() []string {
   153  	files := str.StringList(
   154  		p.GoFiles,
   155  		p.CgoFiles,
   156  		// no p.CompiledGoFiles, because they are from GoFiles or generated by us
   157  		p.IgnoredGoFiles,
   158  		// no p.InvalidGoFiles, because they are from GoFiles
   159  		p.IgnoredOtherFiles,
   160  		p.CFiles,
   161  		p.CXXFiles,
   162  		p.MFiles,
   163  		p.HFiles,
   164  		p.FFiles,
   165  		p.SFiles,
   166  		p.SwigFiles,
   167  		p.SwigCXXFiles,
   168  		p.SysoFiles,
   169  		p.TestGoFiles,
   170  		p.XTestGoFiles,
   171  	)
   172  
   173  	// EmbedFiles may overlap with the other files.
   174  	// Dedup, but delay building the map as long as possible.
   175  	// Only files in the current directory (no slash in name)
   176  	// need to be checked against the files variable above.
   177  	var have map[string]bool
   178  	for _, file := range p.EmbedFiles {
   179  		if !strings.Contains(file, "/") {
   180  			if have == nil {
   181  				have = make(map[string]bool)
   182  				for _, file := range files {
   183  					have[file] = true
   184  				}
   185  			}
   186  			if have[file] {
   187  				continue
   188  			}
   189  		}
   190  		files = append(files, file)
   191  	}
   192  	return files
   193  }
   194  
   195  // Desc returns the package "description", for use in b.showOutput.
   196  func (p *Package) Desc() string {
   197  	if p.ForTest != "" {
   198  		return p.ImportPath + " [" + p.ForTest + ".test]"
   199  	}
   200  	if p.Internal.ForMain != "" {
   201  		return p.ImportPath + " [" + p.Internal.ForMain + "]"
   202  	}
   203  	return p.ImportPath
   204  }
   205  
   206  // IsTestOnly reports whether p is a test-only package.
   207  //
   208  // A “test-only” package is one that:
   209  //   - is a test-only variant of an ordinary package, or
   210  //   - is a synthesized "main" package for a test binary, or
   211  //   - contains only _test.go files.
   212  func (p *Package) IsTestOnly() bool {
   213  	return p.ForTest != "" ||
   214  		p.Internal.TestmainGo != nil ||
   215  		len(p.TestGoFiles)+len(p.XTestGoFiles) > 0 && len(p.GoFiles)+len(p.CgoFiles) == 0
   216  }
   217  
   218  type PackageInternal struct {
   219  	// Unexported fields are not part of the public API.
   220  	Build             *build.Package
   221  	Imports           []*Package           // this package's direct imports
   222  	CompiledImports   []string             // additional Imports necessary when using CompiledGoFiles (all from standard library); 1:1 with the end of PackagePublic.Imports
   223  	RawImports        []string             // this package's original imports as they appear in the text of the program; 1:1 with the end of PackagePublic.Imports
   224  	ForceLibrary      bool                 // this package is a library (even if named "main")
   225  	CmdlineFiles      bool                 // package built from files listed on command line
   226  	CmdlinePkg        bool                 // package listed on command line
   227  	CmdlinePkgLiteral bool                 // package listed as literal on command line (not via wildcard)
   228  	Local             bool                 // imported via local path (./ or ../)
   229  	LocalPrefix       string               // interpret ./ and ../ imports relative to this prefix
   230  	ExeName           string               // desired name for temporary executable
   231  	FuzzInstrument    bool                 // package should be instrumented for fuzzing
   232  	Cover             CoverSetup           // coverage mode and other setup info of -cover is being applied to this package
   233  	CoverVars         map[string]*CoverVar // variables created by coverage analysis
   234  	OmitDebug         bool                 // tell linker not to write debug information
   235  	GobinSubdir       bool                 // install target would be subdir of GOBIN
   236  	BuildInfo         *debug.BuildInfo     // add this info to package main
   237  	TestmainGo        *[]byte              // content for _testmain.go
   238  	Embed             map[string][]string  // //go:embed comment mapping
   239  	OrigImportPath    string               // original import path before adding '_test' suffix
   240  	PGOProfile        string               // path to PGO profile
   241  	ForMain           string               // the main package if this package is built specifically for it
   242  
   243  	Asmflags   []string // -asmflags for this package
   244  	Gcflags    []string // -gcflags for this package
   245  	Ldflags    []string // -ldflags for this package
   246  	Gccgoflags []string // -gccgoflags for this package
   247  }
   248  
   249  // A NoGoError indicates that no Go files for the package were applicable to the
   250  // build for that package.
   251  //
   252  // That may be because there were no files whatsoever, or because all files were
   253  // excluded, or because all non-excluded files were test sources.
   254  type NoGoError struct {
   255  	Package *Package
   256  }
   257  
   258  func (e *NoGoError) Error() string {
   259  	if len(e.Package.IgnoredGoFiles) > 0 {
   260  		// Go files exist, but they were ignored due to build constraints.
   261  		return "build constraints exclude all Go files in " + e.Package.Dir
   262  	}
   263  	if len(e.Package.TestGoFiles)+len(e.Package.XTestGoFiles) > 0 {
   264  		// Test Go files exist, but we're not interested in them.
   265  		// The double-negative is unfortunate but we want e.Package.Dir
   266  		// to appear at the end of error message.
   267  		return "no non-test Go files in " + e.Package.Dir
   268  	}
   269  	return "no Go files in " + e.Package.Dir
   270  }
   271  
   272  // setLoadPackageDataError presents an error found when loading package data
   273  // as a *PackageError. It has special cases for some common errors to improve
   274  // messages shown to users and reduce redundancy.
   275  //
   276  // setLoadPackageDataError returns true if it's safe to load information about
   277  // imported packages, for example, if there was a parse error loading imports
   278  // in one file, but other files are okay.
   279  func (p *Package) setLoadPackageDataError(err error, path string, stk *ImportStack, importPos []token.Position) {
   280  	matchErr, isMatchErr := err.(*search.MatchError)
   281  	if isMatchErr && matchErr.Match.Pattern() == path {
   282  		if matchErr.Match.IsLiteral() {
   283  			// The error has a pattern has a pattern similar to the import path.
   284  			// It may be slightly different (./foo matching example.com/foo),
   285  			// but close enough to seem redundant.
   286  			// Unwrap the error so we don't show the pattern.
   287  			err = matchErr.Err
   288  		}
   289  	}
   290  
   291  	// Replace (possibly wrapped) *build.NoGoError with *load.NoGoError.
   292  	// The latter is more specific about the cause.
   293  	var nogoErr *build.NoGoError
   294  	if errors.As(err, &nogoErr) {
   295  		if p.Dir == "" && nogoErr.Dir != "" {
   296  			p.Dir = nogoErr.Dir
   297  		}
   298  		err = &NoGoError{Package: p}
   299  	}
   300  
   301  	// Take only the first error from a scanner.ErrorList. PackageError only
   302  	// has room for one position, so we report the first error with a position
   303  	// instead of all of the errors without a position.
   304  	var pos string
   305  	var isScanErr bool
   306  	if scanErr, ok := err.(scanner.ErrorList); ok && len(scanErr) > 0 {
   307  		isScanErr = true // For stack push/pop below.
   308  
   309  		scanPos := scanErr[0].Pos
   310  		scanPos.Filename = base.ShortPath(scanPos.Filename)
   311  		pos = scanPos.String()
   312  		err = errors.New(scanErr[0].Msg)
   313  	}
   314  
   315  	// Report the error on the importing package if the problem is with the import declaration
   316  	// for example, if the package doesn't exist or if the import path is malformed.
   317  	// On the other hand, don't include a position if the problem is with the imported package,
   318  	// for example there are no Go files (NoGoError), or there's a problem in the imported
   319  	// package's source files themselves (scanner errors).
   320  	//
   321  	// TODO(matloob): Perhaps make each of those the errors in the first group
   322  	// (including modload.ImportMissingError, ImportMissingSumError, and the
   323  	// corresponding "cannot find package %q in any of" GOPATH-mode error
   324  	// produced in build.(*Context).Import; modload.AmbiguousImportError,
   325  	// and modload.PackageNotInModuleError; and the malformed module path errors
   326  	// produced in golang.org/x/mod/module.CheckMod) implement an interface
   327  	// to make it easier to check for them? That would save us from having to
   328  	// move the modload errors into this package to avoid a package import cycle,
   329  	// and from having to export an error type for the errors produced in build.
   330  	if !isMatchErr && (nogoErr != nil || isScanErr) {
   331  		stk.Push(ImportInfo{Pkg: path, Pos: extractFirstImport(importPos)})
   332  		defer stk.Pop()
   333  	}
   334  
   335  	p.Error = &PackageError{
   336  		ImportStack: stk.Copy(),
   337  		Pos:         pos,
   338  		Err:         err,
   339  	}
   340  	p.Incomplete = true
   341  
   342  	top, ok := stk.Top()
   343  	if ok && path != top.Pkg {
   344  		p.Error.setPos(importPos)
   345  	}
   346  }
   347  
   348  // Resolve returns the resolved version of imports,
   349  // which should be p.TestImports or p.XTestImports, NOT p.Imports.
   350  // The imports in p.TestImports and p.XTestImports are not recursively
   351  // loaded during the initial load of p, so they list the imports found in
   352  // the source file, but most processing should be over the vendor-resolved
   353  // import paths. We do this resolution lazily both to avoid file system work
   354  // and because the eventual real load of the test imports (during 'go test')
   355  // can produce better error messages if it starts with the original paths.
   356  // The initial load of p loads all the non-test imports and rewrites
   357  // the vendored paths, so nothing should ever call p.vendored(p.Imports).
   358  func (p *Package) Resolve(imports []string) []string {
   359  	if len(imports) > 0 && len(p.Imports) > 0 && &imports[0] == &p.Imports[0] {
   360  		panic("internal error: p.Resolve(p.Imports) called")
   361  	}
   362  	seen := make(map[string]bool)
   363  	var all []string
   364  	for _, path := range imports {
   365  		path = ResolveImportPath(p, path)
   366  		if !seen[path] {
   367  			seen[path] = true
   368  			all = append(all, path)
   369  		}
   370  	}
   371  	sort.Strings(all)
   372  	return all
   373  }
   374  
   375  // CoverVar holds the name of the generated coverage variables targeting the named file.
   376  type CoverVar struct {
   377  	File string // local file name
   378  	Var  string // name of count struct
   379  }
   380  
   381  // CoverSetup holds parameters related to coverage setup for a given package (covermode, etc).
   382  type CoverSetup struct {
   383  	Mode    string // coverage mode for this package
   384  	Cfg     string // path to config file to pass to "go tool cover"
   385  	GenMeta bool   // ask cover tool to emit a static meta data if set
   386  }
   387  
   388  func (p *Package) copyBuild(opts PackageOpts, pp *build.Package) {
   389  	p.Internal.Build = pp
   390  
   391  	if pp.PkgTargetRoot != "" && cfg.BuildPkgdir != "" {
   392  		old := pp.PkgTargetRoot
   393  		pp.PkgRoot = cfg.BuildPkgdir
   394  		pp.PkgTargetRoot = cfg.BuildPkgdir
   395  		if pp.PkgObj != "" {
   396  			pp.PkgObj = filepath.Join(cfg.BuildPkgdir, strings.TrimPrefix(pp.PkgObj, old))
   397  		}
   398  	}
   399  
   400  	p.Dir = pp.Dir
   401  	p.ImportPath = pp.ImportPath
   402  	p.ImportComment = pp.ImportComment
   403  	p.Name = pp.Name
   404  	p.Doc = pp.Doc
   405  	p.Root = pp.Root
   406  	p.ConflictDir = pp.ConflictDir
   407  	p.BinaryOnly = pp.BinaryOnly
   408  
   409  	// TODO? Target
   410  	p.Goroot = pp.Goroot || fips140.Snapshot() && str.HasFilePathPrefix(p.Dir, fips140.Dir())
   411  	p.Standard = p.Goroot && p.ImportPath != "" && search.IsStandardImportPath(p.ImportPath)
   412  	p.GoFiles = pp.GoFiles
   413  	p.CgoFiles = pp.CgoFiles
   414  	p.IgnoredGoFiles = pp.IgnoredGoFiles
   415  	p.InvalidGoFiles = pp.InvalidGoFiles
   416  	p.IgnoredOtherFiles = pp.IgnoredOtherFiles
   417  	p.CFiles = pp.CFiles
   418  	p.CXXFiles = pp.CXXFiles
   419  	p.MFiles = pp.MFiles
   420  	p.HFiles = pp.HFiles
   421  	p.FFiles = pp.FFiles
   422  	p.SFiles = pp.SFiles
   423  	p.SwigFiles = pp.SwigFiles
   424  	p.SwigCXXFiles = pp.SwigCXXFiles
   425  	p.SysoFiles = pp.SysoFiles
   426  	if cfg.BuildMSan {
   427  		// There's no way for .syso files to be built both with and without
   428  		// support for memory sanitizer. Assume they are built without,
   429  		// and drop them.
   430  		p.SysoFiles = nil
   431  	}
   432  	p.CgoCFLAGS = pp.CgoCFLAGS
   433  	p.CgoCPPFLAGS = pp.CgoCPPFLAGS
   434  	p.CgoCXXFLAGS = pp.CgoCXXFLAGS
   435  	p.CgoFFLAGS = pp.CgoFFLAGS
   436  	p.CgoLDFLAGS = pp.CgoLDFLAGS
   437  	p.CgoPkgConfig = pp.CgoPkgConfig
   438  	// We modify p.Imports in place, so make copy now.
   439  	p.Imports = make([]string, len(pp.Imports))
   440  	copy(p.Imports, pp.Imports)
   441  	p.Internal.RawImports = pp.Imports
   442  	p.TestGoFiles = pp.TestGoFiles
   443  	p.TestImports = pp.TestImports
   444  	p.XTestGoFiles = pp.XTestGoFiles
   445  	p.XTestImports = pp.XTestImports
   446  	if opts.IgnoreImports {
   447  		p.Imports = nil
   448  		p.Internal.RawImports = nil
   449  		p.TestImports = nil
   450  		p.XTestImports = nil
   451  	}
   452  	p.EmbedPatterns = pp.EmbedPatterns
   453  	p.TestEmbedPatterns = pp.TestEmbedPatterns
   454  	p.XTestEmbedPatterns = pp.XTestEmbedPatterns
   455  	p.Internal.OrigImportPath = pp.ImportPath
   456  }
   457  
   458  // A PackageError describes an error loading information about a package.
   459  type PackageError struct {
   460  	ImportStack      ImportStack // shortest path from package named on command line to this one with position
   461  	Pos              string      // position of error
   462  	Err              error       // the error itself
   463  	IsImportCycle    bool        // the error is an import cycle
   464  	alwaysPrintStack bool        // whether to always print the ImportStack
   465  }
   466  
   467  func (p *PackageError) Error() string {
   468  	// TODO(#43696): decide when to print the stack or the position based on
   469  	// the error type and whether the package is in the main module.
   470  	// Document the rationale.
   471  	if p.Pos != "" && (len(p.ImportStack) == 0 || !p.alwaysPrintStack) {
   472  		// Omit import stack. The full path to the file where the error
   473  		// is the most important thing.
   474  		return p.Pos + ": " + p.Err.Error()
   475  	}
   476  
   477  	// If the error is an ImportPathError, and the last path on the stack appears
   478  	// in the error message, omit that path from the stack to avoid repetition.
   479  	// If an ImportPathError wraps another ImportPathError that matches the
   480  	// last path on the stack, we don't omit the path. An error like
   481  	// "package A imports B: error loading C caused by B" would not be clearer
   482  	// if "imports B" were omitted.
   483  	if len(p.ImportStack) == 0 {
   484  		return p.Err.Error()
   485  	}
   486  	var optpos string
   487  	if p.Pos != "" {
   488  		optpos = "\n\t" + p.Pos
   489  	}
   490  	imports := p.ImportStack.Pkgs()
   491  	if p.IsImportCycle {
   492  		imports = p.ImportStack.PkgsWithPos()
   493  	}
   494  	return "package " + strings.Join(imports, "\n\timports ") + optpos + ": " + p.Err.Error()
   495  }
   496  
   497  func (p *PackageError) Unwrap() error { return p.Err }
   498  
   499  // PackageError implements MarshalJSON so that Err is marshaled as a string
   500  // and non-essential fields are omitted.
   501  func (p *PackageError) MarshalJSON() ([]byte, error) {
   502  	perr := struct {
   503  		ImportStack []string // use []string for package names
   504  		Pos         string
   505  		Err         string
   506  	}{p.ImportStack.Pkgs(), p.Pos, p.Err.Error()}
   507  	return json.Marshal(perr)
   508  }
   509  
   510  func (p *PackageError) setPos(posList []token.Position) {
   511  	if len(posList) == 0 {
   512  		return
   513  	}
   514  	pos := posList[0]
   515  	pos.Filename = base.ShortPath(pos.Filename)
   516  	p.Pos = pos.String()
   517  }
   518  
   519  // ImportPathError is a type of error that prevents a package from being loaded
   520  // for a given import path. When such a package is loaded, a *Package is
   521  // returned with Err wrapping an ImportPathError: the error is attached to
   522  // the imported package, not the importing package.
   523  //
   524  // The string returned by ImportPath must appear in the string returned by
   525  // Error. Errors that wrap ImportPathError (such as PackageError) may omit
   526  // the import path.
   527  type ImportPathError interface {
   528  	error
   529  	ImportPath() string
   530  }
   531  
   532  var (
   533  	_ ImportPathError = (*importError)(nil)
   534  	_ ImportPathError = (*mainPackageError)(nil)
   535  	_ ImportPathError = (*modload.ImportMissingError)(nil)
   536  	_ ImportPathError = (*modload.ImportMissingSumError)(nil)
   537  	_ ImportPathError = (*modload.DirectImportFromImplicitDependencyError)(nil)
   538  )
   539  
   540  type importError struct {
   541  	importPath string
   542  	err        error // created with fmt.Errorf
   543  }
   544  
   545  func ImportErrorf(path, format string, args ...any) ImportPathError {
   546  	err := &importError{importPath: path, err: fmt.Errorf(format, args...)}
   547  	if errStr := err.Error(); !strings.Contains(errStr, path) && !strings.Contains(errStr, strconv.Quote(path)) {
   548  		panic(fmt.Sprintf("path %q not in error %q", path, errStr))
   549  	}
   550  	return err
   551  }
   552  
   553  func (e *importError) Error() string {
   554  	return e.err.Error()
   555  }
   556  
   557  func (e *importError) Unwrap() error {
   558  	// Don't return e.err directly, since we're only wrapping an error if %w
   559  	// was passed to ImportErrorf.
   560  	return errors.Unwrap(e.err)
   561  }
   562  
   563  func (e *importError) ImportPath() string {
   564  	return e.importPath
   565  }
   566  
   567  type ImportInfo struct {
   568  	Pkg string
   569  	Pos *token.Position
   570  }
   571  
   572  // An ImportStack is a stack of import paths, possibly with the suffix " (test)" appended.
   573  // The import path of a test package is the import path of the corresponding
   574  // non-test package with the suffix "_test" added.
   575  type ImportStack []ImportInfo
   576  
   577  func NewImportInfo(pkg string, pos *token.Position) ImportInfo {
   578  	return ImportInfo{Pkg: pkg, Pos: pos}
   579  }
   580  
   581  func (s *ImportStack) Push(p ImportInfo) {
   582  	*s = append(*s, p)
   583  }
   584  
   585  func (s *ImportStack) Pop() {
   586  	*s = (*s)[0 : len(*s)-1]
   587  }
   588  
   589  func (s *ImportStack) Copy() ImportStack {
   590  	return slices.Clone(*s)
   591  }
   592  
   593  func (s *ImportStack) Pkgs() []string {
   594  	ss := make([]string, 0, len(*s))
   595  	for _, v := range *s {
   596  		ss = append(ss, v.Pkg)
   597  	}
   598  	return ss
   599  }
   600  
   601  func (s *ImportStack) PkgsWithPos() []string {
   602  	ss := make([]string, 0, len(*s))
   603  	for _, v := range *s {
   604  		if v.Pos != nil {
   605  			ss = append(ss, v.Pkg+" from "+filepath.Base(v.Pos.Filename))
   606  		} else {
   607  			ss = append(ss, v.Pkg)
   608  		}
   609  	}
   610  	return ss
   611  }
   612  
   613  func (s *ImportStack) Top() (ImportInfo, bool) {
   614  	if len(*s) == 0 {
   615  		return ImportInfo{}, false
   616  	}
   617  	return (*s)[len(*s)-1], true
   618  }
   619  
   620  // shorterThan reports whether sp is shorter than t.
   621  // We use this to record the shortest import sequence
   622  // that leads to a particular package.
   623  func (sp *ImportStack) shorterThan(t []string) bool {
   624  	s := *sp
   625  	if len(s) != len(t) {
   626  		return len(s) < len(t)
   627  	}
   628  	// If they are the same length, settle ties using string ordering.
   629  	for i := range s {
   630  		siPkg := s[i].Pkg
   631  		if siPkg != t[i] {
   632  			return siPkg < t[i]
   633  		}
   634  	}
   635  	return false // they are equal
   636  }
   637  
   638  // packageCache is a lookup cache for LoadImport,
   639  // so that if we look up a package multiple times
   640  // we return the same pointer each time.
   641  var packageCache = map[string]*Package{}
   642  
   643  // dirToImportPath returns the pseudo-import path we use for a package
   644  // outside the Go path. It begins with _/ and then contains the full path
   645  // to the directory. If the package lives in c:\home\gopher\my\pkg then
   646  // the pseudo-import path is _/c_/home/gopher/my/pkg.
   647  // Using a pseudo-import path like this makes the ./ imports no longer
   648  // a special case, so that all the code to deal with ordinary imports works
   649  // automatically.
   650  func dirToImportPath(dir string) string {
   651  	return pathpkg.Join("_", strings.Map(makeImportValid, filepath.ToSlash(dir)))
   652  }
   653  
   654  func makeImportValid(r rune) rune {
   655  	// Should match Go spec, compilers, and ../../go/parser/parser.go:/isValidImport.
   656  	const illegalChars = `!"#$%&'()*,:;<=>?[\]^{|}` + "`\uFFFD"
   657  	if !unicode.IsGraphic(r) || unicode.IsSpace(r) || strings.ContainsRune(illegalChars, r) {
   658  		return '_'
   659  	}
   660  	return r
   661  }
   662  
   663  // Mode flags for loadImport and download (in get.go).
   664  const (
   665  	// ResolveImport means that loadImport should do import path expansion.
   666  	// That is, ResolveImport means that the import path came from
   667  	// a source file and has not been expanded yet to account for
   668  	// vendoring or possible module adjustment.
   669  	// Every import path should be loaded initially with ResolveImport,
   670  	// and then the expanded version (for example with the /vendor/ in it)
   671  	// gets recorded as the canonical import path. At that point, future loads
   672  	// of that package must not pass ResolveImport, because
   673  	// disallowVendor will reject direct use of paths containing /vendor/.
   674  	ResolveImport = 1 << iota
   675  
   676  	// ResolveModule is for download (part of "go get") and indicates
   677  	// that the module adjustment should be done, but not vendor adjustment.
   678  	ResolveModule
   679  
   680  	// GetTestDeps is for download (part of "go get") and indicates
   681  	// that test dependencies should be fetched too.
   682  	GetTestDeps
   683  
   684  	// The remainder are internal modes for calls to loadImport.
   685  
   686  	// cmdlinePkg is for a package mentioned on the command line.
   687  	cmdlinePkg
   688  
   689  	// cmdlinePkgLiteral is for a package mentioned on the command line
   690  	// without using any wildcards or meta-patterns.
   691  	cmdlinePkgLiteral
   692  )
   693  
   694  // LoadPackage does Load import, but without a parent package load context
   695  func LoadPackage(ctx context.Context, opts PackageOpts, path, srcDir string, stk *ImportStack, importPos []token.Position, mode int) *Package {
   696  	p, err := loadImport(ctx, opts, nil, path, srcDir, nil, stk, importPos, mode)
   697  	if err != nil {
   698  		base.Fatalf("internal error: loadImport of %q with nil parent returned an error", path)
   699  	}
   700  	return p
   701  }
   702  
   703  // loadImport scans the directory named by path, which must be an import path,
   704  // but possibly a local import path (an absolute file system path or one beginning
   705  // with ./ or ../). A local relative path is interpreted relative to srcDir.
   706  // It returns a *Package describing the package found in that directory.
   707  // loadImport does not set tool flags and should only be used by
   708  // this package, as part of a bigger load operation.
   709  // The returned PackageError, if any, describes why parent is not allowed
   710  // to import the named package, with the error referring to importPos.
   711  // The PackageError can only be non-nil when parent is not nil.
   712  func loadImport(ctx context.Context, opts PackageOpts, pre *preload, path, srcDir string, parent *Package, stk *ImportStack, importPos []token.Position, mode int) (*Package, *PackageError) {
   713  	ctx, span := trace.StartSpan(ctx, "modload.loadImport "+path)
   714  	defer span.Done()
   715  
   716  	if path == "" {
   717  		panic("LoadImport called with empty package path")
   718  	}
   719  
   720  	var parentPath, parentRoot string
   721  	parentIsStd := false
   722  	if parent != nil {
   723  		parentPath = parent.ImportPath
   724  		parentRoot = parent.Root
   725  		parentIsStd = parent.Standard
   726  	}
   727  	bp, loaded, err := loadPackageData(ctx, path, parentPath, srcDir, parentRoot, parentIsStd, mode)
   728  	if loaded && pre != nil && !opts.IgnoreImports {
   729  		pre.preloadImports(ctx, opts, bp.Imports, bp)
   730  	}
   731  	if bp == nil {
   732  		p := &Package{
   733  			PackagePublic: PackagePublic{
   734  				ImportPath: path,
   735  				Incomplete: true,
   736  			},
   737  		}
   738  		if importErr, ok := err.(ImportPathError); !ok || importErr.ImportPath() != path {
   739  			// Only add path to the error's import stack if it's not already present
   740  			// in the error.
   741  			//
   742  			// TODO(bcmills): setLoadPackageDataError itself has a similar Push / Pop
   743  			// sequence that empirically doesn't trigger for these errors, guarded by
   744  			// a somewhat complex condition. Figure out how to generalize that
   745  			// condition and eliminate the explicit calls here.
   746  			stk.Push(ImportInfo{Pkg: path, Pos: extractFirstImport(importPos)})
   747  			defer stk.Pop()
   748  		}
   749  		p.setLoadPackageDataError(err, path, stk, nil)
   750  		return p, nil
   751  	}
   752  
   753  	setCmdline := func(p *Package) {
   754  		if mode&cmdlinePkg != 0 {
   755  			p.Internal.CmdlinePkg = true
   756  		}
   757  		if mode&cmdlinePkgLiteral != 0 {
   758  			p.Internal.CmdlinePkgLiteral = true
   759  		}
   760  	}
   761  
   762  	importPath := bp.ImportPath
   763  	p := packageCache[importPath]
   764  	if p != nil {
   765  		stk.Push(ImportInfo{Pkg: path, Pos: extractFirstImport(importPos)})
   766  		p = reusePackage(p, stk)
   767  		stk.Pop()
   768  		setCmdline(p)
   769  	} else {
   770  		p = new(Package)
   771  		p.Internal.Local = build.IsLocalImport(path)
   772  		p.ImportPath = importPath
   773  		packageCache[importPath] = p
   774  
   775  		setCmdline(p)
   776  
   777  		// Load package.
   778  		// loadPackageData may return bp != nil even if an error occurs,
   779  		// in order to return partial information.
   780  		p.load(ctx, opts, path, stk, importPos, bp, err)
   781  
   782  		if !cfg.ModulesEnabled && path != cleanImport(path) {
   783  			p.Error = &PackageError{
   784  				ImportStack: stk.Copy(),
   785  				Err:         ImportErrorf(path, "non-canonical import path %q: should be %q", path, pathpkg.Clean(path)),
   786  			}
   787  			p.Incomplete = true
   788  			p.Error.setPos(importPos)
   789  		}
   790  	}
   791  
   792  	// Checked on every import because the rules depend on the code doing the importing.
   793  	if perr := disallowInternal(ctx, srcDir, parent, parentPath, p, stk); perr != nil {
   794  		perr.setPos(importPos)
   795  		return p, perr
   796  	}
   797  	if mode&ResolveImport != 0 {
   798  		if perr := disallowVendor(srcDir, path, parentPath, p, stk); perr != nil {
   799  			perr.setPos(importPos)
   800  			return p, perr
   801  		}
   802  	}
   803  
   804  	if p.Name == "main" && parent != nil && parent.Dir != p.Dir {
   805  		perr := &PackageError{
   806  			ImportStack: stk.Copy(),
   807  			Err:         ImportErrorf(path, "import %q is a program, not an importable package", path),
   808  		}
   809  		perr.setPos(importPos)
   810  		return p, perr
   811  	}
   812  
   813  	if p.Internal.Local && parent != nil && !parent.Internal.Local {
   814  		var err error
   815  		if path == "." {
   816  			err = ImportErrorf(path, "%s: cannot import current directory", path)
   817  		} else {
   818  			err = ImportErrorf(path, "local import %q in non-local package", path)
   819  		}
   820  		perr := &PackageError{
   821  			ImportStack: stk.Copy(),
   822  			Err:         err,
   823  		}
   824  		perr.setPos(importPos)
   825  		return p, perr
   826  	}
   827  
   828  	return p, nil
   829  }
   830  
   831  func extractFirstImport(importPos []token.Position) *token.Position {
   832  	if len(importPos) == 0 {
   833  		return nil
   834  	}
   835  	return &importPos[0]
   836  }
   837  
   838  // loadPackageData loads information needed to construct a *Package. The result
   839  // is cached, and later calls to loadPackageData for the same package will return
   840  // the same data.
   841  //
   842  // loadPackageData returns a non-nil package even if err is non-nil unless
   843  // the package path is malformed (for example, the path contains "mod/" or "@").
   844  //
   845  // loadPackageData returns a boolean, loaded, which is true if this is the
   846  // first time the package was loaded. Callers may preload imports in this case.
   847  func loadPackageData(ctx context.Context, path, parentPath, parentDir, parentRoot string, parentIsStd bool, mode int) (bp *build.Package, loaded bool, err error) {
   848  	ctx, span := trace.StartSpan(ctx, "load.loadPackageData "+path)
   849  	defer span.Done()
   850  
   851  	if path == "" {
   852  		panic("loadPackageData called with empty package path")
   853  	}
   854  
   855  	if strings.HasPrefix(path, "mod/") {
   856  		// Paths beginning with "mod/" might accidentally
   857  		// look in the module cache directory tree in $GOPATH/pkg/mod/.
   858  		// This prefix is owned by the Go core for possible use in the
   859  		// standard library (since it does not begin with a domain name),
   860  		// so it's OK to disallow entirely.
   861  		return nil, false, fmt.Errorf("disallowed import path %q", path)
   862  	}
   863  
   864  	if strings.Contains(path, "@") {
   865  		return nil, false, errors.New("can only use path@version syntax with 'go get' and 'go install' in module-aware mode")
   866  	}
   867  
   868  	// Determine canonical package path and directory.
   869  	// For a local import the identifier is the pseudo-import path
   870  	// we create from the full directory to the package.
   871  	// Otherwise it is the usual import path.
   872  	// For vendored imports, it is the expanded form.
   873  	//
   874  	// Note that when modules are enabled, local import paths are normally
   875  	// canonicalized by modload.LoadPackages before now. However, if there's an
   876  	// error resolving a local path, it will be returned untransformed
   877  	// so that 'go list -e' reports something useful.
   878  	importKey := importSpec{
   879  		path:        path,
   880  		parentPath:  parentPath,
   881  		parentDir:   parentDir,
   882  		parentRoot:  parentRoot,
   883  		parentIsStd: parentIsStd,
   884  		mode:        mode,
   885  	}
   886  	r := resolvedImportCache.Do(importKey, func() resolvedImport {
   887  		var r resolvedImport
   888  		if newPath, dir, ok := fips140.ResolveImport(path); ok {
   889  			r.path = newPath
   890  			r.dir = dir
   891  		} else if cfg.ModulesEnabled {
   892  			r.dir, r.path, r.err = modload.Lookup(parentPath, parentIsStd, path)
   893  		} else if build.IsLocalImport(path) {
   894  			r.dir = filepath.Join(parentDir, path)
   895  			r.path = dirToImportPath(r.dir)
   896  		} else if mode&ResolveImport != 0 {
   897  			// We do our own path resolution, because we want to
   898  			// find out the key to use in packageCache without the
   899  			// overhead of repeated calls to buildContext.Import.
   900  			// The code is also needed in a few other places anyway.
   901  			r.path = resolveImportPath(path, parentPath, parentDir, parentRoot, parentIsStd)
   902  		} else if mode&ResolveModule != 0 {
   903  			r.path = moduleImportPath(path, parentPath, parentDir, parentRoot)
   904  		}
   905  		if r.path == "" {
   906  			r.path = path
   907  		}
   908  		return r
   909  	})
   910  	// Invariant: r.path is set to the resolved import path. If the path cannot
   911  	// be resolved, r.path is set to path, the source import path.
   912  	// r.path is never empty.
   913  
   914  	// Load the package from its directory. If we already found the package's
   915  	// directory when resolving its import path, use that.
   916  	p, err := packageDataCache.Do(r.path, func() (*build.Package, error) {
   917  		loaded = true
   918  		var data struct {
   919  			p   *build.Package
   920  			err error
   921  		}
   922  		if r.dir != "" {
   923  			var buildMode build.ImportMode
   924  			buildContext := cfg.BuildContext
   925  			if !cfg.ModulesEnabled {
   926  				buildMode = build.ImportComment
   927  			} else {
   928  				buildContext.GOPATH = "" // Clear GOPATH so packages are imported as pure module packages
   929  			}
   930  			modroot := modload.PackageModRoot(ctx, r.path)
   931  			if modroot == "" && str.HasPathPrefix(r.dir, cfg.GOROOTsrc) {
   932  				modroot = cfg.GOROOTsrc
   933  				gorootSrcCmd := filepath.Join(cfg.GOROOTsrc, "cmd")
   934  				if str.HasPathPrefix(r.dir, gorootSrcCmd) {
   935  					modroot = gorootSrcCmd
   936  				}
   937  			}
   938  			if modroot != "" {
   939  				if rp, err := modindex.GetPackage(modroot, r.dir); err == nil {
   940  					data.p, data.err = rp.Import(cfg.BuildContext, buildMode)
   941  					goto Happy
   942  				} else if !errors.Is(err, modindex.ErrNotIndexed) {
   943  					base.Fatal(err)
   944  				}
   945  			}
   946  			data.p, data.err = buildContext.ImportDir(r.dir, buildMode)
   947  		Happy:
   948  			if cfg.ModulesEnabled {
   949  				// Override data.p.Root, since ImportDir sets it to $GOPATH, if
   950  				// the module is inside $GOPATH/src.
   951  				if info := modload.PackageModuleInfo(ctx, path); info != nil {
   952  					data.p.Root = info.Dir
   953  				}
   954  			}
   955  			if r.err != nil {
   956  				if data.err != nil {
   957  					// ImportDir gave us one error, and the module loader gave us another.
   958  					// We arbitrarily choose to keep the error from ImportDir because
   959  					// that's what our tests already expect, and it seems to provide a bit
   960  					// more detail in most cases.
   961  				} else if errors.Is(r.err, imports.ErrNoGo) {
   962  					// ImportDir said there were files in the package, but the module
   963  					// loader said there weren't. Which one is right?
   964  					// Without this special-case hack, the TestScript/test_vet case fails
   965  					// on the vetfail/p1 package (added in CL 83955).
   966  					// Apparently, imports.ShouldBuild biases toward rejecting files
   967  					// with invalid build constraints, whereas ImportDir biases toward
   968  					// accepting them.
   969  					//
   970  					// TODO(#41410: Figure out how this actually ought to work and fix
   971  					// this mess).
   972  				} else {
   973  					data.err = r.err
   974  				}
   975  			}
   976  		} else if r.err != nil {
   977  			data.p = new(build.Package)
   978  			data.err = r.err
   979  		} else if cfg.ModulesEnabled && path != "unsafe" {
   980  			data.p = new(build.Package)
   981  			data.err = fmt.Errorf("unknown import path %q: internal error: module loader did not resolve import", r.path)
   982  		} else {
   983  			buildMode := build.ImportComment
   984  			if mode&ResolveImport == 0 || r.path != path {
   985  				// Not vendoring, or we already found the vendored path.
   986  				buildMode |= build.IgnoreVendor
   987  			}
   988  			data.p, data.err = cfg.BuildContext.Import(r.path, parentDir, buildMode)
   989  		}
   990  		data.p.ImportPath = r.path
   991  
   992  		// Set data.p.BinDir in cases where go/build.Context.Import
   993  		// may give us a path we don't want.
   994  		if !data.p.Goroot {
   995  			if cfg.GOBIN != "" {
   996  				data.p.BinDir = cfg.GOBIN
   997  			} else if cfg.ModulesEnabled {
   998  				data.p.BinDir = modload.BinDir()
   999  			}
  1000  		}
  1001  
  1002  		if !cfg.ModulesEnabled && data.err == nil &&
  1003  			data.p.ImportComment != "" && data.p.ImportComment != path &&
  1004  			!strings.Contains(path, "/vendor/") && !strings.HasPrefix(path, "vendor/") {
  1005  			data.err = fmt.Errorf("code in directory %s expects import %q", data.p.Dir, data.p.ImportComment)
  1006  		}
  1007  		return data.p, data.err
  1008  	})
  1009  
  1010  	return p, loaded, err
  1011  }
  1012  
  1013  // importSpec describes an import declaration in source code. It is used as a
  1014  // cache key for resolvedImportCache.
  1015  type importSpec struct {
  1016  	path                              string
  1017  	parentPath, parentDir, parentRoot string
  1018  	parentIsStd                       bool
  1019  	mode                              int
  1020  }
  1021  
  1022  // resolvedImport holds a canonical identifier for a package. It may also contain
  1023  // a path to the package's directory and an error if one occurred. resolvedImport
  1024  // is the value type in resolvedImportCache.
  1025  type resolvedImport struct {
  1026  	path, dir string
  1027  	err       error
  1028  }
  1029  
  1030  // resolvedImportCache maps import strings to canonical package names.
  1031  var resolvedImportCache par.Cache[importSpec, resolvedImport]
  1032  
  1033  // packageDataCache maps canonical package names (string) to package metadata.
  1034  var packageDataCache par.ErrCache[string, *build.Package]
  1035  
  1036  // preloadWorkerCount is the number of concurrent goroutines that can load
  1037  // packages. Experimentally, there are diminishing returns with more than
  1038  // 4 workers. This was measured on the following machines.
  1039  //
  1040  // * MacBookPro with a 4-core Intel Core i7 CPU
  1041  // * Linux workstation with 6-core Intel Xeon CPU
  1042  // * Linux workstation with 24-core Intel Xeon CPU
  1043  //
  1044  // It is very likely (though not confirmed) that this workload is limited
  1045  // by memory bandwidth. We don't have a good way to determine the number of
  1046  // workers that would saturate the bus though, so runtime.GOMAXPROCS
  1047  // seems like a reasonable default.
  1048  var preloadWorkerCount = runtime.GOMAXPROCS(0)
  1049  
  1050  // preload holds state for managing concurrent preloading of package data.
  1051  //
  1052  // A preload should be created with newPreload before loading a large
  1053  // package graph. flush must be called when package loading is complete
  1054  // to ensure preload goroutines are no longer active. This is necessary
  1055  // because of global mutable state that cannot safely be read and written
  1056  // concurrently. In particular, packageDataCache may be cleared by "go get"
  1057  // in GOPATH mode, and modload.loaded (accessed via modload.Lookup) may be
  1058  // modified by modload.LoadPackages.
  1059  type preload struct {
  1060  	cancel chan struct{}
  1061  	sema   chan struct{}
  1062  }
  1063  
  1064  // newPreload creates a new preloader. flush must be called later to avoid
  1065  // accessing global state while it is being modified.
  1066  func newPreload() *preload {
  1067  	pre := &preload{
  1068  		cancel: make(chan struct{}),
  1069  		sema:   make(chan struct{}, preloadWorkerCount),
  1070  	}
  1071  	return pre
  1072  }
  1073  
  1074  // preloadMatches loads data for package paths matched by patterns.
  1075  // When preloadMatches returns, some packages may not be loaded yet, but
  1076  // loadPackageData and loadImport are always safe to call.
  1077  func (pre *preload) preloadMatches(ctx context.Context, opts PackageOpts, matches []*search.Match) {
  1078  	for _, m := range matches {
  1079  		for _, pkg := range m.Pkgs {
  1080  			select {
  1081  			case <-pre.cancel:
  1082  				return
  1083  			case pre.sema <- struct{}{}:
  1084  				go func(pkg string) {
  1085  					mode := 0 // don't use vendoring or module import resolution
  1086  					bp, loaded, err := loadPackageData(ctx, pkg, "", base.Cwd(), "", false, mode)
  1087  					<-pre.sema
  1088  					if bp != nil && loaded && err == nil && !opts.IgnoreImports {
  1089  						pre.preloadImports(ctx, opts, bp.Imports, bp)
  1090  					}
  1091  				}(pkg)
  1092  			}
  1093  		}
  1094  	}
  1095  }
  1096  
  1097  // preloadImports queues a list of imports for preloading.
  1098  // When preloadImports returns, some packages may not be loaded yet,
  1099  // but loadPackageData and loadImport are always safe to call.
  1100  func (pre *preload) preloadImports(ctx context.Context, opts PackageOpts, imports []string, parent *build.Package) {
  1101  	parentIsStd := parent.Goroot && parent.ImportPath != "" && search.IsStandardImportPath(parent.ImportPath)
  1102  	for _, path := range imports {
  1103  		if path == "C" || path == "unsafe" {
  1104  			continue
  1105  		}
  1106  		select {
  1107  		case <-pre.cancel:
  1108  			return
  1109  		case pre.sema <- struct{}{}:
  1110  			go func(path string) {
  1111  				bp, loaded, err := loadPackageData(ctx, path, parent.ImportPath, parent.Dir, parent.Root, parentIsStd, ResolveImport)
  1112  				<-pre.sema
  1113  				if bp != nil && loaded && err == nil && !opts.IgnoreImports {
  1114  					pre.preloadImports(ctx, opts, bp.Imports, bp)
  1115  				}
  1116  			}(path)
  1117  		}
  1118  	}
  1119  }
  1120  
  1121  // flush stops pending preload operations. flush blocks until preload calls to
  1122  // loadPackageData have completed. The preloader will not make any new calls
  1123  // to loadPackageData.
  1124  func (pre *preload) flush() {
  1125  	// flush is usually deferred.
  1126  	// Don't hang program waiting for workers on panic.
  1127  	if v := recover(); v != nil {
  1128  		panic(v)
  1129  	}
  1130  
  1131  	close(pre.cancel)
  1132  	for i := 0; i < preloadWorkerCount; i++ {
  1133  		pre.sema <- struct{}{}
  1134  	}
  1135  }
  1136  
  1137  func cleanImport(path string) string {
  1138  	orig := path
  1139  	path = pathpkg.Clean(path)
  1140  	if strings.HasPrefix(orig, "./") && path != ".." && !strings.HasPrefix(path, "../") {
  1141  		path = "./" + path
  1142  	}
  1143  	return path
  1144  }
  1145  
  1146  var isDirCache par.Cache[string, bool]
  1147  
  1148  func isDir(path string) bool {
  1149  	return isDirCache.Do(path, func() bool {
  1150  		fi, err := fsys.Stat(path)
  1151  		return err == nil && fi.IsDir()
  1152  	})
  1153  }
  1154  
  1155  // ResolveImportPath returns the true meaning of path when it appears in parent.
  1156  // There are two different resolutions applied.
  1157  // First, there is Go 1.5 vendoring (golang.org/s/go15vendor).
  1158  // If vendor expansion doesn't trigger, then the path is also subject to
  1159  // Go 1.11 module legacy conversion (golang.org/issue/25069).
  1160  func ResolveImportPath(parent *Package, path string) (found string) {
  1161  	var parentPath, parentDir, parentRoot string
  1162  	parentIsStd := false
  1163  	if parent != nil {
  1164  		parentPath = parent.ImportPath
  1165  		parentDir = parent.Dir
  1166  		parentRoot = parent.Root
  1167  		parentIsStd = parent.Standard
  1168  	}
  1169  	return resolveImportPath(path, parentPath, parentDir, parentRoot, parentIsStd)
  1170  }
  1171  
  1172  func resolveImportPath(path, parentPath, parentDir, parentRoot string, parentIsStd bool) (found string) {
  1173  	if cfg.ModulesEnabled {
  1174  		if _, p, e := modload.Lookup(parentPath, parentIsStd, path); e == nil {
  1175  			return p
  1176  		}
  1177  		return path
  1178  	}
  1179  	found = vendoredImportPath(path, parentPath, parentDir, parentRoot)
  1180  	if found != path {
  1181  		return found
  1182  	}
  1183  	return moduleImportPath(path, parentPath, parentDir, parentRoot)
  1184  }
  1185  
  1186  // dirAndRoot returns the source directory and workspace root
  1187  // for the package p, guaranteeing that root is a path prefix of dir.
  1188  func dirAndRoot(path string, dir, root string) (string, string) {
  1189  	origDir, origRoot := dir, root
  1190  	dir = filepath.Clean(dir)
  1191  	root = filepath.Join(root, "src")
  1192  	if !str.HasFilePathPrefix(dir, root) || path != "command-line-arguments" && filepath.Join(root, path) != dir {
  1193  		// Look for symlinks before reporting error.
  1194  		dir = expandPath(dir)
  1195  		root = expandPath(root)
  1196  	}
  1197  
  1198  	if !str.HasFilePathPrefix(dir, root) || len(dir) <= len(root) || dir[len(root)] != filepath.Separator || path != "command-line-arguments" && !build.IsLocalImport(path) && filepath.Join(root, path) != dir {
  1199  		debug.PrintStack()
  1200  		base.Fatalf("unexpected directory layout:\n"+
  1201  			"	import path: %s\n"+
  1202  			"	root: %s\n"+
  1203  			"	dir: %s\n"+
  1204  			"	expand root: %s\n"+
  1205  			"	expand dir: %s\n"+
  1206  			"	separator: %s",
  1207  			path,
  1208  			filepath.Join(origRoot, "src"),
  1209  			filepath.Clean(origDir),
  1210  			origRoot,
  1211  			origDir,
  1212  			string(filepath.Separator))
  1213  	}
  1214  
  1215  	return dir, root
  1216  }
  1217  
  1218  // vendoredImportPath returns the vendor-expansion of path when it appears in parent.
  1219  // If parent is x/y/z, then path might expand to x/y/z/vendor/path, x/y/vendor/path,
  1220  // x/vendor/path, vendor/path, or else stay path if none of those exist.
  1221  // vendoredImportPath returns the expanded path or, if no expansion is found, the original.
  1222  func vendoredImportPath(path, parentPath, parentDir, parentRoot string) (found string) {
  1223  	if parentRoot == "" {
  1224  		return path
  1225  	}
  1226  
  1227  	dir, root := dirAndRoot(parentPath, parentDir, parentRoot)
  1228  
  1229  	vpath := "vendor/" + path
  1230  	for i := len(dir); i >= len(root); i-- {
  1231  		if i < len(dir) && dir[i] != filepath.Separator {
  1232  			continue
  1233  		}
  1234  		// Note: checking for the vendor directory before checking
  1235  		// for the vendor/path directory helps us hit the
  1236  		// isDir cache more often. It also helps us prepare a more useful
  1237  		// list of places we looked, to report when an import is not found.
  1238  		if !isDir(filepath.Join(dir[:i], "vendor")) {
  1239  			continue
  1240  		}
  1241  		targ := filepath.Join(dir[:i], vpath)
  1242  		if isDir(targ) && hasGoFiles(targ) {
  1243  			importPath := parentPath
  1244  			if importPath == "command-line-arguments" {
  1245  				// If parent.ImportPath is 'command-line-arguments'.
  1246  				// set to relative directory to root (also chopped root directory)
  1247  				importPath = dir[len(root)+1:]
  1248  			}
  1249  			// We started with parent's dir c:\gopath\src\foo\bar\baz\quux\xyzzy.
  1250  			// We know the import path for parent's dir.
  1251  			// We chopped off some number of path elements and
  1252  			// added vendor\path to produce c:\gopath\src\foo\bar\baz\vendor\path.
  1253  			// Now we want to know the import path for that directory.
  1254  			// Construct it by chopping the same number of path elements
  1255  			// (actually the same number of bytes) from parent's import path
  1256  			// and then append /vendor/path.
  1257  			chopped := len(dir) - i
  1258  			if chopped == len(importPath)+1 {
  1259  				// We walked up from c:\gopath\src\foo\bar
  1260  				// and found c:\gopath\src\vendor\path.
  1261  				// We chopped \foo\bar (length 8) but the import path is "foo/bar" (length 7).
  1262  				// Use "vendor/path" without any prefix.
  1263  				return vpath
  1264  			}
  1265  			return importPath[:len(importPath)-chopped] + "/" + vpath
  1266  		}
  1267  	}
  1268  	return path
  1269  }
  1270  
  1271  var (
  1272  	modulePrefix   = []byte("\nmodule ")
  1273  	goModPathCache par.Cache[string, string]
  1274  )
  1275  
  1276  // goModPath returns the module path in the go.mod in dir, if any.
  1277  func goModPath(dir string) (path string) {
  1278  	return goModPathCache.Do(dir, func() string {
  1279  		data, err := os.ReadFile(filepath.Join(dir, "go.mod"))
  1280  		if err != nil {
  1281  			return ""
  1282  		}
  1283  		var i int
  1284  		if bytes.HasPrefix(data, modulePrefix[1:]) {
  1285  			i = 0
  1286  		} else {
  1287  			i = bytes.Index(data, modulePrefix)
  1288  			if i < 0 {
  1289  				return ""
  1290  			}
  1291  			i++
  1292  		}
  1293  		line := data[i:]
  1294  
  1295  		// Cut line at \n, drop trailing \r if present.
  1296  		if j := bytes.IndexByte(line, '\n'); j >= 0 {
  1297  			line = line[:j]
  1298  		}
  1299  		if line[len(line)-1] == '\r' {
  1300  			line = line[:len(line)-1]
  1301  		}
  1302  		line = line[len("module "):]
  1303  
  1304  		// If quoted, unquote.
  1305  		path = strings.TrimSpace(string(line))
  1306  		if path != "" && path[0] == '"' {
  1307  			s, err := strconv.Unquote(path)
  1308  			if err != nil {
  1309  				return ""
  1310  			}
  1311  			path = s
  1312  		}
  1313  		return path
  1314  	})
  1315  }
  1316  
  1317  // findVersionElement returns the slice indices of the final version element /vN in path.
  1318  // If there is no such element, it returns -1, -1.
  1319  func findVersionElement(path string) (i, j int) {
  1320  	j = len(path)
  1321  	for i = len(path) - 1; i >= 0; i-- {
  1322  		if path[i] == '/' {
  1323  			if isVersionElement(path[i+1 : j]) {
  1324  				return i, j
  1325  			}
  1326  			j = i
  1327  		}
  1328  	}
  1329  	return -1, -1
  1330  }
  1331  
  1332  // isVersionElement reports whether s is a well-formed path version element:
  1333  // v2, v3, v10, etc, but not v0, v05, v1.
  1334  func isVersionElement(s string) bool {
  1335  	if len(s) < 2 || s[0] != 'v' || s[1] == '0' || s[1] == '1' && len(s) == 2 {
  1336  		return false
  1337  	}
  1338  	for i := 1; i < len(s); i++ {
  1339  		if s[i] < '0' || '9' < s[i] {
  1340  			return false
  1341  		}
  1342  	}
  1343  	return true
  1344  }
  1345  
  1346  // moduleImportPath translates import paths found in go modules
  1347  // back down to paths that can be resolved in ordinary builds.
  1348  //
  1349  // Define “new” code as code with a go.mod file in the same directory
  1350  // or a parent directory. If an import in new code says x/y/v2/z but
  1351  // x/y/v2/z does not exist and x/y/go.mod says “module x/y/v2”,
  1352  // then go build will read the import as x/y/z instead.
  1353  // See golang.org/issue/25069.
  1354  func moduleImportPath(path, parentPath, parentDir, parentRoot string) (found string) {
  1355  	if parentRoot == "" {
  1356  		return path
  1357  	}
  1358  
  1359  	// If there are no vN elements in path, leave it alone.
  1360  	// (The code below would do the same, but only after
  1361  	// some other file system accesses that we can avoid
  1362  	// here by returning early.)
  1363  	if i, _ := findVersionElement(path); i < 0 {
  1364  		return path
  1365  	}
  1366  
  1367  	dir, root := dirAndRoot(parentPath, parentDir, parentRoot)
  1368  
  1369  	// Consider dir and parents, up to and including root.
  1370  	for i := len(dir); i >= len(root); i-- {
  1371  		if i < len(dir) && dir[i] != filepath.Separator {
  1372  			continue
  1373  		}
  1374  		if goModPath(dir[:i]) != "" {
  1375  			goto HaveGoMod
  1376  		}
  1377  	}
  1378  	// This code is not in a tree with a go.mod,
  1379  	// so apply no changes to the path.
  1380  	return path
  1381  
  1382  HaveGoMod:
  1383  	// This import is in a tree with a go.mod.
  1384  	// Allow it to refer to code in GOPATH/src/x/y/z as x/y/v2/z
  1385  	// if GOPATH/src/x/y/go.mod says module "x/y/v2",
  1386  
  1387  	// If x/y/v2/z exists, use it unmodified.
  1388  	if bp, _ := cfg.BuildContext.Import(path, "", build.IgnoreVendor); bp.Dir != "" {
  1389  		return path
  1390  	}
  1391  
  1392  	// Otherwise look for a go.mod supplying a version element.
  1393  	// Some version-like elements may appear in paths but not
  1394  	// be module versions; we skip over those to look for module
  1395  	// versions. For example the module m/v2 might have a
  1396  	// package m/v2/api/v1/foo.
  1397  	limit := len(path)
  1398  	for limit > 0 {
  1399  		i, j := findVersionElement(path[:limit])
  1400  		if i < 0 {
  1401  			return path
  1402  		}
  1403  		if bp, _ := cfg.BuildContext.Import(path[:i], "", build.IgnoreVendor); bp.Dir != "" {
  1404  			if mpath := goModPath(bp.Dir); mpath != "" {
  1405  				// Found a valid go.mod file, so we're stopping the search.
  1406  				// If the path is m/v2/p and we found m/go.mod that says
  1407  				// "module m/v2", then we return "m/p".
  1408  				if mpath == path[:j] {
  1409  					return path[:i] + path[j:]
  1410  				}
  1411  				// Otherwise just return the original path.
  1412  				// We didn't find anything worth rewriting,
  1413  				// and the go.mod indicates that we should
  1414  				// not consider parent directories.
  1415  				return path
  1416  			}
  1417  		}
  1418  		limit = i
  1419  	}
  1420  	return path
  1421  }
  1422  
  1423  // hasGoFiles reports whether dir contains any files with names ending in .go.
  1424  // For a vendor check we must exclude directories that contain no .go files.
  1425  // Otherwise it is not possible to vendor just a/b/c and still import the
  1426  // non-vendored a/b. See golang.org/issue/13832.
  1427  func hasGoFiles(dir string) bool {
  1428  	files, _ := os.ReadDir(dir)
  1429  	for _, f := range files {
  1430  		if !f.IsDir() && strings.HasSuffix(f.Name(), ".go") {
  1431  			return true
  1432  		}
  1433  	}
  1434  	return false
  1435  }
  1436  
  1437  // reusePackage reuses package p to satisfy the import at the top
  1438  // of the import stack stk. If this use causes an import loop,
  1439  // reusePackage updates p's error information to record the loop.
  1440  func reusePackage(p *Package, stk *ImportStack) *Package {
  1441  	// We use p.Internal.Imports==nil to detect a package that
  1442  	// is in the midst of its own loadPackage call
  1443  	// (all the recursion below happens before p.Internal.Imports gets set).
  1444  	if p.Internal.Imports == nil {
  1445  		if p.Error == nil {
  1446  			p.Error = &PackageError{
  1447  				ImportStack:   stk.Copy(),
  1448  				Err:           errors.New("import cycle not allowed"),
  1449  				IsImportCycle: true,
  1450  			}
  1451  		} else if !p.Error.IsImportCycle {
  1452  			// If the error is already set, but it does not indicate that
  1453  			// we are in an import cycle, set IsImportCycle so that we don't
  1454  			// end up stuck in a loop down the road.
  1455  			p.Error.IsImportCycle = true
  1456  		}
  1457  		p.Incomplete = true
  1458  	}
  1459  	// Don't rewrite the import stack in the error if we have an import cycle.
  1460  	// If we do, we'll lose the path that describes the cycle.
  1461  	if p.Error != nil && p.Error.ImportStack != nil &&
  1462  		!p.Error.IsImportCycle && stk.shorterThan(p.Error.ImportStack.Pkgs()) {
  1463  		p.Error.ImportStack = stk.Copy()
  1464  	}
  1465  	return p
  1466  }
  1467  
  1468  // disallowInternal checks that srcDir (containing package importerPath, if non-empty)
  1469  // is allowed to import p.
  1470  // If the import is allowed, disallowInternal returns the original package p.
  1471  // If not, it returns a new package containing just an appropriate error.
  1472  func disallowInternal(ctx context.Context, srcDir string, importer *Package, importerPath string, p *Package, stk *ImportStack) *PackageError {
  1473  	// golang.org/s/go14internal:
  1474  	// An import of a path containing the element “internal”
  1475  	// is disallowed if the importing code is outside the tree
  1476  	// rooted at the parent of the “internal” directory.
  1477  
  1478  	// There was an error loading the package; stop here.
  1479  	if p.Error != nil {
  1480  		return nil
  1481  	}
  1482  
  1483  	// The generated 'testmain' package is allowed to access testing/internal/...,
  1484  	// as if it were generated into the testing directory tree
  1485  	// (it's actually in a temporary directory outside any Go tree).
  1486  	// This cleans up a former kludge in passing functionality to the testing package.
  1487  	if str.HasPathPrefix(p.ImportPath, "testing/internal") && importerPath == "testmain" {
  1488  		return nil
  1489  	}
  1490  
  1491  	// We can't check standard packages with gccgo.
  1492  	if cfg.BuildContext.Compiler == "gccgo" && p.Standard {
  1493  		return nil
  1494  	}
  1495  
  1496  	// The sort package depends on internal/reflectlite, but during bootstrap
  1497  	// the path rewriting causes the normal internal checks to fail.
  1498  	// Instead, just ignore the internal rules during bootstrap.
  1499  	if p.Standard && strings.HasPrefix(importerPath, "bootstrap/") {
  1500  		return nil
  1501  	}
  1502  
  1503  	// importerPath is empty: we started
  1504  	// with a name given on the command line, not an
  1505  	// import. Anything listed on the command line is fine.
  1506  	if importerPath == "" {
  1507  		return nil
  1508  	}
  1509  
  1510  	// Check for "internal" element: three cases depending on begin of string and/or end of string.
  1511  	i, ok := findInternal(p.ImportPath)
  1512  	if !ok {
  1513  		return nil
  1514  	}
  1515  
  1516  	// Internal is present.
  1517  	// Map import path back to directory corresponding to parent of internal.
  1518  	if i > 0 {
  1519  		i-- // rewind over slash in ".../internal"
  1520  	}
  1521  
  1522  	// FIPS-140 snapshots are special, because they comes from a non-GOROOT
  1523  	// directory, so the usual directory rules don't work apply, or rather they
  1524  	// apply differently depending on whether we are using a snapshot or the
  1525  	// in-tree copy of the code. We apply a consistent rule here:
  1526  	// crypto/internal/fips140 can only see crypto/internal, never top-of-tree internal.
  1527  	// Similarly, crypto/... can see crypto/internal/fips140 even though the usual rules
  1528  	// would not allow it in snapshot mode.
  1529  	if str.HasPathPrefix(importerPath, "crypto") && str.HasPathPrefix(p.ImportPath, "crypto/internal/fips140") {
  1530  		return nil // crypto can use crypto/internal/fips140
  1531  	}
  1532  	if str.HasPathPrefix(importerPath, "crypto/internal/fips140") {
  1533  		if str.HasPathPrefix(p.ImportPath, "crypto/internal") {
  1534  			return nil // crypto/internal/fips140 can use crypto/internal
  1535  		}
  1536  		goto Error
  1537  	}
  1538  
  1539  	if p.Module == nil {
  1540  		parent := p.Dir[:i+len(p.Dir)-len(p.ImportPath)]
  1541  
  1542  		if str.HasFilePathPrefix(filepath.Clean(srcDir), filepath.Clean(parent)) {
  1543  			return nil
  1544  		}
  1545  
  1546  		// Look for symlinks before reporting error.
  1547  		srcDir = expandPath(srcDir)
  1548  		parent = expandPath(parent)
  1549  		if str.HasFilePathPrefix(filepath.Clean(srcDir), filepath.Clean(parent)) {
  1550  			return nil
  1551  		}
  1552  	} else {
  1553  		// p is in a module, so make it available based on the importer's import path instead
  1554  		// of the file path (https://golang.org/issue/23970).
  1555  		if importer.Internal.CmdlineFiles {
  1556  			// The importer is a list of command-line files.
  1557  			// Pretend that the import path is the import path of the
  1558  			// directory containing them.
  1559  			// If the directory is outside the main modules, this will resolve to ".",
  1560  			// which is not a prefix of any valid module.
  1561  			importerPath, _ = modload.MainModules.DirImportPath(ctx, importer.Dir)
  1562  		}
  1563  		parentOfInternal := p.ImportPath[:i]
  1564  		if str.HasPathPrefix(importerPath, parentOfInternal) {
  1565  			return nil
  1566  		}
  1567  	}
  1568  
  1569  Error:
  1570  	// Internal is present, and srcDir is outside parent's tree. Not allowed.
  1571  	perr := &PackageError{
  1572  		alwaysPrintStack: true,
  1573  		ImportStack:      stk.Copy(),
  1574  		Err:              ImportErrorf(p.ImportPath, "use of internal package %s not allowed", p.ImportPath),
  1575  	}
  1576  	return perr
  1577  }
  1578  
  1579  // findInternal looks for the final "internal" path element in the given import path.
  1580  // If there isn't one, findInternal returns ok=false.
  1581  // Otherwise, findInternal returns ok=true and the index of the "internal".
  1582  func findInternal(path string) (index int, ok bool) {
  1583  	// Three cases, depending on internal at start/end of string or not.
  1584  	// The order matters: we must return the index of the final element,
  1585  	// because the final one produces the most restrictive requirement
  1586  	// on the importer.
  1587  	switch {
  1588  	case strings.HasSuffix(path, "/internal"):
  1589  		return len(path) - len("internal"), true
  1590  	case strings.Contains(path, "/internal/"):
  1591  		return strings.LastIndex(path, "/internal/") + 1, true
  1592  	case path == "internal", strings.HasPrefix(path, "internal/"):
  1593  		return 0, true
  1594  	}
  1595  	return 0, false
  1596  }
  1597  
  1598  // disallowVendor checks that srcDir is allowed to import p as path.
  1599  // If the import is allowed, disallowVendor returns the original package p.
  1600  // If not, it returns a PackageError.
  1601  func disallowVendor(srcDir string, path string, importerPath string, p *Package, stk *ImportStack) *PackageError {
  1602  	// If the importerPath is empty, we started
  1603  	// with a name given on the command line, not an
  1604  	// import. Anything listed on the command line is fine.
  1605  	if importerPath == "" {
  1606  		return nil
  1607  	}
  1608  
  1609  	if perr := disallowVendorVisibility(srcDir, p, importerPath, stk); perr != nil {
  1610  		return perr
  1611  	}
  1612  
  1613  	// Paths like x/vendor/y must be imported as y, never as x/vendor/y.
  1614  	if i, ok := FindVendor(path); ok {
  1615  		perr := &PackageError{
  1616  			ImportStack: stk.Copy(),
  1617  			Err:         ImportErrorf(path, "%s must be imported as %s", path, path[i+len("vendor/"):]),
  1618  		}
  1619  		return perr
  1620  	}
  1621  
  1622  	return nil
  1623  }
  1624  
  1625  // disallowVendorVisibility checks that srcDir is allowed to import p.
  1626  // The rules are the same as for /internal/ except that a path ending in /vendor
  1627  // is not subject to the rules, only subdirectories of vendor.
  1628  // This allows people to have packages and commands named vendor,
  1629  // for maximal compatibility with existing source trees.
  1630  func disallowVendorVisibility(srcDir string, p *Package, importerPath string, stk *ImportStack) *PackageError {
  1631  	// The stack does not include p.ImportPath.
  1632  	// If there's nothing on the stack, we started
  1633  	// with a name given on the command line, not an
  1634  	// import. Anything listed on the command line is fine.
  1635  	if importerPath == "" {
  1636  		return nil
  1637  	}
  1638  
  1639  	// Check for "vendor" element.
  1640  	i, ok := FindVendor(p.ImportPath)
  1641  	if !ok {
  1642  		return nil
  1643  	}
  1644  
  1645  	// Vendor is present.
  1646  	// Map import path back to directory corresponding to parent of vendor.
  1647  	if i > 0 {
  1648  		i-- // rewind over slash in ".../vendor"
  1649  	}
  1650  	truncateTo := i + len(p.Dir) - len(p.ImportPath)
  1651  	if truncateTo < 0 || len(p.Dir) < truncateTo {
  1652  		return nil
  1653  	}
  1654  	parent := p.Dir[:truncateTo]
  1655  	if str.HasFilePathPrefix(filepath.Clean(srcDir), filepath.Clean(parent)) {
  1656  		return nil
  1657  	}
  1658  
  1659  	// Look for symlinks before reporting error.
  1660  	srcDir = expandPath(srcDir)
  1661  	parent = expandPath(parent)
  1662  	if str.HasFilePathPrefix(filepath.Clean(srcDir), filepath.Clean(parent)) {
  1663  		return nil
  1664  	}
  1665  
  1666  	// Vendor is present, and srcDir is outside parent's tree. Not allowed.
  1667  
  1668  	perr := &PackageError{
  1669  		ImportStack: stk.Copy(),
  1670  		Err:         errors.New("use of vendored package not allowed"),
  1671  	}
  1672  	return perr
  1673  }
  1674  
  1675  // FindVendor looks for the last non-terminating "vendor" path element in the given import path.
  1676  // If there isn't one, FindVendor returns ok=false.
  1677  // Otherwise, FindVendor returns ok=true and the index of the "vendor".
  1678  //
  1679  // Note that terminating "vendor" elements don't count: "x/vendor" is its own package,
  1680  // not the vendored copy of an import "" (the empty import path).
  1681  // This will allow people to have packages or commands named vendor.
  1682  // This may help reduce breakage, or it may just be confusing. We'll see.
  1683  func FindVendor(path string) (index int, ok bool) {
  1684  	// Two cases, depending on internal at start of string or not.
  1685  	// The order matters: we must return the index of the final element,
  1686  	// because the final one is where the effective import path starts.
  1687  	switch {
  1688  	case strings.Contains(path, "/vendor/"):
  1689  		return strings.LastIndex(path, "/vendor/") + 1, true
  1690  	case strings.HasPrefix(path, "vendor/"):
  1691  		return 0, true
  1692  	}
  1693  	return 0, false
  1694  }
  1695  
  1696  type TargetDir int
  1697  
  1698  const (
  1699  	ToTool    TargetDir = iota // to GOROOT/pkg/tool (default for cmd/*)
  1700  	ToBin                      // to bin dir inside package root (default for non-cmd/*)
  1701  	StalePath                  // an old import path; fail to build
  1702  )
  1703  
  1704  // InstallTargetDir reports the target directory for installing the command p.
  1705  func InstallTargetDir(p *Package) TargetDir {
  1706  	if strings.HasPrefix(p.ImportPath, "code.google.com/p/go.tools/cmd/") {
  1707  		return StalePath
  1708  	}
  1709  	if p.Goroot && strings.HasPrefix(p.ImportPath, "cmd/") && p.Name == "main" {
  1710  		switch p.ImportPath {
  1711  		case "cmd/go", "cmd/gofmt":
  1712  			return ToBin
  1713  		}
  1714  		return ToTool
  1715  	}
  1716  	return ToBin
  1717  }
  1718  
  1719  var cgoExclude = map[string]bool{
  1720  	"runtime/cgo": true,
  1721  }
  1722  
  1723  var cgoSyscallExclude = map[string]bool{
  1724  	"runtime/cgo":  true,
  1725  	"runtime/race": true,
  1726  	"runtime/msan": true,
  1727  	"runtime/asan": true,
  1728  }
  1729  
  1730  var foldPath = make(map[string]string)
  1731  
  1732  // exeFromImportPath returns an executable name
  1733  // for a package using the import path.
  1734  //
  1735  // The executable name is the last element of the import path.
  1736  // In module-aware mode, an additional rule is used on import paths
  1737  // consisting of two or more path elements. If the last element is
  1738  // a vN path element specifying the major version, then the
  1739  // second last element of the import path is used instead.
  1740  func (p *Package) exeFromImportPath() string {
  1741  	_, elem := pathpkg.Split(p.ImportPath)
  1742  	if cfg.ModulesEnabled {
  1743  		// If this is example.com/mycmd/v2, it's more useful to
  1744  		// install it as mycmd than as v2. See golang.org/issue/24667.
  1745  		if elem != p.ImportPath && isVersionElement(elem) {
  1746  			_, elem = pathpkg.Split(pathpkg.Dir(p.ImportPath))
  1747  		}
  1748  	}
  1749  	return elem
  1750  }
  1751  
  1752  // exeFromFiles returns an executable name for a package
  1753  // using the first element in GoFiles or CgoFiles collections without the prefix.
  1754  //
  1755  // Returns empty string in case of empty collection.
  1756  func (p *Package) exeFromFiles() string {
  1757  	var src string
  1758  	if len(p.GoFiles) > 0 {
  1759  		src = p.GoFiles[0]
  1760  	} else if len(p.CgoFiles) > 0 {
  1761  		src = p.CgoFiles[0]
  1762  	} else {
  1763  		return ""
  1764  	}
  1765  	_, elem := filepath.Split(src)
  1766  	return elem[:len(elem)-len(".go")]
  1767  }
  1768  
  1769  // DefaultExecName returns the default executable name for a package
  1770  func (p *Package) DefaultExecName() string {
  1771  	if p.Internal.CmdlineFiles {
  1772  		return p.exeFromFiles()
  1773  	}
  1774  	return p.exeFromImportPath()
  1775  }
  1776  
  1777  // load populates p using information from bp, err, which should
  1778  // be the result of calling build.Context.Import.
  1779  // stk contains the import stack, not including path itself.
  1780  func (p *Package) load(ctx context.Context, opts PackageOpts, path string, stk *ImportStack, importPos []token.Position, bp *build.Package, err error) {
  1781  	p.copyBuild(opts, bp)
  1782  
  1783  	// The localPrefix is the path we interpret ./ imports relative to,
  1784  	// if we support them at all (not in module mode!).
  1785  	// Synthesized main packages sometimes override this.
  1786  	if p.Internal.Local && !cfg.ModulesEnabled {
  1787  		p.Internal.LocalPrefix = dirToImportPath(p.Dir)
  1788  	}
  1789  
  1790  	// setError sets p.Error if it hasn't already been set. We may proceed
  1791  	// after encountering some errors so that 'go list -e' has more complete
  1792  	// output. If there's more than one error, we should report the first.
  1793  	setError := func(err error) {
  1794  		if p.Error == nil {
  1795  			p.Error = &PackageError{
  1796  				ImportStack: stk.Copy(),
  1797  				Err:         err,
  1798  			}
  1799  			p.Incomplete = true
  1800  
  1801  			// Add the importer's position information if the import position exists, and
  1802  			// the current package being examined is the importer.
  1803  			// If we have not yet accepted package p onto the import stack,
  1804  			// then the cause of the error is not within p itself: the error
  1805  			// must be either in an explicit command-line argument,
  1806  			// or on the importer side (indicated by a non-empty importPos).
  1807  			top, ok := stk.Top()
  1808  			if ok && path != top.Pkg && len(importPos) > 0 {
  1809  				p.Error.setPos(importPos)
  1810  			}
  1811  		}
  1812  	}
  1813  
  1814  	if err != nil {
  1815  		p.Incomplete = true
  1816  		p.setLoadPackageDataError(err, path, stk, importPos)
  1817  	}
  1818  
  1819  	useBindir := p.Name == "main"
  1820  	if !p.Standard {
  1821  		switch cfg.BuildBuildmode {
  1822  		case "c-archive", "c-shared", "plugin":
  1823  			useBindir = false
  1824  		}
  1825  	}
  1826  
  1827  	if useBindir {
  1828  		// Report an error when the old code.google.com/p/go.tools paths are used.
  1829  		if InstallTargetDir(p) == StalePath {
  1830  			// TODO(matloob): remove this branch, and StalePath itself. code.google.com/p/go is so
  1831  			// old, even this code checking for it is stale now!
  1832  			newPath := strings.Replace(p.ImportPath, "code.google.com/p/go.", "golang.org/x/", 1)
  1833  			e := ImportErrorf(p.ImportPath, "the %v command has moved; use %v instead.", p.ImportPath, newPath)
  1834  			setError(e)
  1835  			return
  1836  		}
  1837  		elem := p.DefaultExecName() + cfg.ExeSuffix
  1838  		full := filepath.Join(cfg.BuildContext.GOOS+"_"+cfg.BuildContext.GOARCH, elem)
  1839  		if cfg.BuildContext.GOOS != runtime.GOOS || cfg.BuildContext.GOARCH != runtime.GOARCH {
  1840  			// Install cross-compiled binaries to subdirectories of bin.
  1841  			elem = full
  1842  		}
  1843  		if p.Internal.Build.BinDir == "" && cfg.ModulesEnabled {
  1844  			p.Internal.Build.BinDir = modload.BinDir()
  1845  		}
  1846  		if p.Internal.Build.BinDir != "" {
  1847  			// Install to GOBIN or bin of GOPATH entry.
  1848  			p.Target = filepath.Join(p.Internal.Build.BinDir, elem)
  1849  			if !p.Goroot && strings.Contains(elem, string(filepath.Separator)) && cfg.GOBIN != "" {
  1850  				// Do not create $GOBIN/goos_goarch/elem.
  1851  				p.Target = ""
  1852  				p.Internal.GobinSubdir = true
  1853  			}
  1854  		}
  1855  		if InstallTargetDir(p) == ToTool {
  1856  			// This is for 'go tool'.
  1857  			// Override all the usual logic and force it into the tool directory.
  1858  			if cfg.BuildToolchainName == "gccgo" {
  1859  				p.Target = filepath.Join(build.ToolDir, elem)
  1860  			} else {
  1861  				p.Target = filepath.Join(cfg.GOROOTpkg, "tool", full)
  1862  			}
  1863  		}
  1864  	} else if p.Internal.Local {
  1865  		// Local import turned into absolute path.
  1866  		// No permanent install target.
  1867  		p.Target = ""
  1868  	} else if p.Standard && cfg.BuildContext.Compiler == "gccgo" {
  1869  		// gccgo has a preinstalled standard library that cmd/go cannot rebuild.
  1870  		p.Target = ""
  1871  	} else {
  1872  		p.Target = p.Internal.Build.PkgObj
  1873  		if cfg.BuildBuildmode == "shared" && p.Internal.Build.PkgTargetRoot != "" {
  1874  			// TODO(matloob): This shouldn't be necessary, but the cmd/cgo/internal/testshared
  1875  			// test fails without Target set for this condition. Figure out why and
  1876  			// fix it.
  1877  			p.Target = filepath.Join(p.Internal.Build.PkgTargetRoot, p.ImportPath+".a")
  1878  		}
  1879  		if cfg.BuildLinkshared && p.Internal.Build.PkgTargetRoot != "" {
  1880  			// TODO(bcmills): The reliance on PkgTargetRoot implies that -linkshared does
  1881  			// not work for any package that lacks a PkgTargetRoot — such as a non-main
  1882  			// package in module mode. We should probably fix that.
  1883  			targetPrefix := filepath.Join(p.Internal.Build.PkgTargetRoot, p.ImportPath)
  1884  			p.Target = targetPrefix + ".a"
  1885  			shlibnamefile := targetPrefix + ".shlibname"
  1886  			shlib, err := os.ReadFile(shlibnamefile)
  1887  			if err != nil && !os.IsNotExist(err) {
  1888  				base.Fatalf("reading shlibname: %v", err)
  1889  			}
  1890  			if err == nil {
  1891  				libname := strings.TrimSpace(string(shlib))
  1892  				if cfg.BuildContext.Compiler == "gccgo" {
  1893  					p.Shlib = filepath.Join(p.Internal.Build.PkgTargetRoot, "shlibs", libname)
  1894  				} else {
  1895  					p.Shlib = filepath.Join(p.Internal.Build.PkgTargetRoot, libname)
  1896  				}
  1897  			}
  1898  		}
  1899  	}
  1900  
  1901  	// Build augmented import list to add implicit dependencies.
  1902  	// Be careful not to add imports twice, just to avoid confusion.
  1903  	importPaths := p.Imports
  1904  	addImport := func(path string, forCompiler bool) {
  1905  		for _, p := range importPaths {
  1906  			if path == p {
  1907  				return
  1908  			}
  1909  		}
  1910  		importPaths = append(importPaths, path)
  1911  		if forCompiler {
  1912  			p.Internal.CompiledImports = append(p.Internal.CompiledImports, path)
  1913  		}
  1914  	}
  1915  
  1916  	if !opts.IgnoreImports {
  1917  		// Cgo translation adds imports of "unsafe", "runtime/cgo" and "syscall",
  1918  		// except for certain packages, to avoid circular dependencies.
  1919  		if p.UsesCgo() {
  1920  			addImport("unsafe", true)
  1921  		}
  1922  		if p.UsesCgo() && (!p.Standard || !cgoExclude[p.ImportPath]) && cfg.BuildContext.Compiler != "gccgo" {
  1923  			addImport("runtime/cgo", true)
  1924  		}
  1925  		if p.UsesCgo() && (!p.Standard || !cgoSyscallExclude[p.ImportPath]) {
  1926  			addImport("syscall", true)
  1927  		}
  1928  
  1929  		// SWIG adds imports of some standard packages.
  1930  		if p.UsesSwig() {
  1931  			addImport("unsafe", true)
  1932  			if cfg.BuildContext.Compiler != "gccgo" {
  1933  				addImport("runtime/cgo", true)
  1934  			}
  1935  			addImport("syscall", true)
  1936  			addImport("sync", true)
  1937  
  1938  			// TODO: The .swig and .swigcxx files can use
  1939  			// %go_import directives to import other packages.
  1940  		}
  1941  
  1942  		// The linker loads implicit dependencies.
  1943  		if p.Name == "main" && !p.Internal.ForceLibrary {
  1944  			ldDeps, err := LinkerDeps(p)
  1945  			if err != nil {
  1946  				setError(err)
  1947  				return
  1948  			}
  1949  			for _, dep := range ldDeps {
  1950  				addImport(dep, false)
  1951  			}
  1952  		}
  1953  	}
  1954  
  1955  	// Check for case-insensitive collisions of import paths.
  1956  	// If modifying, consider changing checkPathCollisions() in
  1957  	// src/cmd/go/internal/modcmd/vendor.go
  1958  	fold := str.ToFold(p.ImportPath)
  1959  	if other := foldPath[fold]; other == "" {
  1960  		foldPath[fold] = p.ImportPath
  1961  	} else if other != p.ImportPath {
  1962  		setError(ImportErrorf(p.ImportPath, "case-insensitive import collision: %q and %q", p.ImportPath, other))
  1963  		return
  1964  	}
  1965  
  1966  	if !SafeArg(p.ImportPath) {
  1967  		setError(ImportErrorf(p.ImportPath, "invalid import path %q", p.ImportPath))
  1968  		return
  1969  	}
  1970  
  1971  	// Errors after this point are caused by this package, not the importing
  1972  	// package. Pushing the path here prevents us from reporting the error
  1973  	// with the position of the import declaration.
  1974  	stk.Push(ImportInfo{Pkg: path, Pos: extractFirstImport(importPos)})
  1975  	defer stk.Pop()
  1976  
  1977  	pkgPath := p.ImportPath
  1978  	if p.Internal.CmdlineFiles {
  1979  		pkgPath = "command-line-arguments"
  1980  	}
  1981  	if cfg.ModulesEnabled {
  1982  		p.Module = modload.PackageModuleInfo(ctx, pkgPath)
  1983  	}
  1984  	p.DefaultGODEBUG = defaultGODEBUG(p, nil, nil, nil)
  1985  
  1986  	if !opts.SuppressEmbedFiles {
  1987  		p.EmbedFiles, p.Internal.Embed, err = resolveEmbed(p.Dir, p.EmbedPatterns)
  1988  		if err != nil {
  1989  			p.Incomplete = true
  1990  			setError(err)
  1991  			embedErr := err.(*EmbedError)
  1992  			p.Error.setPos(p.Internal.Build.EmbedPatternPos[embedErr.Pattern])
  1993  		}
  1994  	}
  1995  
  1996  	// Check for case-insensitive collision of input files.
  1997  	// To avoid problems on case-insensitive files, we reject any package
  1998  	// where two different input files have equal names under a case-insensitive
  1999  	// comparison.
  2000  	inputs := p.AllFiles()
  2001  	f1, f2 := str.FoldDup(inputs)
  2002  	if f1 != "" {
  2003  		setError(fmt.Errorf("case-insensitive file name collision: %q and %q", f1, f2))
  2004  		return
  2005  	}
  2006  
  2007  	// If first letter of input file is ASCII, it must be alphanumeric.
  2008  	// This avoids files turning into flags when invoking commands,
  2009  	// and other problems we haven't thought of yet.
  2010  	// Also, _cgo_ files must be generated by us, not supplied.
  2011  	// They are allowed to have //go:cgo_ldflag directives.
  2012  	// The directory scan ignores files beginning with _,
  2013  	// so we shouldn't see any _cgo_ files anyway, but just be safe.
  2014  	for _, file := range inputs {
  2015  		if !SafeArg(file) || strings.HasPrefix(file, "_cgo_") {
  2016  			setError(fmt.Errorf("invalid input file name %q", file))
  2017  			return
  2018  		}
  2019  	}
  2020  	if name := pathpkg.Base(p.ImportPath); !SafeArg(name) {
  2021  		setError(fmt.Errorf("invalid input directory name %q", name))
  2022  		return
  2023  	}
  2024  	if strings.ContainsAny(p.Dir, "\r\n") {
  2025  		setError(fmt.Errorf("invalid package directory %q", p.Dir))
  2026  		return
  2027  	}
  2028  
  2029  	// Build list of imported packages and full dependency list.
  2030  	imports := make([]*Package, 0, len(p.Imports))
  2031  	for i, path := range importPaths {
  2032  		if path == "C" {
  2033  			continue
  2034  		}
  2035  		p1, err := loadImport(ctx, opts, nil, path, p.Dir, p, stk, p.Internal.Build.ImportPos[path], ResolveImport)
  2036  		if err != nil && p.Error == nil {
  2037  			p.Error = err
  2038  			p.Incomplete = true
  2039  		}
  2040  
  2041  		path = p1.ImportPath
  2042  		importPaths[i] = path
  2043  		if i < len(p.Imports) {
  2044  			p.Imports[i] = path
  2045  		}
  2046  
  2047  		imports = append(imports, p1)
  2048  		if p1.Incomplete {
  2049  			p.Incomplete = true
  2050  		}
  2051  	}
  2052  	p.Internal.Imports = imports
  2053  	if p.Error == nil && p.Name == "main" && !p.Internal.ForceLibrary && !p.Incomplete && !opts.SuppressBuildInfo {
  2054  		// TODO(bcmills): loading VCS metadata can be fairly slow.
  2055  		// Consider starting this as a background goroutine and retrieving the result
  2056  		// asynchronously when we're actually ready to build the package, or when we
  2057  		// actually need to evaluate whether the package's metadata is stale.
  2058  		p.setBuildInfo(ctx, opts.AutoVCS)
  2059  	}
  2060  
  2061  	// If cgo is not enabled, ignore cgo supporting sources
  2062  	// just as we ignore go files containing import "C".
  2063  	if !cfg.BuildContext.CgoEnabled {
  2064  		p.CFiles = nil
  2065  		p.CXXFiles = nil
  2066  		p.MFiles = nil
  2067  		p.SwigFiles = nil
  2068  		p.SwigCXXFiles = nil
  2069  		// Note that SFiles are okay (they go to the Go assembler)
  2070  		// and HFiles are okay (they might be used by the SFiles).
  2071  		// Also Sysofiles are okay (they might not contain object
  2072  		// code; see issue #16050).
  2073  	}
  2074  
  2075  	// The gc toolchain only permits C source files with cgo or SWIG.
  2076  	if len(p.CFiles) > 0 && !p.UsesCgo() && !p.UsesSwig() && cfg.BuildContext.Compiler == "gc" {
  2077  		setError(fmt.Errorf("C source files not allowed when not using cgo or SWIG: %s", strings.Join(p.CFiles, " ")))
  2078  		return
  2079  	}
  2080  
  2081  	// C++, Objective-C, and Fortran source files are permitted only with cgo or SWIG,
  2082  	// regardless of toolchain.
  2083  	if len(p.CXXFiles) > 0 && !p.UsesCgo() && !p.UsesSwig() {
  2084  		setError(fmt.Errorf("C++ source files not allowed when not using cgo or SWIG: %s", strings.Join(p.CXXFiles, " ")))
  2085  		return
  2086  	}
  2087  	if len(p.MFiles) > 0 && !p.UsesCgo() && !p.UsesSwig() {
  2088  		setError(fmt.Errorf("Objective-C source files not allowed when not using cgo or SWIG: %s", strings.Join(p.MFiles, " ")))
  2089  		return
  2090  	}
  2091  	if len(p.FFiles) > 0 && !p.UsesCgo() && !p.UsesSwig() {
  2092  		setError(fmt.Errorf("Fortran source files not allowed when not using cgo or SWIG: %s", strings.Join(p.FFiles, " ")))
  2093  		return
  2094  	}
  2095  }
  2096  
  2097  // An EmbedError indicates a problem with a go:embed directive.
  2098  type EmbedError struct {
  2099  	Pattern string
  2100  	Err     error
  2101  }
  2102  
  2103  func (e *EmbedError) Error() string {
  2104  	return fmt.Sprintf("pattern %s: %v", e.Pattern, e.Err)
  2105  }
  2106  
  2107  func (e *EmbedError) Unwrap() error {
  2108  	return e.Err
  2109  }
  2110  
  2111  // ResolveEmbed resolves //go:embed patterns and returns only the file list.
  2112  // For use by go mod vendor to find embedded files it should copy into the
  2113  // vendor directory.
  2114  // TODO(#42504): Once go mod vendor uses load.PackagesAndErrors, just
  2115  // call (*Package).ResolveEmbed
  2116  func ResolveEmbed(dir string, patterns []string) ([]string, error) {
  2117  	files, _, err := resolveEmbed(dir, patterns)
  2118  	return files, err
  2119  }
  2120  
  2121  // resolveEmbed resolves //go:embed patterns to precise file lists.
  2122  // It sets files to the list of unique files matched (for go list),
  2123  // and it sets pmap to the more precise mapping from
  2124  // patterns to files.
  2125  func resolveEmbed(pkgdir string, patterns []string) (files []string, pmap map[string][]string, err error) {
  2126  	var pattern string
  2127  	defer func() {
  2128  		if err != nil {
  2129  			err = &EmbedError{
  2130  				Pattern: pattern,
  2131  				Err:     err,
  2132  			}
  2133  		}
  2134  	}()
  2135  
  2136  	// TODO(rsc): All these messages need position information for better error reports.
  2137  	pmap = make(map[string][]string)
  2138  	have := make(map[string]int)
  2139  	dirOK := make(map[string]bool)
  2140  	pid := 0 // pattern ID, to allow reuse of have map
  2141  	for _, pattern = range patterns {
  2142  		pid++
  2143  
  2144  		glob, all := strings.CutPrefix(pattern, "all:")
  2145  		// Check pattern is valid for //go:embed.
  2146  		if _, err := pathpkg.Match(glob, ""); err != nil || !validEmbedPattern(glob) {
  2147  			return nil, nil, fmt.Errorf("invalid pattern syntax")
  2148  		}
  2149  
  2150  		// Glob to find matches.
  2151  		match, err := fsys.Glob(str.QuoteGlob(str.WithFilePathSeparator(pkgdir)) + filepath.FromSlash(glob))
  2152  		if err != nil {
  2153  			return nil, nil, err
  2154  		}
  2155  
  2156  		// Filter list of matches down to the ones that will still exist when
  2157  		// the directory is packaged up as a module. (If p.Dir is in the module cache,
  2158  		// only those files exist already, but if p.Dir is in the current module,
  2159  		// then there may be other things lying around, like symbolic links or .git directories.)
  2160  		var list []string
  2161  		for _, file := range match {
  2162  			// relative path to p.Dir which begins without prefix slash
  2163  			rel := filepath.ToSlash(str.TrimFilePathPrefix(file, pkgdir))
  2164  
  2165  			what := "file"
  2166  			info, err := fsys.Lstat(file)
  2167  			if err != nil {
  2168  				return nil, nil, err
  2169  			}
  2170  			if info.IsDir() {
  2171  				what = "directory"
  2172  			}
  2173  
  2174  			// Check that directories along path do not begin a new module
  2175  			// (do not contain a go.mod).
  2176  			for dir := file; len(dir) > len(pkgdir)+1 && !dirOK[dir]; dir = filepath.Dir(dir) {
  2177  				if _, err := fsys.Stat(filepath.Join(dir, "go.mod")); err == nil {
  2178  					return nil, nil, fmt.Errorf("cannot embed %s %s: in different module", what, rel)
  2179  				}
  2180  				if dir != file {
  2181  					if info, err := fsys.Lstat(dir); err == nil && !info.IsDir() {
  2182  						return nil, nil, fmt.Errorf("cannot embed %s %s: in non-directory %s", what, rel, dir[len(pkgdir)+1:])
  2183  					}
  2184  				}
  2185  				dirOK[dir] = true
  2186  				if elem := filepath.Base(dir); isBadEmbedName(elem) {
  2187  					if dir == file {
  2188  						return nil, nil, fmt.Errorf("cannot embed %s %s: invalid name %s", what, rel, elem)
  2189  					} else {
  2190  						return nil, nil, fmt.Errorf("cannot embed %s %s: in invalid directory %s", what, rel, elem)
  2191  					}
  2192  				}
  2193  			}
  2194  
  2195  			switch {
  2196  			default:
  2197  				return nil, nil, fmt.Errorf("cannot embed irregular file %s", rel)
  2198  
  2199  			case info.Mode().IsRegular():
  2200  				if have[rel] != pid {
  2201  					have[rel] = pid
  2202  					list = append(list, rel)
  2203  				}
  2204  
  2205  			case info.IsDir():
  2206  				// Gather all files in the named directory, stopping at module boundaries
  2207  				// and ignoring files that wouldn't be packaged into a module.
  2208  				count := 0
  2209  				err := fsys.WalkDir(file, func(path string, d fs.DirEntry, err error) error {
  2210  					if err != nil {
  2211  						return err
  2212  					}
  2213  					rel := filepath.ToSlash(str.TrimFilePathPrefix(path, pkgdir))
  2214  					name := d.Name()
  2215  					if path != file && (isBadEmbedName(name) || ((name[0] == '.' || name[0] == '_') && !all)) {
  2216  						// Ignore bad names, assuming they won't go into modules.
  2217  						// Also avoid hidden files that user may not know about.
  2218  						// See golang.org/issue/42328.
  2219  						if d.IsDir() {
  2220  							return fs.SkipDir
  2221  						}
  2222  						return nil
  2223  					}
  2224  					if d.IsDir() {
  2225  						if _, err := fsys.Stat(filepath.Join(path, "go.mod")); err == nil {
  2226  							return filepath.SkipDir
  2227  						}
  2228  						return nil
  2229  					}
  2230  					if !d.Type().IsRegular() {
  2231  						return nil
  2232  					}
  2233  					count++
  2234  					if have[rel] != pid {
  2235  						have[rel] = pid
  2236  						list = append(list, rel)
  2237  					}
  2238  					return nil
  2239  				})
  2240  				if err != nil {
  2241  					return nil, nil, err
  2242  				}
  2243  				if count == 0 {
  2244  					return nil, nil, fmt.Errorf("cannot embed directory %s: contains no embeddable files", rel)
  2245  				}
  2246  			}
  2247  		}
  2248  
  2249  		if len(list) == 0 {
  2250  			return nil, nil, fmt.Errorf("no matching files found")
  2251  		}
  2252  		sort.Strings(list)
  2253  		pmap[pattern] = list
  2254  	}
  2255  
  2256  	for file := range have {
  2257  		files = append(files, file)
  2258  	}
  2259  	sort.Strings(files)
  2260  	return files, pmap, nil
  2261  }
  2262  
  2263  func validEmbedPattern(pattern string) bool {
  2264  	return pattern != "." && fs.ValidPath(pattern)
  2265  }
  2266  
  2267  // isBadEmbedName reports whether name is the base name of a file that
  2268  // can't or won't be included in modules and therefore shouldn't be treated
  2269  // as existing for embedding.
  2270  func isBadEmbedName(name string) bool {
  2271  	if err := module.CheckFilePath(name); err != nil {
  2272  		return true
  2273  	}
  2274  	switch name {
  2275  	// Empty string should be impossible but make it bad.
  2276  	case "":
  2277  		return true
  2278  	// Version control directories won't be present in module.
  2279  	case ".bzr", ".hg", ".git", ".svn":
  2280  		return true
  2281  	}
  2282  	return false
  2283  }
  2284  
  2285  // vcsStatusCache maps repository directories (string)
  2286  // to their VCS information.
  2287  var vcsStatusCache par.ErrCache[string, vcs.Status]
  2288  
  2289  func appendBuildSetting(info *debug.BuildInfo, key, value string) {
  2290  	value = strings.ReplaceAll(value, "\n", " ") // make value safe
  2291  	info.Settings = append(info.Settings, debug.BuildSetting{Key: key, Value: value})
  2292  }
  2293  
  2294  // setBuildInfo gathers build information and sets it into
  2295  // p.Internal.BuildInfo, which will later be formatted as a string and embedded
  2296  // in the binary. setBuildInfo should only be called on a main package with no
  2297  // errors.
  2298  //
  2299  // This information can be retrieved using debug.ReadBuildInfo.
  2300  //
  2301  // Note that the GoVersion field is not set here to avoid encoding it twice.
  2302  // It is stored separately in the binary, mostly for historical reasons.
  2303  func (p *Package) setBuildInfo(ctx context.Context, autoVCS bool) {
  2304  	setPkgErrorf := func(format string, args ...any) {
  2305  		if p.Error == nil {
  2306  			p.Error = &PackageError{Err: fmt.Errorf(format, args...)}
  2307  			p.Incomplete = true
  2308  		}
  2309  	}
  2310  
  2311  	var debugModFromModinfo func(*modinfo.ModulePublic) *debug.Module
  2312  	debugModFromModinfo = func(mi *modinfo.ModulePublic) *debug.Module {
  2313  		version := mi.Version
  2314  		if version == "" {
  2315  			version = "(devel)"
  2316  		}
  2317  		dm := &debug.Module{
  2318  			Path:    mi.Path,
  2319  			Version: version,
  2320  		}
  2321  		if mi.Replace != nil {
  2322  			dm.Replace = debugModFromModinfo(mi.Replace)
  2323  		} else if mi.Version != "" && cfg.BuildMod != "vendor" {
  2324  			dm.Sum = modfetch.Sum(ctx, module.Version{Path: mi.Path, Version: mi.Version})
  2325  		}
  2326  		return dm
  2327  	}
  2328  
  2329  	var main debug.Module
  2330  	if p.Module != nil {
  2331  		main = *debugModFromModinfo(p.Module)
  2332  	}
  2333  
  2334  	visited := make(map[*Package]bool)
  2335  	mdeps := make(map[module.Version]*debug.Module)
  2336  	var q []*Package
  2337  	q = append(q, p.Internal.Imports...)
  2338  	for len(q) > 0 {
  2339  		p1 := q[0]
  2340  		q = q[1:]
  2341  		if visited[p1] {
  2342  			continue
  2343  		}
  2344  		visited[p1] = true
  2345  		if p1.Module != nil {
  2346  			m := module.Version{Path: p1.Module.Path, Version: p1.Module.Version}
  2347  			if p1.Module.Path != main.Path && mdeps[m] == nil {
  2348  				mdeps[m] = debugModFromModinfo(p1.Module)
  2349  			}
  2350  		}
  2351  		q = append(q, p1.Internal.Imports...)
  2352  	}
  2353  	sortedMods := make([]module.Version, 0, len(mdeps))
  2354  	for mod := range mdeps {
  2355  		sortedMods = append(sortedMods, mod)
  2356  	}
  2357  	gover.ModSort(sortedMods)
  2358  	deps := make([]*debug.Module, len(sortedMods))
  2359  	for i, mod := range sortedMods {
  2360  		deps[i] = mdeps[mod]
  2361  	}
  2362  
  2363  	pkgPath := p.ImportPath
  2364  	if p.Internal.CmdlineFiles {
  2365  		pkgPath = "command-line-arguments"
  2366  	}
  2367  	info := &debug.BuildInfo{
  2368  		Path: pkgPath,
  2369  		Main: main,
  2370  		Deps: deps,
  2371  	}
  2372  	appendSetting := func(key, value string) {
  2373  		appendBuildSetting(info, key, value)
  2374  	}
  2375  
  2376  	// Add command-line flags relevant to the build.
  2377  	// This is informational, not an exhaustive list.
  2378  	// Please keep the list sorted.
  2379  	if cfg.BuildASan {
  2380  		appendSetting("-asan", "true")
  2381  	}
  2382  	if BuildAsmflags.present {
  2383  		appendSetting("-asmflags", BuildAsmflags.String())
  2384  	}
  2385  	buildmode := cfg.BuildBuildmode
  2386  	if buildmode == "default" {
  2387  		if p.Name == "main" {
  2388  			buildmode = "exe"
  2389  		} else {
  2390  			buildmode = "archive"
  2391  		}
  2392  	}
  2393  	appendSetting("-buildmode", buildmode)
  2394  	appendSetting("-compiler", cfg.BuildContext.Compiler)
  2395  	if gccgoflags := BuildGccgoflags.String(); gccgoflags != "" && cfg.BuildContext.Compiler == "gccgo" {
  2396  		appendSetting("-gccgoflags", gccgoflags)
  2397  	}
  2398  	if gcflags := BuildGcflags.String(); gcflags != "" && cfg.BuildContext.Compiler == "gc" {
  2399  		appendSetting("-gcflags", gcflags)
  2400  	}
  2401  	if ldflags := BuildLdflags.String(); ldflags != "" {
  2402  		// https://go.dev/issue/52372: only include ldflags if -trimpath is not set,
  2403  		// since it can include system paths through various linker flags (notably
  2404  		// -extar, -extld, and -extldflags).
  2405  		//
  2406  		// TODO: since we control cmd/link, in theory we can parse ldflags to
  2407  		// determine whether they may refer to system paths. If we do that, we can
  2408  		// redact only those paths from the recorded -ldflags setting and still
  2409  		// record the system-independent parts of the flags.
  2410  		if !cfg.BuildTrimpath {
  2411  			appendSetting("-ldflags", ldflags)
  2412  		}
  2413  	}
  2414  	if cfg.BuildCover {
  2415  		appendSetting("-cover", "true")
  2416  	}
  2417  	if cfg.BuildMSan {
  2418  		appendSetting("-msan", "true")
  2419  	}
  2420  	// N.B. -pgo added later by setPGOProfilePath.
  2421  	if cfg.BuildRace {
  2422  		appendSetting("-race", "true")
  2423  	}
  2424  	if tags := cfg.BuildContext.BuildTags; len(tags) > 0 {
  2425  		appendSetting("-tags", strings.Join(tags, ","))
  2426  	}
  2427  	if cfg.BuildTrimpath {
  2428  		appendSetting("-trimpath", "true")
  2429  	}
  2430  	if p.DefaultGODEBUG != "" {
  2431  		appendSetting("DefaultGODEBUG", p.DefaultGODEBUG)
  2432  	}
  2433  	cgo := "0"
  2434  	if cfg.BuildContext.CgoEnabled {
  2435  		cgo = "1"
  2436  	}
  2437  	appendSetting("CGO_ENABLED", cgo)
  2438  	// https://go.dev/issue/52372: only include CGO flags if -trimpath is not set.
  2439  	// (If -trimpath is set, it is possible that these flags include system paths.)
  2440  	// If cgo is involved, reproducibility is already pretty well ruined anyway,
  2441  	// given that we aren't stamping header or library versions.
  2442  	//
  2443  	// TODO(bcmills): perhaps we could at least parse the flags and stamp the
  2444  	// subset of flags that are known not to be paths?
  2445  	if cfg.BuildContext.CgoEnabled && !cfg.BuildTrimpath {
  2446  		for _, name := range []string{"CGO_CFLAGS", "CGO_CPPFLAGS", "CGO_CXXFLAGS", "CGO_LDFLAGS"} {
  2447  			appendSetting(name, cfg.Getenv(name))
  2448  		}
  2449  	}
  2450  	appendSetting("GOARCH", cfg.BuildContext.GOARCH)
  2451  	if cfg.RawGOEXPERIMENT != "" {
  2452  		appendSetting("GOEXPERIMENT", cfg.RawGOEXPERIMENT)
  2453  	}
  2454  	if fips140.Enabled() {
  2455  		appendSetting("GOFIPS140", fips140.Version())
  2456  	}
  2457  	appendSetting("GOOS", cfg.BuildContext.GOOS)
  2458  	if key, val, _ := cfg.GetArchEnv(); key != "" && val != "" {
  2459  		appendSetting(key, val)
  2460  	}
  2461  
  2462  	// Add VCS status if all conditions are true:
  2463  	//
  2464  	// - -buildvcs is enabled.
  2465  	// - p is a non-test contained within a main module (there may be multiple
  2466  	//   main modules in a workspace, but local replacements don't count).
  2467  	// - Both the current directory and p's module's root directory are contained
  2468  	//   in the same local repository.
  2469  	// - We know the VCS commands needed to get the status.
  2470  	setVCSError := func(err error) {
  2471  		setPkgErrorf("error obtaining VCS status: %v\n\tUse -buildvcs=false to disable VCS stamping.", err)
  2472  	}
  2473  
  2474  	var repoDir string
  2475  	var vcsCmd *vcs.Cmd
  2476  	var err error
  2477  	const allowNesting = true
  2478  
  2479  	wantVCS := false
  2480  	switch cfg.BuildBuildvcs {
  2481  	case "true":
  2482  		wantVCS = true // Include VCS metadata even for tests if requested explicitly; see https://go.dev/issue/52648.
  2483  	case "auto":
  2484  		wantVCS = autoVCS && !p.IsTestOnly()
  2485  	case "false":
  2486  	default:
  2487  		panic(fmt.Sprintf("unexpected value for cfg.BuildBuildvcs: %q", cfg.BuildBuildvcs))
  2488  	}
  2489  
  2490  	if wantVCS && p.Module != nil && p.Module.Version == "" && !p.Standard {
  2491  		if p.Module.Path == "bootstrap" && cfg.GOROOT == os.Getenv("GOROOT_BOOTSTRAP") {
  2492  			// During bootstrapping, the bootstrap toolchain is built in module
  2493  			// "bootstrap" (instead of "std"), with GOROOT set to GOROOT_BOOTSTRAP
  2494  			// (so the bootstrap toolchain packages don't even appear to be in GOROOT).
  2495  			goto omitVCS
  2496  		}
  2497  		repoDir, vcsCmd, err = vcs.FromDir(base.Cwd(), "", allowNesting)
  2498  		if err != nil && !errors.Is(err, os.ErrNotExist) {
  2499  			setVCSError(err)
  2500  			return
  2501  		}
  2502  		if !str.HasFilePathPrefix(p.Module.Dir, repoDir) &&
  2503  			!str.HasFilePathPrefix(repoDir, p.Module.Dir) {
  2504  			// The module containing the main package does not overlap with the
  2505  			// repository containing the working directory. Don't include VCS info.
  2506  			// If the repo contains the module or vice versa, but they are not
  2507  			// the same directory, it's likely an error (see below).
  2508  			goto omitVCS
  2509  		}
  2510  		if cfg.BuildBuildvcs == "auto" && vcsCmd != nil && vcsCmd.Cmd != "" {
  2511  			if _, err := pathcache.LookPath(vcsCmd.Cmd); err != nil {
  2512  				// We fould a repository, but the required VCS tool is not present.
  2513  				// "-buildvcs=auto" means that we should silently drop the VCS metadata.
  2514  				goto omitVCS
  2515  			}
  2516  		}
  2517  	}
  2518  	if repoDir != "" && vcsCmd.Status != nil {
  2519  		// Check that the current directory, package, and module are in the same
  2520  		// repository. vcs.FromDir allows nested Git repositories, but nesting
  2521  		// is not allowed for other VCS tools. The current directory may be outside
  2522  		// p.Module.Dir when a workspace is used.
  2523  		pkgRepoDir, _, err := vcs.FromDir(p.Dir, "", allowNesting)
  2524  		if err != nil {
  2525  			setVCSError(err)
  2526  			return
  2527  		}
  2528  		if pkgRepoDir != repoDir {
  2529  			if cfg.BuildBuildvcs != "auto" {
  2530  				setVCSError(fmt.Errorf("main package is in repository %q but current directory is in repository %q", pkgRepoDir, repoDir))
  2531  				return
  2532  			}
  2533  			goto omitVCS
  2534  		}
  2535  		modRepoDir, _, err := vcs.FromDir(p.Module.Dir, "", allowNesting)
  2536  		if err != nil {
  2537  			setVCSError(err)
  2538  			return
  2539  		}
  2540  		if modRepoDir != repoDir {
  2541  			if cfg.BuildBuildvcs != "auto" {
  2542  				setVCSError(fmt.Errorf("main module is in repository %q but current directory is in repository %q", modRepoDir, repoDir))
  2543  				return
  2544  			}
  2545  			goto omitVCS
  2546  		}
  2547  
  2548  		st, err := vcsStatusCache.Do(repoDir, func() (vcs.Status, error) {
  2549  			return vcsCmd.Status(vcsCmd, repoDir)
  2550  		})
  2551  		if err != nil {
  2552  			setVCSError(err)
  2553  			return
  2554  		}
  2555  
  2556  		appendSetting("vcs", vcsCmd.Cmd)
  2557  		if st.Revision != "" {
  2558  			appendSetting("vcs.revision", st.Revision)
  2559  		}
  2560  		if !st.CommitTime.IsZero() {
  2561  			stamp := st.CommitTime.UTC().Format(time.RFC3339Nano)
  2562  			appendSetting("vcs.time", stamp)
  2563  		}
  2564  		appendSetting("vcs.modified", strconv.FormatBool(st.Uncommitted))
  2565  		// Determine the correct version of this module at the current revision and update the build metadata accordingly.
  2566  		repo := modfetch.LookupLocal(ctx, repoDir)
  2567  		revInfo, err := repo.Stat(ctx, st.Revision)
  2568  		if err != nil {
  2569  			goto omitVCS
  2570  		}
  2571  		vers := revInfo.Version
  2572  		if vers != "" {
  2573  			if st.Uncommitted {
  2574  				// SemVer build metadata is dot-separated https://semver.org/#spec-item-10
  2575  				if strings.HasSuffix(vers, "+incompatible") {
  2576  					vers += ".dirty"
  2577  				} else {
  2578  					vers += "+dirty"
  2579  				}
  2580  			}
  2581  			info.Main.Version = vers
  2582  		}
  2583  	}
  2584  omitVCS:
  2585  
  2586  	p.Internal.BuildInfo = info
  2587  }
  2588  
  2589  // SafeArg reports whether arg is a "safe" command-line argument,
  2590  // meaning that when it appears in a command-line, it probably
  2591  // doesn't have some special meaning other than its own name.
  2592  // Obviously args beginning with - are not safe (they look like flags).
  2593  // Less obviously, args beginning with @ are not safe (they look like
  2594  // GNU binutils flagfile specifiers, sometimes called "response files").
  2595  // To be conservative, we reject almost any arg beginning with non-alphanumeric ASCII.
  2596  // We accept leading . _ and / as likely in file system paths.
  2597  // There is a copy of this function in cmd/compile/internal/gc/noder.go.
  2598  func SafeArg(name string) bool {
  2599  	if name == "" {
  2600  		return false
  2601  	}
  2602  	c := name[0]
  2603  	return '0' <= c && c <= '9' || 'A' <= c && c <= 'Z' || 'a' <= c && c <= 'z' || c == '.' || c == '_' || c == '/' || c >= utf8.RuneSelf
  2604  }
  2605  
  2606  // LinkerDeps returns the list of linker-induced dependencies for main package p.
  2607  func LinkerDeps(p *Package) ([]string, error) {
  2608  	// Everything links runtime.
  2609  	deps := []string{"runtime"}
  2610  
  2611  	// External linking mode forces an import of runtime/cgo.
  2612  	if what := externalLinkingReason(p); what != "" && cfg.BuildContext.Compiler != "gccgo" {
  2613  		if !cfg.BuildContext.CgoEnabled {
  2614  			return nil, fmt.Errorf("%s requires external (cgo) linking, but cgo is not enabled", what)
  2615  		}
  2616  		deps = append(deps, "runtime/cgo")
  2617  	}
  2618  	// On ARM with GOARM=5, it forces an import of math, for soft floating point.
  2619  	if cfg.Goarch == "arm" {
  2620  		deps = append(deps, "math")
  2621  	}
  2622  	// Using the race detector forces an import of runtime/race.
  2623  	if cfg.BuildRace {
  2624  		deps = append(deps, "runtime/race")
  2625  	}
  2626  	// Using memory sanitizer forces an import of runtime/msan.
  2627  	if cfg.BuildMSan {
  2628  		deps = append(deps, "runtime/msan")
  2629  	}
  2630  	// Using address sanitizer forces an import of runtime/asan.
  2631  	if cfg.BuildASan {
  2632  		deps = append(deps, "runtime/asan")
  2633  	}
  2634  	// Building for coverage forces an import of runtime/coverage.
  2635  	if cfg.BuildCover && cfg.Experiment.CoverageRedesign {
  2636  		deps = append(deps, "runtime/coverage")
  2637  	}
  2638  
  2639  	return deps, nil
  2640  }
  2641  
  2642  // externalLinkingReason reports the reason external linking is required
  2643  // even for programs that do not use cgo, or the empty string if external
  2644  // linking is not required.
  2645  func externalLinkingReason(p *Package) (what string) {
  2646  	// Some targets must use external linking even inside GOROOT.
  2647  	if platform.MustLinkExternal(cfg.Goos, cfg.Goarch, false) {
  2648  		return cfg.Goos + "/" + cfg.Goarch
  2649  	}
  2650  
  2651  	// Some build modes always require external linking.
  2652  	switch cfg.BuildBuildmode {
  2653  	case "c-shared":
  2654  		if cfg.BuildContext.GOARCH == "wasm" {
  2655  			break
  2656  		}
  2657  		fallthrough
  2658  	case "plugin":
  2659  		return "-buildmode=" + cfg.BuildBuildmode
  2660  	}
  2661  
  2662  	// Using -linkshared always requires external linking.
  2663  	if cfg.BuildLinkshared {
  2664  		return "-linkshared"
  2665  	}
  2666  
  2667  	// Decide whether we are building a PIE,
  2668  	// bearing in mind that some systems default to PIE.
  2669  	isPIE := false
  2670  	if cfg.BuildBuildmode == "pie" {
  2671  		isPIE = true
  2672  	} else if cfg.BuildBuildmode == "default" && platform.DefaultPIE(cfg.BuildContext.GOOS, cfg.BuildContext.GOARCH, cfg.BuildRace) {
  2673  		isPIE = true
  2674  	}
  2675  	// If we are building a PIE, and we are on a system
  2676  	// that does not support PIE with internal linking mode,
  2677  	// then we must use external linking.
  2678  	if isPIE && !platform.InternalLinkPIESupported(cfg.BuildContext.GOOS, cfg.BuildContext.GOARCH) {
  2679  		if cfg.BuildBuildmode == "pie" {
  2680  			return "-buildmode=pie"
  2681  		}
  2682  		return "default PIE binary"
  2683  	}
  2684  
  2685  	// Using -ldflags=-linkmode=external forces external linking.
  2686  	// If there are multiple -linkmode options, the last one wins.
  2687  	if p != nil {
  2688  		ldflags := BuildLdflags.For(p)
  2689  		for i := len(ldflags) - 1; i >= 0; i-- {
  2690  			a := ldflags[i]
  2691  			if a == "-linkmode=external" ||
  2692  				a == "-linkmode" && i+1 < len(ldflags) && ldflags[i+1] == "external" {
  2693  				return a
  2694  			} else if a == "-linkmode=internal" ||
  2695  				a == "-linkmode" && i+1 < len(ldflags) && ldflags[i+1] == "internal" {
  2696  				return ""
  2697  			}
  2698  		}
  2699  	}
  2700  
  2701  	return ""
  2702  }
  2703  
  2704  // mkAbs rewrites list, which must be paths relative to p.Dir,
  2705  // into a sorted list of absolute paths. It edits list in place but for
  2706  // convenience also returns list back to its caller.
  2707  func (p *Package) mkAbs(list []string) []string {
  2708  	for i, f := range list {
  2709  		list[i] = filepath.Join(p.Dir, f)
  2710  	}
  2711  	sort.Strings(list)
  2712  	return list
  2713  }
  2714  
  2715  // InternalGoFiles returns the list of Go files being built for the package,
  2716  // using absolute paths.
  2717  func (p *Package) InternalGoFiles() []string {
  2718  	return p.mkAbs(str.StringList(p.GoFiles, p.CgoFiles, p.TestGoFiles))
  2719  }
  2720  
  2721  // InternalXGoFiles returns the list of Go files being built for the XTest package,
  2722  // using absolute paths.
  2723  func (p *Package) InternalXGoFiles() []string {
  2724  	return p.mkAbs(p.XTestGoFiles)
  2725  }
  2726  
  2727  // InternalAllGoFiles returns the list of all Go files possibly relevant for the package,
  2728  // using absolute paths. "Possibly relevant" means that files are not excluded
  2729  // due to build tags, but files with names beginning with . or _ are still excluded.
  2730  func (p *Package) InternalAllGoFiles() []string {
  2731  	return p.mkAbs(str.StringList(p.IgnoredGoFiles, p.GoFiles, p.CgoFiles, p.TestGoFiles, p.XTestGoFiles))
  2732  }
  2733  
  2734  // UsesSwig reports whether the package needs to run SWIG.
  2735  func (p *Package) UsesSwig() bool {
  2736  	return len(p.SwigFiles) > 0 || len(p.SwigCXXFiles) > 0
  2737  }
  2738  
  2739  // UsesCgo reports whether the package needs to run cgo
  2740  func (p *Package) UsesCgo() bool {
  2741  	return len(p.CgoFiles) > 0
  2742  }
  2743  
  2744  // PackageList returns the list of packages in the dag rooted at roots
  2745  // as visited in a depth-first post-order traversal.
  2746  func PackageList(roots []*Package) []*Package {
  2747  	seen := map[*Package]bool{}
  2748  	all := []*Package{}
  2749  	var walk func(*Package)
  2750  	walk = func(p *Package) {
  2751  		if seen[p] {
  2752  			return
  2753  		}
  2754  		seen[p] = true
  2755  		for _, p1 := range p.Internal.Imports {
  2756  			walk(p1)
  2757  		}
  2758  		all = append(all, p)
  2759  	}
  2760  	for _, root := range roots {
  2761  		walk(root)
  2762  	}
  2763  	return all
  2764  }
  2765  
  2766  // TestPackageList returns the list of packages in the dag rooted at roots
  2767  // as visited in a depth-first post-order traversal, including the test
  2768  // imports of the roots. This ignores errors in test packages.
  2769  func TestPackageList(ctx context.Context, opts PackageOpts, roots []*Package) []*Package {
  2770  	seen := map[*Package]bool{}
  2771  	all := []*Package{}
  2772  	var walk func(*Package)
  2773  	walk = func(p *Package) {
  2774  		if seen[p] {
  2775  			return
  2776  		}
  2777  		seen[p] = true
  2778  		for _, p1 := range p.Internal.Imports {
  2779  			walk(p1)
  2780  		}
  2781  		all = append(all, p)
  2782  	}
  2783  	walkTest := func(root *Package, path string) {
  2784  		var stk ImportStack
  2785  		p1, err := loadImport(ctx, opts, nil, path, root.Dir, root, &stk, root.Internal.Build.TestImportPos[path], ResolveImport)
  2786  		if err != nil && root.Error == nil {
  2787  			// Assign error importing the package to the importer.
  2788  			root.Error = err
  2789  			root.Incomplete = true
  2790  		}
  2791  		if p1.Error == nil {
  2792  			walk(p1)
  2793  		}
  2794  	}
  2795  	for _, root := range roots {
  2796  		walk(root)
  2797  		for _, path := range root.TestImports {
  2798  			walkTest(root, path)
  2799  		}
  2800  		for _, path := range root.XTestImports {
  2801  			walkTest(root, path)
  2802  		}
  2803  	}
  2804  	return all
  2805  }
  2806  
  2807  // LoadImportWithFlags loads the package with the given import path and
  2808  // sets tool flags on that package. This function is useful loading implicit
  2809  // dependencies (like sync/atomic for coverage).
  2810  // TODO(jayconrod): delete this function and set flags automatically
  2811  // in LoadImport instead.
  2812  func LoadImportWithFlags(path, srcDir string, parent *Package, stk *ImportStack, importPos []token.Position, mode int) (*Package, *PackageError) {
  2813  	p, err := loadImport(context.TODO(), PackageOpts{}, nil, path, srcDir, parent, stk, importPos, mode)
  2814  	setToolFlags(p)
  2815  	return p, err
  2816  }
  2817  
  2818  // LoadPackageWithFlags is the same as LoadImportWithFlags but without a parent.
  2819  // It's then guaranteed to not return an error
  2820  func LoadPackageWithFlags(path, srcDir string, stk *ImportStack, importPos []token.Position, mode int) *Package {
  2821  	p := LoadPackage(context.TODO(), PackageOpts{}, path, srcDir, stk, importPos, mode)
  2822  	setToolFlags(p)
  2823  	return p
  2824  }
  2825  
  2826  // PackageOpts control the behavior of PackagesAndErrors and other package
  2827  // loading functions.
  2828  type PackageOpts struct {
  2829  	// IgnoreImports controls whether we ignore explicit and implicit imports
  2830  	// when loading packages.  Implicit imports are added when supporting Cgo
  2831  	// or SWIG and when linking main packages.
  2832  	IgnoreImports bool
  2833  
  2834  	// ModResolveTests indicates whether calls to the module loader should also
  2835  	// resolve test dependencies of the requested packages.
  2836  	//
  2837  	// If ModResolveTests is true, then the module loader needs to resolve test
  2838  	// dependencies at the same time as packages; otherwise, the test dependencies
  2839  	// of those packages could be missing, and resolving those missing dependencies
  2840  	// could change the selected versions of modules that provide other packages.
  2841  	ModResolveTests bool
  2842  
  2843  	// MainOnly is true if the caller only wants to load main packages.
  2844  	// For a literal argument matching a non-main package, a stub may be returned
  2845  	// with an error. For a non-literal argument (with "..."), non-main packages
  2846  	// are not be matched, and their dependencies may not be loaded. A warning
  2847  	// may be printed for non-literal arguments that match no main packages.
  2848  	MainOnly bool
  2849  
  2850  	// AutoVCS controls whether we also load version-control metadata for main packages
  2851  	// when -buildvcs=auto (the default).
  2852  	AutoVCS bool
  2853  
  2854  	// SuppressBuildInfo is true if the caller does not need p.Stale, p.StaleReason, or p.Internal.BuildInfo
  2855  	// to be populated on the package.
  2856  	SuppressBuildInfo bool
  2857  
  2858  	// SuppressEmbedFiles is true if the caller does not need any embed files to be populated on the
  2859  	// package.
  2860  	SuppressEmbedFiles bool
  2861  }
  2862  
  2863  // PackagesAndErrors returns the packages named by the command line arguments
  2864  // 'patterns'. If a named package cannot be loaded, PackagesAndErrors returns
  2865  // a *Package with the Error field describing the failure. If errors are found
  2866  // loading imported packages, the DepsErrors field is set. The Incomplete field
  2867  // may be set as well.
  2868  //
  2869  // To obtain a flat list of packages, use PackageList.
  2870  // To report errors loading packages, use ReportPackageErrors.
  2871  func PackagesAndErrors(ctx context.Context, opts PackageOpts, patterns []string) []*Package {
  2872  	ctx, span := trace.StartSpan(ctx, "load.PackagesAndErrors")
  2873  	defer span.Done()
  2874  
  2875  	for _, p := range patterns {
  2876  		// Listing is only supported with all patterns referring to either:
  2877  		// - Files that are part of the same directory.
  2878  		// - Explicit package paths or patterns.
  2879  		if strings.HasSuffix(p, ".go") {
  2880  			// We need to test whether the path is an actual Go file and not a
  2881  			// package path or pattern ending in '.go' (see golang.org/issue/34653).
  2882  			if fi, err := fsys.Stat(p); err == nil && !fi.IsDir() {
  2883  				pkgs := []*Package{GoFilesPackage(ctx, opts, patterns)}
  2884  				setPGOProfilePath(pkgs)
  2885  				return pkgs
  2886  			}
  2887  		}
  2888  	}
  2889  
  2890  	var matches []*search.Match
  2891  	if modload.Init(); cfg.ModulesEnabled {
  2892  		modOpts := modload.PackageOpts{
  2893  			ResolveMissingImports: true,
  2894  			LoadTests:             opts.ModResolveTests,
  2895  			SilencePackageErrors:  true,
  2896  		}
  2897  		matches, _ = modload.LoadPackages(ctx, modOpts, patterns...)
  2898  	} else {
  2899  		noModRoots := []string{}
  2900  		matches = search.ImportPaths(patterns, noModRoots)
  2901  	}
  2902  
  2903  	var (
  2904  		pkgs    []*Package
  2905  		stk     ImportStack
  2906  		seenPkg = make(map[*Package]bool)
  2907  	)
  2908  
  2909  	pre := newPreload()
  2910  	defer pre.flush()
  2911  	pre.preloadMatches(ctx, opts, matches)
  2912  
  2913  	for _, m := range matches {
  2914  		for _, pkg := range m.Pkgs {
  2915  			if pkg == "" {
  2916  				panic(fmt.Sprintf("ImportPaths returned empty package for pattern %s", m.Pattern()))
  2917  			}
  2918  			mode := cmdlinePkg
  2919  			if m.IsLiteral() {
  2920  				// Note: do not set = m.IsLiteral unconditionally
  2921  				// because maybe we'll see p matching both
  2922  				// a literal and also a non-literal pattern.
  2923  				mode |= cmdlinePkgLiteral
  2924  			}
  2925  			p, perr := loadImport(ctx, opts, pre, pkg, base.Cwd(), nil, &stk, nil, mode)
  2926  			if perr != nil {
  2927  				base.Fatalf("internal error: loadImport of %q with nil parent returned an error", pkg)
  2928  			}
  2929  			p.Match = append(p.Match, m.Pattern())
  2930  			if seenPkg[p] {
  2931  				continue
  2932  			}
  2933  			seenPkg[p] = true
  2934  			pkgs = append(pkgs, p)
  2935  		}
  2936  
  2937  		if len(m.Errs) > 0 {
  2938  			// In addition to any packages that were actually resolved from the
  2939  			// pattern, there was some error in resolving the pattern itself.
  2940  			// Report it as a synthetic package.
  2941  			p := new(Package)
  2942  			p.ImportPath = m.Pattern()
  2943  			// Pass an empty ImportStack and nil importPos: the error arose from a pattern, not an import.
  2944  			var stk ImportStack
  2945  			var importPos []token.Position
  2946  			p.setLoadPackageDataError(m.Errs[0], m.Pattern(), &stk, importPos)
  2947  			p.Incomplete = true
  2948  			p.Match = append(p.Match, m.Pattern())
  2949  			p.Internal.CmdlinePkg = true
  2950  			if m.IsLiteral() {
  2951  				p.Internal.CmdlinePkgLiteral = true
  2952  			}
  2953  			pkgs = append(pkgs, p)
  2954  		}
  2955  	}
  2956  
  2957  	if opts.MainOnly {
  2958  		pkgs = mainPackagesOnly(pkgs, matches)
  2959  	}
  2960  
  2961  	// Now that CmdlinePkg is set correctly,
  2962  	// compute the effective flags for all loaded packages
  2963  	// (not just the ones matching the patterns but also
  2964  	// their dependencies).
  2965  	setToolFlags(pkgs...)
  2966  
  2967  	setPGOProfilePath(pkgs)
  2968  
  2969  	return pkgs
  2970  }
  2971  
  2972  // setPGOProfilePath sets the PGO profile path for pkgs.
  2973  // In -pgo=auto mode, it finds the default PGO profile.
  2974  func setPGOProfilePath(pkgs []*Package) {
  2975  	updateBuildInfo := func(p *Package, file string) {
  2976  		// Don't create BuildInfo for packages that didn't already have it.
  2977  		if p.Internal.BuildInfo == nil {
  2978  			return
  2979  		}
  2980  
  2981  		if cfg.BuildTrimpath {
  2982  			appendBuildSetting(p.Internal.BuildInfo, "-pgo", filepath.Base(file))
  2983  		} else {
  2984  			appendBuildSetting(p.Internal.BuildInfo, "-pgo", file)
  2985  		}
  2986  		// Adding -pgo breaks the sort order in BuildInfo.Settings. Restore it.
  2987  		slices.SortFunc(p.Internal.BuildInfo.Settings, func(x, y debug.BuildSetting) int {
  2988  			return strings.Compare(x.Key, y.Key)
  2989  		})
  2990  	}
  2991  
  2992  	switch cfg.BuildPGO {
  2993  	case "off":
  2994  		return
  2995  
  2996  	case "auto":
  2997  		// Locate PGO profiles from the main packages, and
  2998  		// attach the profile to the main package and its
  2999  		// dependencies.
  3000  		// If we're building multiple main packages, they may
  3001  		// have different profiles. We may need to split (unshare)
  3002  		// the dependency graph so they can attach different
  3003  		// profiles.
  3004  		for _, p := range pkgs {
  3005  			if p.Name != "main" {
  3006  				continue
  3007  			}
  3008  			pmain := p
  3009  			file := filepath.Join(pmain.Dir, "default.pgo")
  3010  			if _, err := os.Stat(file); err != nil {
  3011  				continue // no profile
  3012  			}
  3013  
  3014  			// Packages already visited. The value should replace
  3015  			// the key, as it may be a forked copy of the original
  3016  			// Package.
  3017  			visited := make(map[*Package]*Package)
  3018  			var split func(p *Package) *Package
  3019  			split = func(p *Package) *Package {
  3020  				if p1 := visited[p]; p1 != nil {
  3021  					return p1
  3022  				}
  3023  
  3024  				if len(pkgs) > 1 && p != pmain {
  3025  					// Make a copy, then attach profile.
  3026  					// No need to copy if there is only one root package (we can
  3027  					// attach profile directly in-place).
  3028  					// Also no need to copy the main package.
  3029  					if p.Internal.PGOProfile != "" {
  3030  						panic("setPGOProfilePath: already have profile")
  3031  					}
  3032  					p1 := new(Package)
  3033  					*p1 = *p
  3034  					// Unalias the Imports and Internal.Imports slices,
  3035  					// which we're going to modify. We don't copy other slices as
  3036  					// we don't change them.
  3037  					p1.Imports = slices.Clone(p.Imports)
  3038  					p1.Internal.Imports = slices.Clone(p.Internal.Imports)
  3039  					p1.Internal.ForMain = pmain.ImportPath
  3040  					visited[p] = p1
  3041  					p = p1
  3042  				} else {
  3043  					visited[p] = p
  3044  				}
  3045  				p.Internal.PGOProfile = file
  3046  				updateBuildInfo(p, file)
  3047  				// Recurse to dependencies.
  3048  				for i, pp := range p.Internal.Imports {
  3049  					p.Internal.Imports[i] = split(pp)
  3050  				}
  3051  				return p
  3052  			}
  3053  
  3054  			// Replace the package and imports with the PGO version.
  3055  			split(pmain)
  3056  		}
  3057  
  3058  	default:
  3059  		// Profile specified from the command line.
  3060  		// Make it absolute path, as the compiler runs on various directories.
  3061  		file, err := filepath.Abs(cfg.BuildPGO)
  3062  		if err != nil {
  3063  			base.Fatalf("fail to get absolute path of PGO file %s: %v", cfg.BuildPGO, err)
  3064  		}
  3065  
  3066  		for _, p := range PackageList(pkgs) {
  3067  			p.Internal.PGOProfile = file
  3068  			updateBuildInfo(p, file)
  3069  		}
  3070  	}
  3071  }
  3072  
  3073  // CheckPackageErrors prints errors encountered loading pkgs and their
  3074  // dependencies, then exits with a non-zero status if any errors were found.
  3075  func CheckPackageErrors(pkgs []*Package) {
  3076  	PackageErrors(pkgs, func(p *Package) {
  3077  		DefaultPrinter().Errorf(p, "%v", p.Error)
  3078  	})
  3079  	base.ExitIfErrors()
  3080  }
  3081  
  3082  // PackageErrors calls report for errors encountered loading pkgs and their dependencies.
  3083  func PackageErrors(pkgs []*Package, report func(*Package)) {
  3084  	var anyIncomplete, anyErrors bool
  3085  	for _, pkg := range pkgs {
  3086  		if pkg.Incomplete {
  3087  			anyIncomplete = true
  3088  		}
  3089  	}
  3090  	if anyIncomplete {
  3091  		all := PackageList(pkgs)
  3092  		for _, p := range all {
  3093  			if p.Error != nil {
  3094  				report(p)
  3095  				anyErrors = true
  3096  			}
  3097  		}
  3098  	}
  3099  	if anyErrors {
  3100  		return
  3101  	}
  3102  
  3103  	// Check for duplicate loads of the same package.
  3104  	// That should be impossible, but if it does happen then
  3105  	// we end up trying to build the same package twice,
  3106  	// usually in parallel overwriting the same files,
  3107  	// which doesn't work very well.
  3108  	seen := map[string]bool{}
  3109  	reported := map[string]bool{}
  3110  	for _, pkg := range PackageList(pkgs) {
  3111  		// -pgo=auto with multiple main packages can cause a package being
  3112  		// built multiple times (with different profiles).
  3113  		// We check that package import path + profile path is unique.
  3114  		key := pkg.ImportPath
  3115  		if pkg.Internal.PGOProfile != "" {
  3116  			key += " pgo:" + pkg.Internal.PGOProfile
  3117  		}
  3118  		if seen[key] && !reported[key] {
  3119  			reported[key] = true
  3120  			base.Errorf("internal error: duplicate loads of %s", pkg.ImportPath)
  3121  		}
  3122  		seen[key] = true
  3123  	}
  3124  	if len(reported) > 0 {
  3125  		base.ExitIfErrors()
  3126  	}
  3127  }
  3128  
  3129  // mainPackagesOnly filters out non-main packages matched only by arguments
  3130  // containing "..." and returns the remaining main packages.
  3131  //
  3132  // Packages with missing, invalid, or ambiguous names may be treated as
  3133  // possibly-main packages.
  3134  //
  3135  // mainPackagesOnly sets a non-main package's Error field and returns it if it
  3136  // is named by a literal argument.
  3137  //
  3138  // mainPackagesOnly prints warnings for non-literal arguments that only match
  3139  // non-main packages.
  3140  func mainPackagesOnly(pkgs []*Package, matches []*search.Match) []*Package {
  3141  	treatAsMain := map[string]bool{}
  3142  	for _, m := range matches {
  3143  		if m.IsLiteral() {
  3144  			for _, path := range m.Pkgs {
  3145  				treatAsMain[path] = true
  3146  			}
  3147  		}
  3148  	}
  3149  
  3150  	var mains []*Package
  3151  	for _, pkg := range pkgs {
  3152  		if pkg.Name == "main" || (pkg.Name == "" && pkg.Error != nil) {
  3153  			treatAsMain[pkg.ImportPath] = true
  3154  			mains = append(mains, pkg)
  3155  			continue
  3156  		}
  3157  
  3158  		if len(pkg.InvalidGoFiles) > 0 { // TODO(#45999): && pkg.Name == "", but currently go/build sets pkg.Name arbitrarily if it is ambiguous.
  3159  			// The package has (or may have) conflicting names, and we can't easily
  3160  			// tell whether one of them is "main". So assume that it could be, and
  3161  			// report an error for the package.
  3162  			treatAsMain[pkg.ImportPath] = true
  3163  		}
  3164  		if treatAsMain[pkg.ImportPath] {
  3165  			if pkg.Error == nil {
  3166  				pkg.Error = &PackageError{Err: &mainPackageError{importPath: pkg.ImportPath}}
  3167  				pkg.Incomplete = true
  3168  			}
  3169  			mains = append(mains, pkg)
  3170  		}
  3171  	}
  3172  
  3173  	for _, m := range matches {
  3174  		if m.IsLiteral() || len(m.Pkgs) == 0 {
  3175  			continue
  3176  		}
  3177  		foundMain := false
  3178  		for _, path := range m.Pkgs {
  3179  			if treatAsMain[path] {
  3180  				foundMain = true
  3181  				break
  3182  			}
  3183  		}
  3184  		if !foundMain {
  3185  			fmt.Fprintf(os.Stderr, "go: warning: %q matched only non-main packages\n", m.Pattern())
  3186  		}
  3187  	}
  3188  
  3189  	return mains
  3190  }
  3191  
  3192  type mainPackageError struct {
  3193  	importPath string
  3194  }
  3195  
  3196  func (e *mainPackageError) Error() string {
  3197  	return fmt.Sprintf("package %s is not a main package", e.importPath)
  3198  }
  3199  
  3200  func (e *mainPackageError) ImportPath() string {
  3201  	return e.importPath
  3202  }
  3203  
  3204  func setToolFlags(pkgs ...*Package) {
  3205  	for _, p := range PackageList(pkgs) {
  3206  		p.Internal.Asmflags = BuildAsmflags.For(p)
  3207  		p.Internal.Gcflags = BuildGcflags.For(p)
  3208  		p.Internal.Ldflags = BuildLdflags.For(p)
  3209  		p.Internal.Gccgoflags = BuildGccgoflags.For(p)
  3210  	}
  3211  }
  3212  
  3213  // GoFilesPackage creates a package for building a collection of Go files
  3214  // (typically named on the command line). The target is named p.a for
  3215  // package p or named after the first Go file for package main.
  3216  func GoFilesPackage(ctx context.Context, opts PackageOpts, gofiles []string) *Package {
  3217  	modload.Init()
  3218  
  3219  	for _, f := range gofiles {
  3220  		if !strings.HasSuffix(f, ".go") {
  3221  			pkg := new(Package)
  3222  			pkg.Internal.Local = true
  3223  			pkg.Internal.CmdlineFiles = true
  3224  			pkg.Name = f
  3225  			pkg.Error = &PackageError{
  3226  				Err: fmt.Errorf("named files must be .go files: %s", pkg.Name),
  3227  			}
  3228  			pkg.Incomplete = true
  3229  			return pkg
  3230  		}
  3231  	}
  3232  
  3233  	var stk ImportStack
  3234  	ctxt := cfg.BuildContext
  3235  	ctxt.UseAllFiles = true
  3236  
  3237  	// Synthesize fake "directory" that only shows the named files,
  3238  	// to make it look like this is a standard package or
  3239  	// command directory. So that local imports resolve
  3240  	// consistently, the files must all be in the same directory.
  3241  	var dirent []fs.FileInfo
  3242  	var dir string
  3243  	for _, file := range gofiles {
  3244  		fi, err := fsys.Stat(file)
  3245  		if err != nil {
  3246  			base.Fatalf("%s", err)
  3247  		}
  3248  		if fi.IsDir() {
  3249  			base.Fatalf("%s is a directory, should be a Go file", file)
  3250  		}
  3251  		dir1 := filepath.Dir(file)
  3252  		if dir == "" {
  3253  			dir = dir1
  3254  		} else if dir != dir1 {
  3255  			base.Fatalf("named files must all be in one directory; have %s and %s", dir, dir1)
  3256  		}
  3257  		dirent = append(dirent, fi)
  3258  	}
  3259  	ctxt.ReadDir = func(string) ([]fs.FileInfo, error) { return dirent, nil }
  3260  
  3261  	if cfg.ModulesEnabled {
  3262  		modload.ImportFromFiles(ctx, gofiles)
  3263  	}
  3264  
  3265  	var err error
  3266  	if dir == "" {
  3267  		dir = base.Cwd()
  3268  	}
  3269  	dir, err = filepath.Abs(dir)
  3270  	if err != nil {
  3271  		base.Fatalf("%s", err)
  3272  	}
  3273  
  3274  	bp, err := ctxt.ImportDir(dir, 0)
  3275  	pkg := new(Package)
  3276  	pkg.Internal.Local = true
  3277  	pkg.Internal.CmdlineFiles = true
  3278  	pkg.load(ctx, opts, "command-line-arguments", &stk, nil, bp, err)
  3279  	if !cfg.ModulesEnabled {
  3280  		pkg.Internal.LocalPrefix = dirToImportPath(dir)
  3281  	}
  3282  	pkg.ImportPath = "command-line-arguments"
  3283  	pkg.Target = ""
  3284  	pkg.Match = gofiles
  3285  
  3286  	if pkg.Name == "main" {
  3287  		exe := pkg.DefaultExecName() + cfg.ExeSuffix
  3288  
  3289  		if cfg.GOBIN != "" {
  3290  			pkg.Target = filepath.Join(cfg.GOBIN, exe)
  3291  		} else if cfg.ModulesEnabled {
  3292  			pkg.Target = filepath.Join(modload.BinDir(), exe)
  3293  		}
  3294  	}
  3295  
  3296  	if opts.MainOnly && pkg.Name != "main" && pkg.Error == nil {
  3297  		pkg.Error = &PackageError{Err: &mainPackageError{importPath: pkg.ImportPath}}
  3298  		pkg.Incomplete = true
  3299  	}
  3300  	setToolFlags(pkg)
  3301  
  3302  	return pkg
  3303  }
  3304  
  3305  // PackagesAndErrorsOutsideModule is like PackagesAndErrors but runs in
  3306  // module-aware mode and ignores the go.mod file in the current directory or any
  3307  // parent directory, if there is one. This is used in the implementation of 'go
  3308  // install pkg@version' and other commands that support similar forms.
  3309  //
  3310  // modload.ForceUseModules must be true, and modload.RootMode must be NoRoot
  3311  // before calling this function.
  3312  //
  3313  // PackagesAndErrorsOutsideModule imposes several constraints to avoid
  3314  // ambiguity. All arguments must have the same version suffix (not just a suffix
  3315  // that resolves to the same version). They must refer to packages in the same
  3316  // module, which must not be std or cmd. That module is not considered the main
  3317  // module, but its go.mod file (if it has one) must not contain directives that
  3318  // would cause it to be interpreted differently if it were the main module
  3319  // (replace, exclude).
  3320  func PackagesAndErrorsOutsideModule(ctx context.Context, opts PackageOpts, args []string) ([]*Package, error) {
  3321  	if !modload.ForceUseModules {
  3322  		panic("modload.ForceUseModules must be true")
  3323  	}
  3324  	if modload.RootMode != modload.NoRoot {
  3325  		panic("modload.RootMode must be NoRoot")
  3326  	}
  3327  
  3328  	// Check that the arguments satisfy syntactic constraints.
  3329  	var version string
  3330  	var firstPath string
  3331  	for _, arg := range args {
  3332  		if i := strings.Index(arg, "@"); i >= 0 {
  3333  			firstPath, version = arg[:i], arg[i+1:]
  3334  			if version == "" {
  3335  				return nil, fmt.Errorf("%s: version must not be empty", arg)
  3336  			}
  3337  			break
  3338  		}
  3339  	}
  3340  	patterns := make([]string, len(args))
  3341  	for i, arg := range args {
  3342  		p, found := strings.CutSuffix(arg, "@"+version)
  3343  		if !found {
  3344  			return nil, fmt.Errorf("%s: all arguments must refer to packages in the same module at the same version (@%s)", arg, version)
  3345  		}
  3346  		switch {
  3347  		case build.IsLocalImport(p):
  3348  			return nil, fmt.Errorf("%s: argument must be a package path, not a relative path", arg)
  3349  		case filepath.IsAbs(p):
  3350  			return nil, fmt.Errorf("%s: argument must be a package path, not an absolute path", arg)
  3351  		case search.IsMetaPackage(p):
  3352  			return nil, fmt.Errorf("%s: argument must be a package path, not a meta-package", arg)
  3353  		case pathpkg.Clean(p) != p:
  3354  			return nil, fmt.Errorf("%s: argument must be a clean package path", arg)
  3355  		case !strings.Contains(p, "...") && search.IsStandardImportPath(p) && modindex.IsStandardPackage(cfg.GOROOT, cfg.BuildContext.Compiler, p):
  3356  			return nil, fmt.Errorf("%s: argument must not be a package in the standard library", arg)
  3357  		default:
  3358  			patterns[i] = p
  3359  		}
  3360  	}
  3361  
  3362  	// Query the module providing the first argument, load its go.mod file, and
  3363  	// check that it doesn't contain directives that would cause it to be
  3364  	// interpreted differently if it were the main module.
  3365  	//
  3366  	// If multiple modules match the first argument, accept the longest match
  3367  	// (first result). It's possible this module won't provide packages named by
  3368  	// later arguments, and other modules would. Let's not try to be too
  3369  	// magical though.
  3370  	allowed := modload.CheckAllowed
  3371  	if modload.IsRevisionQuery(firstPath, version) {
  3372  		// Don't check for retractions if a specific revision is requested.
  3373  		allowed = nil
  3374  	}
  3375  	noneSelected := func(path string) (version string) { return "none" }
  3376  	qrs, err := modload.QueryPackages(ctx, patterns[0], version, noneSelected, allowed)
  3377  	if err != nil {
  3378  		return nil, fmt.Errorf("%s: %w", args[0], err)
  3379  	}
  3380  	rootMod := qrs[0].Mod
  3381  	deprecation, err := modload.CheckDeprecation(ctx, rootMod)
  3382  	if err != nil {
  3383  		return nil, fmt.Errorf("%s: %w", args[0], err)
  3384  	}
  3385  	if deprecation != "" {
  3386  		fmt.Fprintf(os.Stderr, "go: module %s is deprecated: %s\n", rootMod.Path, modload.ShortMessage(deprecation, ""))
  3387  	}
  3388  	data, err := modfetch.GoMod(ctx, rootMod.Path, rootMod.Version)
  3389  	if err != nil {
  3390  		return nil, fmt.Errorf("%s: %w", args[0], err)
  3391  	}
  3392  	f, err := modfile.Parse("go.mod", data, nil)
  3393  	if err != nil {
  3394  		return nil, fmt.Errorf("%s (in %s): %w", args[0], rootMod, err)
  3395  	}
  3396  	directiveFmt := "%s (in %s):\n" +
  3397  		"\tThe go.mod file for the module providing named packages contains one or\n" +
  3398  		"\tmore %s directives. It must not contain directives that would cause\n" +
  3399  		"\tit to be interpreted differently than if it were the main module."
  3400  	if len(f.Replace) > 0 {
  3401  		return nil, fmt.Errorf(directiveFmt, args[0], rootMod, "replace")
  3402  	}
  3403  	if len(f.Exclude) > 0 {
  3404  		return nil, fmt.Errorf(directiveFmt, args[0], rootMod, "exclude")
  3405  	}
  3406  
  3407  	// Since we are in NoRoot mode, the build list initially contains only
  3408  	// the dummy command-line-arguments module. Add a requirement on the
  3409  	// module that provides the packages named on the command line.
  3410  	if _, err := modload.EditBuildList(ctx, nil, []module.Version{rootMod}); err != nil {
  3411  		return nil, fmt.Errorf("%s: %w", args[0], err)
  3412  	}
  3413  
  3414  	// Load packages for all arguments.
  3415  	pkgs := PackagesAndErrors(ctx, opts, patterns)
  3416  
  3417  	// Check that named packages are all provided by the same module.
  3418  	for _, pkg := range pkgs {
  3419  		var pkgErr error
  3420  		if pkg.Module == nil {
  3421  			// Packages in std, cmd, and their vendored dependencies
  3422  			// don't have this field set.
  3423  			pkgErr = fmt.Errorf("package %s not provided by module %s", pkg.ImportPath, rootMod)
  3424  		} else if pkg.Module.Path != rootMod.Path || pkg.Module.Version != rootMod.Version {
  3425  			pkgErr = fmt.Errorf("package %s provided by module %s@%s\n\tAll packages must be provided by the same module (%s).", pkg.ImportPath, pkg.Module.Path, pkg.Module.Version, rootMod)
  3426  		}
  3427  		if pkgErr != nil && pkg.Error == nil {
  3428  			pkg.Error = &PackageError{Err: pkgErr}
  3429  			pkg.Incomplete = true
  3430  		}
  3431  	}
  3432  
  3433  	matchers := make([]func(string) bool, len(patterns))
  3434  	for i, p := range patterns {
  3435  		if strings.Contains(p, "...") {
  3436  			matchers[i] = pkgpattern.MatchPattern(p)
  3437  		}
  3438  	}
  3439  	return pkgs, nil
  3440  }
  3441  
  3442  // EnsureImport ensures that package p imports the named package.
  3443  func EnsureImport(p *Package, pkg string) {
  3444  	for _, d := range p.Internal.Imports {
  3445  		if d.Name == pkg {
  3446  			return
  3447  		}
  3448  	}
  3449  
  3450  	p1, err := LoadImportWithFlags(pkg, p.Dir, p, &ImportStack{}, nil, 0)
  3451  	if err != nil {
  3452  		base.Fatalf("load %s: %v", pkg, err)
  3453  	}
  3454  	if p1.Error != nil {
  3455  		base.Fatalf("load %s: %v", pkg, p1.Error)
  3456  	}
  3457  
  3458  	p.Internal.Imports = append(p.Internal.Imports, p1)
  3459  }
  3460  
  3461  // PrepareForCoverageBuild is a helper invoked for "go install
  3462  // -cover", "go run -cover", and "go build -cover" (but not used by
  3463  // "go test -cover"). It walks through the packages being built (and
  3464  // dependencies) and marks them for coverage instrumentation when
  3465  // appropriate, and possibly adding additional deps where needed.
  3466  func PrepareForCoverageBuild(pkgs []*Package) {
  3467  	var match []func(*Package) bool
  3468  
  3469  	matchMainModAndCommandLine := func(p *Package) bool {
  3470  		// note that p.Standard implies p.Module == nil below.
  3471  		return p.Internal.CmdlineFiles || p.Internal.CmdlinePkg || (p.Module != nil && p.Module.Main)
  3472  	}
  3473  
  3474  	if len(cfg.BuildCoverPkg) != 0 {
  3475  		// If -coverpkg has been specified, then we instrument only
  3476  		// the specific packages selected by the user-specified pattern(s).
  3477  		match = make([]func(*Package) bool, len(cfg.BuildCoverPkg))
  3478  		for i := range cfg.BuildCoverPkg {
  3479  			match[i] = MatchPackage(cfg.BuildCoverPkg[i], base.Cwd())
  3480  		}
  3481  	} else {
  3482  		// Without -coverpkg, instrument only packages in the main module
  3483  		// (if any), as well as packages/files specifically named on the
  3484  		// command line.
  3485  		match = []func(*Package) bool{matchMainModAndCommandLine}
  3486  	}
  3487  
  3488  	// Visit the packages being built or installed, along with all of
  3489  	// their dependencies, and mark them to be instrumented, taking
  3490  	// into account the matchers we've set up in the sequence above.
  3491  	SelectCoverPackages(PackageList(pkgs), match, "build")
  3492  }
  3493  
  3494  func SelectCoverPackages(roots []*Package, match []func(*Package) bool, op string) []*Package {
  3495  	var warntag string
  3496  	var includeMain bool
  3497  	switch op {
  3498  	case "build":
  3499  		warntag = "built"
  3500  		includeMain = true
  3501  	case "test":
  3502  		warntag = "tested"
  3503  	default:
  3504  		panic("internal error, bad mode passed to SelectCoverPackages")
  3505  	}
  3506  
  3507  	covered := []*Package{}
  3508  	matched := make([]bool, len(match))
  3509  	for _, p := range roots {
  3510  		haveMatch := false
  3511  		for i := range match {
  3512  			if match[i](p) {
  3513  				matched[i] = true
  3514  				haveMatch = true
  3515  			}
  3516  		}
  3517  		if !haveMatch {
  3518  			continue
  3519  		}
  3520  
  3521  		// There is nothing to cover in package unsafe; it comes from
  3522  		// the compiler.
  3523  		if p.ImportPath == "unsafe" {
  3524  			continue
  3525  		}
  3526  
  3527  		// A package which only has test files can't be imported as a
  3528  		// dependency, and at the moment we don't try to instrument it
  3529  		// for coverage. There isn't any technical reason why
  3530  		// *_test.go files couldn't be instrumented, but it probably
  3531  		// doesn't make much sense to lump together coverage metrics
  3532  		// (ex: percent stmts covered) of *_test.go files with
  3533  		// non-test Go code.
  3534  		if len(p.GoFiles)+len(p.CgoFiles) == 0 {
  3535  			continue
  3536  		}
  3537  
  3538  		// Silently ignore attempts to run coverage on sync/atomic
  3539  		// and/or internal/runtime/atomic when using atomic coverage
  3540  		// mode. Atomic coverage mode uses sync/atomic, so we can't
  3541  		// also do coverage on it.
  3542  		if cfg.BuildCoverMode == "atomic" && p.Standard &&
  3543  			(p.ImportPath == "sync/atomic" || p.ImportPath == "internal/runtime/atomic") {
  3544  			continue
  3545  		}
  3546  
  3547  		// If using the race detector, silently ignore attempts to run
  3548  		// coverage on the runtime packages. It will cause the race
  3549  		// detector to be invoked before it has been initialized. Note
  3550  		// the use of "regonly" instead of just ignoring the package
  3551  		// completely-- we do this due to the requirements of the
  3552  		// package ID numbering scheme. See the comment in
  3553  		// $GOROOT/src/internal/coverage/pkid.go dealing with
  3554  		// hard-coding of runtime package IDs.
  3555  		cmode := cfg.BuildCoverMode
  3556  		if cfg.BuildRace && p.Standard && (p.ImportPath == "runtime" || strings.HasPrefix(p.ImportPath, "runtime/internal")) {
  3557  			cmode = "regonly"
  3558  		}
  3559  
  3560  		// If -coverpkg is in effect and for some reason we don't want
  3561  		// coverage data for the main package, make sure that we at
  3562  		// least process it for registration hooks.
  3563  		if includeMain && p.Name == "main" && !haveMatch {
  3564  			haveMatch = true
  3565  			cmode = "regonly"
  3566  		}
  3567  
  3568  		// Mark package for instrumentation.
  3569  		p.Internal.Cover.Mode = cmode
  3570  		covered = append(covered, p)
  3571  
  3572  		// Force import of sync/atomic into package if atomic mode.
  3573  		if cfg.BuildCoverMode == "atomic" {
  3574  			EnsureImport(p, "sync/atomic")
  3575  		}
  3576  
  3577  		// Generate covervars if using legacy coverage design.
  3578  		if !cfg.Experiment.CoverageRedesign {
  3579  			var coverFiles []string
  3580  			coverFiles = append(coverFiles, p.GoFiles...)
  3581  			coverFiles = append(coverFiles, p.CgoFiles...)
  3582  			p.Internal.CoverVars = DeclareCoverVars(p, coverFiles...)
  3583  		}
  3584  	}
  3585  
  3586  	// Warn about -coverpkg arguments that are not actually used.
  3587  	for i := range cfg.BuildCoverPkg {
  3588  		if !matched[i] {
  3589  			fmt.Fprintf(os.Stderr, "warning: no packages being %s depend on matches for pattern %s\n", warntag, cfg.BuildCoverPkg[i])
  3590  		}
  3591  	}
  3592  
  3593  	return covered
  3594  }
  3595  
  3596  // DeclareCoverVars attaches the required cover variables names
  3597  // to the files, to be used when annotating the files. This
  3598  // function only called when using legacy coverage test/build
  3599  // (e.g. GOEXPERIMENT=coverageredesign is off).
  3600  func DeclareCoverVars(p *Package, files ...string) map[string]*CoverVar {
  3601  	coverVars := make(map[string]*CoverVar)
  3602  	coverIndex := 0
  3603  	// We create the cover counters as new top-level variables in the package.
  3604  	// We need to avoid collisions with user variables (GoCover_0 is unlikely but still)
  3605  	// and more importantly with dot imports of other covered packages,
  3606  	// so we append 12 hex digits from the SHA-256 of the import path.
  3607  	// The point is only to avoid accidents, not to defeat users determined to
  3608  	// break things.
  3609  	sum := sha256.Sum256([]byte(p.ImportPath))
  3610  	h := fmt.Sprintf("%x", sum[:6])
  3611  	for _, file := range files {
  3612  		if base.IsTestFile(file) {
  3613  			continue
  3614  		}
  3615  		// For a package that is "local" (imported via ./ import or command line, outside GOPATH),
  3616  		// we record the full path to the file name.
  3617  		// Otherwise we record the import path, then a forward slash, then the file name.
  3618  		// This makes profiles within GOPATH file system-independent.
  3619  		// These names appear in the cmd/cover HTML interface.
  3620  		var longFile string
  3621  		if p.Internal.Local {
  3622  			longFile = filepath.Join(p.Dir, file)
  3623  		} else {
  3624  			longFile = pathpkg.Join(p.ImportPath, file)
  3625  		}
  3626  		coverVars[file] = &CoverVar{
  3627  			File: longFile,
  3628  			Var:  fmt.Sprintf("GoCover_%d_%x", coverIndex, h),
  3629  		}
  3630  		coverIndex++
  3631  	}
  3632  	return coverVars
  3633  }
  3634  

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