diff options
Diffstat (limited to 'vendor/golang.org/x/tools/go/loader/loader.go')
| -rw-r--r-- | vendor/golang.org/x/tools/go/loader/loader.go | 1077 |
1 files changed, 1077 insertions, 0 deletions
diff --git a/vendor/golang.org/x/tools/go/loader/loader.go b/vendor/golang.org/x/tools/go/loader/loader.go new file mode 100644 index 0000000..de756f7 --- /dev/null +++ b/vendor/golang.org/x/tools/go/loader/loader.go @@ -0,0 +1,1077 @@ +// Copyright 2013 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package loader + +// See doc.go for package documentation and implementation notes. + +import ( + "errors" + "fmt" + "go/ast" + "go/build" + "go/parser" + "go/token" + "go/types" + "os" + "path/filepath" + "sort" + "strings" + "sync" + "time" + + "golang.org/x/tools/go/ast/astutil" +) + +var ignoreVendor build.ImportMode + +const trace = false // show timing info for type-checking + +// Config specifies the configuration for loading a whole program from +// Go source code. +// The zero value for Config is a ready-to-use default configuration. +type Config struct { + // Fset is the file set for the parser to use when loading the + // program. If nil, it may be lazily initialized by any + // method of Config. + Fset *token.FileSet + + // ParserMode specifies the mode to be used by the parser when + // loading source packages. + ParserMode parser.Mode + + // TypeChecker contains options relating to the type checker. + // + // The supplied IgnoreFuncBodies is not used; the effective + // value comes from the TypeCheckFuncBodies func below. + // The supplied Import function is not used either. + TypeChecker types.Config + + // TypeCheckFuncBodies is a predicate over package paths. + // A package for which the predicate is false will + // have its package-level declarations type checked, but not + // its function bodies; this can be used to quickly load + // dependencies from source. If nil, all func bodies are type + // checked. + TypeCheckFuncBodies func(path string) bool + + // If Build is non-nil, it is used to locate source packages. + // Otherwise &build.Default is used. + // + // By default, cgo is invoked to preprocess Go files that + // import the fake package "C". This behaviour can be + // disabled by setting CGO_ENABLED=0 in the environment prior + // to startup, or by setting Build.CgoEnabled=false. + Build *build.Context + + // The current directory, used for resolving relative package + // references such as "./go/loader". If empty, os.Getwd will be + // used instead. + Cwd string + + // If DisplayPath is non-nil, it is used to transform each + // file name obtained from Build.Import(). This can be used + // to prevent a virtualized build.Config's file names from + // leaking into the user interface. + DisplayPath func(path string) string + + // If AllowErrors is true, Load will return a Program even + // if some of the its packages contained I/O, parser or type + // errors; such errors are accessible via PackageInfo.Errors. If + // false, Load will fail if any package had an error. + AllowErrors bool + + // CreatePkgs specifies a list of non-importable initial + // packages to create. The resulting packages will appear in + // the corresponding elements of the Program.Created slice. + CreatePkgs []PkgSpec + + // ImportPkgs specifies a set of initial packages to load. + // The map keys are package paths. + // + // The map value indicates whether to load tests. If true, Load + // will add and type-check two lists of files to the package: + // non-test files followed by in-package *_test.go files. In + // addition, it will append the external test package (if any) + // to Program.Created. + ImportPkgs map[string]bool + + // FindPackage is called during Load to create the build.Package + // for a given import path from a given directory. + // If FindPackage is nil, (*build.Context).Import is used. + // A client may use this hook to adapt to a proprietary build + // system that does not follow the "go build" layout + // conventions, for example. + // + // It must be safe to call concurrently from multiple goroutines. + FindPackage func(ctxt *build.Context, importPath, fromDir string, mode build.ImportMode) (*build.Package, error) + + // AfterTypeCheck is called immediately after a list of files + // has been type-checked and appended to info.Files. + // + // This optional hook function is the earliest opportunity for + // the client to observe the output of the type checker, + // which may be useful to reduce analysis latency when loading + // a large program. + // + // The function is permitted to modify info.Info, for instance + // to clear data structures that are no longer needed, which can + // dramatically reduce peak memory consumption. + // + // The function may be called twice for the same PackageInfo: + // once for the files of the package and again for the + // in-package test files. + // + // It must be safe to call concurrently from multiple goroutines. + AfterTypeCheck func(info *PackageInfo, files []*ast.File) +} + +// A PkgSpec specifies a non-importable package to be created by Load. +// Files are processed first, but typically only one of Files and +// Filenames is provided. The path needn't be globally unique. +// +// For vendoring purposes, the package's directory is the one that +// contains the first file. +type PkgSpec struct { + Path string // package path ("" => use package declaration) + Files []*ast.File // ASTs of already-parsed files + Filenames []string // names of files to be parsed +} + +// A Program is a Go program loaded from source as specified by a Config. +type Program struct { + Fset *token.FileSet // the file set for this program + + // Created[i] contains the initial package whose ASTs or + // filenames were supplied by Config.CreatePkgs[i], followed by + // the external test package, if any, of each package in + // Config.ImportPkgs ordered by ImportPath. + // + // NOTE: these files must not import "C". Cgo preprocessing is + // only performed on imported packages, not ad hoc packages. + // + // TODO(adonovan): we need to copy and adapt the logic of + // goFilesPackage (from $GOROOT/src/cmd/go/build.go) and make + // Config.Import and Config.Create methods return the same kind + // of entity, essentially a build.Package. + // Perhaps we can even reuse that type directly. + Created []*PackageInfo + + // Imported contains the initially imported packages, + // as specified by Config.ImportPkgs. + Imported map[string]*PackageInfo + + // AllPackages contains the PackageInfo of every package + // encountered by Load: all initial packages and all + // dependencies, including incomplete ones. + AllPackages map[*types.Package]*PackageInfo + + // importMap is the canonical mapping of package paths to + // packages. It contains all Imported initial packages, but not + // Created ones, and all imported dependencies. + importMap map[string]*types.Package +} + +// PackageInfo holds the ASTs and facts derived by the type-checker +// for a single package. +// +// Not mutated once exposed via the API. +// +type PackageInfo struct { + Pkg *types.Package + Importable bool // true if 'import "Pkg.Path()"' would resolve to this + TransitivelyErrorFree bool // true if Pkg and all its dependencies are free of errors + Files []*ast.File // syntax trees for the package's files + Errors []error // non-nil if the package had errors + types.Info // type-checker deductions. + dir string // package directory + + checker *types.Checker // transient type-checker state + errorFunc func(error) +} + +func (info *PackageInfo) String() string { return info.Pkg.Path() } + +func (info *PackageInfo) appendError(err error) { + if info.errorFunc != nil { + info.errorFunc(err) + } else { + fmt.Fprintln(os.Stderr, err) + } + info.Errors = append(info.Errors, err) +} + +func (conf *Config) fset() *token.FileSet { + if conf.Fset == nil { + conf.Fset = token.NewFileSet() + } + return conf.Fset +} + +// ParseFile is a convenience function (intended for testing) that invokes +// the parser using the Config's FileSet, which is initialized if nil. +// +// src specifies the parser input as a string, []byte, or io.Reader, and +// filename is its apparent name. If src is nil, the contents of +// filename are read from the file system. +// +func (conf *Config) ParseFile(filename string, src interface{}) (*ast.File, error) { + // TODO(adonovan): use conf.build() etc like parseFiles does. + return parser.ParseFile(conf.fset(), filename, src, conf.ParserMode) +} + +// FromArgsUsage is a partial usage message that applications calling +// FromArgs may wish to include in their -help output. +const FromArgsUsage = ` +<args> is a list of arguments denoting a set of initial packages. +It may take one of two forms: + +1. A list of *.go source files. + + All of the specified files are loaded, parsed and type-checked + as a single package. All the files must belong to the same directory. + +2. A list of import paths, each denoting a package. + + The package's directory is found relative to the $GOROOT and + $GOPATH using similar logic to 'go build', and the *.go files in + that directory are loaded, parsed and type-checked as a single + package. + + In addition, all *_test.go files in the directory are then loaded + and parsed. Those files whose package declaration equals that of + the non-*_test.go files are included in the primary package. Test + files whose package declaration ends with "_test" are type-checked + as another package, the 'external' test package, so that a single + import path may denote two packages. (Whether this behaviour is + enabled is tool-specific, and may depend on additional flags.) + +A '--' argument terminates the list of packages. +` + +// FromArgs interprets args as a set of initial packages to load from +// source and updates the configuration. It returns the list of +// unconsumed arguments. +// +// It is intended for use in command-line interfaces that require a +// set of initial packages to be specified; see FromArgsUsage message +// for details. +// +// Only superficial errors are reported at this stage; errors dependent +// on I/O are detected during Load. +// +func (conf *Config) FromArgs(args []string, xtest bool) ([]string, error) { + var rest []string + for i, arg := range args { + if arg == "--" { + rest = args[i+1:] + args = args[:i] + break // consume "--" and return the remaining args + } + } + + if len(args) > 0 && strings.HasSuffix(args[0], ".go") { + // Assume args is a list of a *.go files + // denoting a single ad hoc package. + for _, arg := range args { + if !strings.HasSuffix(arg, ".go") { + return nil, fmt.Errorf("named files must be .go files: %s", arg) + } + } + conf.CreateFromFilenames("", args...) + } else { + // Assume args are directories each denoting a + // package and (perhaps) an external test, iff xtest. + for _, arg := range args { + if xtest { + conf.ImportWithTests(arg) + } else { + conf.Import(arg) + } + } + } + + return rest, nil +} + +// CreateFromFilenames is a convenience function that adds +// a conf.CreatePkgs entry to create a package of the specified *.go +// files. +// +func (conf *Config) CreateFromFilenames(path string, filenames ...string) { + conf.CreatePkgs = append(conf.CreatePkgs, PkgSpec{Path: path, Filenames: filenames}) +} + +// CreateFromFiles is a convenience function that adds a conf.CreatePkgs +// entry to create package of the specified path and parsed files. +// +func (conf *Config) CreateFromFiles(path string, files ...*ast.File) { + conf.CreatePkgs = append(conf.CreatePkgs, PkgSpec{Path: path, Files: files}) +} + +// ImportWithTests is a convenience function that adds path to +// ImportPkgs, the set of initial source packages located relative to +// $GOPATH. The package will be augmented by any *_test.go files in +// its directory that contain a "package x" (not "package x_test") +// declaration. +// +// In addition, if any *_test.go files contain a "package x_test" +// declaration, an additional package comprising just those files will +// be added to CreatePkgs. +// +func (conf *Config) ImportWithTests(path string) { conf.addImport(path, true) } + +// Import is a convenience function that adds path to ImportPkgs, the +// set of initial packages that will be imported from source. +// +func (conf *Config) Import(path string) { conf.addImport(path, false) } + +func (conf *Config) addImport(path string, tests bool) { + if path == "C" { + return // ignore; not a real package + } + if conf.ImportPkgs == nil { + conf.ImportPkgs = make(map[string]bool) + } + conf.ImportPkgs[path] = conf.ImportPkgs[path] || tests +} + +// PathEnclosingInterval returns the PackageInfo and ast.Node that +// contain source interval [start, end), and all the node's ancestors +// up to the AST root. It searches all ast.Files of all packages in prog. +// exact is defined as for astutil.PathEnclosingInterval. +// +// The zero value is returned if not found. +// +func (prog *Program) PathEnclosingInterval(start, end token.Pos) (pkg *PackageInfo, path []ast.Node, exact bool) { + for _, info := range prog.AllPackages { + for _, f := range info.Files { + if f.Pos() == token.NoPos { + // This can happen if the parser saw + // too many errors and bailed out. + // (Use parser.AllErrors to prevent that.) + continue + } + if !tokenFileContainsPos(prog.Fset.File(f.Pos()), start) { + continue + } + if path, exact := astutil.PathEnclosingInterval(f, start, end); path != nil { + return info, path, exact + } + } + } + return nil, nil, false +} + +// InitialPackages returns a new slice containing the set of initial +// packages (Created + Imported) in unspecified order. +// +func (prog *Program) InitialPackages() []*PackageInfo { + infos := make([]*PackageInfo, 0, len(prog.Created)+len(prog.Imported)) + infos = append(infos, prog.Created...) + for _, info := range prog.Imported { + infos = append(infos, info) + } + return infos +} + +// Package returns the ASTs and results of type checking for the +// specified package. +func (prog *Program) Package(path string) *PackageInfo { + if info, ok := prog.AllPackages[prog.importMap[path]]; ok { + return info + } + for _, info := range prog.Created { + if path == info.Pkg.Path() { + return info + } + } + return nil +} + +// ---------- Implementation ---------- + +// importer holds the working state of the algorithm. +type importer struct { + conf *Config // the client configuration + start time.Time // for logging + + progMu sync.Mutex // guards prog + prog *Program // the resulting program + + // findpkg is a memoization of FindPackage. + findpkgMu sync.Mutex // guards findpkg + findpkg map[findpkgKey]*findpkgValue + + importedMu sync.Mutex // guards imported + imported map[string]*importInfo // all imported packages (incl. failures) by import path + + // import dependency graph: graph[x][y] => x imports y + // + // Since non-importable packages cannot be cyclic, we ignore + // their imports, thus we only need the subgraph over importable + // packages. Nodes are identified by their import paths. + graphMu sync.Mutex + graph map[string]map[string]bool +} + +type findpkgKey struct { + importPath string + fromDir string + mode build.ImportMode +} + +type findpkgValue struct { + ready chan struct{} // closed to broadcast readiness + bp *build.Package + err error +} + +// importInfo tracks the success or failure of a single import. +// +// Upon completion, exactly one of info and err is non-nil: +// info on successful creation of a package, err otherwise. +// A successful package may still contain type errors. +// +type importInfo struct { + path string // import path + info *PackageInfo // results of typechecking (including errors) + complete chan struct{} // closed to broadcast that info is set. +} + +// awaitCompletion blocks until ii is complete, +// i.e. the info field is safe to inspect. +func (ii *importInfo) awaitCompletion() { + <-ii.complete // wait for close +} + +// Complete marks ii as complete. +// Its info and err fields will not be subsequently updated. +func (ii *importInfo) Complete(info *PackageInfo) { + if info == nil { + panic("info == nil") + } + ii.info = info + close(ii.complete) +} + +type importError struct { + path string // import path + err error // reason for failure to create a package +} + +// Load creates the initial packages specified by conf.{Create,Import}Pkgs, +// loading their dependencies packages as needed. +// +// On success, Load returns a Program containing a PackageInfo for +// each package. On failure, it returns an error. +// +// If AllowErrors is true, Load will return a Program even if some +// packages contained I/O, parser or type errors, or if dependencies +// were missing. (Such errors are accessible via PackageInfo.Errors. If +// false, Load will fail if any package had an error. +// +// It is an error if no packages were loaded. +// +func (conf *Config) Load() (*Program, error) { + // Create a simple default error handler for parse/type errors. + if conf.TypeChecker.Error == nil { + conf.TypeChecker.Error = func(e error) { fmt.Fprintln(os.Stderr, e) } + } + + // Set default working directory for relative package references. + if conf.Cwd == "" { + var err error + conf.Cwd, err = os.Getwd() + if err != nil { + return nil, err + } + } + + // Install default FindPackage hook using go/build logic. + if conf.FindPackage == nil { + conf.FindPackage = (*build.Context).Import + } + + prog := &Program{ + Fset: conf.fset(), + Imported: make(map[string]*PackageInfo), + importMap: make(map[string]*types.Package), + AllPackages: make(map[*types.Package]*PackageInfo), + } + + imp := importer{ + conf: conf, + prog: prog, + findpkg: make(map[findpkgKey]*findpkgValue), + imported: make(map[string]*importInfo), + start: time.Now(), + graph: make(map[string]map[string]bool), + } + + // -- loading proper (concurrent phase) -------------------------------- + + var errpkgs []string // packages that contained errors + + // Load the initially imported packages and their dependencies, + // in parallel. + // No vendor check on packages imported from the command line. + infos, importErrors := imp.importAll("", conf.Cwd, conf.ImportPkgs, ignoreVendor) + for _, ie := range importErrors { + conf.TypeChecker.Error(ie.err) // failed to create package + errpkgs = append(errpkgs, ie.path) + } + for _, info := range infos { + prog.Imported[info.Pkg.Path()] = info + } + + // Augment the designated initial packages by their tests. + // Dependencies are loaded in parallel. + var xtestPkgs []*build.Package + for importPath, augment := range conf.ImportPkgs { + if !augment { + continue + } + + // No vendor check on packages imported from command line. + bp, err := imp.findPackage(importPath, conf.Cwd, ignoreVendor) + if err != nil { + // Package not found, or can't even parse package declaration. + // Already reported by previous loop; ignore it. + continue + } + + // Needs external test package? + if len(bp.XTestGoFiles) > 0 { + xtestPkgs = append(xtestPkgs, bp) + } + + // Consult the cache using the canonical package path. + path := bp.ImportPath + imp.importedMu.Lock() // (unnecessary, we're sequential here) + ii, ok := imp.imported[path] + // Paranoid checks added due to issue #11012. + if !ok { + // Unreachable. + // The previous loop called importAll and thus + // startLoad for each path in ImportPkgs, which + // populates imp.imported[path] with a non-zero value. + panic(fmt.Sprintf("imported[%q] not found", path)) + } + if ii == nil { + // Unreachable. + // The ii values in this loop are the same as in + // the previous loop, which enforced the invariant + // that at least one of ii.err and ii.info is non-nil. + panic(fmt.Sprintf("imported[%q] == nil", path)) + } + if ii.info == nil { + // Unreachable. + // awaitCompletion has the postcondition + // ii.info != nil. + panic(fmt.Sprintf("imported[%q].info = nil", path)) + } + info := ii.info + imp.importedMu.Unlock() + + // Parse the in-package test files. + files, errs := imp.conf.parsePackageFiles(bp, 't') + for _, err := range errs { + info.appendError(err) + } + + // The test files augmenting package P cannot be imported, + // but may import packages that import P, + // so we must disable the cycle check. + imp.addFiles(info, files, false) + } + + createPkg := func(path, dir string, files []*ast.File, errs []error) { + info := imp.newPackageInfo(path, dir) + for _, err := range errs { + info.appendError(err) + } + + // Ad hoc packages are non-importable, + // so no cycle check is needed. + // addFiles loads dependencies in parallel. + imp.addFiles(info, files, false) + prog.Created = append(prog.Created, info) + } + + // Create packages specified by conf.CreatePkgs. + for _, cp := range conf.CreatePkgs { + files, errs := parseFiles(conf.fset(), conf.build(), nil, conf.Cwd, cp.Filenames, conf.ParserMode) + files = append(files, cp.Files...) + + path := cp.Path + if path == "" { + if len(files) > 0 { + path = files[0].Name.Name + } else { + path = "(unnamed)" + } + } + + dir := conf.Cwd + if len(files) > 0 && files[0].Pos().IsValid() { + dir = filepath.Dir(conf.fset().File(files[0].Pos()).Name()) + } + createPkg(path, dir, files, errs) + } + + // Create external test packages. + sort.Sort(byImportPath(xtestPkgs)) + for _, bp := range xtestPkgs { + files, errs := imp.conf.parsePackageFiles(bp, 'x') + createPkg(bp.ImportPath+"_test", bp.Dir, files, errs) + } + + // -- finishing up (sequential) ---------------------------------------- + + if len(prog.Imported)+len(prog.Created) == 0 { + return nil, errors.New("no initial packages were loaded") + } + + // Create infos for indirectly imported packages. + // e.g. incomplete packages without syntax, loaded from export data. + for _, obj := range prog.importMap { + info := prog.AllPackages[obj] + if info == nil { + prog.AllPackages[obj] = &PackageInfo{Pkg: obj, Importable: true} + } else { + // finished + info.checker = nil + info.errorFunc = nil + } + } + + if !conf.AllowErrors { + // Report errors in indirectly imported packages. + for _, info := range prog.AllPackages { + if len(info.Errors) > 0 { + errpkgs = append(errpkgs, info.Pkg.Path()) + } + } + if errpkgs != nil { + var more string + if len(errpkgs) > 3 { + more = fmt.Sprintf(" and %d more", len(errpkgs)-3) + errpkgs = errpkgs[:3] + } + return nil, fmt.Errorf("couldn't load packages due to errors: %s%s", + strings.Join(errpkgs, ", "), more) + } + } + + markErrorFreePackages(prog.AllPackages) + + return prog, nil +} + +type byImportPath []*build.Package + +func (b byImportPath) Len() int { return len(b) } +func (b byImportPath) Less(i, j int) bool { return b[i].ImportPath < b[j].ImportPath } +func (b byImportPath) Swap(i, j int) { b[i], b[j] = b[j], b[i] } + +// markErrorFreePackages sets the TransitivelyErrorFree flag on all +// applicable packages. +func markErrorFreePackages(allPackages map[*types.Package]*PackageInfo) { + // Build the transpose of the import graph. + importedBy := make(map[*types.Package]map[*types.Package]bool) + for P := range allPackages { + for _, Q := range P.Imports() { + clients, ok := importedBy[Q] + if !ok { + clients = make(map[*types.Package]bool) + importedBy[Q] = clients + } + clients[P] = true + } + } + + // Find all packages reachable from some error package. + reachable := make(map[*types.Package]bool) + var visit func(*types.Package) + visit = func(p *types.Package) { + if !reachable[p] { + reachable[p] = true + for q := range importedBy[p] { + visit(q) + } + } + } + for _, info := range allPackages { + if len(info.Errors) > 0 { + visit(info.Pkg) + } + } + + // Mark the others as "transitively error-free". + for _, info := range allPackages { + if !reachable[info.Pkg] { + info.TransitivelyErrorFree = true + } + } +} + +// build returns the effective build context. +func (conf *Config) build() *build.Context { + if conf.Build != nil { + return conf.Build + } + return &build.Default +} + +// parsePackageFiles enumerates the files belonging to package path, +// then loads, parses and returns them, plus a list of I/O or parse +// errors that were encountered. +// +// 'which' indicates which files to include: +// 'g': include non-test *.go source files (GoFiles + processed CgoFiles) +// 't': include in-package *_test.go source files (TestGoFiles) +// 'x': include external *_test.go source files. (XTestGoFiles) +// +func (conf *Config) parsePackageFiles(bp *build.Package, which rune) ([]*ast.File, []error) { + if bp.ImportPath == "unsafe" { + return nil, nil + } + var filenames []string + switch which { + case 'g': + filenames = bp.GoFiles + case 't': + filenames = bp.TestGoFiles + case 'x': + filenames = bp.XTestGoFiles + default: + panic(which) + } + + files, errs := parseFiles(conf.fset(), conf.build(), conf.DisplayPath, bp.Dir, filenames, conf.ParserMode) + + // Preprocess CgoFiles and parse the outputs (sequentially). + if which == 'g' && bp.CgoFiles != nil { + cgofiles, err := processCgoFiles(bp, conf.fset(), conf.DisplayPath, conf.ParserMode) + if err != nil { + errs = append(errs, err) + } else { + files = append(files, cgofiles...) + } + } + + return files, errs +} + +// doImport imports the package denoted by path. +// It implements the types.Importer signature. +// +// It returns an error if a package could not be created +// (e.g. go/build or parse error), but type errors are reported via +// the types.Config.Error callback (the first of which is also saved +// in the package's PackageInfo). +// +// Idempotent. +// +func (imp *importer) doImport(from *PackageInfo, to string) (*types.Package, error) { + if to == "C" { + // This should be unreachable, but ad hoc packages are + // not currently subject to cgo preprocessing. + // See https://github.com/golang/go/issues/11627. + return nil, fmt.Errorf(`the loader doesn't cgo-process ad hoc packages like %q; see Go issue 11627`, + from.Pkg.Path()) + } + + bp, err := imp.findPackage(to, from.dir, 0) + if err != nil { + return nil, err + } + + // The standard unsafe package is handled specially, + // and has no PackageInfo. + if bp.ImportPath == "unsafe" { + return types.Unsafe, nil + } + + // Look for the package in the cache using its canonical path. + path := bp.ImportPath + imp.importedMu.Lock() + ii := imp.imported[path] + imp.importedMu.Unlock() + if ii == nil { + panic("internal error: unexpected import: " + path) + } + if ii.info != nil { + return ii.info.Pkg, nil + } + + // Import of incomplete package: this indicates a cycle. + fromPath := from.Pkg.Path() + if cycle := imp.findPath(path, fromPath); cycle != nil { + cycle = append([]string{fromPath}, cycle...) + return nil, fmt.Errorf("import cycle: %s", strings.Join(cycle, " -> ")) + } + + panic("internal error: import of incomplete (yet acyclic) package: " + fromPath) +} + +// findPackage locates the package denoted by the importPath in the +// specified directory. +func (imp *importer) findPackage(importPath, fromDir string, mode build.ImportMode) (*build.Package, error) { + // We use a non-blocking duplicate-suppressing cache (gopl.io ยง9.7) + // to avoid holding the lock around FindPackage. + key := findpkgKey{importPath, fromDir, mode} + imp.findpkgMu.Lock() + v, ok := imp.findpkg[key] + if ok { + // cache hit + imp.findpkgMu.Unlock() + + <-v.ready // wait for entry to become ready + } else { + // Cache miss: this goroutine becomes responsible for + // populating the map entry and broadcasting its readiness. + v = &findpkgValue{ready: make(chan struct{})} + imp.findpkg[key] = v + imp.findpkgMu.Unlock() + + ioLimit <- true + v.bp, v.err = imp.conf.FindPackage(imp.conf.build(), importPath, fromDir, mode) + <-ioLimit + + if _, ok := v.err.(*build.NoGoError); ok { + v.err = nil // empty directory is not an error + } + + close(v.ready) // broadcast ready condition + } + return v.bp, v.err +} + +// importAll loads, parses, and type-checks the specified packages in +// parallel and returns their completed importInfos in unspecified order. +// +// fromPath is the package path of the importing package, if it is +// importable, "" otherwise. It is used for cycle detection. +// +// fromDir is the directory containing the import declaration that +// caused these imports. +// +func (imp *importer) importAll(fromPath, fromDir string, imports map[string]bool, mode build.ImportMode) (infos []*PackageInfo, errors []importError) { + // TODO(adonovan): opt: do the loop in parallel once + // findPackage is non-blocking. + var pending []*importInfo + for importPath := range imports { + bp, err := imp.findPackage(importPath, fromDir, mode) + if err != nil { + errors = append(errors, importError{ + path: importPath, + err: err, + }) + continue + } + pending = append(pending, imp.startLoad(bp)) + } + + if fromPath != "" { + // We're loading a set of imports. + // + // We must record graph edges from the importing package + // to its dependencies, and check for cycles. + imp.graphMu.Lock() + deps, ok := imp.graph[fromPath] + if !ok { + deps = make(map[string]bool) + imp.graph[fromPath] = deps + } + for _, ii := range pending { + deps[ii.path] = true + } + imp.graphMu.Unlock() + } + + for _, ii := range pending { + if fromPath != "" { + if cycle := imp.findPath(ii.path, fromPath); cycle != nil { + // Cycle-forming import: we must not await its + // completion since it would deadlock. + // + // We don't record the error in ii since + // the error is really associated with the + // cycle-forming edge, not the package itself. + // (Also it would complicate the + // invariants of importPath completion.) + if trace { + fmt.Fprintf(os.Stderr, "import cycle: %q\n", cycle) + } + continue + } + } + ii.awaitCompletion() + infos = append(infos, ii.info) + } + + return infos, errors +} + +// findPath returns an arbitrary path from 'from' to 'to' in the import +// graph, or nil if there was none. +func (imp *importer) findPath(from, to string) []string { + imp.graphMu.Lock() + defer imp.graphMu.Unlock() + + seen := make(map[string]bool) + var search func(stack []string, importPath string) []string + search = func(stack []string, importPath string) []string { + if !seen[importPath] { + seen[importPath] = true + stack = append(stack, importPath) + if importPath == to { + return stack + } + for x := range imp.graph[importPath] { + if p := search(stack, x); p != nil { + return p + } + } + } + return nil + } + return search(make([]string, 0, 20), from) +} + +// startLoad initiates the loading, parsing and type-checking of the +// specified package and its dependencies, if it has not already begun. +// +// It returns an importInfo, not necessarily in a completed state. The +// caller must call awaitCompletion() before accessing its info field. +// +// startLoad is concurrency-safe and idempotent. +// +func (imp *importer) startLoad(bp *build.Package) *importInfo { + path := bp.ImportPath + imp.importedMu.Lock() + ii, ok := imp.imported[path] + if !ok { + ii = &importInfo{path: path, complete: make(chan struct{})} + imp.imported[path] = ii + go func() { + info := imp.load(bp) + ii.Complete(info) + }() + } + imp.importedMu.Unlock() + + return ii +} + +// load implements package loading by parsing Go source files +// located by go/build. +func (imp *importer) load(bp *build.Package) *PackageInfo { + info := imp.newPackageInfo(bp.ImportPath, bp.Dir) + info.Importable = true + files, errs := imp.conf.parsePackageFiles(bp, 'g') + for _, err := range errs { + info.appendError(err) + } + + imp.addFiles(info, files, true) + + imp.progMu.Lock() + imp.prog.importMap[bp.ImportPath] = info.Pkg + imp.progMu.Unlock() + + return info +} + +// addFiles adds and type-checks the specified files to info, loading +// their dependencies if needed. The order of files determines the +// package initialization order. It may be called multiple times on the +// same package. Errors are appended to the info.Errors field. +// +// cycleCheck determines whether the imports within files create +// dependency edges that should be checked for potential cycles. +// +func (imp *importer) addFiles(info *PackageInfo, files []*ast.File, cycleCheck bool) { + // Ensure the dependencies are loaded, in parallel. + var fromPath string + if cycleCheck { + fromPath = info.Pkg.Path() + } + // TODO(adonovan): opt: make the caller do scanImports. + // Callers with a build.Package can skip it. + imp.importAll(fromPath, info.dir, scanImports(files), 0) + + if trace { + fmt.Fprintf(os.Stderr, "%s: start %q (%d)\n", + time.Since(imp.start), info.Pkg.Path(), len(files)) + } + + // Don't call checker.Files on Unsafe, even with zero files, + // because it would mutate the package, which is a global. + if info.Pkg == types.Unsafe { + if len(files) > 0 { + panic(`"unsafe" package contains unexpected files`) + } + } else { + // Ignore the returned (first) error since we + // already collect them all in the PackageInfo. + info.checker.Files(files) + info.Files = append(info.Files, files...) + } + + if imp.conf.AfterTypeCheck != nil { + imp.conf.AfterTypeCheck(info, files) + } + + if trace { + fmt.Fprintf(os.Stderr, "%s: stop %q\n", + time.Since(imp.start), info.Pkg.Path()) + } +} + +func (imp *importer) newPackageInfo(path, dir string) *PackageInfo { + var pkg *types.Package + if path == "unsafe" { + pkg = types.Unsafe + } else { + pkg = types.NewPackage(path, "") + } + info := &PackageInfo{ + Pkg: pkg, + Info: types.Info{ + Types: make(map[ast.Expr]types.TypeAndValue), + Defs: make(map[*ast.Ident]types.Object), + Uses: make(map[*ast.Ident]types.Object), + Implicits: make(map[ast.Node]types.Object), + Scopes: make(map[ast.Node]*types.Scope), + Selections: make(map[*ast.SelectorExpr]*types.Selection), + }, + errorFunc: imp.conf.TypeChecker.Error, + dir: dir, + } + + // Copy the types.Config so we can vary it across PackageInfos. + tc := imp.conf.TypeChecker + tc.IgnoreFuncBodies = false + if f := imp.conf.TypeCheckFuncBodies; f != nil { + tc.IgnoreFuncBodies = !f(path) + } + tc.Importer = closure{imp, info} + tc.Error = info.appendError // appendError wraps the user's Error function + + info.checker = types.NewChecker(&tc, imp.conf.fset(), pkg, &info.Info) + imp.progMu.Lock() + imp.prog.AllPackages[pkg] = info + imp.progMu.Unlock() + return info +} + +type closure struct { + imp *importer + info *PackageInfo +} + +func (c closure) Import(to string) (*types.Package, error) { return c.imp.doImport(c.info, to) } |