1 // Copyright 2013 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.
8 "cmd/compile/internal/syntax"
11 . "internal/types/errors"
18 // A declInfo describes a package-level const, type, var, or func declaration.
19 type declInfo struct {
20 file *Scope // scope of file containing this declaration
21 lhs []*Var // lhs of n:1 variable declarations, or nil
22 vtyp syntax.Expr // type, or nil (for const and var declarations only)
23 init syntax.Expr // init/orig expression, or nil (for const and var declarations only)
24 inherited bool // if set, the init expression is inherited from a previous constant declaration
25 tdecl *syntax.TypeDecl // type declaration, or nil
26 fdecl *syntax.FuncDecl // func declaration, or nil
28 // The deps field tracks initialization expression dependencies.
29 deps map[Object]bool // lazily initialized
32 // hasInitializer reports whether the declared object has an initialization
33 // expression or function body.
34 func (d *declInfo) hasInitializer() bool {
35 return d.init != nil || d.fdecl != nil && d.fdecl.Body != nil
38 // addDep adds obj to the set of objects d's init expression depends on.
39 func (d *declInfo) addDep(obj Object) {
42 m = make(map[Object]bool)
48 // arity checks that the lhs and rhs of a const or var decl
49 // have a matching number of names and initialization values.
50 // If inherited is set, the initialization values are from
51 // another (constant) declaration.
52 func (check *Checker) arity(pos syntax.Pos, names []*syntax.Name, inits []syntax.Expr, constDecl, inherited bool) {
56 const code = WrongAssignCount
61 check.errorf(pos, code, "extra init expr at %s", n.Pos())
63 check.errorf(n, code, "extra init expr %s", n)
65 case l > r && (constDecl || r != 1): // if r == 1 it may be a multi-valued function and we can't say anything yet
67 check.errorf(n, code, "missing init expr for %s", n.Value)
71 func validatedImportPath(path string) (string, error) {
72 s, err := strconv.Unquote(path)
77 return "", fmt.Errorf("empty string")
79 const illegalChars = `!"#$%&'()*,:;<=>?[\]^{|}` + "`\uFFFD"
81 if !unicode.IsGraphic(r) || unicode.IsSpace(r) || strings.ContainsRune(illegalChars, r) {
82 return s, fmt.Errorf("invalid character %#U", r)
88 // declarePkgObj declares obj in the package scope, records its ident -> obj mapping,
89 // and updates check.objMap. The object must not be a function or method.
90 func (check *Checker) declarePkgObj(ident *syntax.Name, obj Object, d *declInfo) {
91 assert(ident.Value == obj.Name())
93 // spec: "A package-scope or file-scope identifier with name init
94 // may only be declared to be a function with this (func()) signature."
95 if ident.Value == "init" {
96 check.error(ident, InvalidInitDecl, "cannot declare init - must be func")
100 // spec: "The main package must have package name main and declare
101 // a function main that takes no arguments and returns no value."
102 if ident.Value == "main" && check.pkg.name == "main" {
103 check.error(ident, InvalidMainDecl, "cannot declare main - must be func")
107 check.declare(check.pkg.scope, ident, obj, nopos)
108 check.objMap[obj] = d
109 obj.setOrder(uint32(len(check.objMap)))
112 // filename returns a filename suitable for debugging output.
113 func (check *Checker) filename(fileNo int) string {
114 file := check.files[fileNo]
115 if pos := file.Pos(); pos.IsKnown() {
116 // return check.fset.File(pos).Name()
117 // TODO(gri) do we need the actual file name here?
118 return pos.RelFilename()
120 return fmt.Sprintf("file[%d]", fileNo)
123 func (check *Checker) importPackage(pos syntax.Pos, path, dir string) *Package {
124 // If we already have a package for the given (path, dir)
125 // pair, use it instead of doing a full import.
126 // Checker.impMap only caches packages that are marked Complete
127 // or fake (dummy packages for failed imports). Incomplete but
128 // non-fake packages do require an import to complete them.
129 key := importKey{path, dir}
130 imp := check.impMap[key]
135 // no package yet => import it
136 if path == "C" && (check.conf.FakeImportC || check.conf.go115UsesCgo) {
137 imp = NewPackage("C", "C")
138 imp.fake = true // package scope is not populated
139 imp.cgo = check.conf.go115UsesCgo
143 if importer := check.conf.Importer; importer == nil {
144 err = fmt.Errorf("Config.Importer not installed")
145 } else if importerFrom, ok := importer.(ImporterFrom); ok {
146 imp, err = importerFrom.ImportFrom(path, dir, 0)
147 if imp == nil && err == nil {
148 err = fmt.Errorf("Config.Importer.ImportFrom(%s, %s, 0) returned nil but no error", path, dir)
151 imp, err = importer.Import(path)
152 if imp == nil && err == nil {
153 err = fmt.Errorf("Config.Importer.Import(%s) returned nil but no error", path)
156 // make sure we have a valid package name
157 // (errors here can only happen through manipulation of packages after creation)
158 if err == nil && imp != nil && (imp.name == "_" || imp.name == "") {
159 err = fmt.Errorf("invalid package name: %q", imp.name)
160 imp = nil // create fake package below
163 check.errorf(pos, BrokenImport, "could not import %s (%s)", path, err)
165 // create a new fake package
166 // come up with a sensible package name (heuristic)
168 if i := len(name); i > 0 && name[i-1] == '/' {
171 if i := strings.LastIndex(name, "/"); i >= 0 {
174 imp = NewPackage(path, name)
176 // continue to use the package as best as we can
177 imp.fake = true // avoid follow-up lookup failures
181 // package should be complete or marked fake, but be cautious
182 if imp.complete || imp.fake {
183 check.impMap[key] = imp
184 // Once we've formatted an error message, keep the pkgPathMap
185 // up-to-date on subsequent imports. It is used for package
186 // qualification in error messages.
187 if check.pkgPathMap != nil {
188 check.markImports(imp)
193 // something went wrong (importer may have returned incomplete package without error)
197 // collectObjects collects all file and package objects and inserts them
198 // into their respective scopes. It also performs imports and associates
199 // methods with receiver base type names.
200 func (check *Checker) collectObjects() {
203 // pkgImports is the set of packages already imported by any package file seen
204 // so far. Used to avoid duplicate entries in pkg.imports. Allocate and populate
205 // it (pkg.imports may not be empty if we are checking test files incrementally).
206 // Note that pkgImports is keyed by package (and thus package path), not by an
207 // importKey value. Two different importKey values may map to the same package
208 // which is why we cannot use the check.impMap here.
209 var pkgImports = make(map[*Package]bool)
210 for _, imp := range pkg.imports {
211 pkgImports[imp] = true
214 type methodInfo struct {
216 ptr bool // true if pointer receiver
217 recv *syntax.Name // receiver type name
219 var methods []methodInfo // collected methods with valid receivers and non-blank _ names
220 var fileScopes []*Scope
221 for fileNo, file := range check.files {
222 // The package identifier denotes the current package,
223 // but there is no corresponding package object.
224 check.recordDef(file.PkgName, nil)
226 fileScope := NewScope(pkg.scope, syntax.StartPos(file), syntax.EndPos(file), check.filename(fileNo))
227 fileScopes = append(fileScopes, fileScope)
228 check.recordScope(file, fileScope)
230 // determine file directory, necessary to resolve imports
231 // FileName may be "" (typically for tests) in which case
232 // we get "." as the directory which is what we would want.
233 fileDir := dir(file.PkgName.Pos().RelFilename()) // TODO(gri) should this be filename?
235 first := -1 // index of first ConstDecl in the current group, or -1
236 var last *syntax.ConstDecl // last ConstDecl with init expressions, or nil
237 for index, decl := range file.DeclList {
238 if _, ok := decl.(*syntax.ConstDecl); !ok {
239 first = -1 // we're not in a constant declaration
242 switch s := decl.(type) {
243 case *syntax.ImportDecl:
245 if s.Path == nil || s.Path.Bad {
246 continue // error reported during parsing
248 path, err := validatedImportPath(s.Path.Value)
250 check.errorf(s.Path, BadImportPath, "invalid import path (%s)", err)
254 imp := check.importPackage(s.Path.Pos(), path, fileDir)
259 // local name overrides imported package name
261 if s.LocalPkgName != nil {
262 name = s.LocalPkgName.Value
264 // match 1.17 cmd/compile (not prescribed by spec)
265 check.error(s.LocalPkgName, ImportCRenamed, `cannot rename import "C"`)
271 check.error(s, InvalidInitDecl, "cannot import package as init - init must be a func")
275 // add package to list of explicit imports
276 // (this functionality is provided as a convenience
277 // for clients; it is not needed for type-checking)
278 if !pkgImports[imp] {
279 pkgImports[imp] = true
280 pkg.imports = append(pkg.imports, imp)
283 pkgName := NewPkgName(s.Pos(), pkg, name, imp)
284 if s.LocalPkgName != nil {
285 // in a dot-import, the dot represents the package
286 check.recordDef(s.LocalPkgName, pkgName)
288 check.recordImplicit(s, pkgName)
292 // match 1.17 cmd/compile (not prescribed by spec)
296 // add import to file scope
297 check.imports = append(check.imports, pkgName)
300 if check.dotImportMap == nil {
301 check.dotImportMap = make(map[dotImportKey]*PkgName)
303 // merge imported scope with file scope
304 for name, obj := range imp.scope.elems {
305 // Note: Avoid eager resolve(name, obj) here, so we only
306 // resolve dot-imported objects as needed.
308 // A package scope may contain non-exported objects,
309 // do not import them!
310 if isExported(name) {
311 // declare dot-imported object
312 // (Do not use check.declare because it modifies the object
313 // via Object.setScopePos, which leads to a race condition;
314 // the object may be imported into more than one file scope
315 // concurrently. See go.dev/issue/32154.)
316 if alt := fileScope.Lookup(name); alt != nil {
318 err.code = DuplicateDecl
319 err.errorf(s.LocalPkgName, "%s redeclared in this block", alt.Name())
320 err.recordAltDecl(alt)
323 fileScope.insert(name, obj)
324 check.dotImportMap[dotImportKey{fileScope, name}] = pkgName
329 // declare imported package object in file scope
330 // (no need to provide s.LocalPkgName since we called check.recordDef earlier)
331 check.declare(fileScope, nil, pkgName, nopos)
334 case *syntax.ConstDecl:
335 // iota is the index of the current constDecl within the group
336 if first < 0 || s.Group == nil || file.DeclList[index-1].(*syntax.ConstDecl).Group != s.Group {
340 iota := constant.MakeInt64(int64(index - first))
342 // determine which initialization expressions to use
345 case s.Type != nil || s.Values != nil:
349 last = new(syntax.ConstDecl) // make sure last exists
353 // declare all constants
354 values := syntax.UnpackListExpr(last.Values)
355 for i, name := range s.NameList {
356 obj := NewConst(name.Pos(), pkg, name.Value, nil, iota)
363 d := &declInfo{file: fileScope, vtyp: last.Type, init: init, inherited: inherited}
364 check.declarePkgObj(name, obj, d)
367 // Constants must always have init values.
368 check.arity(s.Pos(), s.NameList, values, true, inherited)
370 case *syntax.VarDecl:
371 lhs := make([]*Var, len(s.NameList))
372 // If there's exactly one rhs initializer, use
373 // the same declInfo d1 for all lhs variables
374 // so that each lhs variable depends on the same
375 // rhs initializer (n:1 var declaration).
377 if _, ok := s.Values.(*syntax.ListExpr); !ok {
378 // The lhs elements are only set up after the for loop below,
379 // but that's ok because declarePkgObj only collects the declInfo
380 // for a later phase.
381 d1 = &declInfo{file: fileScope, lhs: lhs, vtyp: s.Type, init: s.Values}
384 // declare all variables
385 values := syntax.UnpackListExpr(s.Values)
386 for i, name := range s.NameList {
387 obj := NewVar(name.Pos(), pkg, name.Value, nil)
392 // individual assignments
397 d = &declInfo{file: fileScope, vtyp: s.Type, init: init}
400 check.declarePkgObj(name, obj, d)
403 // If we have no type, we must have values.
404 if s.Type == nil || values != nil {
405 check.arity(s.Pos(), s.NameList, values, false, false)
408 case *syntax.TypeDecl:
409 _ = len(s.TParamList) != 0 && check.verifyVersionf(s.TParamList[0], go1_18, "type parameter")
410 obj := NewTypeName(s.Name.Pos(), pkg, s.Name.Value, nil)
411 check.declarePkgObj(s.Name, obj, &declInfo{file: fileScope, tdecl: s})
413 case *syntax.FuncDecl:
415 obj := NewFunc(s.Name.Pos(), pkg, name, nil)
416 hasTParamError := false // avoid duplicate type parameter errors
419 if name == "init" || name == "main" && pkg.name == "main" {
420 code := InvalidInitDecl
422 code = InvalidMainDecl
424 if len(s.TParamList) != 0 {
425 check.softErrorf(s.TParamList[0], code, "func %s must have no type parameters", name)
426 hasTParamError = true
428 if t := s.Type; len(t.ParamList) != 0 || len(t.ResultList) != 0 {
429 check.softErrorf(s.Name, code, "func %s must have no arguments and no return values", name)
432 // don't declare init functions in the package scope - they are invisible
434 obj.parent = pkg.scope
435 check.recordDef(s.Name, obj)
436 // init functions must have a body
438 // TODO(gri) make this error message consistent with the others above
439 check.softErrorf(obj.pos, MissingInitBody, "missing function body")
442 check.declare(pkg.scope, s.Name, obj, nopos)
447 ptr, recv, _ := check.unpackRecv(s.Recv.Type, false)
448 // Methods with invalid receiver cannot be associated to a type, and
449 // methods with blank _ names are never found; no need to collect any
450 // of them. They will still be type-checked with all the other functions.
451 if recv != nil && name != "_" {
452 methods = append(methods, methodInfo{obj, ptr, recv})
454 check.recordDef(s.Name, obj)
456 _ = len(s.TParamList) != 0 && !hasTParamError && check.verifyVersionf(s.TParamList[0], go1_18, "type parameter")
457 info := &declInfo{file: fileScope, fdecl: s}
458 // Methods are not package-level objects but we still track them in the
459 // object map so that we can handle them like regular functions (if the
460 // receiver is invalid); also we need their fdecl info when associating
461 // them with their receiver base type, below.
462 check.objMap[obj] = info
463 obj.setOrder(uint32(len(check.objMap)))
466 check.errorf(s, InvalidSyntaxTree, "unknown syntax.Decl node %T", s)
471 // verify that objects in package and file scopes have different names
472 for _, scope := range fileScopes {
473 for name, obj := range scope.elems {
474 if alt := pkg.scope.Lookup(name); alt != nil {
475 obj = resolve(name, obj)
477 err.code = DuplicateDecl
478 if pkg, ok := obj.(*PkgName); ok {
479 err.errorf(alt, "%s already declared through import of %s", alt.Name(), pkg.Imported())
480 err.recordAltDecl(pkg)
482 err.errorf(alt, "%s already declared through dot-import of %s", alt.Name(), obj.Pkg())
483 // TODO(gri) dot-imported objects don't have a position; recordAltDecl won't print anything
484 err.recordAltDecl(obj)
491 // Now that we have all package scope objects and all methods,
492 // associate methods with receiver base type name where possible.
493 // Ignore methods that have an invalid receiver. They will be
494 // type-checked later, with regular functions.
496 check.methods = make(map[*TypeName][]*Func)
497 for i := range methods {
499 // Determine the receiver base type and associate m with it.
500 ptr, base := check.resolveBaseTypeName(m.ptr, m.recv, fileScopes)
502 m.obj.hasPtrRecv_ = ptr
503 check.methods[base] = append(check.methods[base], m.obj)
509 // unpackRecv unpacks a receiver type and returns its components: ptr indicates whether
510 // rtyp is a pointer receiver, rname is the receiver type name, and tparams are its
511 // type parameters, if any. The type parameters are only unpacked if unpackParams is
512 // set. If rname is nil, the receiver is unusable (i.e., the source has a bug which we
513 // cannot easily work around).
514 func (check *Checker) unpackRecv(rtyp syntax.Expr, unpackParams bool) (ptr bool, rname *syntax.Name, tparams []*syntax.Name) {
515 L: // unpack receiver type
516 // This accepts invalid receivers such as ***T and does not
517 // work for other invalid receivers, but we don't care. The
518 // validity of receiver expressions is checked elsewhere.
520 switch t := rtyp.(type) {
521 case *syntax.ParenExpr:
523 // case *ast.StarExpr:
526 case *syntax.Operation:
527 if t.Op != syntax.Mul || t.Y != nil {
537 // unpack type parameters, if any
538 if ptyp, _ := rtyp.(*syntax.IndexExpr); ptyp != nil {
541 for _, arg := range syntax.UnpackListExpr(ptyp.Index) {
543 switch arg := arg.(type) {
546 case *syntax.BadExpr:
547 // ignore - error already reported by parser
549 check.error(ptyp, InvalidSyntaxTree, "parameterized receiver contains nil parameters")
551 check.errorf(arg, BadDecl, "receiver type parameter %s must be an identifier", arg)
554 par = syntax.NewName(arg.Pos(), "_")
556 tparams = append(tparams, par)
562 // unpack receiver name
563 if name, _ := rtyp.(*syntax.Name); name != nil {
570 // resolveBaseTypeName returns the non-alias base type name for typ, and whether
571 // there was a pointer indirection to get to it. The base type name must be declared
572 // in package scope, and there can be at most one pointer indirection. If no such type
573 // name exists, the returned base is nil.
574 func (check *Checker) resolveBaseTypeName(seenPtr bool, typ syntax.Expr, fileScopes []*Scope) (ptr bool, base *TypeName) {
575 // Algorithm: Starting from a type expression, which may be a name,
576 // we follow that type through alias declarations until we reach a
577 // non-alias type name. If we encounter anything but pointer types or
578 // parentheses we're done. If we encounter more than one pointer type
581 var seen map[*TypeName]bool
583 // check if we have a pointer type
584 // if pexpr, _ := typ.(*ast.StarExpr); pexpr != nil {
585 if pexpr, _ := typ.(*syntax.Operation); pexpr != nil && pexpr.Op == syntax.Mul && pexpr.Y == nil {
586 // if we've already seen a pointer, we're done
591 typ = syntax.Unparen(pexpr.X) // continue with pointer base type
594 // typ must be a name, or a C.name cgo selector.
596 switch typ := typ.(type) {
599 case *syntax.SelectorExpr:
600 // C.struct_foo is a valid type name for packages using cgo.
602 // Detect this case, and adjust name so that the correct TypeName is
604 if ident, _ := typ.X.(*syntax.Name); ident != nil && ident.Value == "C" {
605 // Check whether "C" actually resolves to an import of "C", by looking
606 // in the appropriate file scope.
608 for _, scope := range fileScopes {
609 if scope.Contains(ident.Pos()) {
610 obj = scope.Lookup(ident.Value)
613 // If Config.go115UsesCgo is set, the typechecker will resolve Cgo
614 // selectors to their cgo name. We must do the same here.
615 if pname, _ := obj.(*PkgName); pname != nil {
616 if pname.imported.cgo { // only set if Config.go115UsesCgo is set
617 name = "_Ctype_" + typ.Sel.Value
628 // name must denote an object found in the current package scope
629 // (note that dot-imported objects are not in the package scope!)
630 obj := check.pkg.scope.Lookup(name)
635 // the object must be a type name...
636 tname, _ := obj.(*TypeName)
641 // ... which we have not seen before
646 // we're done if tdecl defined tname as a new type
647 // (rather than an alias)
648 tdecl := check.objMap[tname].tdecl // must exist for objects in package scope
653 // otherwise, continue resolving
656 seen = make(map[*TypeName]bool)
662 // packageObjects typechecks all package objects, but not function bodies.
663 func (check *Checker) packageObjects() {
664 // process package objects in source order for reproducible results
665 objList := make([]Object, len(check.objMap))
667 for obj := range check.objMap {
671 sort.Sort(inSourceOrder(objList))
673 // add new methods to already type-checked types (from a prior Checker.Files call)
674 for _, obj := range objList {
675 if obj, _ := obj.(*TypeName); obj != nil && obj.typ != nil {
676 check.collectMethods(obj)
680 if check.enableAlias {
681 // With Alias nodes we can process declarations in any order.
682 for _, obj := range objList {
683 check.objDecl(obj, nil)
686 // Without Alias nodes, we process non-alias type declarations first, followed by
687 // alias declarations, and then everything else. This appears to avoid most situations
688 // where the type of an alias is needed before it is available.
689 // There may still be cases where this is not good enough (see also go.dev/issue/25838).
690 // In those cases Checker.ident will report an error ("invalid use of type alias").
691 var aliasList []*TypeName
692 var othersList []Object // everything that's not a type
693 // phase 1: non-alias type declarations
694 for _, obj := range objList {
695 if tname, _ := obj.(*TypeName); tname != nil {
696 if check.objMap[tname].tdecl.Alias {
697 aliasList = append(aliasList, tname)
699 check.objDecl(obj, nil)
702 othersList = append(othersList, obj)
705 // phase 2: alias type declarations
706 for _, obj := range aliasList {
707 check.objDecl(obj, nil)
709 // phase 3: all other declarations
710 for _, obj := range othersList {
711 check.objDecl(obj, nil)
715 // At this point we may have a non-empty check.methods map; this means that not all
716 // entries were deleted at the end of typeDecl because the respective receiver base
717 // types were not found. In that case, an error was reported when declaring those
718 // methods. We can now safely discard this map.
722 // inSourceOrder implements the sort.Sort interface.
723 type inSourceOrder []Object
725 func (a inSourceOrder) Len() int { return len(a) }
726 func (a inSourceOrder) Less(i, j int) bool { return a[i].order() < a[j].order() }
727 func (a inSourceOrder) Swap(i, j int) { a[i], a[j] = a[j], a[i] }
729 // unusedImports checks for unused imports.
730 func (check *Checker) unusedImports() {
731 // If function bodies are not checked, packages' uses are likely missing - don't check.
732 if check.conf.IgnoreFuncBodies {
736 // spec: "It is illegal (...) to directly import a package without referring to
737 // any of its exported identifiers. To import a package solely for its side-effects
738 // (initialization), use the blank identifier as explicit package name."
740 for _, obj := range check.imports {
741 if !obj.used && obj.name != "_" {
742 check.errorUnusedPkg(obj)
747 func (check *Checker) errorUnusedPkg(obj *PkgName) {
748 // If the package was imported with a name other than the final
749 // import path element, show it explicitly in the error message.
750 // Note that this handles both renamed imports and imports of
751 // packages containing unconventional package declarations.
752 // Note that this uses / always, even on Windows, because Go import
753 // paths always use forward slashes.
754 path := obj.imported.path
756 if i := strings.LastIndex(elem, "/"); i >= 0 {
759 if obj.name == "" || obj.name == "." || obj.name == elem {
760 check.softErrorf(obj, UnusedImport, "%q imported and not used", path)
762 check.softErrorf(obj, UnusedImport, "%q imported as %s and not used", path, obj.name)
766 // dir makes a good-faith attempt to return the directory
767 // portion of path. If path is empty, the result is ".".
768 // (Per the go/build package dependency tests, we cannot import
769 // path/filepath and simply use filepath.Dir.)
770 func dir(path string) string {
771 if i := strings.LastIndexAny(path, `/\`); i > 0 {