2 // Copyright 2013 The Go Authors. All rights reserved.
3 // Use of this source code is governed by a BSD-style
4 // license that can be found in the LICENSE file.
9 "cmd/compile/internal/syntax"
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) {
60 check.errorf(pos, "extra init expr at %s", n.Pos())
62 check.errorf(n, "extra init expr %s", n)
64 case l > r && (constDecl || r != 1): // if r == 1 it may be a multi-valued function and we can't say anything yet
66 check.errorf(n, "missing init expr for %s", n.Value)
70 func validatedImportPath(path string) (string, error) {
71 s, err := strconv.Unquote(path)
76 return "", fmt.Errorf("empty string")
78 const illegalChars = `!"#$%&'()*,:;<=>?[\]^{|}` + "`\uFFFD"
80 if !unicode.IsGraphic(r) || unicode.IsSpace(r) || strings.ContainsRune(illegalChars, r) {
81 return s, fmt.Errorf("invalid character %#U", r)
87 // declarePkgObj declares obj in the package scope, records its ident -> obj mapping,
88 // and updates check.objMap. The object must not be a function or method.
89 func (check *Checker) declarePkgObj(ident *syntax.Name, obj Object, d *declInfo) {
90 assert(ident.Value == obj.Name())
92 // spec: "A package-scope or file-scope identifier with name init
93 // may only be declared to be a function with this (func()) signature."
94 if ident.Value == "init" {
95 check.errorf(ident, "cannot declare init - must be func")
99 // spec: "The main package must have package name main and declare
100 // a function main that takes no arguments and returns no value."
101 if ident.Value == "main" && check.pkg.name == "main" {
102 check.errorf(ident, "cannot declare main - must be func")
106 check.declare(check.pkg.scope, ident, obj, nopos)
107 check.objMap[obj] = d
108 obj.setOrder(uint32(len(check.objMap)))
111 // filename returns a filename suitable for debugging output.
112 func (check *Checker) filename(fileNo int) string {
113 file := check.files[fileNo]
114 if pos := file.Pos(); pos.IsKnown() {
115 // return check.fset.File(pos).Name()
116 // TODO(gri) do we need the actual file name here?
117 return pos.RelFilename()
119 return fmt.Sprintf("file[%d]", fileNo)
122 func (check *Checker) importPackage(pos syntax.Pos, path, dir string) *Package {
123 // If we already have a package for the given (path, dir)
124 // pair, use it instead of doing a full import.
125 // Checker.impMap only caches packages that are marked Complete
126 // or fake (dummy packages for failed imports). Incomplete but
127 // non-fake packages do require an import to complete them.
128 key := importKey{path, dir}
129 imp := check.impMap[key]
134 // no package yet => import it
135 if path == "C" && (check.conf.FakeImportC || check.conf.go115UsesCgo) {
136 imp = NewPackage("C", "C")
137 imp.fake = true // package scope is not populated
138 imp.cgo = check.conf.go115UsesCgo
142 if importer := check.conf.Importer; importer == nil {
143 err = fmt.Errorf("Config.Importer not installed")
144 } else if importerFrom, ok := importer.(ImporterFrom); ok {
145 imp, err = importerFrom.ImportFrom(path, dir, 0)
146 if imp == nil && err == nil {
147 err = fmt.Errorf("Config.Importer.ImportFrom(%s, %s, 0) returned nil but no error", path, dir)
150 imp, err = importer.Import(path)
151 if imp == nil && err == nil {
152 err = fmt.Errorf("Config.Importer.Import(%s) returned nil but no error", path)
155 // make sure we have a valid package name
156 // (errors here can only happen through manipulation of packages after creation)
157 if err == nil && imp != nil && (imp.name == "_" || imp.name == "") {
158 err = fmt.Errorf("invalid package name: %q", imp.name)
159 imp = nil // create fake package below
162 check.errorf(pos, "could not import %s (%s)", path, err)
164 // create a new fake package
165 // come up with a sensible package name (heuristic)
167 if i := len(name); i > 0 && name[i-1] == '/' {
170 if i := strings.LastIndex(name, "/"); i >= 0 {
173 imp = NewPackage(path, name)
175 // continue to use the package as best as we can
176 imp.fake = true // avoid follow-up lookup failures
180 // package should be complete or marked fake, but be cautious
181 if imp.complete || imp.fake {
182 check.impMap[key] = imp
183 check.pkgCnt[imp.name]++
187 // something went wrong (importer may have returned incomplete package without error)
191 // collectObjects collects all file and package objects and inserts them
192 // into their respective scopes. It also performs imports and associates
193 // methods with receiver base type names.
194 func (check *Checker) collectObjects() {
197 // pkgImports is the set of packages already imported by any package file seen
198 // so far. Used to avoid duplicate entries in pkg.imports. Allocate and populate
199 // it (pkg.imports may not be empty if we are checking test files incrementally).
200 // Note that pkgImports is keyed by package (and thus package path), not by an
201 // importKey value. Two different importKey values may map to the same package
202 // which is why we cannot use the check.impMap here.
203 var pkgImports = make(map[*Package]bool)
204 for _, imp := range pkg.imports {
205 pkgImports[imp] = true
208 type methodInfo struct {
210 ptr bool // true if pointer receiver
211 recv *syntax.Name // receiver type name
213 var methods []methodInfo // collected methods with valid receivers and non-blank _ names
214 var fileScopes []*Scope
215 for fileNo, file := range check.files {
216 // The package identifier denotes the current package,
217 // but there is no corresponding package object.
218 check.recordDef(file.PkgName, nil)
220 fileScope := NewScope(check.pkg.scope, startPos(file), endPos(file), check.filename(fileNo))
221 fileScopes = append(fileScopes, fileScope)
222 check.recordScope(file, fileScope)
224 // determine file directory, necessary to resolve imports
225 // FileName may be "" (typically for tests) in which case
226 // we get "." as the directory which is what we would want.
227 fileDir := dir(file.PkgName.Pos().RelFilename()) // TODO(gri) should this be filename?
229 first := -1 // index of first ConstDecl in the current group, or -1
230 var last *syntax.ConstDecl // last ConstDecl with init expressions, or nil
231 for index, decl := range file.DeclList {
232 if _, ok := decl.(*syntax.ConstDecl); !ok {
233 first = -1 // we're not in a constant declaration
236 switch s := decl.(type) {
237 case *syntax.ImportDecl:
239 path, err := validatedImportPath(s.Path.Value)
241 check.errorf(s.Path, "invalid import path (%s)", err)
245 imp := check.importPackage(s.Path.Pos(), path, fileDir)
250 // add package to list of explicit imports
251 // (this functionality is provided as a convenience
252 // for clients; it is not needed for type-checking)
253 if !pkgImports[imp] {
254 pkgImports[imp] = true
255 pkg.imports = append(pkg.imports, imp)
258 // local name overrides imported package name
260 if s.LocalPkgName != nil {
261 name = s.LocalPkgName.Value
263 // match cmd/compile (not prescribed by spec)
264 check.errorf(s.LocalPkgName, `cannot rename import "C"`)
268 check.errorf(s.LocalPkgName, "cannot declare init - must be func")
273 obj := NewPkgName(s.Pos(), pkg, name, imp)
274 if s.LocalPkgName != nil {
275 // in a dot-import, the dot represents the package
276 check.recordDef(s.LocalPkgName, obj)
278 check.recordImplicit(s, obj)
282 // match cmd/compile (not prescribed by spec)
286 // add import to file scope
288 // merge imported scope with file scope
289 for _, obj := range imp.scope.elems {
290 // A package scope may contain non-exported objects,
291 // do not import them!
293 // declare dot-imported object
294 // (Do not use check.declare because it modifies the object
295 // via Object.setScopePos, which leads to a race condition;
296 // the object may be imported into more than one file scope
297 // concurrently. See issue #32154.)
298 if alt := fileScope.Insert(obj); alt != nil {
299 check.errorf(s.LocalPkgName, "%s redeclared in this block", obj.Name())
300 check.reportAltDecl(alt)
304 // add position to set of dot-import positions for this file
305 // (this is only needed for "imported but not used" errors)
306 check.addUnusedDotImport(fileScope, imp, s.Pos())
308 // declare imported package object in file scope
309 // (no need to provide s.LocalPkgName since we called check.recordDef earlier)
310 check.declare(fileScope, nil, obj, nopos)
313 case *syntax.ConstDecl:
314 // iota is the index of the current constDecl within the group
315 if first < 0 || file.DeclList[index-1].(*syntax.ConstDecl).Group != s.Group {
319 iota := constant.MakeInt64(int64(index - first))
321 // determine which initialization expressions to use
324 case s.Type != nil || s.Values != nil:
328 last = new(syntax.ConstDecl) // make sure last exists
332 // declare all constants
333 values := unpackExpr(last.Values)
334 for i, name := range s.NameList {
335 obj := NewConst(name.Pos(), pkg, name.Value, nil, iota)
342 d := &declInfo{file: fileScope, vtyp: last.Type, init: init, inherited: inherited}
343 check.declarePkgObj(name, obj, d)
346 // Constants must always have init values.
347 check.arity(s.Pos(), s.NameList, values, true, inherited)
349 case *syntax.VarDecl:
350 lhs := make([]*Var, len(s.NameList))
351 // If there's exactly one rhs initializer, use
352 // the same declInfo d1 for all lhs variables
353 // so that each lhs variable depends on the same
354 // rhs initializer (n:1 var declaration).
356 if _, ok := s.Values.(*syntax.ListExpr); !ok {
357 // The lhs elements are only set up after the for loop below,
358 // but that's ok because declarePkgObj only collects the declInfo
359 // for a later phase.
360 d1 = &declInfo{file: fileScope, lhs: lhs, vtyp: s.Type, init: s.Values}
363 // declare all variables
364 values := unpackExpr(s.Values)
365 for i, name := range s.NameList {
366 obj := NewVar(name.Pos(), pkg, name.Value, nil)
371 // individual assignments
376 d = &declInfo{file: fileScope, vtyp: s.Type, init: init}
379 check.declarePkgObj(name, obj, d)
382 // If we have no type, we must have values.
383 if s.Type == nil || values != nil {
384 check.arity(s.Pos(), s.NameList, values, false, false)
387 case *syntax.TypeDecl:
388 obj := NewTypeName(s.Name.Pos(), pkg, s.Name.Value, nil)
389 check.declarePkgObj(s.Name, obj, &declInfo{file: fileScope, tdecl: s})
391 case *syntax.FuncDecl:
392 d := s // TODO(gri) get rid of this
394 obj := NewFunc(d.Name.Pos(), pkg, name, nil)
398 if d.TParamList != nil {
399 //check.softErrorf(d.TParamList.Pos(), "func init must have no type parameters")
400 check.softErrorf(d.Name, "func init must have no type parameters")
402 if t := d.Type; len(t.ParamList) != 0 || len(t.ResultList) != 0 {
403 check.softErrorf(d, "func init must have no arguments and no return values")
405 // don't declare init functions in the package scope - they are invisible
406 obj.parent = pkg.scope
407 check.recordDef(d.Name, obj)
408 // init functions must have a body
410 // TODO(gri) make this error message consistent with the others above
411 check.softErrorf(obj.pos, "missing function body")
414 check.declare(pkg.scope, d.Name, obj, nopos)
419 if !methodTypeParamsOk && len(d.TParamList) != 0 {
420 //check.invalidASTf(d.TParamList.Pos(), "method must have no type parameters")
421 check.invalidASTf(d, "method must have no type parameters")
423 ptr, recv, _ := check.unpackRecv(d.Recv.Type, false)
424 // (Methods with invalid receiver cannot be associated to a type, and
425 // methods with blank _ names are never found; no need to collect any
426 // of them. They will still be type-checked with all the other functions.)
427 if recv != nil && name != "_" {
428 methods = append(methods, methodInfo{obj, ptr, recv})
430 check.recordDef(d.Name, obj)
432 info := &declInfo{file: fileScope, fdecl: d}
433 // Methods are not package-level objects but we still track them in the
434 // object map so that we can handle them like regular functions (if the
435 // receiver is invalid); also we need their fdecl info when associating
436 // them with their receiver base type, below.
437 check.objMap[obj] = info
438 obj.setOrder(uint32(len(check.objMap)))
441 check.invalidASTf(s, "unknown syntax.Decl node %T", s)
446 // verify that objects in package and file scopes have different names
447 for _, scope := range fileScopes {
448 for _, obj := range scope.elems {
449 if alt := pkg.scope.Lookup(obj.Name()); alt != nil {
450 if pkg, ok := obj.(*PkgName); ok {
451 check.errorf(alt, "%s already declared through import of %s", alt.Name(), pkg.Imported())
452 check.reportAltDecl(pkg)
454 check.errorf(alt, "%s already declared through dot-import of %s", alt.Name(), obj.Pkg())
455 // TODO(gri) dot-imported objects don't have a position; reportAltDecl won't print anything
456 check.reportAltDecl(obj)
462 // Now that we have all package scope objects and all methods,
463 // associate methods with receiver base type name where possible.
464 // Ignore methods that have an invalid receiver. They will be
465 // type-checked later, with regular functions.
467 check.methods = make(map[*TypeName][]*Func)
468 for i := range methods {
470 // Determine the receiver base type and associate m with it.
471 ptr, base := check.resolveBaseTypeName(m.ptr, m.recv)
473 m.obj.hasPtrRecv = ptr
474 check.methods[base] = append(check.methods[base], m.obj)
480 // unpackRecv unpacks a receiver type and returns its components: ptr indicates whether
481 // rtyp is a pointer receiver, rname is the receiver type name, and tparams are its
482 // type parameters, if any. The type parameters are only unpacked if unpackParams is
483 // set. If rname is nil, the receiver is unusable (i.e., the source has a bug which we
484 // cannot easily work around).
485 func (check *Checker) unpackRecv(rtyp syntax.Expr, unpackParams bool) (ptr bool, rname *syntax.Name, tparams []*syntax.Name) {
486 L: // unpack receiver type
487 // This accepts invalid receivers such as ***T and does not
488 // work for other invalid receivers, but we don't care. The
489 // validity of receiver expressions is checked elsewhere.
491 switch t := rtyp.(type) {
492 case *syntax.ParenExpr:
494 // case *ast.StarExpr:
496 case *syntax.Operation:
497 if t.Op != syntax.Mul || t.Y != nil {
506 // unpack type parameters, if any
507 if ptyp, _ := rtyp.(*syntax.IndexExpr); ptyp != nil {
510 for _, arg := range unpackExpr(ptyp.Index) {
512 switch arg := arg.(type) {
515 case *syntax.BadExpr:
516 // ignore - error already reported by parser
518 check.invalidASTf(ptyp, "parameterized receiver contains nil parameters")
520 check.errorf(arg, "receiver type parameter %s must be an identifier", arg)
523 par = newName(arg.Pos(), "_")
525 tparams = append(tparams, par)
531 // unpack receiver name
532 if name, _ := rtyp.(*syntax.Name); name != nil {
539 // resolveBaseTypeName returns the non-alias base type name for typ, and whether
540 // there was a pointer indirection to get to it. The base type name must be declared
541 // in package scope, and there can be at most one pointer indirection. If no such type
542 // name exists, the returned base is nil.
543 func (check *Checker) resolveBaseTypeName(seenPtr bool, typ syntax.Expr) (ptr bool, base *TypeName) {
544 // Algorithm: Starting from a type expression, which may be a name,
545 // we follow that type through alias declarations until we reach a
546 // non-alias type name. If we encounter anything but pointer types or
547 // parentheses we're done. If we encounter more than one pointer type
550 var seen map[*TypeName]bool
554 // check if we have a pointer type
555 // if pexpr, _ := typ.(*ast.StarExpr); pexpr != nil {
556 if pexpr, _ := typ.(*syntax.Operation); pexpr != nil && pexpr.Op == syntax.Mul && pexpr.Y == nil {
557 // if we've already seen a pointer, we're done
562 typ = unparen(pexpr.X) // continue with pointer base type
565 // typ must be a name
566 name, _ := typ.(*syntax.Name)
571 // name must denote an object found in the current package scope
572 // (note that dot-imported objects are not in the package scope!)
573 obj := check.pkg.scope.Lookup(name.Value)
578 // the object must be a type name...
579 tname, _ := obj.(*TypeName)
584 // ... which we have not seen before
589 // we're done if tdecl defined tname as a new type
590 // (rather than an alias)
591 tdecl := check.objMap[tname].tdecl // must exist for objects in package scope
596 // otherwise, continue resolving
599 seen = make(map[*TypeName]bool)
605 // packageObjects typechecks all package objects, but not function bodies.
606 func (check *Checker) packageObjects() {
607 // process package objects in source order for reproducible results
608 objList := make([]Object, len(check.objMap))
610 for obj := range check.objMap {
614 sort.Sort(inSourceOrder(objList))
616 // add new methods to already type-checked types (from a prior Checker.Files call)
617 for _, obj := range objList {
618 if obj, _ := obj.(*TypeName); obj != nil && obj.typ != nil {
619 check.collectMethods(obj)
623 // We process non-alias declarations first, in order to avoid situations where
624 // the type of an alias declaration is needed before it is available. In general
625 // this is still not enough, as it is possible to create sufficiently convoluted
626 // recursive type definitions that will cause a type alias to be needed before it
627 // is available (see issue #25838 for examples).
628 // As an aside, the cmd/compiler suffers from the same problem (#25838).
629 var aliasList []*TypeName
631 for _, obj := range objList {
632 // If we have a type alias, collect it for the 2nd phase.
633 if tname, _ := obj.(*TypeName); tname != nil && check.objMap[tname].tdecl.Alias {
634 aliasList = append(aliasList, tname)
638 check.objDecl(obj, nil)
641 for _, obj := range aliasList {
642 check.objDecl(obj, nil)
645 // At this point we may have a non-empty check.methods map; this means that not all
646 // entries were deleted at the end of typeDecl because the respective receiver base
647 // types were not found. In that case, an error was reported when declaring those
648 // methods. We can now safely discard this map.
652 // inSourceOrder implements the sort.Sort interface.
653 type inSourceOrder []Object
655 func (a inSourceOrder) Len() int { return len(a) }
656 func (a inSourceOrder) Less(i, j int) bool { return a[i].order() < a[j].order() }
657 func (a inSourceOrder) Swap(i, j int) { a[i], a[j] = a[j], a[i] }
659 // unusedImports checks for unused imports.
660 func (check *Checker) unusedImports() {
661 // if function bodies are not checked, packages' uses are likely missing - don't check
662 if check.conf.IgnoreFuncBodies {
666 // spec: "It is illegal (...) to directly import a package without referring to
667 // any of its exported identifiers. To import a package solely for its side-effects
668 // (initialization), use the blank identifier as explicit package name."
670 // check use of regular imported packages
671 for _, scope := range check.pkg.scope.children /* file scopes */ {
672 for _, obj := range scope.elems {
673 if obj, ok := obj.(*PkgName); ok {
674 // Unused "blank imports" are automatically ignored
675 // since _ identifiers are not entered into scopes.
677 path := obj.imported.path
678 base := pkgName(path)
679 if obj.name == base {
680 check.softErrorf(obj.pos, "%q imported but not used", path)
682 check.softErrorf(obj.pos, "%q imported but not used as %s", path, obj.name)
689 // check use of dot-imported packages
690 for _, unusedDotImports := range check.unusedDotImports {
691 for pkg, pos := range unusedDotImports {
692 check.softErrorf(pos, "%q imported but not used", pkg.path)
697 // pkgName returns the package name (last element) of an import path.
698 func pkgName(path string) string {
699 if i := strings.LastIndex(path, "/"); i >= 0 {
705 // dir makes a good-faith attempt to return the directory
706 // portion of path. If path is empty, the result is ".".
707 // (Per the go/build package dependency tests, we cannot import
708 // path/filepath and simply use filepath.Dir.)
709 func dir(path string) string {
710 if i := strings.LastIndexAny(path, `/\`); i > 0 {