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.
5 // This file implements the Check function, which drives type-checking.
17 // debugging/development support
19 debug = false // leave on during development
20 trace = false // turn on for detailed type resolution traces
22 // TODO(rfindley): add compiler error message handling from types2, guarded
23 // behind this flag, so that we can keep the code in sync.
24 compilerErrorMessages = false // match compiler error messages
27 // exprInfo stores information about an untyped expression.
28 type exprInfo struct {
29 isLhs bool // expression is lhs operand of a shift with delayed type-check
32 val constant.Value // constant value; or nil (if not a constant)
35 // An environment represents the environment within which an object is
37 type environment struct {
38 decl *declInfo // package-level declaration whose init expression/function body is checked
39 scope *Scope // top-most scope for lookups
40 pos token.Pos // if valid, identifiers are looked up as if at position pos (used by Eval)
41 iota constant.Value // value of iota in a constant declaration; nil otherwise
42 errpos positioner // if set, identifier position of a constant with inherited initializer
43 inTParamList bool // set if inside a type parameter list
44 sig *Signature // function signature if inside a function; nil otherwise
45 isPanic map[*ast.CallExpr]bool // set of panic call expressions (used for termination check)
46 hasLabel bool // set if a function makes use of labels (only ~1% of functions); unused outside functions
47 hasCallOrRecv bool // set if an expression contains a function call or channel receive operation
50 // lookup looks up name in the current environment and returns the matching object, or nil.
51 func (env *environment) lookup(name string) Object {
52 _, obj := env.scope.LookupParent(name, env.pos)
56 // An importKey identifies an imported package by import path and source directory
57 // (directory containing the file containing the import). In practice, the directory
58 // may always be the same, or may not matter. Given an (import path, directory), an
59 // importer must always return the same package (but given two different import paths,
60 // an importer may still return the same package by mapping them to the same package
62 type importKey struct {
66 // A dotImportKey describes a dot-imported object in the given scope.
67 type dotImportKey struct {
72 // An action describes a (delayed) action.
74 f func() // action to be executed
75 desc *actionDesc // action description; may be nil, requires debug to be set
78 // If debug is set, describef sets a printf-formatted description for action a.
79 // Otherwise, it is a no-op.
80 func (a *action) describef(pos positioner, format string, args ...any) {
82 a.desc = &actionDesc{pos, format, args}
86 // An actionDesc provides information on an action.
87 // For debugging only.
88 type actionDesc struct {
94 // A Checker maintains the state of the type checker.
95 // It must be created with NewChecker.
97 // package information
98 // (initialized by NewChecker, valid for the life-time of checker)
100 ctxt *Context // context for de-duplicating instances
104 version version // accepted language version
105 nextID uint64 // unique Id for type parameters (first valid Id is 1)
106 objMap map[Object]*declInfo // maps package-level objects and (non-interface) methods to declaration info
107 impMap map[importKey]*Package // maps (import path, source directory) to (complete or fake) package
108 infoMap map[*Named]typeInfo // maps named types to their associated type info (for cycle detection)
110 // pkgPathMap maps package names to the set of distinct import paths we've
111 // seen for that name, anywhere in the import graph. It is used for
112 // disambiguating package names in error messages.
114 // pkgPathMap is allocated lazily, so that we don't pay the price of building
115 // it on the happy path. seenPkgMap tracks the packages that we've already
117 pkgPathMap map[string]map[string]bool
118 seenPkgMap map[*Package]bool
120 // information collected during type-checking of a set of package files
121 // (initialized by Files, valid only for the duration of check.Files;
122 // maps and lists are allocated on demand)
123 files []*ast.File // package files
124 imports []*PkgName // list of imported packages
125 dotImportMap map[dotImportKey]*PkgName // maps dot-imported objects to the package they were dot-imported through
126 recvTParamMap map[*ast.Ident]*TypeParam // maps blank receiver type parameters to their type
127 brokenAliases map[*TypeName]bool // set of aliases with broken (not yet determined) types
128 unionTypeSets map[*Union]*_TypeSet // computed type sets for union types
129 mono monoGraph // graph for detecting non-monomorphizable instantiation loops
131 firstErr error // first error encountered
132 methods map[*TypeName][]*Func // maps package scope type names to associated non-blank (non-interface) methods
133 untyped map[ast.Expr]exprInfo // map of expressions without final type
134 delayed []action // stack of delayed action segments; segments are processed in FIFO order
135 objPath []Object // path of object dependencies during type inference (for cycle reporting)
136 cleaners []cleaner // list of types that may need a final cleanup at the end of type-checking
138 // environment within which the current object is type-checked (valid only
139 // for the duration of type-checking a specific object)
143 indent int // indentation for tracing
146 // addDeclDep adds the dependency edge (check.decl -> to) if check.decl exists
147 func (check *Checker) addDeclDep(to Object) {
150 return // not in a package-level init expression
152 if _, found := check.objMap[to]; !found {
153 return // to is not a package-level object
158 // brokenAlias records that alias doesn't have a determined type yet.
159 // It also sets alias.typ to Typ[Invalid].
160 func (check *Checker) brokenAlias(alias *TypeName) {
161 if check.brokenAliases == nil {
162 check.brokenAliases = make(map[*TypeName]bool)
164 check.brokenAliases[alias] = true
165 alias.typ = Typ[Invalid]
168 // validAlias records that alias has the valid type typ (possibly Typ[Invalid]).
169 func (check *Checker) validAlias(alias *TypeName, typ Type) {
170 delete(check.brokenAliases, alias)
174 // isBrokenAlias reports whether alias doesn't have a determined type yet.
175 func (check *Checker) isBrokenAlias(alias *TypeName) bool {
176 return alias.typ == Typ[Invalid] && check.brokenAliases[alias]
179 func (check *Checker) rememberUntyped(e ast.Expr, lhs bool, mode operandMode, typ *Basic, val constant.Value) {
182 m = make(map[ast.Expr]exprInfo)
185 m[e] = exprInfo{lhs, mode, typ, val}
188 // later pushes f on to the stack of actions that will be processed later;
189 // either at the end of the current statement, or in case of a local constant
190 // or variable declaration, before the constant or variable is in scope
191 // (so that f still sees the scope before any new declarations).
192 // later returns the pushed action so one can provide a description
193 // via action.describef for debugging, if desired.
194 func (check *Checker) later(f func()) *action {
195 i := len(check.delayed)
196 check.delayed = append(check.delayed, action{f: f})
197 return &check.delayed[i]
200 // push pushes obj onto the object path and returns its index in the path.
201 func (check *Checker) push(obj Object) int {
202 check.objPath = append(check.objPath, obj)
203 return len(check.objPath) - 1
206 // pop pops and returns the topmost object from the object path.
207 func (check *Checker) pop() Object {
208 i := len(check.objPath) - 1
209 obj := check.objPath[i]
210 check.objPath[i] = nil
211 check.objPath = check.objPath[:i]
215 type cleaner interface {
219 // needsCleanup records objects/types that implement the cleanup method
220 // which will be called at the end of type-checking.
221 func (check *Checker) needsCleanup(c cleaner) {
222 check.cleaners = append(check.cleaners, c)
225 // NewChecker returns a new Checker instance for a given package.
226 // Package files may be added incrementally via checker.Files.
227 func NewChecker(conf *Config, fset *token.FileSet, pkg *Package, info *Info) *Checker {
228 // make sure we have a configuration
233 // make sure we have an info struct
238 version, err := parseGoVersion(conf.GoVersion)
240 panic(fmt.Sprintf("invalid Go version %q (%v)", conf.GoVersion, err))
250 objMap: make(map[Object]*declInfo),
251 impMap: make(map[importKey]*Package),
252 infoMap: make(map[*Named]typeInfo),
256 // initFiles initializes the files-specific portion of checker.
257 // The provided files must all belong to the same package.
258 func (check *Checker) initFiles(files []*ast.File) {
259 // start with a clean slate (check.Files may be called multiple times)
262 check.dotImportMap = nil
271 // determine package name and collect valid files
273 for _, file := range files {
274 switch name := file.Name.Name; pkg.name {
279 check.errorf(file.Name, _BlankPkgName, "invalid package name _")
284 check.files = append(check.files, file)
287 check.errorf(atPos(file.Package), _MismatchedPkgName, "package %s; expected %s", name, pkg.name)
293 // A bailout panic is used for early termination.
294 type bailout struct{}
296 func (check *Checker) handleBailout(err *error) {
297 switch p := recover().(type) {
299 // normal return or early exit
300 *err = check.firstErr
307 // Files checks the provided files as part of the checker's package.
308 func (check *Checker) Files(files []*ast.File) error { return check.checkFiles(files) }
310 var errBadCgo = errors.New("cannot use FakeImportC and go115UsesCgo together")
312 func (check *Checker) checkFiles(files []*ast.File) (err error) {
313 if check.conf.FakeImportC && check.conf.go115UsesCgo {
317 defer check.handleBailout(&err)
319 print := func(msg string) {
326 print("== initFiles ==")
327 check.initFiles(files)
329 print("== collectObjects ==")
330 check.collectObjects()
332 print("== packageObjects ==")
333 check.packageObjects()
335 print("== processDelayed ==")
336 check.processDelayed(0) // incl. all functions
338 print("== cleanup ==")
341 print("== initOrder ==")
344 if !check.conf.DisableUnusedImportCheck {
345 print("== unusedImports ==")
346 check.unusedImports()
349 print("== recordUntyped ==")
350 check.recordUntyped()
352 if check.firstErr == nil {
353 // TODO(mdempsky): Ensure monomorph is safe when errors exist.
357 check.pkg.complete = true
359 // no longer needed - release memory
361 check.dotImportMap = nil
362 check.pkgPathMap = nil
363 check.seenPkgMap = nil
364 check.recvTParamMap = nil
365 check.brokenAliases = nil
366 check.unionTypeSets = nil
369 // TODO(rFindley) There's more memory we should release at this point.
374 // processDelayed processes all delayed actions pushed after top.
375 func (check *Checker) processDelayed(top int) {
376 // If each delayed action pushes a new action, the
377 // stack will continue to grow during this loop.
378 // However, it is only processing functions (which
379 // are processed in a delayed fashion) that may
380 // add more actions (such as nested functions), so
381 // this is a sufficiently bounded process.
382 for i := top; i < len(check.delayed); i++ {
383 a := &check.delayed[i]
384 if trace && a.desc != nil {
386 check.trace(a.desc.pos.Pos(), "-- "+a.desc.format, a.desc.args...)
388 a.f() // may append to check.delayed
390 assert(top <= len(check.delayed)) // stack must not have shrunk
391 check.delayed = check.delayed[:top]
394 // cleanup runs cleanup for all collected cleaners.
395 func (check *Checker) cleanup() {
396 // Don't use a range clause since Named.cleanup may add more cleaners.
397 for i := 0; i < len(check.cleaners); i++ {
398 check.cleaners[i].cleanup()
403 func (check *Checker) record(x *operand) {
404 // convert x into a user-friendly set of values
405 // TODO(gri) this code can be simplified
407 var val constant.Value
419 assert(x.expr != nil && typ != nil)
422 // delay type and value recording until we know the type
423 // or until the end of type checking
424 check.rememberUntyped(x.expr, false, x.mode, typ.(*Basic), val)
426 check.recordTypeAndValue(x.expr, x.mode, typ, val)
430 func (check *Checker) recordUntyped() {
431 if !debug && check.Types == nil {
432 return // nothing to do
435 for x, info := range check.untyped {
436 if debug && isTyped(info.typ) {
437 check.dump("%v: %s (type %s) is typed", x.Pos(), x, info.typ)
440 check.recordTypeAndValue(x, info.mode, info.typ, info.val)
444 func (check *Checker) recordTypeAndValue(x ast.Expr, mode operandMode, typ Type, val constant.Value) {
450 if mode == constant_ {
452 // We check allBasic(typ, IsConstType) here as constant expressions may be
453 // recorded as type parameters.
454 assert(typ == Typ[Invalid] || allBasic(typ, IsConstType))
456 if m := check.Types; m != nil {
457 m[x] = TypeAndValue{mode, typ, val}
461 func (check *Checker) recordBuiltinType(f ast.Expr, sig *Signature) {
462 // f must be a (possibly parenthesized, possibly qualified)
463 // identifier denoting a built-in (including unsafe's non-constant
464 // functions Add and Slice): record the signature for f and possible
467 check.recordTypeAndValue(f, builtin, sig, nil)
468 switch p := f.(type) {
469 case *ast.Ident, *ast.SelectorExpr:
479 func (check *Checker) recordCommaOkTypes(x ast.Expr, a [2]Type) {
481 if a[0] == nil || a[1] == nil {
484 assert(isTyped(a[0]) && isTyped(a[1]) && (isBoolean(a[1]) || a[1] == universeError))
485 if m := check.Types; m != nil {
488 assert(tv.Type != nil) // should have been recorded already
491 NewVar(pos, check.pkg, "", a[0]),
492 NewVar(pos, check.pkg, "", a[1]),
495 // if x is a parenthesized expression (p.X), update p.X
496 p, _ := x.(*ast.ParenExpr)
505 // recordInstance records instantiation information into check.Info, if the
506 // Instances map is non-nil. The given expr must be an ident, selector, or
507 // index (list) expr with ident or selector operand.
509 // TODO(rfindley): the expr parameter is fragile. See if we can access the
510 // instantiated identifier in some other way.
511 func (check *Checker) recordInstance(expr ast.Expr, targs []Type, typ Type) {
512 ident := instantiatedIdent(expr)
515 if m := check.Instances; m != nil {
516 m[ident] = Instance{newTypeList(targs), typ}
520 func instantiatedIdent(expr ast.Expr) *ast.Ident {
521 var selOrIdent ast.Expr
522 switch e := expr.(type) {
525 case *ast.IndexListExpr:
527 case *ast.SelectorExpr, *ast.Ident:
530 switch x := selOrIdent.(type) {
533 case *ast.SelectorExpr:
536 panic("instantiated ident not found")
539 func (check *Checker) recordDef(id *ast.Ident, obj Object) {
541 if m := check.Defs; m != nil {
546 func (check *Checker) recordUse(id *ast.Ident, obj Object) {
549 if m := check.Uses; m != nil {
554 func (check *Checker) recordImplicit(node ast.Node, obj Object) {
557 if m := check.Implicits; m != nil {
562 func (check *Checker) recordSelection(x *ast.SelectorExpr, kind SelectionKind, recv Type, obj Object, index []int, indirect bool) {
563 assert(obj != nil && (recv == nil || len(index) > 0))
564 check.recordUse(x.Sel, obj)
565 if m := check.Selections; m != nil {
566 m[x] = &Selection{kind, recv, obj, index, indirect}
570 func (check *Checker) recordScope(node ast.Node, scope *Scope) {
573 if m := check.Scopes; m != nil {