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.
15 . "internal/types/errors"
18 // nopos indicates an unknown position
21 // debugging/development support
22 const debug = false // leave on during development
24 // exprInfo stores information about an untyped expression.
25 type exprInfo struct {
26 isLhs bool // expression is lhs operand of a shift with delayed type-check
29 val constant.Value // constant value; or nil (if not a constant)
32 // An environment represents the environment within which an object is
34 type environment struct {
35 decl *declInfo // package-level declaration whose init expression/function body is checked
36 scope *Scope // top-most scope for lookups
37 pos token.Pos // if valid, identifiers are looked up as if at position pos (used by Eval)
38 iota constant.Value // value of iota in a constant declaration; nil otherwise
39 errpos positioner // if set, identifier position of a constant with inherited initializer
40 inTParamList bool // set if inside a type parameter list
41 sig *Signature // function signature if inside a function; nil otherwise
42 isPanic map[*ast.CallExpr]bool // set of panic call expressions (used for termination check)
43 hasLabel bool // set if a function makes use of labels (only ~1% of functions); unused outside functions
44 hasCallOrRecv bool // set if an expression contains a function call or channel receive operation
47 // lookup looks up name in the current environment and returns the matching object, or nil.
48 func (env *environment) lookup(name string) Object {
49 _, obj := env.scope.LookupParent(name, env.pos)
53 // An importKey identifies an imported package by import path and source directory
54 // (directory containing the file containing the import). In practice, the directory
55 // may always be the same, or may not matter. Given an (import path, directory), an
56 // importer must always return the same package (but given two different import paths,
57 // an importer may still return the same package by mapping them to the same package
59 type importKey struct {
63 // A dotImportKey describes a dot-imported object in the given scope.
64 type dotImportKey struct {
69 // An action describes a (delayed) action.
71 f func() // action to be executed
72 desc *actionDesc // action description; may be nil, requires debug to be set
75 // If debug is set, describef sets a printf-formatted description for action a.
76 // Otherwise, it is a no-op.
77 func (a *action) describef(pos positioner, format string, args ...any) {
79 a.desc = &actionDesc{pos, format, args}
83 // An actionDesc provides information on an action.
84 // For debugging only.
85 type actionDesc struct {
91 // A Checker maintains the state of the type checker.
92 // It must be created with NewChecker.
94 // package information
95 // (initialized by NewChecker, valid for the life-time of checker)
97 ctxt *Context // context for de-duplicating instances
101 version version // accepted language version
102 nextID uint64 // unique Id for type parameters (first valid Id is 1)
103 objMap map[Object]*declInfo // maps package-level objects and (non-interface) methods to declaration info
104 impMap map[importKey]*Package // maps (import path, source directory) to (complete or fake) package
105 valids instanceLookup // valid *Named (incl. instantiated) types per the validType check
107 // pkgPathMap maps package names to the set of distinct import paths we've
108 // seen for that name, anywhere in the import graph. It is used for
109 // disambiguating package names in error messages.
111 // pkgPathMap is allocated lazily, so that we don't pay the price of building
112 // it on the happy path. seenPkgMap tracks the packages that we've already
114 pkgPathMap map[string]map[string]bool
115 seenPkgMap map[*Package]bool
117 // information collected during type-checking of a set of package files
118 // (initialized by Files, valid only for the duration of check.Files;
119 // maps and lists are allocated on demand)
120 files []*ast.File // package files
121 posVers map[*token.File]version // Pos -> Go version mapping
122 imports []*PkgName // list of imported packages
123 dotImportMap map[dotImportKey]*PkgName // maps dot-imported objects to the package they were dot-imported through
124 recvTParamMap map[*ast.Ident]*TypeParam // maps blank receiver type parameters to their type
125 brokenAliases map[*TypeName]bool // set of aliases with broken (not yet determined) types
126 unionTypeSets map[*Union]*_TypeSet // computed type sets for union types
127 mono monoGraph // graph for detecting non-monomorphizable instantiation loops
129 firstErr error // first error encountered
130 methods map[*TypeName][]*Func // maps package scope type names to associated non-blank (non-interface) methods
131 untyped map[ast.Expr]exprInfo // map of expressions without final type
132 delayed []action // stack of delayed action segments; segments are processed in FIFO order
133 objPath []Object // path of object dependencies during type inference (for cycle reporting)
134 cleaners []cleaner // list of types that may need a final cleanup at the end of type-checking
136 // environment within which the current object is type-checked (valid only
137 // for the duration of type-checking a specific object)
141 indent int // indentation for tracing
144 // addDeclDep adds the dependency edge (check.decl -> to) if check.decl exists
145 func (check *Checker) addDeclDep(to Object) {
148 return // not in a package-level init expression
150 if _, found := check.objMap[to]; !found {
151 return // to is not a package-level object
156 // brokenAlias records that alias doesn't have a determined type yet.
157 // It also sets alias.typ to Typ[Invalid].
158 func (check *Checker) brokenAlias(alias *TypeName) {
159 if check.brokenAliases == nil {
160 check.brokenAliases = make(map[*TypeName]bool)
162 check.brokenAliases[alias] = true
163 alias.typ = Typ[Invalid]
166 // validAlias records that alias has the valid type typ (possibly Typ[Invalid]).
167 func (check *Checker) validAlias(alias *TypeName, typ Type) {
168 delete(check.brokenAliases, alias)
172 // isBrokenAlias reports whether alias doesn't have a determined type yet.
173 func (check *Checker) isBrokenAlias(alias *TypeName) bool {
174 return alias.typ == Typ[Invalid] && check.brokenAliases[alias]
177 func (check *Checker) rememberUntyped(e ast.Expr, lhs bool, mode operandMode, typ *Basic, val constant.Value) {
180 m = make(map[ast.Expr]exprInfo)
183 m[e] = exprInfo{lhs, mode, typ, val}
186 // later pushes f on to the stack of actions that will be processed later;
187 // either at the end of the current statement, or in case of a local constant
188 // or variable declaration, before the constant or variable is in scope
189 // (so that f still sees the scope before any new declarations).
190 // later returns the pushed action so one can provide a description
191 // via action.describef for debugging, if desired.
192 func (check *Checker) later(f func()) *action {
193 i := len(check.delayed)
194 check.delayed = append(check.delayed, action{f: f})
195 return &check.delayed[i]
198 // push pushes obj onto the object path and returns its index in the path.
199 func (check *Checker) push(obj Object) int {
200 check.objPath = append(check.objPath, obj)
201 return len(check.objPath) - 1
204 // pop pops and returns the topmost object from the object path.
205 func (check *Checker) pop() Object {
206 i := len(check.objPath) - 1
207 obj := check.objPath[i]
208 check.objPath[i] = nil
209 check.objPath = check.objPath[:i]
213 type cleaner interface {
217 // needsCleanup records objects/types that implement the cleanup method
218 // which will be called at the end of type-checking.
219 func (check *Checker) needsCleanup(c cleaner) {
220 check.cleaners = append(check.cleaners, c)
223 // NewChecker returns a new Checker instance for a given package.
224 // Package files may be added incrementally via checker.Files.
225 func NewChecker(conf *Config, fset *token.FileSet, pkg *Package, info *Info) *Checker {
226 // make sure we have a configuration
231 // make sure we have an info struct
236 version, err := parseGoVersion(conf.GoVersion)
238 panic(fmt.Sprintf("invalid Go version %q (%v)", conf.GoVersion, err))
248 objMap: make(map[Object]*declInfo),
249 impMap: make(map[importKey]*Package),
253 // initFiles initializes the files-specific portion of checker.
254 // The provided files must all belong to the same package.
255 func (check *Checker) initFiles(files []*ast.File) {
256 // start with a clean slate (check.Files may be called multiple times)
259 check.dotImportMap = nil
268 // determine package name and collect valid files
270 for _, file := range files {
271 switch name := file.Name.Name; pkg.name {
276 check.error(file.Name, BlankPkgName, "invalid package name _")
281 check.files = append(check.files, file)
284 check.errorf(atPos(file.Package), MismatchedPkgName, "package %s; expected %s", name, pkg.name)
289 for _, file := range check.files {
290 v, _ := parseGoVersion(file.GoVersion)
292 if v.equal(check.version) {
295 // Go 1.21 introduced the feature of setting the go.mod
296 // go line to an early version of Go and allowing //go:build lines
297 // to “upgrade” the Go version in a given file.
298 // We can do that backwards compatibly.
299 // Go 1.21 also introduced the feature of allowing //go:build lines
300 // to “downgrade” the Go version in a given file.
301 // That can't be done compatibly in general, since before the
302 // build lines were ignored and code got the module's Go version.
303 // To work around this, downgrades are only allowed when the
304 // module's Go version is Go 1.21 or later.
305 if v.before(check.version) && check.version.before(version{1, 21}) {
308 if check.posVers == nil {
309 check.posVers = make(map[*token.File]version)
311 check.posVers[check.fset.File(file.FileStart)] = v
316 // A posVers records that the file starting at pos declares the Go version vers.
317 type posVers struct {
322 // A bailout panic is used for early termination.
323 type bailout struct{}
325 func (check *Checker) handleBailout(err *error) {
326 switch p := recover().(type) {
328 // normal return or early exit
329 *err = check.firstErr
336 // Files checks the provided files as part of the checker's package.
337 func (check *Checker) Files(files []*ast.File) error { return check.checkFiles(files) }
339 var errBadCgo = errors.New("cannot use FakeImportC and go115UsesCgo together")
341 func (check *Checker) checkFiles(files []*ast.File) (err error) {
342 if check.conf.FakeImportC && check.conf.go115UsesCgo {
346 defer check.handleBailout(&err)
348 print := func(msg string) {
349 if check.conf._Trace {
355 print("== initFiles ==")
356 check.initFiles(files)
358 print("== collectObjects ==")
359 check.collectObjects()
361 print("== packageObjects ==")
362 check.packageObjects()
364 print("== processDelayed ==")
365 check.processDelayed(0) // incl. all functions
367 print("== cleanup ==")
370 print("== initOrder ==")
373 if !check.conf.DisableUnusedImportCheck {
374 print("== unusedImports ==")
375 check.unusedImports()
378 print("== recordUntyped ==")
379 check.recordUntyped()
381 if check.firstErr == nil {
382 // TODO(mdempsky): Ensure monomorph is safe when errors exist.
386 check.pkg.complete = true
388 // no longer needed - release memory
390 check.dotImportMap = nil
391 check.pkgPathMap = nil
392 check.seenPkgMap = nil
393 check.recvTParamMap = nil
394 check.brokenAliases = nil
395 check.unionTypeSets = nil
398 // TODO(rFindley) There's more memory we should release at this point.
403 // processDelayed processes all delayed actions pushed after top.
404 func (check *Checker) processDelayed(top int) {
405 // If each delayed action pushes a new action, the
406 // stack will continue to grow during this loop.
407 // However, it is only processing functions (which
408 // are processed in a delayed fashion) that may
409 // add more actions (such as nested functions), so
410 // this is a sufficiently bounded process.
411 for i := top; i < len(check.delayed); i++ {
412 a := &check.delayed[i]
413 if check.conf._Trace {
415 check.trace(a.desc.pos.Pos(), "-- "+a.desc.format, a.desc.args...)
417 check.trace(nopos, "-- delayed %p", a.f)
420 a.f() // may append to check.delayed
421 if check.conf._Trace {
425 assert(top <= len(check.delayed)) // stack must not have shrunk
426 check.delayed = check.delayed[:top]
429 // cleanup runs cleanup for all collected cleaners.
430 func (check *Checker) cleanup() {
431 // Don't use a range clause since Named.cleanup may add more cleaners.
432 for i := 0; i < len(check.cleaners); i++ {
433 check.cleaners[i].cleanup()
438 func (check *Checker) record(x *operand) {
439 // convert x into a user-friendly set of values
440 // TODO(gri) this code can be simplified
442 var val constant.Value
454 assert(x.expr != nil && typ != nil)
457 // delay type and value recording until we know the type
458 // or until the end of type checking
459 check.rememberUntyped(x.expr, false, x.mode, typ.(*Basic), val)
461 check.recordTypeAndValue(x.expr, x.mode, typ, val)
465 func (check *Checker) recordUntyped() {
466 if !debug && check.Types == nil {
467 return // nothing to do
470 for x, info := range check.untyped {
471 if debug && isTyped(info.typ) {
472 check.dump("%v: %s (type %s) is typed", x.Pos(), x, info.typ)
475 check.recordTypeAndValue(x, info.mode, info.typ, info.val)
479 func (check *Checker) recordTypeAndValue(x ast.Expr, mode operandMode, typ Type, val constant.Value) {
485 if mode == constant_ {
487 // We check allBasic(typ, IsConstType) here as constant expressions may be
488 // recorded as type parameters.
489 assert(typ == Typ[Invalid] || allBasic(typ, IsConstType))
491 if m := check.Types; m != nil {
492 m[x] = TypeAndValue{mode, typ, val}
496 func (check *Checker) recordBuiltinType(f ast.Expr, sig *Signature) {
497 // f must be a (possibly parenthesized, possibly qualified)
498 // identifier denoting a built-in (including unsafe's non-constant
499 // functions Add and Slice): record the signature for f and possible
502 check.recordTypeAndValue(f, builtin, sig, nil)
503 switch p := f.(type) {
504 case *ast.Ident, *ast.SelectorExpr:
514 // recordCommaOkTypes updates recorded types to reflect that x is used in a commaOk context
515 // (and therefore has tuple type).
516 func (check *Checker) recordCommaOkTypes(x ast.Expr, a []*operand) {
519 if a[0].mode == invalid {
522 t0, t1 := a[0].typ, a[1].typ
523 assert(isTyped(t0) && isTyped(t1) && (isBoolean(t1) || t1 == universeError))
524 if m := check.Types; m != nil {
527 assert(tv.Type != nil) // should have been recorded already
530 NewVar(pos, check.pkg, "", t0),
531 NewVar(pos, check.pkg, "", t1),
534 // if x is a parenthesized expression (p.X), update p.X
535 p, _ := x.(*ast.ParenExpr)
544 // recordInstance records instantiation information into check.Info, if the
545 // Instances map is non-nil. The given expr must be an ident, selector, or
546 // index (list) expr with ident or selector operand.
548 // TODO(rfindley): the expr parameter is fragile. See if we can access the
549 // instantiated identifier in some other way.
550 func (check *Checker) recordInstance(expr ast.Expr, targs []Type, typ Type) {
551 ident := instantiatedIdent(expr)
554 if m := check.Instances; m != nil {
555 m[ident] = Instance{newTypeList(targs), typ}
559 func instantiatedIdent(expr ast.Expr) *ast.Ident {
560 var selOrIdent ast.Expr
561 switch e := expr.(type) {
564 case *ast.IndexListExpr:
566 case *ast.SelectorExpr, *ast.Ident:
569 switch x := selOrIdent.(type) {
572 case *ast.SelectorExpr:
575 panic("instantiated ident not found")
578 func (check *Checker) recordDef(id *ast.Ident, obj Object) {
580 if m := check.Defs; m != nil {
585 func (check *Checker) recordUse(id *ast.Ident, obj Object) {
588 if m := check.Uses; m != nil {
593 func (check *Checker) recordImplicit(node ast.Node, obj Object) {
596 if m := check.Implicits; m != nil {
601 func (check *Checker) recordSelection(x *ast.SelectorExpr, kind SelectionKind, recv Type, obj Object, index []int, indirect bool) {
602 assert(obj != nil && (recv == nil || len(index) > 0))
603 check.recordUse(x.Sel, obj)
604 if m := check.Selections; m != nil {
605 m[x] = &Selection{kind, recv, obj, index, indirect}
609 func (check *Checker) recordScope(node ast.Node, scope *Scope) {
612 if m := check.Scopes; m != nil {