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 // debugging/development support
20 debug = false // leave on during development
21 trace = false // turn on for detailed type resolution traces
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 imports []*PkgName // list of imported packages
122 dotImportMap map[dotImportKey]*PkgName // maps dot-imported objects to the package they were dot-imported through
123 recvTParamMap map[*ast.Ident]*TypeParam // maps blank receiver type parameters to their type
124 brokenAliases map[*TypeName]bool // set of aliases with broken (not yet determined) types
125 unionTypeSets map[*Union]*_TypeSet // computed type sets for union types
126 mono monoGraph // graph for detecting non-monomorphizable instantiation loops
128 firstErr error // first error encountered
129 methods map[*TypeName][]*Func // maps package scope type names to associated non-blank (non-interface) methods
130 untyped map[ast.Expr]exprInfo // map of expressions without final type
131 delayed []action // stack of delayed action segments; segments are processed in FIFO order
132 objPath []Object // path of object dependencies during type inference (for cycle reporting)
133 cleaners []cleaner // list of types that may need a final cleanup at the end of type-checking
135 // environment within which the current object is type-checked (valid only
136 // for the duration of type-checking a specific object)
140 indent int // indentation for tracing
143 // addDeclDep adds the dependency edge (check.decl -> to) if check.decl exists
144 func (check *Checker) addDeclDep(to Object) {
147 return // not in a package-level init expression
149 if _, found := check.objMap[to]; !found {
150 return // to is not a package-level object
155 // brokenAlias records that alias doesn't have a determined type yet.
156 // It also sets alias.typ to Typ[Invalid].
157 func (check *Checker) brokenAlias(alias *TypeName) {
158 if check.brokenAliases == nil {
159 check.brokenAliases = make(map[*TypeName]bool)
161 check.brokenAliases[alias] = true
162 alias.typ = Typ[Invalid]
165 // validAlias records that alias has the valid type typ (possibly Typ[Invalid]).
166 func (check *Checker) validAlias(alias *TypeName, typ Type) {
167 delete(check.brokenAliases, alias)
171 // isBrokenAlias reports whether alias doesn't have a determined type yet.
172 func (check *Checker) isBrokenAlias(alias *TypeName) bool {
173 return alias.typ == Typ[Invalid] && check.brokenAliases[alias]
176 func (check *Checker) rememberUntyped(e ast.Expr, lhs bool, mode operandMode, typ *Basic, val constant.Value) {
179 m = make(map[ast.Expr]exprInfo)
182 m[e] = exprInfo{lhs, mode, typ, val}
185 // later pushes f on to the stack of actions that will be processed later;
186 // either at the end of the current statement, or in case of a local constant
187 // or variable declaration, before the constant or variable is in scope
188 // (so that f still sees the scope before any new declarations).
189 // later returns the pushed action so one can provide a description
190 // via action.describef for debugging, if desired.
191 func (check *Checker) later(f func()) *action {
192 i := len(check.delayed)
193 check.delayed = append(check.delayed, action{f: f})
194 return &check.delayed[i]
197 // push pushes obj onto the object path and returns its index in the path.
198 func (check *Checker) push(obj Object) int {
199 check.objPath = append(check.objPath, obj)
200 return len(check.objPath) - 1
203 // pop pops and returns the topmost object from the object path.
204 func (check *Checker) pop() Object {
205 i := len(check.objPath) - 1
206 obj := check.objPath[i]
207 check.objPath[i] = nil
208 check.objPath = check.objPath[:i]
212 type cleaner interface {
216 // needsCleanup records objects/types that implement the cleanup method
217 // which will be called at the end of type-checking.
218 func (check *Checker) needsCleanup(c cleaner) {
219 check.cleaners = append(check.cleaners, c)
222 // NewChecker returns a new Checker instance for a given package.
223 // Package files may be added incrementally via checker.Files.
224 func NewChecker(conf *Config, fset *token.FileSet, pkg *Package, info *Info) *Checker {
225 // make sure we have a configuration
230 // make sure we have an info struct
235 version, err := parseGoVersion(conf.GoVersion)
237 panic(fmt.Sprintf("invalid Go version %q (%v)", conf.GoVersion, err))
247 objMap: make(map[Object]*declInfo),
248 impMap: make(map[importKey]*Package),
252 // initFiles initializes the files-specific portion of checker.
253 // The provided files must all belong to the same package.
254 func (check *Checker) initFiles(files []*ast.File) {
255 // start with a clean slate (check.Files may be called multiple times)
258 check.dotImportMap = nil
267 // determine package name and collect valid files
269 for _, file := range files {
270 switch name := file.Name.Name; pkg.name {
275 check.errorf(file.Name, BlankPkgName, "invalid package name _")
280 check.files = append(check.files, file)
283 check.errorf(atPos(file.Package), MismatchedPkgName, "package %s; expected %s", name, pkg.name)
289 // A bailout panic is used for early termination.
290 type bailout struct{}
292 func (check *Checker) handleBailout(err *error) {
293 switch p := recover().(type) {
295 // normal return or early exit
296 *err = check.firstErr
303 // Files checks the provided files as part of the checker's package.
304 func (check *Checker) Files(files []*ast.File) error { return check.checkFiles(files) }
306 var errBadCgo = errors.New("cannot use FakeImportC and go115UsesCgo together")
308 func (check *Checker) checkFiles(files []*ast.File) (err error) {
309 if check.conf.FakeImportC && check.conf.go115UsesCgo {
313 defer check.handleBailout(&err)
315 print := func(msg string) {
322 print("== initFiles ==")
323 check.initFiles(files)
325 print("== collectObjects ==")
326 check.collectObjects()
328 print("== packageObjects ==")
329 check.packageObjects()
331 print("== processDelayed ==")
332 check.processDelayed(0) // incl. all functions
334 print("== cleanup ==")
337 print("== initOrder ==")
340 if !check.conf.DisableUnusedImportCheck {
341 print("== unusedImports ==")
342 check.unusedImports()
345 print("== recordUntyped ==")
346 check.recordUntyped()
348 if check.firstErr == nil {
349 // TODO(mdempsky): Ensure monomorph is safe when errors exist.
353 check.pkg.complete = true
355 // no longer needed - release memory
357 check.dotImportMap = nil
358 check.pkgPathMap = nil
359 check.seenPkgMap = nil
360 check.recvTParamMap = nil
361 check.brokenAliases = nil
362 check.unionTypeSets = nil
365 // TODO(rFindley) There's more memory we should release at this point.
370 // processDelayed processes all delayed actions pushed after top.
371 func (check *Checker) processDelayed(top int) {
372 // If each delayed action pushes a new action, the
373 // stack will continue to grow during this loop.
374 // However, it is only processing functions (which
375 // are processed in a delayed fashion) that may
376 // add more actions (such as nested functions), so
377 // this is a sufficiently bounded process.
378 for i := top; i < len(check.delayed); i++ {
379 a := &check.delayed[i]
382 check.trace(a.desc.pos.Pos(), "-- "+a.desc.format, a.desc.args...)
384 check.trace(token.NoPos, "-- delayed %p", a.f)
387 a.f() // may append to check.delayed
392 assert(top <= len(check.delayed)) // stack must not have shrunk
393 check.delayed = check.delayed[:top]
396 // cleanup runs cleanup for all collected cleaners.
397 func (check *Checker) cleanup() {
398 // Don't use a range clause since Named.cleanup may add more cleaners.
399 for i := 0; i < len(check.cleaners); i++ {
400 check.cleaners[i].cleanup()
405 func (check *Checker) record(x *operand) {
406 // convert x into a user-friendly set of values
407 // TODO(gri) this code can be simplified
409 var val constant.Value
421 assert(x.expr != nil && typ != nil)
424 // delay type and value recording until we know the type
425 // or until the end of type checking
426 check.rememberUntyped(x.expr, false, x.mode, typ.(*Basic), val)
428 check.recordTypeAndValue(x.expr, x.mode, typ, val)
432 func (check *Checker) recordUntyped() {
433 if !debug && check.Types == nil {
434 return // nothing to do
437 for x, info := range check.untyped {
438 if debug && isTyped(info.typ) {
439 check.dump("%v: %s (type %s) is typed", x.Pos(), x, info.typ)
442 check.recordTypeAndValue(x, info.mode, info.typ, info.val)
446 func (check *Checker) recordTypeAndValue(x ast.Expr, mode operandMode, typ Type, val constant.Value) {
452 if mode == constant_ {
454 // We check allBasic(typ, IsConstType) here as constant expressions may be
455 // recorded as type parameters.
456 assert(typ == Typ[Invalid] || allBasic(typ, IsConstType))
458 if m := check.Types; m != nil {
459 m[x] = TypeAndValue{mode, typ, val}
463 func (check *Checker) recordBuiltinType(f ast.Expr, sig *Signature) {
464 // f must be a (possibly parenthesized, possibly qualified)
465 // identifier denoting a built-in (including unsafe's non-constant
466 // functions Add and Slice): record the signature for f and possible
469 check.recordTypeAndValue(f, builtin, sig, nil)
470 switch p := f.(type) {
471 case *ast.Ident, *ast.SelectorExpr:
481 func (check *Checker) recordCommaOkTypes(x ast.Expr, a [2]Type) {
483 if a[0] == nil || a[1] == nil {
486 assert(isTyped(a[0]) && isTyped(a[1]) && (isBoolean(a[1]) || a[1] == universeError))
487 if m := check.Types; m != nil {
490 assert(tv.Type != nil) // should have been recorded already
493 NewVar(pos, check.pkg, "", a[0]),
494 NewVar(pos, check.pkg, "", a[1]),
497 // if x is a parenthesized expression (p.X), update p.X
498 p, _ := x.(*ast.ParenExpr)
507 // recordInstance records instantiation information into check.Info, if the
508 // Instances map is non-nil. The given expr must be an ident, selector, or
509 // index (list) expr with ident or selector operand.
511 // TODO(rfindley): the expr parameter is fragile. See if we can access the
512 // instantiated identifier in some other way.
513 func (check *Checker) recordInstance(expr ast.Expr, targs []Type, typ Type) {
514 ident := instantiatedIdent(expr)
517 if m := check.Instances; m != nil {
518 m[ident] = Instance{newTypeList(targs), typ}
522 func instantiatedIdent(expr ast.Expr) *ast.Ident {
523 var selOrIdent ast.Expr
524 switch e := expr.(type) {
527 case *ast.IndexListExpr:
529 case *ast.SelectorExpr, *ast.Ident:
532 switch x := selOrIdent.(type) {
535 case *ast.SelectorExpr:
538 panic("instantiated ident not found")
541 func (check *Checker) recordDef(id *ast.Ident, obj Object) {
543 if m := check.Defs; m != nil {
548 func (check *Checker) recordUse(id *ast.Ident, obj Object) {
551 if m := check.Uses; m != nil {
556 func (check *Checker) recordImplicit(node ast.Node, obj Object) {
559 if m := check.Implicits; m != nil {
564 func (check *Checker) recordSelection(x *ast.SelectorExpr, kind SelectionKind, recv Type, obj Object, index []int, indirect bool) {
565 assert(obj != nil && (recv == nil || len(index) > 0))
566 check.recordUse(x.Sel, obj)
567 if m := check.Selections; m != nil {
568 m[x] = &Selection{kind, recv, obj, index, indirect}
572 func (check *Checker) recordScope(node ast.Node, scope *Scope) {
575 if m := check.Scopes; m != nil {