1 // Copyright 2014 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"
14 func (err *error_) recordAltDecl(obj Object) {
15 if pos := obj.Pos(); pos.IsKnown() {
16 // We use "other" rather than "previous" here because
17 // the first declaration seen may not be textually
18 // earlier in the source.
19 err.errorf(pos, "other declaration of %s", obj.Name())
23 func (check *Checker) declare(scope *Scope, id *syntax.Name, obj Object, pos syntax.Pos) {
24 // spec: "The blank identifier, represented by the underscore
25 // character _, may be used in a declaration like any other
26 // identifier but the declaration does not introduce a new
28 if obj.Name() != "_" {
29 if alt := scope.Insert(obj); alt != nil {
31 err.code = DuplicateDecl
32 err.errorf(obj, "%s redeclared in this block", obj.Name())
33 err.recordAltDecl(alt)
40 check.recordDef(id, obj)
44 // pathString returns a string of the form a->b-> ... ->g for a path [a, b, ... g].
45 func pathString(path []Object) string {
47 for i, p := range path {
56 // objDecl type-checks the declaration of obj in its respective (file) environment.
57 // For the meaning of def, see Checker.definedType, in typexpr.go.
58 func (check *Checker) objDecl(obj Object, def *Named) {
59 if check.conf.Trace && obj.Type() == nil {
60 if check.indent == 0 {
61 fmt.Println() // empty line between top-level objects for readability
63 check.trace(obj.Pos(), "-- checking %s (%s, objPath = %s)", obj, obj.color(), pathString(check.objPath))
67 check.trace(obj.Pos(), "=> %s (%s)", obj, obj.color())
71 // Checking the declaration of obj means inferring its type
72 // (and possibly its value, for constants).
73 // An object's type (and thus the object) may be in one of
74 // three states which are expressed by colors:
76 // - an object whose type is not yet known is painted white (initial color)
77 // - an object whose type is in the process of being inferred is painted grey
78 // - an object whose type is fully inferred is painted black
80 // During type inference, an object's color changes from white to grey
81 // to black (pre-declared objects are painted black from the start).
82 // A black object (i.e., its type) can only depend on (refer to) other black
83 // ones. White and grey objects may depend on white and black objects.
84 // A dependency on a grey object indicates a cycle which may or may not be
87 // When objects turn grey, they are pushed on the object path (a stack);
88 // they are popped again when they turn black. Thus, if a grey object (a
89 // cycle) is encountered, it is on the object path, and all the objects
90 // it depends on are the remaining objects on that path. Color encoding
91 // is such that the color value of a grey object indicates the index of
92 // that object in the object path.
94 // During type-checking, white objects may be assigned a type without
95 // traversing through objDecl; e.g., when initializing constants and
96 // variables. Update the colors of those objects here (rather than
97 // everywhere where we set the type) to satisfy the color invariants.
98 if obj.color() == white && obj.Type() != nil {
105 assert(obj.Type() == nil)
106 // All color values other than white and black are considered grey.
107 // Because black and white are < grey, all values >= grey are grey.
108 // Use those values to encode the object's index into the object path.
109 obj.setColor(grey + color(check.push(obj)))
111 check.pop().setColor(black)
115 assert(obj.Type() != nil)
119 // Color values other than white or black are considered grey.
123 // We have a (possibly invalid) cycle.
124 // In the existing code, this is marked by a non-nil type
125 // for the object except for constants and variables whose
126 // type may be non-nil (known), or nil if it depends on the
127 // not-yet known initialization value.
128 // In the former case, set the type to Typ[Invalid] because
129 // we have an initialization cycle. The cycle error will be
130 // reported later, when determining initialization order.
131 // TODO(gri) Report cycle here and simplify initialization
133 switch obj := obj.(type) {
135 if !check.validCycle(obj) || obj.typ == nil {
136 obj.typ = Typ[Invalid]
140 if !check.validCycle(obj) || obj.typ == nil {
141 obj.typ = Typ[Invalid]
145 if !check.validCycle(obj) {
147 // (without this, calling underlying()
148 // below may lead to an endless loop
149 // if we have a cycle for a defined
151 obj.typ = Typ[Invalid]
155 if !check.validCycle(obj) {
156 // Don't set obj.typ to Typ[Invalid] here
157 // because plenty of code type-asserts that
158 // functions have a *Signature type. Grey
159 // functions have their type set to an empty
160 // signature which makes it impossible to
161 // initialize a variable with the function.
167 assert(obj.Type() != nil)
171 d := check.objMap[obj]
173 check.dump("%v: %s should have been declared", obj.Pos(), obj)
177 // save/restore current environment and set up object environment
178 defer func(env environment) {
179 check.environment = env
181 check.environment = environment{
185 // Const and var declarations must not have initialization
186 // cycles. We track them by remembering the current declaration
187 // in check.decl. Initialization expressions depending on other
188 // consts, vars, or functions, add dependencies to the current
190 switch obj := obj.(type) {
192 check.decl = d // new package-level const decl
193 check.constDecl(obj, d.vtyp, d.init, d.inherited)
195 check.decl = d // new package-level var decl
196 check.varDecl(obj, d.lhs, d.vtyp, d.init)
198 // invalid recursive types are detected via path
199 check.typeDecl(obj, d.tdecl, def)
200 check.collectMethods(obj) // methods can only be added to top-level types
202 // functions may be recursive - no need to track dependencies
203 check.funcDecl(obj, d)
209 // validCycle reports whether the cycle starting with obj is valid and
210 // reports an error if it is not.
211 func (check *Checker) validCycle(obj Object) (valid bool) {
212 // The object map contains the package scope objects and the non-interface methods.
214 info := check.objMap[obj]
215 inObjMap := info != nil && (info.fdecl == nil || info.fdecl.Recv == nil) // exclude methods
216 isPkgObj := obj.Parent() == check.pkg.scope
217 if isPkgObj != inObjMap {
218 check.dump("%v: inconsistent object map for %s (isPkgObj = %v, inObjMap = %v)", obj.Pos(), obj, isPkgObj, inObjMap)
223 // Count cycle objects.
224 assert(obj.color() >= grey)
225 start := obj.color() - grey // index of obj in objPath
226 cycle := check.objPath[start:]
227 tparCycle := false // if set, the cycle is through a type parameter list
228 nval := 0 // number of (constant or variable) values in the cycle; valid if !generic
229 ndef := 0 // number of type definitions in the cycle; valid if !generic
231 for _, obj := range cycle {
232 switch obj := obj.(type) {
236 // If we reach a generic type that is part of a cycle
237 // and we are in a type parameter list, we have a cycle
238 // through a type parameter list, which is invalid.
239 if check.inTParamList && isGeneric(obj.typ) {
244 // Determine if the type name is an alias or not. For
245 // package-level objects, use the object map which
246 // provides syntactic information (which doesn't rely
247 // on the order in which the objects are set up). For
248 // local objects, we can rely on the order, so use
249 // the object's predicate.
250 // TODO(gri) It would be less fragile to always access
251 // the syntactic information. We should consider storing
252 // this information explicitly in the object.
254 if d := check.objMap[obj]; d != nil {
255 alias = d.tdecl.Alias // package-level object
257 alias = obj.IsAlias() // function local object
269 if check.conf.Trace {
270 check.trace(obj.Pos(), "## cycle detected: objPath = %s->%s (len = %d)", pathString(cycle), obj.Name(), len(cycle))
272 check.trace(obj.Pos(), "## cycle contains: generic type in a type parameter list")
274 check.trace(obj.Pos(), "## cycle contains: %d values, %d type definitions", nval, ndef)
278 check.trace(obj.Pos(), "=> cycle is valid")
280 check.trace(obj.Pos(), "=> error: cycle is invalid")
286 // A cycle involving only constants and variables is invalid but we
287 // ignore them here because they are reported via the initialization
289 if nval == len(cycle) {
293 // A cycle involving only types (and possibly functions) must have at least
294 // one type definition to be permitted: If there is no type definition, we
295 // have a sequence of alias type names which will expand ad infinitum.
296 if nval == 0 && ndef > 0 {
301 check.cycleError(cycle)
305 // cycleError reports a declaration cycle starting with
306 // the object in cycle that is "first" in the source.
307 func (check *Checker) cycleError(cycle []Object) {
308 // name returns the (possibly qualified) object name.
309 // This is needed because with generic types, cycles
310 // may refer to imported types. See go.dev/issue/50788.
311 // TODO(gri) This functionality is used elsewhere. Factor it out.
312 name := func(obj Object) string {
313 return packagePrefix(obj.Pkg(), check.qualifier) + obj.Name()
316 // TODO(gri) Should we start with the last (rather than the first) object in the cycle
317 // since that is the earliest point in the source where we start seeing the
318 // cycle? That would be more consistent with other error messages.
319 i := firstInSrc(cycle)
322 // If obj is a type alias, mark it as valid (not broken) in order to avoid follow-on errors.
323 tname, _ := obj.(*TypeName)
324 if tname != nil && tname.IsAlias() {
325 check.validAlias(tname, Typ[Invalid])
328 // report a more concise error for self references
331 check.errorf(obj, InvalidDeclCycle, "invalid recursive type: %s refers to itself", objName)
333 check.errorf(obj, InvalidDeclCycle, "invalid cycle in declaration: %s refers to itself", objName)
339 err.code = InvalidDeclCycle
341 err.errorf(obj, "invalid recursive type %s", objName)
343 err.errorf(obj, "invalid cycle in declaration of %s", objName)
346 err.errorf(obj, "%s refers to", objName)
354 err.errorf(obj, "%s", objName)
358 // firstInSrc reports the index of the object with the "smallest"
359 // source position in path. path must not be empty.
360 func firstInSrc(path []Object) int {
361 fst, pos := 0, path[0].Pos()
362 for i, t := range path[1:] {
363 if cmpPos(t.Pos(), pos) < 0 {
364 fst, pos = i+1, t.Pos()
370 func (check *Checker) constDecl(obj *Const, typ, init syntax.Expr, inherited bool) {
371 assert(obj.typ == nil)
373 // use the correct value of iota and errpos
374 defer func(iota constant.Value, errpos syntax.Pos) {
376 check.errpos = errpos
377 }(check.iota, check.errpos)
381 // provide valid constant value under all circumstances
382 obj.val = constant.MakeUnknown()
384 // determine type, if any
388 // don't report an error if the type is an invalid C (defined) type
389 // (go.dev/issue/22090)
390 if under(t) != Typ[Invalid] {
391 check.errorf(typ, InvalidConstType, "invalid constant type %s", t)
393 obj.typ = Typ[Invalid]
399 // check initialization
403 // The initialization expression is inherited from a previous
404 // constant declaration, and (error) positions refer to that
405 // expression and not the current constant declaration. Use
406 // the constant identifier position for any errors during
407 // init expression evaluation since that is all we have
408 // (see issues go.dev/issue/42991, go.dev/issue/42992).
409 check.errpos = obj.pos
411 check.expr(nil, &x, init)
413 check.initConst(obj, &x)
416 func (check *Checker) varDecl(obj *Var, lhs []*Var, typ, init syntax.Expr) {
417 assert(obj.typ == nil)
419 // If we have undefined variable types due to errors,
420 // mark variables as used to avoid follow-on errors.
421 // Matches compiler behavior.
423 if obj.typ == Typ[Invalid] {
426 for _, lhs := range lhs {
427 if lhs.typ == Typ[Invalid] {
433 // determine type, if any
435 obj.typ = check.varType(typ)
436 // We cannot spread the type to all lhs variables if there
437 // are more than one since that would mark them as checked
438 // (see Checker.objDecl) and the assignment of init exprs,
439 // if any, would not be checked.
441 // TODO(gri) If we have no init expr, we should distribute
442 // a given type otherwise we need to re-evalate the type
443 // expr for each lhs variable, leading to duplicate work.
446 // check initialization
449 // error reported before by arityMatch
450 obj.typ = Typ[Invalid]
455 if lhs == nil || len(lhs) == 1 {
456 assert(lhs == nil || lhs[0] == obj)
458 check.expr(obj.typ, &x, init)
459 check.initVar(obj, &x, "variable declaration")
464 // obj must be one of lhs
466 for _, lhs := range lhs {
473 panic("inconsistent lhs")
477 // We have multiple variables on the lhs and one init expr.
478 // Make sure all variables have been given the same type if
479 // one was specified, otherwise they assume the type of the
480 // init expression values (was go.dev/issue/15755).
482 for _, lhs := range lhs {
487 check.initVars(lhs, []syntax.Expr{init}, nil)
490 // isImportedConstraint reports whether typ is an imported type constraint.
491 func (check *Checker) isImportedConstraint(typ Type) bool {
492 named, _ := typ.(*Named)
493 if named == nil || named.obj.pkg == check.pkg || named.obj.pkg == nil {
496 u, _ := named.under().(*Interface)
497 return u != nil && !u.IsMethodSet()
500 func (check *Checker) typeDecl(obj *TypeName, tdecl *syntax.TypeDecl, def *Named) {
501 assert(obj.typ == nil)
505 if t, _ := obj.typ.(*Named); t != nil { // type may be invalid
508 // If typ is local, an error was already reported where typ is specified/defined.
509 if check.isImportedConstraint(rhs) && !check.allowVersion(check.pkg, 1, 18) {
510 check.versionErrorf(tdecl.Type, "go1.18", "using type constraint %s", rhs)
512 }).describef(obj, "validType(%s)", obj.Name())
515 if alias && tdecl.TParamList != nil {
516 // The parser will ensure this but we may still get an invalid AST.
517 // Complain and continue as regular type definition.
518 check.error(tdecl, BadDecl, "generic type cannot be alias")
524 if !check.allowVersion(check.pkg, 1, 9) {
525 check.versionErrorf(tdecl, "go1.9", "type aliases")
528 check.brokenAlias(obj)
529 rhs = check.typ(tdecl.Type)
530 check.validAlias(obj, rhs)
534 // type definition or generic type declaration
535 named := check.newNamed(obj, nil, nil)
536 def.setUnderlying(named)
538 if tdecl.TParamList != nil {
539 check.openScope(tdecl, "type parameters")
540 defer check.closeScope()
541 check.collectTypeParams(&named.tparams, tdecl.TParamList)
544 // determine underlying type of named
545 rhs = check.definedType(tdecl.Type, named)
549 // If the underlying type was not set while type-checking the right-hand
550 // side, it is invalid and an error should have been reported elsewhere.
551 if named.underlying == nil {
552 named.underlying = Typ[Invalid]
555 // Disallow a lone type parameter as the RHS of a type declaration (go.dev/issue/45639).
556 // We don't need this restriction anymore if we make the underlying type of a type
557 // parameter its constraint interface: if the RHS is a lone type parameter, we will
558 // use its underlying type (like we do for any RHS in a type declaration), and its
559 // underlying type is an interface and the type declaration is well defined.
560 if isTypeParam(rhs) {
561 check.error(tdecl.Type, MisplacedTypeParam, "cannot use a type parameter as RHS in type declaration")
562 named.underlying = Typ[Invalid]
566 func (check *Checker) collectTypeParams(dst **TypeParamList, list []*syntax.Field) {
567 tparams := make([]*TypeParam, len(list))
569 // Declare type parameters up-front.
570 // The scope of type parameters starts at the beginning of the type parameter
571 // list (so we can have mutually recursive parameterized type bounds).
572 for i, f := range list {
573 tparams[i] = check.declareTypeParam(f.Name)
576 // Set the type parameters before collecting the type constraints because
577 // the parameterized type may be used by the constraints (go.dev/issue/47887).
578 // Example: type T[P T[P]] interface{}
579 *dst = bindTParams(tparams)
581 // Signal to cycle detection that we are in a type parameter list.
582 // We can only be inside one type parameter list at any given time:
583 // function closures may appear inside a type parameter list but they
584 // cannot be generic, and their bodies are processed in delayed and
585 // sequential fashion. Note that with each new declaration, we save
586 // the existing environment and restore it when done; thus inTParamList
587 // is true exactly only when we are in a specific type parameter list.
588 assert(!check.inTParamList)
589 check.inTParamList = true
591 check.inTParamList = false
594 // Keep track of bounds for later validation.
596 for i, f := range list {
597 // Optimization: Re-use the previous type bound if it hasn't changed.
598 // This also preserves the grouped output of type parameter lists
599 // when printing type strings.
600 if i == 0 || f.Type != list[i-1].Type {
601 bound = check.bound(f.Type)
602 if isTypeParam(bound) {
603 // We may be able to allow this since it is now well-defined what
604 // the underlying type and thus type set of a type parameter is.
605 // But we may need some additional form of cycle detection within
606 // type parameter lists.
607 check.error(f.Type, MisplacedTypeParam, "cannot use a type parameter as constraint")
611 tparams[i].bound = bound
615 func (check *Checker) bound(x syntax.Expr) Type {
616 // A type set literal of the form ~T and A|B may only appear as constraint;
617 // embed it in an implicit interface so that only interface type-checking
618 // needs to take care of such type expressions.
619 if op, _ := x.(*syntax.Operation); op != nil && (op.Op == syntax.Tilde || op.Op == syntax.Or) {
620 t := check.typ(&syntax.InterfaceType{MethodList: []*syntax.Field{{Type: x}}})
621 // mark t as implicit interface if all went well
622 if t, _ := t.(*Interface); t != nil {
630 func (check *Checker) declareTypeParam(name *syntax.Name) *TypeParam {
631 // Use Typ[Invalid] for the type constraint to ensure that a type
632 // is present even if the actual constraint has not been assigned
634 // TODO(gri) Need to systematically review all uses of type parameter
635 // constraints to make sure we don't rely on them if they
636 // are not properly set yet.
637 tname := NewTypeName(name.Pos(), check.pkg, name.Value, nil)
638 tpar := check.newTypeParam(tname, Typ[Invalid]) // assigns type to tname as a side-effect
639 check.declare(check.scope, name, tname, check.scope.pos) // TODO(gri) check scope position
643 func (check *Checker) collectMethods(obj *TypeName) {
644 // get associated methods
645 // (Checker.collectObjects only collects methods with non-blank names;
646 // Checker.resolveBaseTypeName ensures that obj is not an alias name
647 // if it has attached methods.)
648 methods := check.methods[obj]
652 delete(check.methods, obj)
653 assert(!check.objMap[obj].tdecl.Alias) // don't use TypeName.IsAlias (requires fully set up object)
655 // use an objset to check for name conflicts
658 // spec: "If the base type is a struct type, the non-blank method
659 // and field names must be distinct."
660 base, _ := obj.typ.(*Named) // shouldn't fail but be conservative
662 assert(base.TypeArgs().Len() == 0) // collectMethods should not be called on an instantiated type
664 // See go.dev/issue/52529: we must delay the expansion of underlying here, as
665 // base may not be fully set-up.
667 check.checkFieldUniqueness(base)
668 }).describef(obj, "verifying field uniqueness for %v", base)
670 // Checker.Files may be called multiple times; additional package files
671 // may add methods to already type-checked types. Add pre-existing methods
672 // so that we can detect redeclarations.
673 for i := 0; i < base.NumMethods(); i++ {
675 assert(m.name != "_")
676 assert(mset.insert(m) == nil)
681 for _, m := range methods {
682 // spec: "For a base type, the non-blank names of methods bound
683 // to it must be unique."
684 assert(m.name != "_")
685 if alt := mset.insert(m); alt != nil {
686 if alt.Pos().IsKnown() {
687 check.errorf(m.pos, DuplicateMethod, "method %s.%s already declared at %s", obj.Name(), m.name, alt.Pos())
689 check.errorf(m.pos, DuplicateMethod, "method %s.%s already declared", obj.Name(), m.name)
700 func (check *Checker) checkFieldUniqueness(base *Named) {
701 if t, _ := base.under().(*Struct); t != nil {
703 for i := 0; i < base.NumMethods(); i++ {
705 assert(m.name != "_")
706 assert(mset.insert(m) == nil)
709 // Check that any non-blank field names of base are distinct from its
711 for _, fld := range t.fields {
713 if alt := mset.insert(fld); alt != nil {
714 // Struct fields should already be unique, so we should only
715 // encounter an alternate via collision with a method name.
718 // For historical consistency, we report the primary error on the
719 // method, and the alt decl on the field.
721 err.code = DuplicateFieldAndMethod
722 err.errorf(alt, "field and method with the same name %s", fld.name)
723 err.recordAltDecl(fld)
731 func (check *Checker) funcDecl(obj *Func, decl *declInfo) {
732 assert(obj.typ == nil)
734 // func declarations cannot use iota
735 assert(check.iota == nil)
737 sig := new(Signature)
738 obj.typ = sig // guard against cycles
740 // Avoid cycle error when referring to method while type-checking the signature.
741 // This avoids a nuisance in the best case (non-parameterized receiver type) and
742 // since the method is not a type, we get an error. If we have a parameterized
743 // receiver type, instantiating the receiver type leads to the instantiation of
744 // its methods, and we don't want a cycle error in that case.
745 // TODO(gri) review if this is correct and/or whether we still need this?
749 check.funcType(sig, fdecl.Recv, fdecl.TParamList, fdecl.Type)
752 if len(fdecl.TParamList) > 0 && fdecl.Body == nil {
753 check.softErrorf(fdecl, BadDecl, "generic function is missing function body")
756 // function body must be type-checked after global declarations
757 // (functions implemented elsewhere have no body)
758 if !check.conf.IgnoreFuncBodies && fdecl.Body != nil {
760 check.funcBody(decl, obj.name, sig, fdecl.Body, nil)
761 }).describef(obj, "func %s", obj.name)
765 func (check *Checker) declStmt(list []syntax.Decl) {
768 first := -1 // index of first ConstDecl in the current group, or -1
769 var last *syntax.ConstDecl // last ConstDecl with init expressions, or nil
770 for index, decl := range list {
771 if _, ok := decl.(*syntax.ConstDecl); !ok {
772 first = -1 // we're not in a constant declaration
775 switch s := decl.(type) {
776 case *syntax.ConstDecl:
777 top := len(check.delayed)
779 // iota is the index of the current constDecl within the group
780 if first < 0 || s.Group == nil || list[index-1].(*syntax.ConstDecl).Group != s.Group {
784 iota := constant.MakeInt64(int64(index - first))
786 // determine which initialization expressions to use
789 case s.Type != nil || s.Values != nil:
793 last = new(syntax.ConstDecl) // make sure last exists
797 // declare all constants
798 lhs := make([]*Const, len(s.NameList))
799 values := unpackExpr(last.Values)
800 for i, name := range s.NameList {
801 obj := NewConst(name.Pos(), pkg, name.Value, nil, iota)
809 check.constDecl(obj, last.Type, init, inherited)
812 // Constants must always have init values.
813 check.arity(s.Pos(), s.NameList, values, true, inherited)
815 // process function literals in init expressions before scope changes
816 check.processDelayed(top)
818 // spec: "The scope of a constant or variable identifier declared
819 // inside a function begins at the end of the ConstSpec or VarSpec
820 // (ShortVarDecl for short variable declarations) and ends at the
821 // end of the innermost containing block."
822 scopePos := syntax.EndPos(s)
823 for i, name := range s.NameList {
824 check.declare(check.scope, name, lhs[i], scopePos)
827 case *syntax.VarDecl:
828 top := len(check.delayed)
830 lhs0 := make([]*Var, len(s.NameList))
831 for i, name := range s.NameList {
832 lhs0[i] = NewVar(name.Pos(), pkg, name.Value, nil)
835 // initialize all variables
836 values := unpackExpr(s.Values)
837 for i, obj := range lhs0 {
841 case len(s.NameList):
845 // rhs is expected to be a multi-valued expression
853 check.varDecl(obj, lhs, s.Type, init)
854 if len(values) == 1 {
855 // If we have a single lhs variable we are done either way.
856 // If we have a single rhs expression, it must be a multi-
857 // valued expression, in which case handling the first lhs
858 // variable will cause all lhs variables to have a type
859 // assigned, and we are done as well.
861 for _, obj := range lhs0 {
862 assert(obj.typ != nil)
869 // If we have no type, we must have values.
870 if s.Type == nil || values != nil {
871 check.arity(s.Pos(), s.NameList, values, false, false)
874 // process function literals in init expressions before scope changes
875 check.processDelayed(top)
877 // declare all variables
878 // (only at this point are the variable scopes (parents) set)
879 scopePos := syntax.EndPos(s) // see constant declarations
880 for i, name := range s.NameList {
881 // see constant declarations
882 check.declare(check.scope, name, lhs0[i], scopePos)
885 case *syntax.TypeDecl:
886 obj := NewTypeName(s.Name.Pos(), pkg, s.Name.Value, nil)
887 // spec: "The scope of a type identifier declared inside a function
888 // begins at the identifier in the TypeSpec and ends at the end of
889 // the innermost containing block."
890 scopePos := s.Name.Pos()
891 check.declare(check.scope, s.Name, obj, scopePos)
892 // mark and unmark type before calling typeDecl; its type is still nil (see Checker.objDecl)
893 obj.setColor(grey + color(check.push(obj)))
894 check.typeDecl(obj, s, nil)
895 check.pop().setColor(black)
898 check.errorf(s, InvalidSyntaxTree, "unknown syntax.Decl node %T", s)