func (tc *typechecker) resolve(obj *ast.Object) {
// check for declaration cycles
if tc.cyclemap[obj] {
tc.Errorf(obj.Pos(), "illegal cycle in declaration of %s", obj.Name)
obj.Kind = ast.Bad
return
}
tc.cyclemap[obj] = true
defer func() {
tc.cyclemap[obj] = false, false
}()
// resolve non-type objects
typ, _ := obj.Type.(*Type)
if typ == nil {
switch obj.Kind {
case ast.Bad:
// ignore
case ast.Con:
tc.declConst(obj)
case ast.Var:
tc.declVar(obj)
obj.Type = tc.typeFor(nil, obj.Decl.(*ast.ValueSpec).Type, false)
case ast.Fun:
obj.Type = NewType(Function)
t := obj.Decl.(*ast.FuncDecl).Type
tc.declSignature(obj.Type.(*Type), nil, t.Params, t.Results)
default:
// type objects have non-nil types when resolve is called
if debug {
fmt.Printf("kind = %s\n", obj.Kind)
}
panic("unreachable")
}
return
}
// resolve type objects
if typ.Form == Unresolved {
tc.typeFor(typ, typ.Obj.Decl.(*ast.TypeSpec).Type, false)
// provide types for all methods
for _, obj := range typ.Scope.Objects {
if obj.Kind == ast.Fun {
assert(obj.Type == nil)
obj.Type = NewType(Method)
f := obj.Decl.(*ast.FuncDecl)
t := f.Type
tc.declSignature(obj.Type.(*Type), f.Recv, t.Params, t.Results)
}
}
}
}
func objDoc(fset *token.FileSet, pkg *ast.Package, tabIndent bool, tabWidth int, obj *ast.Object) *Doc {
decl := obj.Decl
kind := obj.Kind.String()
tp := fset.Position(obj.Pos())
objSrc := ""
pkgName := ""
if pkg != nil && pkg.Name != "builtin" {
pkgName = pkg.Name
}
if obj.Kind == ast.Pkg {
pkgName = ""
doc := ""
// special-case `package name` is generated as a TypeSpec
if v, ok := obj.Decl.(*ast.TypeSpec); ok && v.Doc != nil {
doc = "/*\n" + v.Doc.Text() + "\n*/\n"
}
objSrc = doc + "package " + obj.Name
} else if af, ok := pkg.Files[tp.Filename]; ok {
switch decl.(type) {
case *ast.TypeSpec, *ast.ValueSpec, *ast.Field:
line := tp.Line - 1
for _, cg := range af.Comments {
cgp := fset.Position(cg.End())
if cgp.Filename == tp.Filename && cgp.Line == line {
switch v := decl.(type) {
case *ast.TypeSpec:
v.Doc = cg
case *ast.ValueSpec:
v.Doc = cg
case *ast.Field:
pkgName = ""
kind = "field"
}
break
}
}
}
}
if objSrc == "" {
objSrc, _ = printSrc(fset, decl, tabIndent, tabWidth)
}
return &Doc{
Src: objSrc,
Pkg: pkgName,
Name: obj.Name,
Kind: kind,
Fn: tp.Filename,
Row: tp.Line - 1,
Col: tp.Column - 1,
}
}
// object typechecks an object by assigning it a type; obj.Type must be nil.
// Callers must check obj.Type before calling object; this eliminates a call
// for each identifier that has been typechecked already, a common scenario.
//
func (check *checker) object(obj *ast.Object, cycleOk bool) {
assert(obj.Type == nil)
switch obj.Kind {
case ast.Bad, ast.Pkg:
// nothing to do
case ast.Con, ast.Var:
// The obj.Data field for constants and variables is initialized
// to the respective (hypothetical, for variables) iota value by
// the parser. The object's fields can be in one of the following
// states:
// Type != nil => the constant value is Data
// Type == nil => the object is not typechecked yet, and Data can be:
// Data is int => Data is the value of iota for this declaration
// Data == nil => the object's expression is being evaluated
if obj.Data == nil {
check.errorf(obj.Pos(), "illegal cycle in initialization of %s", obj.Name)
obj.Type = Typ[Invalid]
return
}
spec := obj.Decl.(*ast.ValueSpec)
iota := obj.Data.(int)
obj.Data = nil
// determine initialization expressions
values := spec.Values
if len(values) == 0 && obj.Kind == ast.Con {
values = check.initexprs[spec]
}
check.valueSpec(spec.Pos(), obj, spec.Names, spec.Type, values, iota)
case ast.Typ:
typ := &NamedType{Obj: obj}
obj.Type = typ // "mark" object so recursion terminates
typ.Underlying = underlying(check.typ(obj.Decl.(*ast.TypeSpec).Type, cycleOk))
// typecheck associated method signatures
if obj.Data != nil {
scope := obj.Data.(*ast.Scope)
switch t := typ.Underlying.(type) {
case *Struct:
// struct fields must not conflict with methods
for _, f := range t.Fields {
if m := scope.Lookup(f.Name); m != nil {
check.errorf(m.Pos(), "type %s has both field and method named %s", obj.Name, f.Name)
// ok to continue
}
}
case *Interface:
// methods cannot be associated with an interface type
for _, m := range scope.Objects {
recv := m.Decl.(*ast.FuncDecl).Recv.List[0].Type
check.errorf(recv.Pos(), "invalid receiver type %s (%s is an interface type)", obj.Name, obj.Name)
// ok to continue
}
}
// typecheck method signatures
for _, obj := range scope.Objects {
mdecl := obj.Decl.(*ast.FuncDecl)
sig := check.typ(mdecl.Type, cycleOk).(*Signature)
params, _ := check.collectParams(mdecl.Recv, false)
sig.Recv = params[0] // the parser/assocMethod ensure there is exactly one parameter
obj.Type = sig
check.later(obj, sig, mdecl.Body)
}
}
case ast.Fun:
fdecl := obj.Decl.(*ast.FuncDecl)
// methods are typechecked when their receivers are typechecked
if fdecl.Recv == nil {
sig := check.typ(fdecl.Type, cycleOk).(*Signature)
if obj.Name == "init" && (len(sig.Params) != 0 || len(sig.Results) != 0) {
check.errorf(fdecl.Pos(), "func init must have no arguments and no return values")
// ok to continue
}
obj.Type = sig
check.later(obj, sig, fdecl.Body)
}
default:
panic("unreachable")
}
}
// object typechecks an object by assigning it a type; obj.Type must be nil.
// Callers must check obj.Type before calling object; this eliminates a call
// for each identifier that has been typechecked already, a common scenario.
//
func (check *checker) object(obj *ast.Object, cycleOk bool) {
assert(obj.Type == nil)
switch obj.Kind {
case ast.Bad, ast.Pkg:
// nothing to do
case ast.Con, ast.Var:
// The obj.Data field for constants and variables is initialized
// to the respective (hypothetical, for variables) iota value by
// the parser. The object's fields can be in one of the following
// states:
// Type != nil => the constant value is Data
// Type == nil => the object is not typechecked yet, and Data can be:
// Data is int => Data is the value of iota for this declaration
// Data == nil => the object's expression is being evaluated
if obj.Data == nil {
check.errorf(obj.Pos(), "illegal cycle in initialization of %s", obj.Name)
obj.Type = Typ[Invalid]
return
}
spec := obj.Decl.(*ast.ValueSpec)
iota := obj.Data.(int)
obj.Data = nil
// determine initialization expressions
values := spec.Values
if len(values) == 0 && obj.Kind == ast.Con {
values = check.initexprs[spec]
}
check.valueSpec(spec.Pos(), obj, spec.Names, spec.Type, values, iota)
case ast.Typ:
typ := &NamedType{Obj: obj}
obj.Type = typ // "mark" object so recursion terminates
typ.Underlying = underlying(check.typ(obj.Decl.(*ast.TypeSpec).Type, cycleOk))
// typecheck associated method signatures
if obj.Data != nil {
scope := obj.Data.(*ast.Scope)
switch t := typ.Underlying.(type) {
case *Struct:
// struct fields must not conflict with methods
for _, f := range t.Fields {
if m := scope.Lookup(f.Name); m != nil {
check.errorf(m.Pos(), "type %s has both field and method named %s", obj.Name, f.Name)
}
}
// ok to continue
case *Interface:
// methods cannot be associated with an interface type
for _, m := range scope.Objects {
recv := m.Decl.(*ast.FuncDecl).Recv.List[0].Type
check.errorf(recv.Pos(), "invalid receiver type %s (%s is an interface type)", obj.Name, obj.Name)
}
// ok to continue
}
// typecheck method signatures
for _, m := range scope.Objects {
mdecl := m.Decl.(*ast.FuncDecl)
// TODO(gri) At the moment, the receiver is type-checked when checking
// the method body. Also, we don't properly track if the receiver is
// a pointer (i.e., currently, method sets are too large). FIX THIS.
mtyp := check.typ(mdecl.Type, cycleOk).(*Signature)
m.Type = mtyp
}
}
case ast.Fun:
fdecl := obj.Decl.(*ast.FuncDecl)
if fdecl.Recv != nil {
// This will ensure that the method base type is
// type-checked
check.collectFields(token.FUNC, fdecl.Recv, true)
}
ftyp := check.typ(fdecl.Type, cycleOk).(*Signature)
obj.Type = ftyp
check.function(ftyp, fdecl.Body)
default:
panic("unreachable")
}
}
// obj type checks an object.
func (check *checker) obj(obj *ast.Object, cycleOk bool) {
if trace {
fmt.Printf("obj(%s)\n", obj.Name)
}
if obj.Type != nil {
// object has already been type checked
return
}
switch obj.Kind {
case ast.Bad, ast.Pkg:
// nothing to do
case ast.Con:
if obj.Data == nil {
check.errorf(obj.Pos(), "illegal cycle in initialization of %s", obj.Name)
return
}
spec, ok := obj.Decl.(*ast.ValueSpec)
assert(ok)
// The Data stored with the constant is the value of iota for that
// ast.ValueSpec. Use it for the evaluation of the initialization
// expressions.
iota := obj.Data.(int)
obj.Data = nil
check.decl(spec.Pos(), obj, spec.Names, spec.Type, check.specValues(spec), iota)
case ast.Var:
// TODO(gri) missing cycle detection
spec, ok := obj.Decl.(*ast.ValueSpec)
if !ok {
// TODO(gri) the assertion fails for "x, y := 1, 2, 3" it seems
fmt.Printf("var = %s\n", obj.Name)
}
assert(ok)
check.decl(spec.Pos(), obj, spec.Names, spec.Type, spec.Values, 0)
case ast.Typ:
typ := &NamedType{Obj: obj}
obj.Type = typ // "mark" object so recursion terminates
typ.Underlying = underlying(check.typ(obj.Decl.(*ast.TypeSpec).Type, cycleOk))
// collect associated methods, if any
if obj.Data != nil {
scope := obj.Data.(*ast.Scope)
// struct fields must not conflict with methods
if t, ok := typ.Underlying.(*Struct); ok {
for _, f := range t.Fields {
if m := scope.Lookup(f.Name); m != nil {
check.errorf(m.Pos(), "type %s has both field and method named %s", obj.Name, f.Name)
}
}
}
// collect methods
methods := make(ObjList, len(scope.Objects))
i := 0
for _, m := range scope.Objects {
methods[i] = m
i++
}
methods.Sort()
typ.Methods = methods
// methods cannot be associated with an interface type
// (do this check after sorting for reproducible error positions - needed for testing)
if _, ok := typ.Underlying.(*Interface); ok {
for _, m := range methods {
recv := m.Decl.(*ast.FuncDecl).Recv.List[0].Type
check.errorf(recv.Pos(), "invalid receiver type %s (%s is an interface type)", obj.Name, obj.Name)
}
}
}
case ast.Fun:
fdecl := obj.Decl.(*ast.FuncDecl)
ftyp := check.typ(fdecl.Type, cycleOk).(*Signature)
obj.Type = ftyp
if fdecl.Recv != nil {
// TODO(gri) handle method receiver
}
check.stmt(fdecl.Body)
default:
panic("unreachable")
}
}
