func (f *File) validResults(results *ast.FieldList) *Error {
if results == nil || results.List == nil {
return nil
}
if results.NumFields() != 1 {
err := fmt.Sprint("ERROR: can only return at most one result, not:",
results.NumFields())
return &Error{errors.New(err), results.Pos()}
}
result := results.List[0]
if result == nil {
return nil
}
if result.Names != nil {
return &Error{errors.New(fmt.Sprint("ERROR: can only return nonnamed result, not:", result.Names)), result.Pos()}
}
typ := f.Info.TypeOf(result.Type)
if err := f.validResultType(typ); err != nil {
err.Pos = result.Pos()
if f.validVarDeclType(typ) == nil {
err.Err = errors.New(fmt.Sprint(err.Err) + ", type only valid as a var decl, or param")
} else if f.validParamType(typ) == nil {
err.Err = errors.New(fmt.Sprint(err.Err) + ", type only valid as func param type")
}
return err
}
return nil
}
func (check *Checker) collectParams(scope *Scope, list *ast.FieldList, variadicOk bool) (params []*Var, variadic bool) {
if list == nil {
return
}
var named, anonymous bool
for i, field := range list.List {
ftype := field.Type
if t, _ := ftype.(*ast.Ellipsis); t != nil {
ftype = t.Elt
if variadicOk && i == len(list.List)-1 {
variadic = true
} else {
check.invalidAST(field.Pos(), "... not permitted")
// ignore ... and continue
}
}
typ := check.typ(ftype)
// The parser ensures that f.Tag is nil and we don't
// care if a constructed AST contains a non-nil tag.
if len(field.Names) > 0 {
// named parameter
for _, name := range field.Names {
if name.Name == "" {
check.invalidAST(name.Pos(), "anonymous parameter")
// ok to continue
}
par := NewParam(name.Pos(), check.pkg, name.Name, typ)
check.declare(scope, name, par, scope.pos)
params = append(params, par)
}
named = true
} else {
// anonymous parameter
par := NewParam(ftype.Pos(), check.pkg, "", typ)
check.recordImplicit(field, par)
params = append(params, par)
anonymous = true
}
}
if named && anonymous {
check.invalidAST(list.Pos(), "list contains both named and anonymous parameters")
// ok to continue
}
// For a variadic function, change the last parameter's type from T to []T.
if variadic && len(params) > 0 {
last := params[len(params)-1]
last.typ = &Slice{elem: last.typ}
}
return
}
func (check *checker) collectMethods(list *ast.FieldList) (methods []*Method) {
if list == nil {
return
}
for _, f := range list.List {
typ := check.typ(f.Type, len(f.Names) > 0) // cycles are not ok for embedded interfaces
// the parser ensures that f.Tag is nil and we don't
// care if a constructed AST contains a non-nil tag
if len(f.Names) > 0 {
// methods (the parser ensures that there's only one
// and we don't care if a constructed AST has more)
sig, ok := typ.(*Signature)
if !ok {
check.invalidAST(f.Type.Pos(), "%s is not a method signature", typ)
continue
}
for _, name := range f.Names {
methods = append(methods, &Method{QualifiedName{check.pkg, name.Name}, sig})
}
} else {
// embedded interface
utyp := underlying(typ)
if ityp, ok := utyp.(*Interface); ok {
methods = append(methods, ityp.Methods...)
} else if utyp != Typ[Invalid] {
// if utyp is invalid, don't complain (the root cause was reported before)
check.errorf(f.Type.Pos(), "%s is not an interface type", typ)
}
}
}
// Check for double declarations.
// The parser inserts methods into an interface-local scope, so local
// double declarations are reported by the parser already. We need to
// check again for conflicts due to embedded interfaces. This will lead
// to a 2nd error message if the double declaration was reported before
// by the parser.
// TODO(gri) clean this up a bit
seen := make(map[string]bool)
for _, m := range methods {
if seen[m.Name] {
check.errorf(list.Pos(), "multiple methods named %s", m.Name)
return // keep multiple entries, lookup will only return the first entry
}
seen[m.Name] = true
}
return
}
func (check *checker) collectMethods(list *ast.FieldList) (methods ObjList) {
if list == nil {
return
}
for _, f := range list.List {
typ := check.typ(f.Type, len(f.Names) > 0) // cycles are not ok for embedded interfaces
// the parser ensures that f.Tag is nil and we don't
// care if a constructed AST contains a non-nil tag
if len(f.Names) > 0 {
// methods (the parser ensures that there's only one
// and we don't care if a constructed AST has more)
if _, ok := typ.(*Signature); !ok {
check.invalidAST(f.Type.Pos(), "%s is not a method signature", typ)
continue
}
for _, name := range f.Names {
obj := name.Obj
obj.Type = typ
methods = append(methods, obj)
}
} else {
// embedded interface
utyp := underlying(typ)
if ityp, ok := utyp.(*Interface); ok {
methods = append(methods, ityp.Methods...)
} else if utyp != Typ[Invalid] {
// if utyp is invalid, don't complain (the root cause was reported before)
check.errorf(f.Type.Pos(), "%s is not an interface type", typ)
}
}
}
// check for double declarations
methods.Sort()
prev := ""
for _, obj := range methods {
if obj.Name == prev {
check.errorf(list.Pos(), "multiple methods named %s", prev)
return // keep multiple entries, lookup will only return the first entry
}
}
return
}
func (check *checker) collectMethods(list *ast.FieldList) (methods ObjSet) {
if list == nil {
return
}
for _, f := range list.List {
typ := check.typ(f.Type, len(f.Names) > 0) // cycles are not ok for embedded interfaces
// the parser ensures that f.Tag is nil and we don't
// care if a constructed AST contains a non-nil tag
if len(f.Names) > 0 {
// methods (the parser ensures that there's only one
// and we don't care if a constructed AST has more)
sig, ok := typ.(*Signature)
if !ok {
check.invalidAST(f.Type.Pos(), "%s is not a method signature", typ)
continue
}
for _, name := range f.Names {
// TODO(gri) provide correct declaration info
obj := &Func{check.pkg, name.Name, sig, nil}
if alt := methods.Insert(obj); alt != nil {
check.errorf(list.Pos(), "multiple methods named %s", name.Name)
}
check.register(name, obj)
}
} else {
// embedded interface
utyp := typ.Underlying()
if ityp, ok := utyp.(*Interface); ok {
for _, obj := range ityp.methods.entries {
if alt := methods.Insert(obj); alt != nil {
check.errorf(list.Pos(), "multiple methods named %s", obj.Name())
}
}
} else if utyp != Typ[Invalid] {
// if utyp is invalid, don't complain (the root cause was reported before)
check.errorf(f.Type.Pos(), "%s is not an interface type", typ)
}
}
}
return
}
// funcType type-checks a function or method type.
func (check *Checker) funcType(sig *Signature, recvPar *ast.FieldList, ftyp *ast.FuncType) {
scope := NewScope(check.scope, token.NoPos, token.NoPos, "function")
check.recordScope(ftyp, scope)
recvList, _ := check.collectParams(scope, recvPar, false)
params, variadic := check.collectParams(scope, ftyp.Params, true)
results, _ := check.collectParams(scope, ftyp.Results, false)
if recvPar != nil {
// recv parameter list present (may be empty)
// spec: "The receiver is specified via an extra parameter section preceding the
// method name. That parameter section must declare a single parameter, the receiver."
var recv *Var
switch len(recvList) {
case 0:
check.error(recvPar.Pos(), "method is missing receiver")
recv = NewParam(0, nil, "", Typ[Invalid]) // ignore recv below
default:
// more than one receiver
check.error(recvList[len(recvList)-1].Pos(), "method must have exactly one receiver")
fallthrough // continue with first receiver
case 1:
recv = recvList[0]
}
// spec: "The receiver type must be of the form T or *T where T is a type name."
// (ignore invalid types - error was reported before)
if t, _ := deref(recv.typ); t != Typ[Invalid] {
var err string
if T, _ := t.(*Named); T != nil {
// spec: "The type denoted by T is called the receiver base type; it must not
// be a pointer or interface type and it must be declared in the same package
// as the method."
if T.obj.pkg != check.pkg {
err = "type not defined in this package"
} else {
// TODO(gri) This is not correct if the underlying type is unknown yet.
switch u := T.underlying.(type) {
case *Basic:
// unsafe.Pointer is treated like a regular pointer
if u.kind == UnsafePointer {
err = "unsafe.Pointer"
}
case *Pointer, *Interface:
err = "pointer or interface type"
}
}
} else {
err = "basic or unnamed type"
}
if err != "" {
check.errorf(recv.pos, "invalid receiver %s (%s)", recv.typ, err)
// ok to continue
}
}
sig.recv = recv
}
sig.scope = scope
sig.params = NewTuple(params...)
sig.results = NewTuple(results...)
sig.variadic = variadic
}
func (f *File) validParams(params *ast.FieldList) *Error {
if params == nil {
panic("ERROR: params fieldlist should never be nil")
}
if params.List == nil {
return nil
}
for i := 0; i < params.NumFields(); i++ {
field := params.List[i]
if field == nil {
return &Error{errors.New(fmt.Sprint("ERROR nil field, anonymous fields not allowed!!")), params.Pos()}
}
if len(field.Names) != 1 {
panic("ERROR len(field.Names) != 1!!")
}
name := field.Names[0]
if name == nil {
panic("ERROR name == nil, this shouldn't occur")
}
typ := f.Info.TypeOf(field.Type)
if e := f.validParamType(typ); e != nil {
e.Pos = field.Pos()
return e
}
}
return nil
}
