// Insert inserts the given declaration into the current scope.
func (s *Scope) Insert(decl ast.Decl) error {
// Early return for first-time declarations.
ident := decl.Name()
if ident == nil {
// Anonymous function parameter declaration.
return nil
}
name := ident.String()
prev, ok := s.Decls[name]
if !ok {
s.Decls[name] = decl
return nil
}
prevIdent := prev.Name()
if prevIdent.NamePos == ident.NamePos {
// Identifier already added to scope.
return nil
}
// Previously declared.
if !types.Equal(prev.Type(), decl.Type()) {
return errors.Newf(ident.Start(), "redefinition of %q with type %q instead of %q", name, decl.Type(), prev.Type())
}
// The last tentative definition becomes the definition, unless defined
// explicitly (e.g. having an initializer or function body).
if !s.IsDef(prev) {
s.Decls[name] = decl
return nil
}
// Definition already present in scope.
if s.IsDef(decl) {
// TODO: Consider adding support for multiple errors (and potentially
// warnings and notifications).
//
// If support for notifications are added, add a note of the previous declaration.
// errors.Notef(prevIdent.Start(), "previous definition of %q", name)
return errors.Newf(ident.Start(), "redefinition of %q", name)
}
// Declaration of previously declared identifier.
return nil
}
// IsDef reports whether the given declaration is a definition.
func IsDef(decl ast.Decl) bool {
if _, ok := decl.(*ast.VarDecl); ok {
return true
}
return decl.Value() != nil
}
// isTentativeDef reports whether the given global variable or function
// declaration is a tentative definition.
func isTentativeDef(n ast.Decl) bool {
ident := n.Name()
def := ident.Decl.Name()
return ident.Start() != def.Start()
}