var fileScopes []*Scope
	for fileNo, file := range check.files {
		// The package identifier denotes the current package,
		// but there is no corresponding package object.
		check.recordDef(file.PkgName, nil)

		fileScope := NewScope(pkg.scope, syntax.StartPos(file), syntax.EndPos(file), check.filename(fileNo))
		fileScopes = append(fileScopes, fileScope)
		check.recordScope(file, fileScope)

	var fileScopes []*Scope
	for fileNo, file := range check.files {
		// The package identifier denotes the current package,
		// but there is no corresponding package object.
		check.recordDef(file.Name, nil)

		// Use the actual source file extent rather than *ast.File extent since the
		// latter doesn't include comments which appear at the start or end of the file.

	// Determine if the lhs is a (possibly parenthesized) identifier.
	ident, _ := syntax.Unparen(lhs).(*syntax.Name)

	// Don't evaluate lhs if it is the blank identifier.
	if ident != nil && ident.Value == "_" {
		check.recordDef(ident, nil)
		return nil
	}

	// If the lhs is an identifier denoting a variable v, this reference
	// is not a 'use' of v. Remember current value of v.used and restore
	// after evaluating the lhs via check.expr.

	// Determine if the lhs is a (possibly parenthesized) identifier.
	ident, _ := ast.Unparen(lhs).(*ast.Ident)

	// Don't evaluate lhs if it is the blank identifier.
	if ident != nil && ident.Name == "_" {
		check.recordDef(ident, nil)
		return nil
	}

	// If the lhs is an identifier denoting a variable v, this reference
	// is not a 'use' of v. Remember current value of v.used and restore
	// after evaluating the lhs via check.expr.

				// _ := x.(type) is an invalid short variable declaration
				check.softErrorf(lhs, NoNewVar, "no new variable on left side of :=")
				lhs = nil // avoid declared and not used error below
			} else {
				check.recordDef(lhs, nil) // lhs variable is implicitly declared in each cause clause
			}

			rhs = guard.Rhs[0]

		default:
			check.error(s, InvalidSyntaxTree, "incorrect form of type switch guard")
			return
		}

			// _ := x.(type) is an invalid short variable declaration
			check.softErrorf(lhs, NoNewVar, "no new variable on left side of :=")
			lhs = nil // avoid declared and not used error below
		} else {
			check.recordDef(lhs, nil) // lhs variable is implicitly declared in each cause clause
		}
	}

	// check rhs
	var x operand
	check.expr(nil, &x, guard.X)
	if x.mode == invalid {
		return
	}

	}
	switch x := selOrIdent.(type) {
	case *syntax.Name:
		return x
	case *syntax.SelectorExpr:
		return x.Sel
	}
	panic("instantiated ident not found")
}

func (check *Checker) recordDef(id *syntax.Name, obj Object) {
	assert(id != nil)
	if m := check.Defs; m != nil {
		m[id] = obj
	}
}

func (check *Checker) recordUse(id *syntax.Name, obj Object) {
	assert(id != nil)

	var buf strings.Builder
	buf.WriteString("instantiated ident not found; please report: ")
	ast.Fprint(&buf, token.NewFileSet(), expr, ast.NotNilFilter)
	panic(buf.String())
}

func (check *Checker) recordDef(id *ast.Ident, obj Object) {
	assert(id != nil)
	if m := check.Defs; m != nil {
		m[id] = obj
	}
}

func (check *Checker) recordUse(id *ast.Ident, obj Object) {
	assert(id != nil)
	assert(obj != nil)

			err := check.newError(DuplicateDecl)
			err.addf(obj, "%s redeclared in this block", obj.Name())
			err.addAltDecl(alt)
			err.report()
			return
		}
		obj.setScopePos(pos)
	}
	if id != nil {
		check.recordDef(id, obj)
	}
}

// pathString returns a string of the form a->b-> ... ->g for a path [a, b, ... g].
func pathString(path []Object) string {
	var s string
	for i, p := range path {
		if i > 0 {
			s += "->"

			err := check.newError(DuplicateDecl)
			err.addf(obj, "%s redeclared in this block", obj.Name())
			err.addAltDecl(alt)
			err.report()
			return
		}
		obj.setScopePos(pos)
	}
	if id != nil {
		check.recordDef(id, obj)
	}
}

// pathString returns a string of the form a->b-> ... ->g for a path [a, b, ... g].
func pathString(path []Object) string {
	var s string
	for i, p := range path {
		if i > 0 {
			s += "->"