{"AssignStmt", `x @:= y`},
	{"AssignStmt", `x, ok @:= f()`},
	{"AssignStmt", `x@++`},
	{"AssignStmt", `a[i]@--`},

	{"BranchStmt", `@break`},
	{"BranchStmt", `@break L`},
	{"BranchStmt", `@continue`},
	{"BranchStmt", `@continue L`},
	{"BranchStmt", `@fallthrough`},
	{"BranchStmt", `@goto L`},

	{"CallStmt", `@defer f()`},
	{"CallStmt", `@go f()`},

	{"ReturnStmt", `@return`},

func (check *Checker) blockBranches(all *Scope, parent *block, lstmt *ast.LabeledStmt, list []ast.Stmt) []*ast.BranchStmt {
	b := &block{parent: parent, lstmt: lstmt}

	var (
		varDeclPos         token.Pos
		fwdJumps, badJumps []*ast.BranchStmt
	)

	// All forward jumps jumping over a variable declaration are possibly
	// invalid (they may still jump out of the block and be ok).

func (check *Checker) blockBranches(all *Scope, parent *block, lstmt *syntax.LabeledStmt, list []syntax.Stmt) []*syntax.BranchStmt {
	b := &block{parent, lstmt, nil}

	var (
		varDeclPos         syntax.Pos
		fwdJumps, badJumps []*syntax.BranchStmt
	)

	// All forward jumps jumping over a variable declaration are possibly
	// invalid (they may still jump out of the block and be ok).

func (ls *labelScope) blockBranches(parent *block, ctxt targets, lstmt *LabeledStmt, start Pos, body []Stmt) []*BranchStmt {
	b := &block{parent: parent, start: start, lstmt: lstmt}

	var varPos Pos
	var varName Expr
	var fwdGotos, badGotos []*BranchStmt

	recordVarDecl := func(pos Pos, name Expr) {
		varPos = pos
		varName = name
		// Any existing forward goto jumping over the variable

		if call, ok := syntax.Unparen(s.X).(*syntax.CallExpr); ok && check.isPanic[call] {
			return true
		}

	case *syntax.ReturnStmt:
		return true

	case *syntax.BranchStmt:
		if s.Tok == syntax.Goto || s.Tok == syntax.Fallthrough {
			return true
		}

	case *syntax.BlockStmt:
		return check.isTerminatingList(s.List, "")

	case *syntax.IfStmt:
		if s.Else != nil &&

		b.current = label._goto
		_s = s.Stmt
		goto start // effectively: tailcall stmt(g, s.Stmt, label)

	case *ast.ReturnStmt:
		b.add(s)
		b.current = b.newBlock(KindUnreachable, s)

	case *ast.BranchStmt:
		b.branchStmt(s)

	case *ast.BlockStmt:
		b.stmtList(s.List)

	case *ast.IfStmt:
		if s.Init != nil {
			b.stmt(s.Init)
		}
		then := b.newBlock(KindIfThen, s)
		done := b.newBlock(KindIfDone, s)

		if call, ok := ast.Unparen(s.X).(*ast.CallExpr); ok && check.isPanic[call] {
			return true
		}

	case *ast.ReturnStmt:
		return true

	case *ast.BranchStmt:
		if s.Tok == token.GOTO || s.Tok == token.FALLTHROUGH {
			return true
		}

	case *ast.BlockStmt:
		return check.isTerminatingList(s.List, "")

	case *ast.IfStmt:
		if s.Else != nil &&

	_Select      // select
	_Struct      // struct
	_Switch      // switch
	_Type        // type
	_Var         // var

	// empty line comment to exclude it from .String
	tokenCount //
)

const (
	// for BranchStmt
	Break       = _Break
	Continue    = _Continue
	Fallthrough = _Fallthrough
	Goto        = _Goto

	// for CallStmt
	Go    = _Go
	Defer = _Defer
)

		// statements
		// case *EmptyStmt:
		// case *LabeledStmt:
		// case *BlockStmt:
		// case *ExprStmt:
		case *SendStmt:
			m = n.Chan
		// case *DeclStmt:
		case *AssignStmt:
			m = n.Lhs
		// case *BranchStmt:
		// case *CallStmt:
		// case *ReturnStmt:
		// case *IfStmt:
		// case *ForStmt:
		// case *SwitchStmt:
		// case *SelectStmt:

		// helper nodes
		case *RangeClause:
			if n.Lhs != nil {

		*ast.GoStmt,
		*ast.IncDecStmt,
		*ast.ReturnStmt,
		*ast.SendStmt:
		// no statements inside

	case *ast.BlockStmt:
		for _, stmt := range x.List {
			d.findLabels(stmt)
		}

	case *ast.BranchStmt:
		switch x.Tok {
		case token.GOTO:
			if x.Label != nil {
				d.hasGoto[x.Label.Name] = true
			}

		case token.BREAK:
			stmt := d.breakTarget
			if x.Label != nil {