type Visitor struct {
	fset    *token.FileSet
	types   map[ast.Expr]types.TypeAndValue
	checked map[string]bool
	t       *testing.T
}

func (v *Visitor) Visit(n ast.Node) ast.Visitor {
	c, ok := n.(*ast.CallExpr)
	if !ok {
		return v
	}
	f, ok := c.Fun.(*ast.SelectorExpr)
	if !ok {
		return v
	}
	p, ok := f.X.(*ast.Ident)
	if !ok {
		return v
	}
	if p.Name != "atomic" {
		return v
	}

		if n.High != nil {
			Walk(v, n.High)
		}
		if n.Max != nil {
			Walk(v, n.Max)
		}

	case *TypeAssertExpr:
		Walk(v, n.X)
		if n.Type != nil {
			Walk(v, n.Type)
		}

	case *CallExpr:
		Walk(v, n.Fun)
		walkList(v, n.Args)

	case *StarExpr:
		Walk(v, n.X)

	case *UnaryExpr:
		Walk(v, n.X)

	case *BinaryExpr:
		Walk(v, n.X)
		Walk(v, n.Y)

	case *ast.Spec:
		walkBeforeAfter(*n, before, after)
	case *ast.Stmt:
		walkBeforeAfter(*n, before, after)

	// pointers to struct pointers
	case **ast.BlockStmt:
		walkBeforeAfter(*n, before, after)
	case **ast.CallExpr:
		walkBeforeAfter(*n, before, after)
	case **ast.FieldList:
		walkBeforeAfter(*n, before, after)
	case **ast.FuncType:
		walkBeforeAfter(*n, before, after)
	case **ast.Ident:
		walkBeforeAfter(*n, before, after)

		w.node(n.Type)

	case *TypeSwitchGuard:
		if n.Lhs != nil {
			w.node(n.Lhs)
		}
		w.node(n.X)

	case *Operation:
		w.node(n.X)
		if n.Y != nil {
			w.node(n.Y)
		}

	case *CallExpr:
		w.node(n.Fun)
		w.exprList(n.ArgList)

	case *ListExpr:
		w.exprList(n.ElemList)

	// types
	case *ArrayType:
		if n.Len != nil {
			w.node(n.Len)
		}
		w.node(n.Elem)

	{name: "recv", format: "package main; var x = «<-»x"},
	{name: "call", format: "package main; var x = «f(«1»)»", parseMultiplier: 2},    // Parser nodes: Ident, CallExpr
	{name: "conv", format: "package main; var x = «(*T)(«1»)»", parseMultiplier: 2}, // Parser nodes: ParenExpr, CallExpr
	{name: "label", format: "package main; func main() { «Label:» }"},

			// identifying dead code, continue redirects control flow just
			// like the other terminating statements.
			d.reachable = false
		}

	case *ast.ExprStmt:
		// Call to panic?
		call, ok := x.X.(*ast.CallExpr)
		if ok {
			name, ok := call.Fun.(*ast.Ident)
			if ok && name.Name == "panic" && name.Obj == nil {
				d.reachable = false
			}
		}

	case *ast.ForStmt:
		d.findDead(x.Body)

		}
	}
}

// callMayReturn reports whether the called function may return.
// It is passed to the CFG builder.
func (c *CFGs) callMayReturn(call *ast.CallExpr) (r bool) {
	if id, ok := call.Fun.(*ast.Ident); ok && c.pass.TypesInfo.Uses[id] == panicBuiltin {
		return false // panic never returns
	}

	// Is this a static call? Also includes static functions

		X   Expr  // X.(type)
		expr
	}

	Operation struct {
		Op   Operator
		X, Y Expr // Y == nil means unary expression
		expr
	}

	// Fun(ArgList[0], ArgList[1], ...)
	CallExpr struct {
		Fun     Expr
		ArgList []Expr // nil means no arguments
		HasDots bool   // last argument is followed by ...
		expr
	}

	// ElemList[0], ElemList[1], ...
	ListExpr struct {

		p.next() // consume "++" or "--"
		return s
	}

	// expression
	return &ast.ExprStmt{x[0]}
}

func (p *parser) parseCallExpr() *ast.CallExpr {
	x := p.parseRhs()
	if call, isCall := x.(*ast.CallExpr); isCall {
		return call
	}
	p.errorExpected(x.Pos(), "function/method call")
	return nil
}

func (p *parser) parseGoStmt() ast.Stmt {
	if p.trace {

		} else {
			check.mono.recordInstance(check.pkg, pos, tparams, targs, xlist)
		}
	}).describef(pos, "verify instantiation")

	return inst
}

func (check *Checker) callExpr(x *operand, call *syntax.CallExpr) exprKind {
	var inst *syntax.IndexExpr // function instantiation, if any
	if iexpr, _ := call.Fun.(*syntax.IndexExpr); iexpr != nil {
		if check.indexExpr(x, iexpr) {