func cgoBaseType(info *types.Info, arg ast.Expr) types.Type {
	switch arg := arg.(type) {
	case *ast.CallExpr:
		if len(arg.Args) == 1 && isUnsafePointer(info, arg.Fun) {
			return cgoBaseType(info, arg.Args[0])
		}
	case *ast.StarExpr:
		call, ok := arg.X.(*ast.CallExpr)
		if !ok || len(call.Args) != 1 {
			break
		}
		// Here arg is *f(v).
		t := info.Types[call.Fun].Type
		if t == nil {

	case ir.OPRINT, ir.OPRINTLN:
		return walkPrint(n.(*ir.CallExpr), init)

	case ir.OPANIC:
		n := n.(*ir.UnaryExpr)
		return mkcall("gopanic", nil, init, n.X)

	case ir.ORECOVERFP:
		return walkRecoverFP(n.(*ir.CallExpr), init)

	case ir.OCFUNC:
		return n

	case ir.OCALLINTER, ir.OCALLFUNC:
		n := n.(*ir.CallExpr)
		return walkCall(n, init)

	case ir.OAS, ir.OASOP:

		case *ir.BinaryExpr:
			n.X = o.expr(n.X, nil)
			n.Y = o.expr(n.Y, nil)
		case *ir.MakeExpr:
			n.Len = o.expr(n.Len, nil)
			n.Cap = o.expr(n.Cap, nil)
		case *ir.CallExpr:
			o.exprList(n.Args)
		}
		return
	}

	n := nn.(*ir.CallExpr)
	typecheck.AssertFixedCall(n)

	if ir.IsFuncPCIntrinsic(n) && ir.IsIfaceOfFunc(n.Args[0]) != nil {
		// For internal/abi.FuncPCABIxxx(fn), if fn is a defined function,

		Lparen token.Pos // position of "("
		Type   Expr      // asserted type; nil means type switch X.(type)
		Rparen token.Pos // position of ")"
	}

	// A CallExpr node represents an expression followed by an argument list.
	CallExpr struct {
		Fun      Expr      // function expression
		Lparen   token.Pos // position of "("
		Args     []Expr    // function arguments; or nil

func (f *File) saveExprs(x interface{}, context astContext) {
	switch x := x.(type) {
	case *ast.Expr:
		switch (*x).(type) {
		case *ast.SelectorExpr:
			f.saveRef(x, context)
		}
	case *ast.CallExpr:
		f.saveCall(x, context)
	}
}

// Save references to C.xxx for later processing.
func (f *File) saveRef(n *ast.Expr, context astContext) {
	sel := (*n).(*ast.SelectorExpr)

		}
		return stackTempAddr(init, t)
	}
	types.CalcSize(t)
	n.MarkNonNil()
	return n
}

func walkMinMax(n *ir.CallExpr, init *ir.Nodes) ir.Node {
	init.Append(ir.TakeInit(n)...)
	walkExprList(n.Args, init)
	return n
}

// generate code for print.
func walkPrint(nn *ir.CallExpr, init *ir.Nodes) ir.Node {
	// Hoist all the argument evaluation up before the lock.
	walkExprListCheap(nn.Args, init)

}

func (check *Checker) assignError(rhs []ast.Expr, l, r int) {
	vars := measure(l, "variable")
	vals := measure(r, "value")
	rhs0 := rhs[0]

	if len(rhs) == 1 {
		if call, _ := ast.Unparen(rhs0).(*ast.CallExpr); call != nil {
			check.errorf(rhs0, WrongAssignCount, "assignment mismatch: %s but %s returns %s", vars, call.Fun, vals)
			return
		}
	}

func (check *Checker) assignError(rhs []syntax.Expr, l, r int) {
	vars := measure(l, "variable")
	vals := measure(r, "value")
	rhs0 := rhs[0]

	if len(rhs) == 1 {
		if call, _ := syntax.Unparen(rhs0).(*syntax.CallExpr); call != nil {
			check.errorf(rhs0, WrongAssignCount, "assignment mismatch: %s but %s returns %s", vars, call.Fun, vals)
			return
		}
	}

package cfg

// This file implements the CFG construction pass.

import (
	"fmt"
	"go/ast"
	"go/token"
)

type builder struct {
	cfg       *CFG
	mayReturn func(*ast.CallExpr) bool
	current   *Block
	lblocks   map[string]*lblock // labeled blocks
	targets   *targets           // linked stack of branch targets
}

func (b *builder) stmt(_s ast.Stmt) {

		types := make(map[syntax.Expr]TypeAndValue)
		mustTypecheck(src, nil, &Info{Types: types})

		var n int
		for x, tv := range types {
			if x, _ := x.(*syntax.CallExpr); x != nil {
				// there must be exactly one CallExpr which is the P(val) conversion
				n++
				tpar, _ := tv.Type.(*TypeParam)
				if tpar == nil {
					t.Fatalf("%s: got type %s, want type parameter", ExprString(x), tv.Type)
				}