// Signature = Parameters [ Result ] .
// Result    = Type | Parameters .
//
func (p *parser) parseSignature(recv *types.Var) *types.Signature {
	params, isVariadic := p.parseParameters()

	// optional result type
	var results []*types.Var
	if p.tok == '(' {
		var variadic bool
		results, variadic = p.parseParameters()
		if variadic {
			p.error("... not permitted on result type")
		}
	}

	return types.NewSignature(recv, types.NewTuple(params...), types.NewTuple(results...), isVariadic)
}

// makeLen returns the len builtin specialized to type func(T)int.
func makeLen(T types.Type) *Builtin {
	lenParams := types.NewTuple(anonVar(T))
	return &Builtin{
		name: "len",
		sig:  types.NewSignature(nil, lenParams, lenResults, false),
	}
}

func (p *importer) tuple() *types.Tuple {
	vars := make([]*types.Var, p.int())
	for i := range vars {
		vars[i] = p.param()
	}
	return types.NewTuple(vars...)
}

// ResultList = Type | ParamList .
func (p *parser) parseResultList(pkg *types.Package) *types.Tuple {
	switch p.tok {
	case '<':
		return types.NewTuple(types.NewParam(token.NoPos, pkg, "", p.parseType(pkg)))

	case '(':
		params, _ := p.parseParamList(pkg)
		return params

	default:
		return nil
	}
}

// emitTypeTest emits to f a type test value,ok := x.(t) and returns
// a (value, ok) tuple.  x.Type() must be an interface.
//
func emitTypeTest(f *Function, x Value, t types.Type, pos token.Pos) Value {
	a := &TypeAssert{
		X:            x,
		AssertedType: t,
		CommaOk:      true,
	}
	a.setPos(pos)
	a.setType(types.NewTuple(
		newVar("value", t),
		varOk,
	))
	return f.emit(a)
}

func (p *importer) paramList() (*types.Tuple, bool) {
	n := p.int()
	if n == 0 {
		return nil, false
	}
	// negative length indicates unnamed parameters
	named := true
	if n < 0 {
		n = -n
		named = false
	}
	// n > 0
	params := make([]*types.Var, n)
	isddd := false
	for i := range params {
		params[i], isddd = p.param(named)
	}
	return types.NewTuple(params...), isddd
}

// ParamList = "(" [ { Parameter "," } Parameter ] ")" .
func (p *parser) parseParamList(pkg *types.Package) (*types.Tuple, bool) {
	var list []*types.Var
	isVariadic := false

	p.expect('(')
	for p.tok != ')' && p.tok != scanner.EOF {
		if len(list) > 0 {
			p.expect(',')
		}
		par, variadic := p.parseParam(pkg)
		list = append(list, par)
		if variadic {
			if isVariadic {
				p.error("... not on final argument")
			}
			isVariadic = true
		}
	}
	p.expect(')')

	return types.NewTuple(list...), isVariadic
}

func (p *exporter) assocMethods(named *types.Named) {
	// Sort methods (for determinism).
	var methods []*types.Func
	for i := 0; i < named.NumMethods(); i++ {
		methods = append(methods, named.Method(i))
	}
	sort.Sort(methodsByName(methods))

	p.int(len(methods))

	if trace && methods != nil {
		p.tracef("associated methods {>\n")
	}

	for i, m := range methods {
		if trace && i > 0 {
			p.tracef("\n")
		}

		p.pos(m)
		name := m.Name()
		p.string(name)
		if !exported(name) {
			p.pkg(m.Pkg(), false)
		}

		sig := m.Type().(*types.Signature)
		p.paramList(types.NewTuple(sig.Recv()), false)
		p.paramList(sig.Params(), sig.Variadic())
		p.paramList(sig.Results(), false)
		p.int(0) // dummy value for go:nointerface pragma - ignored by importer
	}

	if trace && methods != nil {
		p.tracef("<\n} ")
	}
}

// makeWrapper returns a synthetic method that delegates to the
// declared method denoted by meth.Obj(), first performing any
// necessary pointer indirections or field selections implied by meth.
//
// The resulting method's receiver type is meth.Recv().
//
// This function is versatile but quite subtle!  Consider the
// following axes of variation when making changes:
//   - optional receiver indirection
//   - optional implicit field selections
//   - meth.Obj() may denote a concrete or an interface method
//   - the result may be a thunk or a wrapper.
//
// EXCLUSIVE_LOCKS_REQUIRED(prog.methodsMu)
//
func makeWrapper(prog *Program, sel *types.Selection) *Function {
	obj := sel.Obj().(*types.Func)       // the declared function
	sig := sel.Type().(*types.Signature) // type of this wrapper

	var recv *types.Var // wrapper's receiver or thunk's params[0]
	name := obj.Name()
	var description string
	var start int // first regular param
	if sel.Kind() == types.MethodExpr {
		name += "$thunk"
		description = "thunk"
		recv = sig.Params().At(0)
		start = 1
	} else {
		description = "wrapper"
		recv = sig.Recv()
	}

	description = fmt.Sprintf("%s for %s", description, sel.Obj())
	if prog.mode&LogSource != 0 {
		defer logStack("make %s to (%s)", description, recv.Type())()
	}
	fn := &Function{
		name:      name,
		method:    sel,
		object:    obj,
		Signature: sig,
		Synthetic: description,
		Prog:      prog,
		pos:       obj.Pos(),
	}
	fn.startBody()
	fn.addSpilledParam(recv)
	createParams(fn, start)

	indices := sel.Index()

	var v Value = fn.Locals[0] // spilled receiver
	if isPointer(sel.Recv()) {
		v = emitLoad(fn, v)

		// For simple indirection wrappers, perform an informative nil-check:
		// "value method (T).f called using nil *T pointer"
		if len(indices) == 1 && !isPointer(recvType(obj)) {
			var c Call
			c.Call.Value = &Builtin{
				name: "ssa:wrapnilchk",
				sig: types.NewSignature(nil,
					types.NewTuple(anonVar(sel.Recv()), anonVar(tString), anonVar(tString)),
					types.NewTuple(anonVar(sel.Recv())), false),
			}
			c.Call.Args = []Value{
				v,
				stringConst(deref(sel.Recv()).String()),
				stringConst(sel.Obj().Name()),
			}
			c.setType(v.Type())
			v = fn.emit(&c)
		}
	}

	// Invariant: v is a pointer, either
	//   value of *A receiver param, or
	// address of  A spilled receiver.

	// We use pointer arithmetic (FieldAddr possibly followed by
	// Load) in preference to value extraction (Field possibly
	// preceded by Load).

	v = emitImplicitSelections(fn, v, indices[:len(indices)-1])

	// Invariant: v is a pointer, either
	//   value of implicit *C field, or
	// address of implicit  C field.

	var c Call
	if r := recvType(obj); !isInterface(r) { // concrete method
		if !isPointer(r) {
			v = emitLoad(fn, v)
		}
		c.Call.Value = prog.declaredFunc(obj)
		c.Call.Args = append(c.Call.Args, v)
	} else {
		c.Call.Method = obj
		c.Call.Value = emitLoad(fn, v)
//.........这里部分代码省略.........

//.........这里部分代码省略.........
			switch x := astutil.RemoveParens(e.X).(type) {
			case *ast.CompositeLit:
				return c.formatExpr("$newDataPointer(%e, %s)", x, c.typeName(c.p.TypeOf(e)))
			case *ast.Ident:
				obj := c.p.Uses[x].(*types.Var)
				if c.p.escapingVars[obj] {
					return c.formatExpr("(%1s.$ptr || (%1s.$ptr = new %2s(function() { return this.$target[0]; }, function($v) { this.$target[0] = $v; }, %1s)))", c.p.objectNames[obj], c.typeName(exprType))
				}
				return c.formatExpr(`(%1s || (%1s = new %2s(function() { return %3s; }, function($v) { %4s })))`, c.varPtrName(obj), c.typeName(exprType), c.objectName(obj), c.translateAssign(x, c.newIdent("$v", exprType), false))
			case *ast.SelectorExpr:
				sel, ok := c.p.SelectionOf(x)
				if !ok {
					// qualified identifier
					obj := c.p.Uses[x.Sel].(*types.Var)
					return c.formatExpr(`(%1s || (%1s = new %2s(function() { return %3s; }, function($v) { %4s })))`, c.varPtrName(obj), c.typeName(exprType), c.objectName(obj), c.translateAssign(x, c.newIdent("$v", exprType), false))
				}
				newSel := &ast.SelectorExpr{X: c.newIdent("this.$target", c.p.TypeOf(x.X)), Sel: x.Sel}
				c.setType(newSel, exprType)
				c.p.additionalSelections[newSel] = sel
				return c.formatExpr("(%1e.$ptr_%2s || (%1e.$ptr_%2s = new %3s(function() { return %4e; }, function($v) { %5s }, %1e)))", x.X, x.Sel.Name, c.typeName(exprType), newSel, c.translateAssign(newSel, c.newIdent("$v", exprType), false))
			case *ast.IndexExpr:
				if _, ok := c.p.TypeOf(x.X).Underlying().(*types.Slice); ok {
					return c.formatExpr("$indexPtr(%1e.$array, %1e.$offset + %2e, %3s)", x.X, x.Index, c.typeName(exprType))
				}
				return c.formatExpr("$indexPtr(%e, %e, %s)", x.X, x.Index, c.typeName(exprType))
			case *ast.StarExpr:
				return c.translateExpr(x.X)
			default:
				panic(fmt.Sprintf("Unhandled: %T\n", x))
			}

		case token.ARROW:
			call := &ast.CallExpr{
				Fun:  c.newIdent("$recv", types.NewSignature(nil, types.NewTuple(types.NewVar(0, nil, "", t)), types.NewTuple(types.NewVar(0, nil, "", exprType), types.NewVar(0, nil, "", types.Typ[types.Bool])), false)),
				Args: []ast.Expr{e.X},
			}
			c.Blocking[call] = true
			if _, isTuple := exprType.(*types.Tuple); isTuple {
				return c.formatExpr("%e", call)
			}
			return c.formatExpr("%e[0]", call)
		}

		basic := t.Underlying().(*types.Basic)
		switch e.Op {
		case token.ADD:
			return c.translateExpr(e.X)
		case token.SUB:
			switch {
			case is64Bit(basic):
				return c.formatExpr("new %1s(-%2h, -%2l)", c.typeName(t), e.X)
			case isComplex(basic):
				return c.formatExpr("new %1s(-%2r, -%2i)", c.typeName(t), e.X)
			case isUnsigned(basic):
				return c.fixNumber(c.formatExpr("-%e", e.X), basic)
			default:
				return c.formatExpr("-%e", e.X)
			}
		case token.XOR:
			if is64Bit(basic) {
				return c.formatExpr("new %1s(~%2h, ~%2l >>> 0)", c.typeName(t), e.X)
			}
			return c.fixNumber(c.formatExpr("~%e", e.X), basic)
		case token.NOT:
			return c.formatExpr("!%e", e.X)
		default:

	"comma-separated list of functions whose results must be used")

var unusedStringMethodsFlag = flag.String("unusedstringmethods",
	"Error,String",
	"comma-separated list of names of methods of type func() string whose results must be used")

func init() {
	register("unusedresult",
		"check for unused result of calls to functions in -unusedfuncs list and methods in -unusedstringmethods list",
		checkUnusedResult,
		exprStmt)
}

// func() string
var sigNoArgsStringResult = types.NewSignature(nil, nil, nil,
	types.NewTuple(types.NewVar(token.NoPos, nil, "", types.Typ[types.String])),
	false)

var unusedFuncs = make(map[string]bool)
var unusedStringMethods = make(map[string]bool)

func initUnusedFlags() {
	commaSplit := func(s string, m map[string]bool) {
		if s != "" {
			for _, name := range strings.Split(s, ",") {
				if len(name) == 0 {
					flag.Usage()
				}
				m[name] = true
			}
		}

//.........这里部分代码省略.........
			iVar := c.newVariable("_i")
			c.Printf("%s = 0;", iVar)
			c.translateLoopingStmt(func() string { return iVar + " < " + length }, s.Body, func() {
				if !isBlank(s.Key) {
					c.Printf("%s", c.translateAssign(s.Key, c.newIdent(iVar, types.Typ[types.Int]), s.Tok == token.DEFINE))
				}
				if !isBlank(s.Value) {
					c.Printf("%s", c.translateAssign(s.Value, c.setType(&ast.IndexExpr{
						X:     c.newIdent(refVar, t),
						Index: c.newIdent(iVar, types.Typ[types.Int]),
					}, elemType), s.Tok == token.DEFINE))
				}
			}, func() {
				c.Printf("%s++;", iVar)
			}, label, c.Flattened[s])

		case *types.Chan:
			okVar := c.newIdent(c.newVariable("_ok"), types.Typ[types.Bool])
			key := s.Key
			tok := s.Tok
			if key == nil {
				key = ast.NewIdent("_")
				tok = token.ASSIGN
			}
			forStmt := &ast.ForStmt{
				Body: &ast.BlockStmt{
					List: []ast.Stmt{
						&ast.AssignStmt{
							Lhs: []ast.Expr{
								key,
								okVar,
							},
							Rhs: []ast.Expr{
								c.setType(&ast.UnaryExpr{X: c.newIdent(refVar, t), Op: token.ARROW}, types.NewTuple(types.NewVar(0, nil, "", t.Elem()), types.NewVar(0, nil, "", types.Typ[types.Bool]))),
							},
							Tok: tok,
						},
						&ast.IfStmt{
							Cond: &ast.UnaryExpr{X: okVar, Op: token.NOT},
							Body: &ast.BlockStmt{List: []ast.Stmt{&ast.BranchStmt{Tok: token.BREAK}}},
						},
						s.Body,
					},
				},
			}
			c.Flattened[forStmt] = true
			c.translateStmt(forStmt, label)

		default:
			panic("")
		}

	case *ast.BranchStmt:
		normalLabel := ""
		blockingLabel := ""
		data := c.flowDatas[nil]
		if s.Label != nil {
			normalLabel = " " + s.Label.Name
			blockingLabel = " s" // use explicit label "s", because surrounding loop may not be flattened
			data = c.flowDatas[c.p.Uses[s.Label].(*types.Label)]
		}
		switch s.Tok {
		case token.BREAK:
			c.PrintCond(data.endCase == 0, fmt.Sprintf("break%s;", normalLabel), fmt.Sprintf("$s = %d; continue%s;", data.endCase, blockingLabel))
		case token.CONTINUE:
			data.postStmt()

func logStack(format string, args ...interface{}) func() {
	msg := fmt.Sprintf(format, args...)
	io.WriteString(os.Stderr, msg)
	io.WriteString(os.Stderr, "\n")
	return func() {
		io.WriteString(os.Stderr, msg)
		io.WriteString(os.Stderr, " end\n")
	}
}

// newVar creates a 'var' for use in a types.Tuple.
func newVar(name string, typ types.Type) *types.Var {
	return types.NewParam(token.NoPos, nil, name, typ)
}

// anonVar creates an anonymous 'var' for use in a types.Tuple.
func anonVar(typ types.Type) *types.Var {
	return newVar("", typ)
}

var lenResults = types.NewTuple(anonVar(tInt))

// makeLen returns the len builtin specialized to type func(T)int.
func makeLen(T types.Type) *Builtin {
	lenParams := types.NewTuple(anonVar(T))
	return &Builtin{
		name: "len",
		sig:  types.NewSignature(nil, lenParams, lenResults, false),
	}
}

//.........这里部分代码省略.........
		var newS ast.Stmt
		switch t := c.info.TypeOf(s.X).Underlying().(type) {
		case *types.Chan:
			key := s.Key
			tok := s.Tok
			if key == nil {
				key = ast.NewIdent("_")
				tok = token.DEFINE
			}
			okVar := c.newIdent(types.Typ[types.Bool])
			if s.Tok == token.ASSIGN {
				*stmts = append(*stmts, &ast.DeclStmt{
					Decl: &ast.GenDecl{
						Tok: token.VAR,
						Specs: []ast.Spec{&ast.ValueSpec{
							Names: []*ast.Ident{okVar},
							Type:  ast.NewIdent("bool"),
						}},
					},
				})
			}
			newS = &ast.ForStmt{
				For: s.For,
				Body: &ast.BlockStmt{
					Lbrace: s.Body.Lbrace,
					List: append([]ast.Stmt{
						&ast.AssignStmt{
							Lhs:    []ast.Expr{key, okVar},
							TokPos: s.TokPos,
							Tok:    tok,
							Rhs: []ast.Expr{c.setType(&ast.UnaryExpr{
								Op: token.ARROW,
								X:  c.newVar(stmts, s.X),
							}, types.NewTuple(
								types.NewVar(token.NoPos, nil, "", t.Elem()),
								types.NewVar(token.NoPos, nil, "", types.Typ[types.Bool]),
							))},
						},
						&ast.IfStmt{
							Cond: c.setType(&ast.UnaryExpr{
								Op: token.NOT,
								X:  okVar,
							}, types.Typ[types.Bool]),
							Body: &ast.BlockStmt{
								List: []ast.Stmt{
									&ast.BranchStmt{Tok: token.BREAK},
								},
							},
						},
					}, c.simplifyStmtList(s.Body.List)...),
					Rbrace: s.Body.Rbrace,
				},
			}

		default:
			newS = &ast.RangeStmt{
				For:    s.For,
				Key:    s.Key,
				Value:  s.Value,
				TokPos: s.TokPos,
				Tok:    s.Tok,
				X:      s.X,
				Body:   c.simplifyBlock(s.Body),
			}
		}
		c.info.Scopes[newS] = c.info.Scopes[s]

// CreateTestMainPackage creates and returns a synthetic "main"
// package that runs all the tests of the supplied packages, similar
// to the one that would be created by the 'go test' tool.
//
// It returns nil if the program contains no tests.
//
func (prog *Program) CreateTestMainPackage(pkgs ...*Package) *Package {
	pkgs, tests, benchmarks, examples := FindTests(pkgs)
	if len(pkgs) == 0 {
		return nil
	}

	testmain := &Package{
		Prog:    prog,
		Members: make(map[string]Member),
		values:  make(map[types.Object]Value),
		Pkg:     types.NewPackage("test$main", "main"),
	}

	// Build package's init function.
	init := &Function{
		name:      "init",
		Signature: new(types.Signature),
		Synthetic: "package initializer",
		Pkg:       testmain,
		Prog:      prog,
	}
	init.startBody()

	if testMainStartBodyHook != nil {
		testMainStartBodyHook(init)
	}

	// Initialize packages to test.
	var pkgpaths []string
	for _, pkg := range pkgs {
		var v Call
		v.Call.Value = pkg.init
		v.setType(types.NewTuple())
		init.emit(&v)

		pkgpaths = append(pkgpaths, pkg.Pkg.Path())
	}
	sort.Strings(pkgpaths)
	init.emit(new(Return))
	init.finishBody()
	testmain.init = init
	testmain.Pkg.MarkComplete()
	testmain.Members[init.name] = init

	// For debugging convenience, define an unexported const
	// that enumerates the packages.
	packagesConst := types.NewConst(token.NoPos, testmain.Pkg, "packages", tString,
		exact.MakeString(strings.Join(pkgpaths, " ")))
	memberFromObject(testmain, packagesConst, nil)

	// Create main *types.Func and *ssa.Function
	mainFunc := types.NewFunc(token.NoPos, testmain.Pkg, "main", new(types.Signature))
	memberFromObject(testmain, mainFunc, nil)
	main := testmain.Func("main")
	main.Synthetic = "test main function"

	main.startBody()

	if testMainStartBodyHook != nil {
		testMainStartBodyHook(main)
	}

	if testingPkg := prog.ImportedPackage("testing"); testingPkg != nil {
		testingMain := testingPkg.Func("Main")
		testingMainParams := testingMain.Signature.Params()

		// The generated code is as if compiled from this:
		//
		// func main() {
		//      match      := func(_, _ string) (bool, error) { return true, nil }
		//      tests      := []testing.InternalTest{{"TestFoo", TestFoo}, ...}
		//      benchmarks := []testing.InternalBenchmark{...}
		//      examples   := []testing.InternalExample{...}
		// 	testing.Main(match, tests, benchmarks, examples)
		// }

		matcher := &Function{
			name:      "matcher",
			Signature: testingMainParams.At(0).Type().(*types.Signature),
			Synthetic: "test matcher predicate",
			parent:    main,
			Pkg:       testmain,
			Prog:      prog,
		}
		main.AnonFuncs = append(main.AnonFuncs, matcher)
		matcher.startBody()
		matcher.emit(&Return{Results: []Value{vTrue, nilConst(types.Universe.Lookup("error").Type())}})
		matcher.finishBody()

		// Emit call: testing.Main(matcher, tests, benchmarks, examples).
		var c Call
		c.Call.Value = testingMain
		c.Call.Args = []Value{
			matcher,
//.........这里部分代码省略.........

// CreateTestMainPackage creates and returns a synthetic "testmain"
// package for the specified package if it defines tests, benchmarks or
// executable examples, or nil otherwise.  The new package is named
// "main" and provides a function named "main" that runs the tests,
// similar to the one that would be created by the 'go test' tool.
//
// Subsequent calls to prog.AllPackages include the new package.
// The package pkg must belong to the program prog.
func (prog *Program) CreateTestMainPackage(pkg *Package) *Package {
	if pkg.Prog != prog {
		log.Fatal("Package does not belong to Program")
	}

	tests, benchmarks, examples, testMainFunc := FindTests(pkg)

	if testMainFunc == nil && tests == nil && benchmarks == nil && examples == nil {
		return nil
	}

	testmain := &Package{
		Prog:    prog,
		Members: make(map[string]Member),
		values:  make(map[types.Object]Value),
		Pkg:     types.NewPackage(pkg.Pkg.Path()+"$testmain", "main"),
	}

	// Build package's init function.
	init := &Function{
		name:      "init",
		Signature: new(types.Signature),
		Synthetic: "package initializer",
		Pkg:       testmain,
		Prog:      prog,
	}
	init.startBody()

	if testMainStartBodyHook != nil {
		testMainStartBodyHook(init)
	}

	// Initialize package under test.
	var v Call
	v.Call.Value = pkg.init
	v.setType(types.NewTuple())
	init.emit(&v)
	init.emit(new(Return))
	init.finishBody()
	testmain.init = init
	testmain.Pkg.MarkComplete()
	testmain.Members[init.name] = init

	// Create main *types.Func and *Function
	mainFunc := types.NewFunc(token.NoPos, testmain.Pkg, "main", new(types.Signature))
	memberFromObject(testmain, mainFunc, nil)
	main := testmain.Func("main")
	main.Synthetic = "test main function"

	main.startBody()

	if testMainStartBodyHook != nil {
		testMainStartBodyHook(main)
	}

	if testingPkg := prog.ImportedPackage("testing"); testingPkg != nil {
		testingMain := testingPkg.Func("Main")
		testingMainParams := testingMain.Signature.Params()

		// The generated code is as if compiled from this:
		//
		// func main() {
		//      match      := func(_, _ string) (bool, error) { return true, nil }
		//      tests      := []testing.InternalTest{{"TestFoo", TestFoo}, ...}
		//      benchmarks := []testing.InternalBenchmark{...}
		//      examples   := []testing.InternalExample{...}
		//	if TestMain is defined {
		// 		m := testing.MainStart(match, tests, benchmarks, examples)
		// 		return TestMain(m)
		// 	} else {
		// 		return testing.Main(match, tests, benchmarks, examples)
		// 	}
		// }

		matcher := &Function{
			name:      "matcher",
			Signature: testingMainParams.At(0).Type().(*types.Signature),
			Synthetic: "test matcher predicate",
			parent:    main,
			Pkg:       testmain,
			Prog:      prog,
		}
		main.AnonFuncs = append(main.AnonFuncs, matcher)
		matcher.startBody()
		matcher.emit(&Return{Results: []Value{vTrue, nilConst(types.Universe.Lookup("error").Type())}})
		matcher.finishBody()

		var c Call
		c.Call.Args = []Value{
			matcher,
			testMainSlice(main, tests, testingMainParams.At(1).Type()),
			testMainSlice(main, benchmarks, testingMainParams.At(2).Type()),
//.........这里部分代码省略.........