示例#1
0
// okPrintfArg compares the formatState to the arguments actually present,
// reporting any discrepancies it can discern. If the final argument is ellipsissed,
// there's little it can do for that.
func (f *File) okPrintfArg(call *ast.CallExpr, state *formatState) (ok bool) {
	var v printVerb
	found := false
	// Linear scan is fast enough for a small list.
	for _, v = range printVerbs {
		if v.verb == state.verb {
			found = true
			break
		}
	}
	if !found {
		f.Badf(call.Pos(), "unrecognized printf verb %q", state.verb)
		return false
	}
	for _, flag := range state.flags {
		if !strings.ContainsRune(v.flags, rune(flag)) {
			f.Badf(call.Pos(), "unrecognized printf flag for verb %q: %q", state.verb, flag)
			return false
		}
	}
	// Verb is good. If len(state.argNums)>trueArgs, we have something like %.*s and all
	// but the final arg must be an integer.
	trueArgs := 1
	if state.verb == '%' {
		trueArgs = 0
	}
	nargs := len(state.argNums)
	for i := 0; i < nargs-trueArgs; i++ {
		argNum := state.argNums[i]
		if !f.argCanBeChecked(call, i, true, state) {
			return
		}
		arg := call.Args[argNum]
		if !f.matchArgType(argInt, nil, arg) {
			f.Badf(call.Pos(), "arg %s for * in printf format not of type int", f.gofmt(arg))
			return false
		}
	}
	if state.verb == '%' {
		return true
	}
	argNum := state.argNums[len(state.argNums)-1]
	if !f.argCanBeChecked(call, len(state.argNums)-1, false, state) {
		return false
	}
	arg := call.Args[argNum]
	if !f.matchArgType(v.typ, nil, arg) {
		typeString := ""
		if typ := f.pkg.types[arg].Type; typ != nil {
			typeString = typ.String()
		}
		f.Badf(call.Pos(), "arg %s for printf verb %%%c of wrong type: %s", f.gofmt(arg), state.verb, typeString)
		return false
	}
	if v.typ&argString != 0 && v.verb != 'T' && !bytes.Contains(state.flags, []byte{'#'}) && f.recursiveStringer(arg) {
		f.Badf(call.Pos(), "arg %s for printf causes recursive call to String method", f.gofmt(arg))
		return false
	}
	return true
}
示例#2
0
// argCanBeChecked reports whether the specified argument is statically present;
// it may be beyond the list of arguments or in a terminal slice... argument, which
// means we can't see it.
func (f *File) argCanBeChecked(call *ast.CallExpr, formatArg int, isStar bool, state *formatState) bool {
	argNum := state.argNums[formatArg]
	if argNum < 0 {
		// Shouldn't happen, so catch it with prejudice.
		panic("negative arg num")
	}
	if argNum < len(call.Args)-1 {
		return true // Always OK.
	}
	if call.Ellipsis.IsValid() {
		return false // We just can't tell; there could be many more arguments.
	}
	if argNum < len(call.Args) {
		return true
	}
	// There are bad indexes in the format or there are fewer arguments than the format needs.
	verb := fmt.Sprintf("verb %%%c", state.verb)
	if isStar {
		verb = "indirect *"
	}
	// This is the argument number relative to the format: Printf("%s", "hi") will give 1 for the "hi".
	arg := argNum - state.firstArg + 1 // People think of arguments as 1-indexed.
	f.Badf(call.Pos(), "missing argument for %s %s: need %d, have %d", state.name, verb, arg, len(call.Args)-state.firstArg)
	return false
}
示例#3
0
// argCanBeChecked reports whether the specified argument is statically present;
// it may be beyond the list of arguments or in a terminal slice... argument, which
// means we can't see it.
func (f *File) argCanBeChecked(call *ast.CallExpr, formatArg int, isStar bool, state *formatState) bool {
	argNum := state.argNums[formatArg]
	if argNum < 0 {
		// Shouldn't happen, so catch it with prejudice.
		panic("negative arg num")
	}
	if argNum == 0 {
		f.Badf(call.Pos(), `index value [0] for %s("%s"); indexes start at 1`, state.name, state.format)
		return false
	}
	if argNum < len(call.Args)-1 {
		return true // Always OK.
	}
	if call.Ellipsis.IsValid() {
		return false // We just can't tell; there could be many more arguments.
	}
	if argNum < len(call.Args) {
		return true
	}
	// There are bad indexes in the format or there are fewer arguments than the format needs.
	// This is the argument number relative to the format: Printf("%s", "hi") will give 1 for the "hi".
	arg := argNum - state.firstArg + 1 // People think of arguments as 1-indexed.
	f.Badf(call.Pos(), `missing argument for %s("%s"): format reads arg %d, have only %d args`, state.name, state.format, arg, len(call.Args)-state.firstArg)
	return false
}
示例#4
0
// conversion typechecks the type conversion conv to type typ. iota is the current
// value of iota or -1 if iota doesn't have a value in the current context. The result
// of the conversion is returned via x. If the conversion has type errors, the returned
// x is marked as invalid (x.mode == invalid).
//
func (check *checker) conversion(x *operand, conv *ast.CallExpr, typ Type, iota int) {
	// all conversions have one argument
	if len(conv.Args) != 1 {
		check.invalidOp(conv.Pos(), "%s conversion requires exactly one argument", conv)
		goto Error
	}

	// evaluate argument
	check.expr(x, conv.Args[0], nil, iota)
	if x.mode == invalid {
		goto Error
	}

	if x.mode == constant && isConstType(typ) {
		// constant conversion
		// TODO(gri) implement this
	} else {
		// non-constant conversion
		if !x.isConvertible(typ) {
			check.invalidOp(conv.Pos(), "cannot convert %s to %s", x, typ)
			goto Error
		}
		x.mode = value
	}

	x.expr = conv
	x.typ = typ
	return

Error:
	x.mode = invalid
}
示例#5
0
// conversion typechecks the type conversion conv to type typ. iota is the current
// value of iota or -1 if iota doesn't have a value in the current context. The result
// of the conversion is returned via x. If the conversion has type errors, the returned
// x is marked as invalid (x.mode == invalid).
//
func (check *checker) conversion(x *operand, conv *ast.CallExpr, typ Type, iota int) {
	// all conversions have one argument
	if len(conv.Args) != 1 {
		check.invalidOp(conv.Pos(), "%s conversion requires exactly one argument", conv)
		goto Error
	}

	// evaluate argument
	check.expr(x, conv.Args[0], nil, iota)
	if x.mode == invalid {
		goto Error
	}

	if x.mode == constant && isConstType(typ) {
		// constant conversion
		typ := typ.Underlying().(*Basic)
		// For now just implement string(x) where x is an integer,
		// as a temporary work-around for issue 4982, which is a
		// common issue.
		if typ.kind == String {
			switch {
			case x.isInteger():
				codepoint := int64(-1)
				if i, ok := exact.Int64Val(x.val); ok {
					codepoint = i
				}
				// If codepoint < 0 the absolute value is too large (or unknown) for
				// conversion. This is the same as converting any other out-of-range
				// value - let string(codepoint) do the work.
				x.val = exact.MakeString(string(codepoint))
			case isString(x.typ):
				// nothing to do
			default:
				goto ErrorMsg
			}
		}
		// TODO(gri) verify the remaining conversions.
	} else {
		// non-constant conversion
		if !x.isConvertible(check.ctxt, typ) {
			goto ErrorMsg
		}
		x.mode = value
	}

	// the conversion argument types are final; for now we just use x.typ
	// TODO(gri) Fix this. For untyped constants, the type should be typ.
	check.updateExprType(x.expr, x.typ, true)

	check.conversions[conv] = true // for cap/len checking
	x.expr = conv
	x.typ = typ
	return

ErrorMsg:
	check.invalidOp(conv.Pos(), "cannot convert %s to %s", x, typ)
Error:
	x.mode = invalid
	x.expr = conv
}
示例#6
0
// checkPrintf checks a call to a formatted print routine such as Printf.
// call.Args[formatIndex] is (well, should be) the format argument.
func (f *File) checkPrintf(call *ast.CallExpr, name string, formatIndex int) {
	if formatIndex >= len(call.Args) {
		f.Bad(call.Pos(), "too few arguments in call to", name)
		return
	}
	lit := f.pkg.types[call.Args[formatIndex]].Value
	if lit == nil {
		if *verbose {
			f.Warn(call.Pos(), "can't check non-constant format in call to", name)
		}
		return
	}
	if lit.Kind() != exact.String {
		f.Badf(call.Pos(), "constant %v not a string in call to %s", lit, name)
		return
	}
	format := exact.StringVal(lit)
	firstArg := formatIndex + 1 // Arguments are immediately after format string.
	if !strings.Contains(format, "%") {
		if len(call.Args) > firstArg {
			f.Badf(call.Pos(), "no formatting directive in %s call", name)
		}
		return
	}
	// Hard part: check formats against args.
	argNum := firstArg
	indexed := false
	for i, w := 0, 0; i < len(format); i += w {
		w = 1
		if format[i] == '%' {
			state := f.parsePrintfVerb(call, name, format[i:], firstArg, argNum)
			if state == nil {
				return
			}
			w = len(state.format)
			if state.indexed {
				indexed = true
			}
			if !f.okPrintfArg(call, state) { // One error per format is enough.
				return
			}
			if len(state.argNums) > 0 {
				// Continue with the next sequential argument.
				argNum = state.argNums[len(state.argNums)-1] + 1
			}
		}
	}
	// Dotdotdot is hard.
	if call.Ellipsis.IsValid() && argNum >= len(call.Args)-1 {
		return
	}
	// If the arguments were direct indexed, we assume the programmer knows what's up.
	// Otherwise, there should be no leftover arguments.
	if !indexed && argNum != len(call.Args) {
		expect := argNum - firstArg
		numArgs := len(call.Args) - firstArg
		f.Badf(call.Pos(), "wrong number of args for format in %s call: %d needed but %d args", name, expect, numArgs)
	}
}
示例#7
0
func (f *File) checkUnsafePointer(x *ast.CallExpr) {
	if !vet("unsafeptr") {
		return
	}
	if len(x.Args) != 1 {
		return
	}
	if f.hasBasicType(x.Fun, types.UnsafePointer) && f.hasBasicType(x.Args[0], types.Uintptr) && !f.isSafeUintptr(x.Args[0]) {
		f.Badf(x.Pos(), "possible misuse of unsafe.Pointer")
	}
}
示例#8
0
// checkPrintf checks a call to a formatted print routine such as Printf.
// call.Args[formatIndex] is (well, should be) the format argument.
func (f *File) checkPrintf(call *ast.CallExpr, name string, formatIndex int) {
	if formatIndex >= len(call.Args) {
		return
	}
	lit := f.literal(call.Args[formatIndex])
	if lit == nil {
		if *verbose {
			f.Warn(call.Pos(), "can't check non-literal format in call to", name)
		}
		return
	}
	if lit.Kind != token.STRING {
		f.Badf(call.Pos(), "literal %v not a string in call to", lit.Value, name)
	}
	format, err := strconv.Unquote(lit.Value)
	if err != nil {
		// Shouldn't happen if parser returned no errors, but be safe.
		f.Badf(call.Pos(), "invalid quoted string literal")
	}
	firstArg := formatIndex + 1 // Arguments are immediately after format string.
	if !strings.Contains(format, "%") {
		if len(call.Args) > firstArg {
			f.Badf(call.Pos(), "no formatting directive in %s call", name)
		}
		return
	}
	// Hard part: check formats against args.
	argNum := firstArg
	for i, w := 0, 0; i < len(format); i += w {
		w = 1
		if format[i] == '%' {
			verb, flags, nbytes, nargs := f.parsePrintfVerb(call, format[i:])
			w = nbytes
			if verb == '%' { // "%%" does nothing interesting.
				continue
			}
			// If we've run out of args, print after loop will pick that up.
			if argNum+nargs <= len(call.Args) {
				f.checkPrintfArg(call, verb, flags, argNum, nargs)
			}
			argNum += nargs
		}
	}
	// TODO: Dotdotdot is hard.
	if call.Ellipsis.IsValid() && argNum != len(call.Args) {
		return
	}
	if argNum != len(call.Args) {
		expect := argNum - firstArg
		numArgs := len(call.Args) - firstArg
		f.Badf(call.Pos(), "wrong number of args for format in %s call: %d needed but %d args", name, expect, numArgs)
	}
}
示例#9
0
文件: print.go 项目: 4honor/obdi
// checkPrint checks a call to an unformatted print routine such as Println.
// call.Args[firstArg] is the first argument to be printed.
func (f *File) checkPrint(call *ast.CallExpr, name string, firstArg int) {
	isLn := strings.HasSuffix(name, "ln")
	isF := strings.HasPrefix(name, "F")
	args := call.Args
	// check for Println(os.Stderr, ...)
	if firstArg == 0 && !isF && len(args) > 0 {
		if sel, ok := args[0].(*ast.SelectorExpr); ok {
			if x, ok := sel.X.(*ast.Ident); ok {
				if x.Name == "os" && strings.HasPrefix(sel.Sel.Name, "Std") {
					f.Badf(call.Pos(), "first argument to %s is %s.%s", name, x.Name, sel.Sel.Name)
				}
			}
		}
	}
	if len(args) <= firstArg {
		// If we have a call to a method called Error that satisfies the Error interface,
		// then it's ok. Otherwise it's something like (*T).Error from the testing package
		// and we need to check it.
		if name == "Error" && f.isErrorMethodCall(call) {
			return
		}
		// If it's an Error call now, it's probably for printing errors.
		if !isLn {
			// Check the signature to be sure: there are niladic functions called "error".
			if firstArg != 0 || f.numArgsInSignature(call) != firstArg {
				f.Badf(call.Pos(), "no args in %s call", name)
			}
		}
		return
	}
	arg := args[firstArg]
	if lit, ok := arg.(*ast.BasicLit); ok && lit.Kind == token.STRING {
		if strings.Contains(lit.Value, "%") {
			f.Badf(call.Pos(), "possible formatting directive in %s call", name)
		}
	}
	if isLn {
		// The last item, if a string, should not have a newline.
		arg = args[len(call.Args)-1]
		if lit, ok := arg.(*ast.BasicLit); ok && lit.Kind == token.STRING {
			if strings.HasSuffix(lit.Value, `\n"`) {
				f.Badf(call.Pos(), "%s call ends with newline", name)
			}
		}
	}
	for _, arg := range args {
		if f.recursiveStringer(arg) {
			f.Badf(call.Pos(), "arg %s for print causes recursive call to String method", f.gofmt(arg))
		}
	}
}
示例#10
0
func (f *File) checkPrintfArg(call *ast.CallExpr, verb rune, flags []byte, argNum, nargs int) {
	// Linear scan is fast enough for a small list.
	for _, v := range printVerbs {
		if v.verb == verb {
			for _, flag := range flags {
				if !strings.ContainsRune(v.flags, rune(flag)) {
					f.Badf(call.Pos(), "unrecognized printf flag for verb %q: %q", verb, flag)
					return
				}
			}
			// Verb is good. If nargs>1, we have something like %.*s and all but the final
			// arg must be integer.
			for i := 0; i < nargs-1; i++ {
				if !f.matchArgType(argInt, call.Args[argNum+i]) {
					f.Badf(call.Pos(), "arg %s for * in printf format not of type int", f.gofmt(call.Args[argNum+i]))
				}
			}
			for _, v := range printVerbs {
				if v.verb == verb {
					arg := call.Args[argNum+nargs-1]
					if !f.matchArgType(v.typ, arg) {
						typeString := ""
						if typ := f.pkg.types[arg]; typ != nil {
							typeString = typ.String()
						}
						f.Badf(call.Pos(), "arg %s for printf verb %%%c of wrong type: %s", f.gofmt(arg), verb, typeString)
					}
					break
				}
			}
			return
		}
	}
	f.Badf(call.Pos(), "unrecognized printf verb %q", verb)
}
示例#11
0
func (f *File) checkPrintfVerb(call *ast.CallExpr, verb rune, flags []byte) {
	// Linear scan is fast enough for a small list.
	for _, v := range printVerbs {
		if v.verb == verb {
			for _, flag := range flags {
				if !strings.ContainsRune(v.flags, rune(flag)) {
					f.Badf(call.Pos(), "unrecognized printf flag for verb %q: %q", verb, flag)
				}
			}
			return
		}
	}
	f.Badf(call.Pos(), "unrecognized printf verb %q", verb)
}
示例#12
0
// parsePrintfVerb looks the formatting directive that begins the format string
// and returns a formatState that encodes what the directive wants, without looking
// at the actual arguments present in the call. The result is nil if there is an error.
func (f *File) parsePrintfVerb(call *ast.CallExpr, name, format string, firstArg, argNum int) *formatState {
	state := &formatState{
		format:   format,
		name:     name,
		flags:    make([]byte, 0, 5),
		argNum:   argNum,
		argNums:  make([]int, 0, 1),
		nbytes:   1, // There's guaranteed to be a percent sign.
		indexed:  false,
		firstArg: firstArg,
		file:     f,
		call:     call,
	}
	// There may be flags.
	state.parseFlags()
	indexPending := false
	// There may be an index.
	if !state.parseIndex() {
		return nil
	}
	// There may be a width.
	if !state.parseNum() {
		return nil
	}
	// There may be a precision.
	if !state.parsePrecision() {
		return nil
	}
	// Now a verb, possibly prefixed by an index (which we may already have).
	if !indexPending && !state.parseIndex() {
		return nil
	}
	if state.nbytes == len(state.format) {
		f.Badf(call.Pos(), "missing verb at end of format string in %s call", name)
		return nil
	}
	verb, w := utf8.DecodeRuneInString(state.format[state.nbytes:])
	state.verb = verb
	state.nbytes += w
	if verb != '%' {
		state.argNums = append(state.argNums, state.argNum)
	}
	state.format = state.format[:state.nbytes]
	return state
}
示例#13
0
文件: print.go 项目: xorrbit/golang
// checkPrintf checks a call to a formatted print routine such as Printf.
// The skip argument records how many arguments to ignore; that is,
// call.Args[skip] is (well, should be) the format argument.
func (f *File) checkPrintf(call *ast.CallExpr, name string, skip int) {
	if len(call.Args) <= skip {
		return
	}
	lit := f.literal(call.Args[skip])
	if lit == nil {
		if *verbose {
			f.Warn(call.Pos(), "can't check non-literal format in call to", name)
		}
		return
	}
	if lit.Kind != token.STRING {
		f.Badf(call.Pos(), "literal %v not a string in call to", lit.Value, name)
	}
	format, err := strconv.Unquote(lit.Value)
	if err != nil {
		f.Badf(call.Pos(), "invalid quoted string literal")
	}
	if !strings.Contains(format, "%") {
		if len(call.Args) > skip+1 {
			f.Badf(call.Pos(), "no formatting directive in %s call", name)
		}
		return
	}
	// Hard part: check formats against args.
	// Trivial but useful test: count.
	numArgs := 0
	for i, w := 0, 0; i < len(format); i += w {
		w = 1
		if format[i] == '%' {
			nbytes, nargs := f.parsePrintfVerb(call, format[i:])
			w = nbytes
			numArgs += nargs
		}
	}
	expect := len(call.Args) - (skip + 1)
	// Don't be too strict on dotdotdot.
	if call.Ellipsis.IsValid() && numArgs >= expect {
		return
	}
	if numArgs != expect {
		f.Badf(call.Pos(), "wrong number of args in %s call: %d needed but %d args", name, numArgs, expect)
	}
}
示例#14
0
// checkPrint checks a call to an unformatted print routine such as Println.
// The skip argument records how many arguments to ignore; that is,
// call.Args[skip] is the first argument to be printed.
func (f *File) checkPrint(call *ast.CallExpr, name string, skip int) {
	isLn := strings.HasSuffix(name, "ln")
	args := call.Args
	if len(args) <= skip {
		if *verbose && !isLn {
			f.Badf(call.Pos(), "no args in %s call", name)
		}
		return
	}
	arg := args[skip]
	if lit, ok := arg.(*ast.BasicLit); ok && lit.Kind == token.STRING {
		if strings.Contains(lit.Value, "%") {
			f.Badf(call.Pos(), "possible formatting directive in %s call", name)
		}
	}
	if isLn {
		// The last item, if a string, should not have a newline.
		arg = args[len(call.Args)-1]
		if lit, ok := arg.(*ast.BasicLit); ok && lit.Kind == token.STRING {
			if strings.HasSuffix(lit.Value, `\n"`) {
				f.Badf(call.Pos(), "%s call ends with newline", name)
			}
		}
	}
}
示例#15
0
文件: flag.go 项目: slyrz/mango
func NewFunctionCall(fs *token.FileSet, n *ast.CallExpr) (*FunctionCall, error) {
	parts := make([]string, 0)
	ast.Inspect(n.Fun, func(n ast.Node) bool {
		if n == nil {
			return true
		}
		switch obj := n.(type) {
		case *ast.SelectorExpr:
			// do nothing, just avoid the default case
			break
		case *ast.Ident:
			parts = append(parts, obj.Name)
		default:
			return false
		}
		return true
	})
	if len(parts) == 0 {
		return nil, ErrNotSupported
	}
	args := make([]string, len(n.Args))
	for i, arg := range n.Args {
		ast.Inspect(arg, func(n ast.Node) bool {
			switch t := n.(type) {
			case *ast.Ident:
				args[i] = t.Name
			case *ast.BasicLit:
				args[i] = t.Value
			}
			return true
		})
	}
	return &FunctionCall{
		Line: fs.Position(n.Pos()).Line,
		Expr: strings.Join(parts, "."),
		Name: parts[len(parts)-1],
		Args: args,
	}, nil
}
示例#16
0
文件: conversions.go 项目: hfeeki/go
// conversion typechecks the type conversion conv to type typ. iota is the current
// value of iota or -1 if iota doesn't have a value in the current context. The result
// of the conversion is returned via x. If the conversion has type errors, the returned
// x is marked as invalid (x.mode == invalid).
//
func (check *checker) conversion(x *operand, conv *ast.CallExpr, typ Type, iota int) {
	// all conversions have one argument
	if len(conv.Args) != 1 {
		check.invalidOp(conv.Pos(), "%s conversion requires exactly one argument", conv)
		goto Error
	}

	// evaluate argument
	check.expr(x, conv.Args[0], nil, iota)
	if x.mode == invalid {
		goto Error
	}

	// TODO(gri) fix this - implement all checks and constant evaluation
	x.mode = value
	x.expr = conv
	x.typ = typ
	return

Error:
	x.mode = invalid
}
示例#17
0
文件: print.go 项目: Harvey-OS/go
// checkPrintf checks a call to a formatted print routine such as Printf.
func (f *File) checkPrintf(call *ast.CallExpr, name string) {
	format, idx := formatString(f, call)
	if idx < 0 {
		if *verbose {
			f.Warn(call.Pos(), "can't check non-constant format in call to", name)
		}
		return
	}

	firstArg := idx + 1 // Arguments are immediately after format string.
	if !strings.Contains(format, "%") {
		if len(call.Args) > firstArg {
			f.Badf(call.Pos(), "no formatting directive in %s call", name)
		}
		return
	}
	// Hard part: check formats against args.
	argNum := firstArg
	maxArgNum := firstArg
	for i, w := 0, 0; i < len(format); i += w {
		w = 1
		if format[i] == '%' {
			state := f.parsePrintfVerb(call, name, format[i:], firstArg, argNum)
			if state == nil {
				return
			}
			w = len(state.format)
			if !f.okPrintfArg(call, state) { // One error per format is enough.
				return
			}
			if len(state.argNums) > 0 {
				// Continue with the next sequential argument.
				argNum = state.argNums[len(state.argNums)-1] + 1
			}
			for _, n := range state.argNums {
				if n >= maxArgNum {
					maxArgNum = n + 1
				}
			}
		}
	}
	// Dotdotdot is hard.
	if call.Ellipsis.IsValid() && maxArgNum >= len(call.Args)-1 {
		return
	}
	// There should be no leftover arguments.
	if maxArgNum != len(call.Args) {
		expect := maxArgNum - firstArg
		numArgs := len(call.Args) - firstArg
		f.Badf(call.Pos(), "wrong number of args for format in %s call: %d needed but %d args", name, expect, numArgs)
	}
}
示例#18
0
文件: source.go 项目: callistoaz/3
func (w *World) compileSource(n *ast.CallExpr) Expr {
	if len(n.Args) != 1 {
		panic(err(n.Pos(), "source() needs 1 string argument, got", len(n.Args)))
	}
	arg := n.Args[0]
	if lit, ok := arg.(*ast.BasicLit); ok && lit.Kind == token.STRING {

		code, err1 := ioutil.ReadFile(lit.Value[1 : len(lit.Value)-1])
		if err1 != nil {
			panic(err(n.Pos(), err1))
		}
		block, err2 := w.Compile(string(code))
		if err1 != nil {
			panic(err(n.Pos(), err2))
		}
		return block
	} else {
		panic(err(n.Pos(), "source() needs literal string argument"))
	}
}
示例#19
0
文件: print.go 项目: xorrbit/golang
// checkPrint checks a call to an unformatted print routine such as Println.
// The skip argument records how many arguments to ignore; that is,
// call.Args[skip] is the first argument to be printed.
func (f *File) checkPrint(call *ast.CallExpr, name string, skip int) {
	isLn := strings.HasSuffix(name, "ln")
	isF := strings.HasPrefix(name, "F")
	args := call.Args
	// check for Println(os.Stderr, ...)
	if skip == 0 && !isF && len(args) > 0 {
		if sel, ok := args[0].(*ast.SelectorExpr); ok {
			if x, ok := sel.X.(*ast.Ident); ok {
				if x.Name == "os" && strings.HasPrefix(sel.Sel.Name, "Std") {
					f.Warnf(call.Pos(), "first argument to %s is %s.%s", name, x.Name, sel.Sel.Name)
				}
			}
		}
	}
	if len(args) <= skip {
		// TODO: check that the receiver of Error() is of type error.
		if !isLn && name != "Error" {
			f.Badf(call.Pos(), "no args in %s call", name)
		}
		return
	}
	arg := args[skip]
	if lit, ok := arg.(*ast.BasicLit); ok && lit.Kind == token.STRING {
		if strings.Contains(lit.Value, "%") {
			f.Badf(call.Pos(), "possible formatting directive in %s call", name)
		}
	}
	if isLn {
		// The last item, if a string, should not have a newline.
		arg = args[len(call.Args)-1]
		if lit, ok := arg.(*ast.BasicLit); ok && lit.Kind == token.STRING {
			if strings.HasSuffix(lit.Value, `\n"`) {
				f.Badf(call.Pos(), "%s call ends with newline", name)
			}
		}
	}
}
示例#20
0
// checkPrintf checks a call to a formatted print routine such as Printf.
// The skip argument records how many arguments to ignore; that is,
// call.Args[skip] is (well, should be) the format argument.
func (f *File) checkPrintf(call *ast.CallExpr, name string, skip int) {
	if len(call.Args) <= skip {
		return
	}
	// Common case: literal is first argument.
	arg := call.Args[skip]
	lit, ok := arg.(*ast.BasicLit)
	if !ok {
		// Too hard to check.
		if *verbose {
			f.Warn(call.Pos(), "can't check non-literal format in call to", name)
		}
		return
	}
	if lit.Kind == token.STRING {
		if !strings.Contains(lit.Value, "%") {
			if len(call.Args) > skip+1 {
				f.Badf(call.Pos(), "no formatting directive in %s call", name)
			}
			return
		}
	}
	// Hard part: check formats against args.
	// Trivial but useful test: count.
	numArgs := 0
	for i, w := 0, 0; i < len(lit.Value); i += w {
		w = 1
		if lit.Value[i] == '%' {
			nbytes, nargs := f.parsePrintfVerb(call, lit.Value[i:])
			w = nbytes
			numArgs += nargs
		}
	}
	expect := len(call.Args) - (skip + 1)
	if numArgs != expect {
		f.Badf(call.Pos(), "wrong number of args in %s call: %d needed but %d args", name, numArgs, expect)
	}
}
示例#21
0
文件: call.go 项目: kyeongdong/3
func (w *World) compileCallExpr(n *ast.CallExpr) Expr {
	// compile function or method to be called
	var f Expr
	var fname string
	switch Fun := n.Fun.(type) {
	default:
		panic(err(n.Pos(), "not allowed:", typ(n.Fun)))
	case *ast.Ident: // function call
		fname = Fun.Name
		if fname == "source" {
			return w.compileSource(n)
		}
		f = w.compileExpr(Fun)
	case *ast.SelectorExpr: // method call
		f = w.compileSelectorStmt(Fun)
		fname = Fun.Sel.Name
	}
	if f.Type().Kind() != reflect.Func {
		panic(err(n.Pos(), "can not call", Format(n)))
	}

	// compile and check args
	args := make([]Expr, len(n.Args))
	variadic := f.Type().IsVariadic()
	if !variadic && len(n.Args) != f.Type().NumIn() {
		panic(err(n.Pos(), fname, "needs", f.Type().NumIn(), "arguments, got", len(n.Args))) // TODO: varargs
	}
	for i := range args {
		if variadic {
			args[i] = w.compileExpr(n.Args[i]) // no type check or conversion
		} else {
			args[i] = typeConv(n.Args[i].Pos(), w.compileExpr(n.Args[i]), f.Type().In(i))
		}
	}
	return &call{f, args}
}
示例#22
0
文件: builtins.go 项目: Greentor/go
// builtin type-checks a call to the built-in specified by id and
// returns true if the call is valid, with *x holding the result;
// but x.expr is not set. If the call is invalid, the result is
// false, and *x is undefined.
//
func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ bool) {
	// append is the only built-in that permits the use of ... for the last argument
	bin := predeclaredFuncs[id]
	if call.Ellipsis.IsValid() && id != _Append {
		check.invalidOp(call.Ellipsis, "invalid use of ... with built-in %s", bin.name)
		check.use(call.Args...)
		return
	}

	// For len(x) and cap(x) we need to know if x contains any function calls or
	// receive operations. Save/restore current setting and set hasCallOrRecv to
	// false for the evaluation of x so that we can check it afterwards.
	// Note: We must do this _before_ calling unpack because unpack evaluates the
	//       first argument before we even call arg(x, 0)!
	if id == _Len || id == _Cap {
		defer func(b bool) {
			check.hasCallOrRecv = b
		}(check.hasCallOrRecv)
		check.hasCallOrRecv = false
	}

	// determine actual arguments
	var arg getter
	nargs := len(call.Args)
	switch id {
	default:
		// make argument getter
		arg, nargs, _ = unpack(func(x *operand, i int) { check.multiExpr(x, call.Args[i]) }, nargs, false)
		if arg == nil {
			return
		}
		// evaluate first argument, if present
		if nargs > 0 {
			arg(x, 0)
			if x.mode == invalid {
				return
			}
		}
	case _Make, _New, _Offsetof, _Trace:
		// arguments require special handling
	}

	// check argument count
	{
		msg := ""
		if nargs < bin.nargs {
			msg = "not enough"
		} else if !bin.variadic && nargs > bin.nargs {
			msg = "too many"
		}
		if msg != "" {
			check.invalidOp(call.Rparen, "%s arguments for %s (expected %d, found %d)", msg, call, bin.nargs, nargs)
			return
		}
	}

	switch id {
	case _Append:
		// append(s S, x ...T) S, where T is the element type of S
		// spec: "The variadic function append appends zero or more values x to s of type
		// S, which must be a slice type, and returns the resulting slice, also of type S.
		// The values x are passed to a parameter of type ...T where T is the element type
		// of S and the respective parameter passing rules apply."
		S := x.typ
		var T Type
		if s, _ := S.Underlying().(*Slice); s != nil {
			T = s.elem
		} else {
			check.invalidArg(x.pos(), "%s is not a slice", x)
			return
		}

		// remember arguments that have been evaluated already
		alist := []operand{*x}

		// spec: "As a special case, append also accepts a first argument assignable
		// to type []byte with a second argument of string type followed by ... .
		// This form appends the bytes of the string.
		if nargs == 2 && call.Ellipsis.IsValid() && x.assignableTo(check.conf, NewSlice(universeByte), nil) {
			arg(x, 1)
			if x.mode == invalid {
				return
			}
			if isString(x.typ) {
				if check.Types != nil {
					sig := makeSig(S, S, x.typ)
					sig.variadic = true
					check.recordBuiltinType(call.Fun, sig)
				}
				x.mode = value
				x.typ = S
				break
			}
			alist = append(alist, *x)
			// fallthrough
		}

		// check general case by creating custom signature
		sig := makeSig(S, S, NewSlice(T)) // []T required for variadic signature
		sig.variadic = true
		check.arguments(x, call, sig, func(x *operand, i int) {
			// only evaluate arguments that have not been evaluated before
			if i < len(alist) {
				*x = alist[i]
				return
			}
			arg(x, i)
		}, nargs)
		// ok to continue even if check.arguments reported errors

		x.mode = value
		x.typ = S
		if check.Types != nil {
			check.recordBuiltinType(call.Fun, sig)
		}

	case _Cap, _Len:
		// cap(x)
		// len(x)
		mode := invalid
		var typ Type
		var val constant.Value
		switch typ = implicitArrayDeref(x.typ.Underlying()); t := typ.(type) {
		case *Basic:
			if isString(t) && id == _Len {
				if x.mode == constant_ {
					mode = constant_
					val = constant.MakeInt64(int64(len(constant.StringVal(x.val))))
				} else {
					mode = value
				}
			}

		case *Array:
			mode = value
			// spec: "The expressions len(s) and cap(s) are constants
			// if the type of s is an array or pointer to an array and
			// the expression s does not contain channel receives or
			// function calls; in this case s is not evaluated."
			if !check.hasCallOrRecv {
				mode = constant_
				val = constant.MakeInt64(t.len)
			}

		case *Slice, *Chan:
			mode = value

		case *Map:
			if id == _Len {
				mode = value
			}
		}

		if mode == invalid {
			check.invalidArg(x.pos(), "%s for %s", x, bin.name)
			return
		}

		x.mode = mode
		x.typ = Typ[Int]
		x.val = val
		if check.Types != nil && mode != constant_ {
			check.recordBuiltinType(call.Fun, makeSig(x.typ, typ))
		}

	case _Close:
		// close(c)
		c, _ := x.typ.Underlying().(*Chan)
		if c == nil {
			check.invalidArg(x.pos(), "%s is not a channel", x)
			return
		}
		if c.dir == RecvOnly {
			check.invalidArg(x.pos(), "%s must not be a receive-only channel", x)
			return
		}

		x.mode = novalue
		if check.Types != nil {
			check.recordBuiltinType(call.Fun, makeSig(nil, c))
		}

	case _Complex:
		// complex(x, y floatT) complexT
		var y operand
		arg(&y, 1)
		if y.mode == invalid {
			return
		}

		// convert or check untyped arguments
		d := 0
		if isUntyped(x.typ) {
			d |= 1
		}
		if isUntyped(y.typ) {
			d |= 2
		}
		switch d {
		case 0:
			// x and y are typed => nothing to do
		case 1:
			// only x is untyped => convert to type of y
			check.convertUntyped(x, y.typ)
		case 2:
			// only y is untyped => convert to type of x
			check.convertUntyped(&y, x.typ)
		case 3:
			// x and y are untyped =>
			// 1) if both are constants, convert them to untyped
			//    floating-point numbers if possible,
			// 2) if one of them is not constant (possible because
			//    it contains a shift that is yet untyped), convert
			//    both of them to float64 since they must have the
			//    same type to succeed (this will result in an error
			//    because shifts of floats are not permitted)
			if x.mode == constant_ && y.mode == constant_ {
				toFloat := func(x *operand) {
					if isNumeric(x.typ) && constant.Sign(constant.Imag(x.val)) == 0 {
						x.typ = Typ[UntypedFloat]
					}
				}
				toFloat(x)
				toFloat(&y)
			} else {
				check.convertUntyped(x, Typ[Float64])
				check.convertUntyped(&y, Typ[Float64])
				// x and y should be invalid now, but be conservative
				// and check below
			}
		}
		if x.mode == invalid || y.mode == invalid {
			return
		}

		// both argument types must be identical
		if !Identical(x.typ, y.typ) {
			check.invalidArg(x.pos(), "mismatched types %s and %s", x.typ, y.typ)
			return
		}

		// the argument types must be of floating-point type
		if !isFloat(x.typ) {
			check.invalidArg(x.pos(), "arguments have type %s, expected floating-point", x.typ)
			return
		}

		// if both arguments are constants, the result is a constant
		if x.mode == constant_ && y.mode == constant_ {
			x.val = constant.BinaryOp(constant.ToFloat(x.val), token.ADD, constant.MakeImag(constant.ToFloat(y.val)))
		} else {
			x.mode = value
		}

		// determine result type
		var res BasicKind
		switch x.typ.Underlying().(*Basic).kind {
		case Float32:
			res = Complex64
		case Float64:
			res = Complex128
		case UntypedFloat:
			res = UntypedComplex
		default:
			unreachable()
		}
		resTyp := Typ[res]

		if check.Types != nil && x.mode != constant_ {
			check.recordBuiltinType(call.Fun, makeSig(resTyp, x.typ, x.typ))
		}

		x.typ = resTyp

	case _Copy:
		// copy(x, y []T) int
		var dst Type
		if t, _ := x.typ.Underlying().(*Slice); t != nil {
			dst = t.elem
		}

		var y operand
		arg(&y, 1)
		if y.mode == invalid {
			return
		}
		var src Type
		switch t := y.typ.Underlying().(type) {
		case *Basic:
			if isString(y.typ) {
				src = universeByte
			}
		case *Slice:
			src = t.elem
		}

		if dst == nil || src == nil {
			check.invalidArg(x.pos(), "copy expects slice arguments; found %s and %s", x, &y)
			return
		}

		if !Identical(dst, src) {
			check.invalidArg(x.pos(), "arguments to copy %s and %s have different element types %s and %s", x, &y, dst, src)
			return
		}

		if check.Types != nil {
			check.recordBuiltinType(call.Fun, makeSig(Typ[Int], x.typ, y.typ))
		}
		x.mode = value
		x.typ = Typ[Int]

	case _Delete:
		// delete(m, k)
		m, _ := x.typ.Underlying().(*Map)
		if m == nil {
			check.invalidArg(x.pos(), "%s is not a map", x)
			return
		}
		arg(x, 1) // k
		if x.mode == invalid {
			return
		}

		if !x.assignableTo(check.conf, m.key, nil) {
			check.invalidArg(x.pos(), "%s is not assignable to %s", x, m.key)
			return
		}

		x.mode = novalue
		if check.Types != nil {
			check.recordBuiltinType(call.Fun, makeSig(nil, m, m.key))
		}

	case _Imag, _Real:
		// imag(complexT) floatT
		// real(complexT) floatT

		// convert or check untyped argument
		if isUntyped(x.typ) {
			if x.mode == constant_ {
				// an untyped constant number can alway be considered
				// as a complex constant
				if isNumeric(x.typ) {
					x.typ = Typ[UntypedComplex]
				}
			} else {
				// an untyped non-constant argument may appear if
				// it contains a (yet untyped non-constant) shift
				// expression: convert it to complex128 which will
				// result in an error (shift of complex value)
				check.convertUntyped(x, Typ[Complex128])
				// x should be invalid now, but be conservative and check
				if x.mode == invalid {
					return
				}
			}
		}

		// the argument must be of complex type
		if !isComplex(x.typ) {
			check.invalidArg(x.pos(), "argument has type %s, expected complex type", x.typ)
			return
		}

		// if the argument is a constant, the result is a constant
		if x.mode == constant_ {
			if id == _Real {
				x.val = constant.Real(x.val)
			} else {
				x.val = constant.Imag(x.val)
			}
		} else {
			x.mode = value
		}

		// determine result type
		var res BasicKind
		switch x.typ.Underlying().(*Basic).kind {
		case Complex64:
			res = Float32
		case Complex128:
			res = Float64
		case UntypedComplex:
			res = UntypedFloat
		default:
			unreachable()
		}
		resTyp := Typ[res]

		if check.Types != nil && x.mode != constant_ {
			check.recordBuiltinType(call.Fun, makeSig(resTyp, x.typ))
		}

		x.typ = resTyp

	case _Make:
		// make(T, n)
		// make(T, n, m)
		// (no argument evaluated yet)
		arg0 := call.Args[0]
		T := check.typ(arg0)
		if T == Typ[Invalid] {
			return
		}

		var min int // minimum number of arguments
		switch T.Underlying().(type) {
		case *Slice:
			min = 2
		case *Map, *Chan:
			min = 1
		default:
			check.invalidArg(arg0.Pos(), "cannot make %s; type must be slice, map, or channel", arg0)
			return
		}
		if nargs < min || min+1 < nargs {
			check.errorf(call.Pos(), "%s expects %d or %d arguments; found %d", call, min, min+1, nargs)
			return
		}
		var sizes []int64 // constant integer arguments, if any
		for _, arg := range call.Args[1:] {
			if s, ok := check.index(arg, -1); ok && s >= 0 {
				sizes = append(sizes, s)
			}
		}
		if len(sizes) == 2 && sizes[0] > sizes[1] {
			check.invalidArg(call.Args[1].Pos(), "length and capacity swapped")
			// safe to continue
		}
		x.mode = value
		x.typ = T
		if check.Types != nil {
			params := [...]Type{T, Typ[Int], Typ[Int]}
			check.recordBuiltinType(call.Fun, makeSig(x.typ, params[:1+len(sizes)]...))
		}

	case _New:
		// new(T)
		// (no argument evaluated yet)
		T := check.typ(call.Args[0])
		if T == Typ[Invalid] {
			return
		}

		x.mode = value
		x.typ = &Pointer{base: T}
		if check.Types != nil {
			check.recordBuiltinType(call.Fun, makeSig(x.typ, T))
		}

	case _Panic:
		// panic(x)
		T := new(Interface)
		check.assignment(x, T, "argument to panic")
		if x.mode == invalid {
			return
		}

		x.mode = novalue
		if check.Types != nil {
			check.recordBuiltinType(call.Fun, makeSig(nil, T))
		}

	case _Print, _Println:
		// print(x, y, ...)
		// println(x, y, ...)
		var params []Type
		if nargs > 0 {
			params = make([]Type, nargs)
			for i := 0; i < nargs; i++ {
				if i > 0 {
					arg(x, i) // first argument already evaluated
				}
				check.assignment(x, nil, "argument to "+predeclaredFuncs[id].name)
				if x.mode == invalid {
					// TODO(gri) "use" all arguments?
					return
				}
				params[i] = x.typ
			}
		}

		x.mode = novalue
		if check.Types != nil {
			check.recordBuiltinType(call.Fun, makeSig(nil, params...))
		}

	case _Recover:
		// recover() interface{}
		x.mode = value
		x.typ = new(Interface)
		if check.Types != nil {
			check.recordBuiltinType(call.Fun, makeSig(x.typ))
		}

	case _Alignof:
		// unsafe.Alignof(x T) uintptr
		check.assignment(x, nil, "argument to unsafe.Alignof")
		if x.mode == invalid {
			return
		}

		x.mode = constant_
		x.val = constant.MakeInt64(check.conf.alignof(x.typ))
		x.typ = Typ[Uintptr]
		// result is constant - no need to record signature

	case _Offsetof:
		// unsafe.Offsetof(x T) uintptr, where x must be a selector
		// (no argument evaluated yet)
		arg0 := call.Args[0]
		selx, _ := unparen(arg0).(*ast.SelectorExpr)
		if selx == nil {
			check.invalidArg(arg0.Pos(), "%s is not a selector expression", arg0)
			check.use(arg0)
			return
		}

		check.expr(x, selx.X)
		if x.mode == invalid {
			return
		}

		base := derefStructPtr(x.typ)
		sel := selx.Sel.Name
		obj, index, indirect := LookupFieldOrMethod(base, false, check.pkg, sel)
		switch obj.(type) {
		case nil:
			check.invalidArg(x.pos(), "%s has no single field %s", base, sel)
			return
		case *Func:
			// TODO(gri) Using derefStructPtr may result in methods being found
			// that don't actually exist. An error either way, but the error
			// message is confusing. See: https://play.golang.org/p/al75v23kUy ,
			// but go/types reports: "invalid argument: x.m is a method value".
			check.invalidArg(arg0.Pos(), "%s is a method value", arg0)
			return
		}
		if indirect {
			check.invalidArg(x.pos(), "field %s is embedded via a pointer in %s", sel, base)
			return
		}

		// TODO(gri) Should we pass x.typ instead of base (and indirect report if derefStructPtr indirected)?
		check.recordSelection(selx, FieldVal, base, obj, index, false)

		offs := check.conf.offsetof(base, index)
		x.mode = constant_
		x.val = constant.MakeInt64(offs)
		x.typ = Typ[Uintptr]
		// result is constant - no need to record signature

	case _Sizeof:
		// unsafe.Sizeof(x T) uintptr
		check.assignment(x, nil, "argument to unsafe.Sizeof")
		if x.mode == invalid {
			return
		}

		x.mode = constant_
		x.val = constant.MakeInt64(check.conf.sizeof(x.typ))
		x.typ = Typ[Uintptr]
		// result is constant - no need to record signature

	case _Assert:
		// assert(pred) causes a typechecker error if pred is false.
		// The result of assert is the value of pred if there is no error.
		// Note: assert is only available in self-test mode.
		if x.mode != constant_ || !isBoolean(x.typ) {
			check.invalidArg(x.pos(), "%s is not a boolean constant", x)
			return
		}
		if x.val.Kind() != constant.Bool {
			check.errorf(x.pos(), "internal error: value of %s should be a boolean constant", x)
			return
		}
		if !constant.BoolVal(x.val) {
			check.errorf(call.Pos(), "%s failed", call)
			// compile-time assertion failure - safe to continue
		}
		// result is constant - no need to record signature

	case _Trace:
		// trace(x, y, z, ...) dumps the positions, expressions, and
		// values of its arguments. The result of trace is the value
		// of the first argument.
		// Note: trace is only available in self-test mode.
		// (no argument evaluated yet)
		if nargs == 0 {
			check.dump("%s: trace() without arguments", call.Pos())
			x.mode = novalue
			break
		}
		var t operand
		x1 := x
		for _, arg := range call.Args {
			check.rawExpr(x1, arg, nil) // permit trace for types, e.g.: new(trace(T))
			check.dump("%s: %s", x1.pos(), x1)
			x1 = &t // use incoming x only for first argument
		}
		// trace is only available in test mode - no need to record signature

	default:
		unreachable()
	}

	return true
}
示例#23
0
// builtin type-checks a call to the built-in specified by id and
// returns true if the call is valid, with *x holding the result;
// but x.expr is not set. If the call is invalid, the result is
// false, and *x is undefined.
//
func (check *checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ bool) {
	// append is the only built-in that permits the use of ... for the last argument
	bin := predeclaredFuncs[id]
	if call.Ellipsis.IsValid() && id != _Append {
		check.invalidOp(call.Ellipsis, "invalid use of ... with built-in %s", bin.name)
		check.use(call.Args)
		return
	}

	// determine actual arguments
	var arg getter
	nargs := len(call.Args)
	switch id {
	default:
		// make argument getter
		arg, nargs = unpack(func(x *operand, i int) { check.expr(x, call.Args[i]) }, nargs, false)
		// evaluate first argument, if present
		if nargs > 0 {
			arg(x, 0)
			if x.mode == invalid {
				return
			}
		}
	case _Make, _New, _Offsetof, _Trace:
		// arguments require special handling
	}

	// check argument count
	{
		msg := ""
		if nargs < bin.nargs {
			msg = "not enough"
		} else if !bin.variadic && nargs > bin.nargs {
			msg = "too many"
		}
		if msg != "" {
			check.invalidOp(call.Rparen, "%s arguments for %s (expected %d, found %d)", msg, call, bin.nargs, nargs)
			return
		}
	}

	switch id {
	case _Append:
		// append(s S, x ...T) S, where T is the element type of S
		// spec: "The variadic function append appends zero or more values x to s of type
		// S, which must be a slice type, and returns the resulting slice, also of type S.
		// The values x are passed to a parameter of type ...T where T is the element type
		// of S and the respective parameter passing rules apply."
		S := x.typ
		var T Type
		if s, _ := S.Underlying().(*Slice); s != nil {
			T = s.elem
		} else {
			check.invalidArg(x.pos(), "%s is not a slice", x)
			return
		}

		// remember arguments that have been evaluated already
		alist := []operand{*x}

		// spec: "As a special case, append also accepts a first argument assignable
		// to type []byte with a second argument of string type followed by ... .
		// This form appends the bytes of the string.
		if nargs == 2 && call.Ellipsis.IsValid() && x.isAssignableTo(check.conf, NewSlice(Typ[Byte])) {
			arg(x, 1)
			if x.mode == invalid {
				return
			}
			if isString(x.typ) {
				if check.Types != nil {
					sig := makeSig(S, S, NewSlice(Typ[Byte]))
					sig.isVariadic = true
					check.recordBuiltinType(call.Fun, sig)
				}
				x.mode = value
				x.typ = S
				break
			}
			alist = append(alist, *x)
			// fallthrough
		}

		// check general case by creating custom signature
		sig := makeSig(S, S, NewSlice(T)) // []T required for variadic signature
		sig.isVariadic = true
		check.arguments(x, call, sig, func(x *operand, i int) {
			// only evaluate arguments that have not been evaluated before
			if i < len(alist) {
				*x = alist[i]
				return
			}
			arg(x, i)
		}, nargs)
		// ok to continue even if check.arguments reported errors

		x.mode = value
		x.typ = S
		if check.Types != nil {
			check.recordBuiltinType(call.Fun, sig)
		}

	case _Cap, _Len:
		// cap(x)
		// len(x)
		mode := invalid
		var typ Type
		var val exact.Value
		switch typ = implicitArrayDeref(x.typ.Underlying()); t := typ.(type) {
		case *Basic:
			if isString(t) && id == _Len {
				if x.mode == constant {
					mode = constant
					val = exact.MakeInt64(int64(len(exact.StringVal(x.val))))
				} else {
					mode = value
				}
			}

		case *Array:
			mode = value
			// spec: "The expressions len(s) and cap(s) are constants
			// if the type of s is an array or pointer to an array and
			// the expression s does not contain channel receives or
			// function calls; in this case s is not evaluated."
			if !check.containsCallsOrReceives(x.expr) {
				mode = constant
				val = exact.MakeInt64(t.len)
			}

		case *Slice, *Chan:
			mode = value

		case *Map:
			if id == _Len {
				mode = value
			}
		}

		if mode == invalid {
			check.invalidArg(x.pos(), "%s for %s", x, bin.name)
			return
		}

		x.mode = mode
		x.typ = Typ[Int]
		x.val = val
		if check.Types != nil && mode != constant {
			check.recordBuiltinType(call.Fun, makeSig(x.typ, typ))
		}

	case _Close:
		// close(c)
		c, _ := x.typ.Underlying().(*Chan)
		if c == nil {
			check.invalidArg(x.pos(), "%s is not a channel", x)
			return
		}
		if c.dir&ast.SEND == 0 {
			check.invalidArg(x.pos(), "%s must not be a receive-only channel", x)
			return
		}

		x.mode = novalue
		if check.Types != nil {
			check.recordBuiltinType(call.Fun, makeSig(nil, c))
		}

	case _Complex:
		// complex(x, y realT) complexT
		if !check.complexArg(x) {
			return
		}

		var y operand
		arg(&y, 1)
		if y.mode == invalid {
			return
		}
		if !check.complexArg(&y) {
			return
		}

		check.convertUntyped(x, y.typ)
		if x.mode == invalid {
			return
		}
		check.convertUntyped(&y, x.typ)
		if y.mode == invalid {
			return
		}

		if !IsIdentical(x.typ, y.typ) {
			check.invalidArg(x.pos(), "mismatched types %s and %s", x.typ, y.typ)
			return
		}

		if x.mode == constant && y.mode == constant {
			x.val = exact.BinaryOp(x.val, token.ADD, exact.MakeImag(y.val))
		} else {
			x.mode = value
		}

		realT := x.typ
		complexT := Typ[Invalid]
		switch realT.Underlying().(*Basic).kind {
		case Float32:
			complexT = Typ[Complex64]
		case Float64:
			complexT = Typ[Complex128]
		case UntypedInt, UntypedRune, UntypedFloat:
			if x.mode == constant {
				realT = defaultType(realT).(*Basic)
				complexT = Typ[UntypedComplex]
			} else {
				// untyped but not constant; probably because one
				// operand is a non-constant shift of untyped lhs
				realT = Typ[Float64]
				complexT = Typ[Complex128]
			}
		default:
			check.invalidArg(x.pos(), "float32 or float64 arguments expected")
			return
		}

		x.typ = complexT
		if check.Types != nil && x.mode != constant {
			check.recordBuiltinType(call.Fun, makeSig(complexT, realT, realT))
		}

		if x.mode != constant {
			// The arguments have now their final types, which at run-
			// time will be materialized. Update the expression trees.
			// If the current types are untyped, the materialized type
			// is the respective default type.
			// (If the result is constant, the arguments are never
			// materialized and there is nothing to do.)
			check.updateExprType(x.expr, realT, true)
			check.updateExprType(y.expr, realT, true)
		}

	case _Copy:
		// copy(x, y []T) int
		var dst Type
		if t, _ := x.typ.Underlying().(*Slice); t != nil {
			dst = t.elem
		}

		var y operand
		arg(&y, 1)
		if y.mode == invalid {
			return
		}
		var src Type
		switch t := y.typ.Underlying().(type) {
		case *Basic:
			if isString(y.typ) {
				src = Typ[Byte]
			}
		case *Slice:
			src = t.elem
		}

		if dst == nil || src == nil {
			check.invalidArg(x.pos(), "copy expects slice arguments; found %s and %s", x, &y)
			return
		}

		if !IsIdentical(dst, src) {
			check.invalidArg(x.pos(), "arguments to copy %s and %s have different element types %s and %s", x, &y, dst, src)
			return
		}

		x.mode = value
		x.typ = Typ[Int]
		if check.Types != nil {
			S := NewSlice(dst)
			check.recordBuiltinType(call.Fun, makeSig(x.typ, S, S))
		}

	case _Delete:
		// delete(m, k)
		m, _ := x.typ.Underlying().(*Map)
		if m == nil {
			check.invalidArg(x.pos(), "%s is not a map", x)
			return
		}
		arg(x, 1) // k
		if x.mode == invalid {
			return
		}

		if !x.isAssignableTo(check.conf, m.key) {
			check.invalidArg(x.pos(), "%s is not assignable to %s", x, m.key)
			return
		}

		x.mode = novalue
		if check.Types != nil {
			check.recordBuiltinType(call.Fun, makeSig(nil, m, m.key))
		}

	case _Imag, _Real:
		// imag(complexT) realT
		// real(complexT) realT
		if !isComplex(x.typ) {
			check.invalidArg(x.pos(), "%s must be a complex number", x)
			return
		}
		if x.mode == constant {
			if id == _Real {
				x.val = exact.Real(x.val)
			} else {
				x.val = exact.Imag(x.val)
			}
		} else {
			x.mode = value
		}
		var k BasicKind
		switch x.typ.Underlying().(*Basic).kind {
		case Complex64:
			k = Float32
		case Complex128:
			k = Float64
		case UntypedComplex:
			k = UntypedFloat
		default:
			unreachable()
		}

		if check.Types != nil && x.mode != constant {
			check.recordBuiltinType(call.Fun, makeSig(Typ[k], x.typ))
		}
		x.typ = Typ[k]

	case _Make:
		// make(T, n)
		// make(T, n, m)
		// (no argument evaluated yet)
		arg0 := call.Args[0]
		T := check.typ(arg0, nil, false)
		if T == Typ[Invalid] {
			return
		}
		var min int // minimum number of arguments
		switch T.Underlying().(type) {
		case *Slice:
			min = 2
		case *Map, *Chan:
			min = 1
		default:
			check.invalidArg(arg0.Pos(), "cannot make %s; type must be slice, map, or channel", arg0)
			return
		}
		if nargs < min || min+1 < nargs {
			check.errorf(call.Pos(), "%s expects %d or %d arguments; found %d", call, min, min+1, nargs)
			return
		}
		var sizes []int64 // constant integer arguments, if any
		for _, arg := range call.Args[1:] {
			if s, ok := check.index(arg, -1); ok && s >= 0 {
				sizes = append(sizes, s)
			}
		}
		if len(sizes) == 2 && sizes[0] > sizes[1] {
			check.invalidArg(call.Args[1].Pos(), "length and capacity swapped")
			// safe to continue
		}
		x.mode = variable
		x.typ = T
		if check.Types != nil {
			params := [...]Type{T, Typ[Int], Typ[Int]}
			check.recordBuiltinType(call.Fun, makeSig(x.typ, params[:1+len(sizes)]...))
		}

	case _New:
		// new(T)
		// (no argument evaluated yet)
		T := check.typ(call.Args[0], nil, false)
		if T == Typ[Invalid] {
			return
		}

		x.mode = variable
		x.typ = &Pointer{base: T}
		if check.Types != nil {
			check.recordBuiltinType(call.Fun, makeSig(x.typ, T))
		}

	case _Panic:
		// panic(x)
		arg(x, 0)
		if x.mode == invalid {
			return
		}
		// TODO(gri) arguments must be assignable to _

		x.mode = novalue
		if check.Types != nil {
			check.recordBuiltinType(call.Fun, makeSig(nil, new(Interface)))
		}

	case _Print, _Println:
		// print(x, y, ...)
		// println(x, y, ...)
		var params []Type
		if nargs > 0 {
			params = make([]Type, nargs)
			params[0] = x.typ // first argument already evaluated
			for i := 1; i < nargs; i++ {
				arg(x, i)
				if x.mode == invalid {
					return
				}
				params[i] = x.typ
				// TODO(gri) arguments must be assignable to _
			}
		}

		x.mode = novalue
		if check.Types != nil {
			check.recordBuiltinType(call.Fun, makeSig(nil, params...))
		}

	case _Recover:
		// recover() interface{}
		x.mode = value
		x.typ = new(Interface)
		if check.Types != nil {
			check.recordBuiltinType(call.Fun, makeSig(x.typ))
		}

	case _Alignof:
		// unsafe.Alignof(x T) uintptr
		// TODO(gri) argument must be assignable to _
		x.mode = constant
		x.val = exact.MakeInt64(check.conf.alignof(x.typ))
		x.typ = Typ[Uintptr]
		// result is constant - no need to record signature

	case _Offsetof:
		// unsafe.Offsetof(x T) uintptr, where x must be a selector
		// (no argument evaluated yet)
		arg0 := call.Args[0]
		selx, _ := unparen(arg0).(*ast.SelectorExpr)
		if selx == nil {
			check.invalidArg(arg0.Pos(), "%s is not a selector expression", arg0)
			check.rawExpr(x, arg0, nil) // evaluate to avoid spurious "declared but not used" errors
			return
		}
		check.expr(x, selx.X)
		if x.mode == invalid {
			return
		}
		base := derefStructPtr(x.typ)
		sel := selx.Sel.Name
		obj, index, indirect := LookupFieldOrMethod(base, check.pkg, sel)
		switch obj.(type) {
		case nil:
			check.invalidArg(x.pos(), "%s has no single field %s", base, sel)
			return
		case *Func:
			check.invalidArg(arg0.Pos(), "%s is a method value", arg0)
			return
		}
		if indirect {
			check.invalidArg(x.pos(), "field %s is embedded via a pointer in %s", sel, base)
			return
		}

		// TODO(gri) Should we pass x.typ instead of base (and indirect report if derefStructPtr indirected)?
		check.recordSelection(selx, FieldVal, base, obj, index, false)

		offs := check.conf.offsetof(base, index)
		x.mode = constant
		x.val = exact.MakeInt64(offs)
		x.typ = Typ[Uintptr]
		// result is constant - no need to record signature

	case _Sizeof:
		// unsafe.Sizeof(x T) uintptr
		// TODO(gri) argument must be assignable to _
		x.mode = constant
		x.val = exact.MakeInt64(check.conf.sizeof(x.typ))
		x.typ = Typ[Uintptr]
		// result is constant - no need to record signature

	case _Assert:
		// assert(pred) causes a typechecker error if pred is false.
		// The result of assert is the value of pred if there is no error.
		// Note: assert is only available in self-test mode.
		if x.mode != constant || !isBoolean(x.typ) {
			check.invalidArg(x.pos(), "%s is not a boolean constant", x)
			return
		}
		if x.val.Kind() != exact.Bool {
			check.errorf(x.pos(), "internal error: value of %s should be a boolean constant", x)
			return
		}
		if !exact.BoolVal(x.val) {
			check.errorf(call.Pos(), "%s failed", call)
			// compile-time assertion failure - safe to continue
		}
		// result is constant - no need to record signature

	case _Trace:
		// trace(x, y, z, ...) dumps the positions, expressions, and
		// values of its arguments. The result of trace is the value
		// of the first argument.
		// Note: trace is only available in self-test mode.
		// (no argument evaluated yet)
		if nargs == 0 {
			check.dump("%s: trace() without arguments", call.Pos())
			x.mode = novalue
			break
		}
		var t operand
		x1 := x
		for _, arg := range call.Args {
			check.rawExpr(x1, arg, nil) // permit trace for types, e.g.: new(trace(T))
			check.dump("%s: %s", x1.pos(), x1)
			x1 = &t // use incoming x only for first argument
		}
		// trace is only available in test mode - no need to record signature

	default:
		unreachable()
	}

	return true
}
示例#24
0
文件: print.go 项目: Harvey-OS/go
// checkPrint checks a call to an unformatted print routine such as Println.
func (f *File) checkPrint(call *ast.CallExpr, name string) {
	firstArg := 0
	typ := f.pkg.types[call.Fun].Type
	if typ == nil {
		// Skip checking functions with unknown type.
		return
	}
	if sig, ok := typ.(*types.Signature); ok {
		if !sig.Variadic() {
			// Skip checking non-variadic functions.
			return
		}
		params := sig.Params()
		firstArg = params.Len() - 1

		typ := params.At(firstArg).Type()
		typ = typ.(*types.Slice).Elem()
		it, ok := typ.(*types.Interface)
		if !ok || !it.Empty() {
			// Skip variadic functions accepting non-interface{} args.
			return
		}
	}
	args := call.Args
	if len(args) <= firstArg {
		// Skip calls without variadic args.
		return
	}
	args = args[firstArg:]

	// check for Println(os.Stderr, ...)
	if firstArg == 0 {
		if sel, ok := args[0].(*ast.SelectorExpr); ok {
			if x, ok := sel.X.(*ast.Ident); ok {
				if x.Name == "os" && strings.HasPrefix(sel.Sel.Name, "Std") {
					f.Badf(call.Pos(), "first argument to %s is %s.%s", name, x.Name, sel.Sel.Name)
				}
			}
		}
	}
	arg := args[0]
	if lit, ok := arg.(*ast.BasicLit); ok && lit.Kind == token.STRING {
		// Ignore trailing % character in lit.Value.
		// The % in "abc 0.0%" couldn't be a formatting directive.
		s := strings.TrimSuffix(lit.Value, `%"`)
		if strings.Contains(s, "%") {
			f.Badf(call.Pos(), "possible formatting directive in %s call", name)
		}
	}
	if strings.HasSuffix(name, "ln") {
		// The last item, if a string, should not have a newline.
		arg = args[len(args)-1]
		if lit, ok := arg.(*ast.BasicLit); ok && lit.Kind == token.STRING {
			if strings.HasSuffix(lit.Value, `\n"`) {
				f.Badf(call.Pos(), "%s call ends with newline", name)
			}
		}
	}
	for _, arg := range args {
		if f.isFunctionValue(arg) {
			f.Badf(call.Pos(), "arg %s in %s call is a function value, not a function call", f.gofmt(arg), name)
		}
		if f.recursiveStringer(arg) {
			f.Badf(call.Pos(), "arg %s in %s call causes recursive call to String method", f.gofmt(arg), name)
		}
	}
}
示例#25
0
// builtin typechecks a built-in call. The built-in type is bin, and iota is the current
// value of iota or -1 if iota doesn't have a value in the current context. The result
// of the call is returned via x. If the call has type errors, the returned x is marked
// as invalid (x.mode == invalid).
//
func (check *checker) builtin(x *operand, call *ast.CallExpr, bin *builtin, iota int) {
	args := call.Args
	id := bin.id

	// declare before goto's
	var arg0 ast.Expr
	var typ0 Type

	// check argument count
	n := len(args)
	msg := ""
	if n < bin.nargs {
		msg = "not enough"
	} else if !bin.isVariadic && n > bin.nargs {
		msg = "too many"
	}
	if msg != "" {
		check.invalidOp(call.Pos(), msg+"arguments for %s (expected %d, found %d)", call, bin.nargs, n)
		goto Error
	}

	// common case: evaluate first argument if present;
	// if it is an expression, x has the expression value
	if n > 0 {
		arg0 = args[0]
		switch id {
		case _Make, _New:
			// argument must be a type
			typ0 = check.typ(arg0, false)
			if typ0 == Typ[Invalid] {
				goto Error
			}
		case _Trace:
			// _Trace implementation does the work
		default:
			// argument must be an expression
			check.expr(x, arg0, nil, iota)
			if x.mode == invalid {
				goto Error
			}
			typ0 = underlying(x.typ)
		}
	}

	switch id {
	case _Append:
		s, ok := typ0.(*Slice)
		if !ok {
			check.invalidArg(x.pos(), "%s is not a typed slice", x)
			goto Error
		}
		for _, arg := range args[1:] {
			check.expr(x, arg, nil, iota)
			if x.mode == invalid {
				goto Error
			}
			// TODO(gri) check assignability
		}
		x.mode = value
		x.typ = s

	case _Cap, _Len:
		mode := invalid
		var val interface{}
		switch typ := implicitDeref(typ0).(type) {
		case *Basic:
			if isString(typ) && id == _Len {
				if x.mode == constant {
					mode = constant
					val = int64(len(x.val.(string)))
				} else {
					mode = value
				}
			}

		case *Array:
			mode = value
			if !containsCallsOrReceives(arg0) {
				mode = constant
				val = typ.Len
			}

		case *Slice, *Chan:
			mode = value

		case *Map:
			if id == _Len {
				mode = value
			}
		}

		if mode == invalid {
			check.invalidArg(x.pos(), "%s for %s", x, bin.name)
			goto Error
		}
		x.mode = mode
		x.typ = Typ[Int]
		x.val = val

	case _Close:
		ch, ok := typ0.(*Chan)
		if !ok {
			check.invalidArg(x.pos(), "%s is not a channel", x)
			goto Error
		}
		if ch.Dir&ast.SEND == 0 {
			check.invalidArg(x.pos(), "%s must not be a receive-only channel", x)
			goto Error
		}
		x.mode = novalue

	case _Complex:
		if !check.complexArg(x) {
			goto Error
		}

		var y operand
		check.expr(&y, args[1], nil, iota)
		if y.mode == invalid {
			goto Error
		}
		if !check.complexArg(&y) {
			goto Error
		}

		check.convertUntyped(x, y.typ)
		if x.mode == invalid {
			goto Error
		}
		check.convertUntyped(&y, x.typ)
		if y.mode == invalid {
			goto Error
		}

		if !isIdentical(x.typ, y.typ) {
			check.invalidArg(x.pos(), "mismatched types %s and %s", x.typ, y.typ)
			goto Error
		}

		if x.mode == constant && y.mode == constant {
			x.val = binaryOpConst(x.val, toImagConst(y.val), token.ADD, false)
		} else {
			x.mode = value
		}

		switch underlying(x.typ).(*Basic).Kind {
		case Float32:
			x.typ = Typ[Complex64]
		case Float64:
			x.typ = Typ[Complex128]
		case UntypedInt, UntypedRune, UntypedFloat:
			x.typ = Typ[UntypedComplex]
		default:
			check.invalidArg(x.pos(), "float32 or float64 arguments expected")
			goto Error
		}

	case _Copy:
		// TODO(gri) implements checks
		unimplemented()
		x.mode = value
		x.typ = Typ[Int]

	case _Delete:
		m, ok := typ0.(*Map)
		if !ok {
			check.invalidArg(x.pos(), "%s is not a map", x)
			goto Error
		}
		check.expr(x, args[1], nil, iota)
		if x.mode == invalid {
			goto Error
		}
		if !x.isAssignable(m.Key) {
			check.invalidArg(x.pos(), "%s is not assignable to %s", x, m.Key)
			goto Error
		}
		x.mode = novalue

	case _Imag, _Real:
		if !isComplex(typ0) {
			check.invalidArg(x.pos(), "%s must be a complex number", x)
			goto Error
		}
		if x.mode == constant {
			// nothing to do for x.val == 0
			if !isZeroConst(x.val) {
				c := x.val.(complex)
				if id == _Real {
					x.val = c.re
				} else {
					x.val = c.im
				}
			}
		} else {
			x.mode = value
		}
		k := Invalid
		switch typ0.(*Basic).Kind {
		case Complex64:
			k = Float32
		case Complex128:
			k = Float64
		case UntypedComplex:
			k = UntypedFloat
		default:
			unreachable()
		}
		x.typ = Typ[k]

	case _Make:
		var min int // minimum number of arguments
		switch underlying(typ0).(type) {
		case *Slice:
			min = 2
		case *Map, *Chan:
			min = 1
		default:
			check.invalidArg(arg0.Pos(), "cannot make %s; type must be slice, map, or channel", arg0)
			goto Error
		}
		if n := len(args); n < min || min+1 < n {
			check.errorf(call.Pos(), "%s expects %d or %d arguments; found %d", call, min, min+1, n)
			goto Error
		}
		var sizes []interface{} // constant integer arguments, if any
		for _, arg := range args[1:] {
			check.expr(x, arg, nil, iota)
			if x.isInteger() {
				if x.mode == constant {
					if isNegConst(x.val) {
						check.invalidArg(x.pos(), "%s must not be negative", x)
						// safe to continue
					} else {
						sizes = append(sizes, x.val) // x.val >= 0
					}
				}
			} else {
				check.invalidArg(x.pos(), "%s must be an integer", x)
				// safe to continue
			}
		}
		if len(sizes) == 2 && compareConst(sizes[0], sizes[1], token.GTR) {
			check.invalidArg(args[1].Pos(), "length and capacity swapped")
			// safe to continue
		}
		x.mode = variable
		x.typ = typ0

	case _New:
		x.mode = variable
		x.typ = &Pointer{Base: typ0}

	case _Panic, _Print, _Println:
		x.mode = novalue

	case _Recover:
		x.mode = value
		x.typ = emptyInterface

	case _Alignof:
		x.mode = constant
		x.typ = Typ[Uintptr]
		// For now we return 1 always as it satisfies the spec's alignment guarantees.
		// TODO(gri) Extend typechecker API so that platform-specific values can be
		//           provided.
		x.val = int64(1)

	case _Offsetof:
		if _, ok := unparen(x.expr).(*ast.SelectorExpr); !ok {
			check.invalidArg(x.pos(), "%s is not a selector", x)
			goto Error
		}
		x.mode = constant
		x.typ = Typ[Uintptr]
		// because of the size guarantees for basic types (> 0 for some),
		// returning 0 is only correct if two distinct non-zero size
		// structs can have the same address (the spec permits that)
		x.val = int64(0)

	case _Sizeof:
		// basic types with specified sizes have size guarantees; for all others we use 0
		var size int64
		if typ, ok := typ0.(*Basic); ok {
			size = typ.Size
		}
		x.mode = constant
		x.typ = Typ[Uintptr]
		x.val = size

	case _Assert:
		// assert(pred) causes a typechecker error if pred is false.
		// The result of assert is the value of pred if there is no error.
		// Note: assert is only available in self-test mode.
		if x.mode != constant || !isBoolean(typ0) {
			check.invalidArg(x.pos(), "%s is not a boolean constant", x)
			goto Error
		}
		pred, ok := x.val.(bool)
		if !ok {
			check.errorf(x.pos(), "internal error: value of %s should be a boolean constant", x)
			goto Error
		}
		if !pred {
			check.errorf(call.Pos(), "%s failed", call)
			// compile-time assertion failure - safe to continue
		}

	case _Trace:
		// trace(x, y, z, ...) dumps the positions, expressions, and
		// values of its arguments. The result of trace is the value
		// of the first argument.
		// Note: trace is only available in self-test mode.
		if len(args) == 0 {
			check.dump("%s: trace() without arguments", call.Pos())
			x.mode = novalue
			x.expr = call
			return
		}
		var t operand
		x1 := x
		for _, arg := range args {
			check.rawExpr(x1, arg, nil, iota, true) // permit trace for types, e.g.: new(trace(T))
			check.dump("%s: %s", x1.pos(), x1)
			x1 = &t // use incoming x only for first argument
		}

	default:
		check.invalidAST(call.Pos(), "unknown builtin id %d", id)
		goto Error
	}

	x.expr = call
	return

Error:
	x.mode = invalid
	x.expr = call
}
示例#26
0
// builtin typechecks a built-in call. The built-in type is bin, and iota is the current
// value of iota or -1 if iota doesn't have a value in the current context. The result
// of the call is returned via x. If the call has type errors, the returned x is marked
// as invalid (x.mode == invalid).
//
func (check *checker) builtin(x *operand, call *ast.CallExpr, bin *builtin, iota int) {
	args := call.Args
	id := bin.id

	// declare before goto's
	var arg0 ast.Expr // first argument, if present

	// check argument count
	n := len(args)
	msg := ""
	if n < bin.nargs {
		msg = "not enough"
	} else if !bin.isVariadic && n > bin.nargs {
		msg = "too many"
	}
	if msg != "" {
		check.invalidOp(call.Pos(), msg+" arguments for %s (expected %d, found %d)", call, bin.nargs, n)
		goto Error
	}

	// common case: evaluate first argument if present;
	// if it is an expression, x has the expression value
	if n > 0 {
		arg0 = args[0]
		switch id {
		case _Make, _New, _Print, _Println, _Offsetof, _Trace:
			// respective cases below do the work
		default:
			// argument must be an expression
			check.expr(x, arg0, nil, iota)
			if x.mode == invalid {
				goto Error
			}
		}
	}

	switch id {
	case _Append:
		if _, ok := underlying(x.typ).(*Slice); !ok {
			check.invalidArg(x.pos(), "%s is not a typed slice", x)
			goto Error
		}
		resultTyp := x.typ
		for _, arg := range args[1:] {
			check.expr(x, arg, nil, iota)
			if x.mode == invalid {
				goto Error
			}
			// TODO(gri) check assignability
		}
		x.mode = value
		x.typ = resultTyp

	case _Cap, _Len:
		mode := invalid
		var val exact.Value
		switch typ := implicitArrayDeref(underlying(x.typ)).(type) {
		case *Basic:
			if isString(typ) && id == _Len {
				if x.mode == constant {
					mode = constant
					val = exact.MakeInt64(int64(len(exact.StringVal(x.val))))
				} else {
					mode = value
				}
			}

		case *Array:
			mode = value
			// spec: "The expressions len(s) and cap(s) are constants
			// if the type of s is an array or pointer to an array and
			// the expression s does not contain channel receives or
			// function calls; in this case s is not evaluated."
			if !check.containsCallsOrReceives(arg0) {
				mode = constant
				val = exact.MakeInt64(typ.Len)
			}

		case *Slice, *Chan:
			mode = value

		case *Map:
			if id == _Len {
				mode = value
			}
		}

		if mode == invalid {
			check.invalidArg(x.pos(), "%s for %s", x, bin.name)
			goto Error
		}
		x.mode = mode
		x.typ = Typ[Int]
		x.val = val

	case _Close:
		ch, ok := underlying(x.typ).(*Chan)
		if !ok {
			check.invalidArg(x.pos(), "%s is not a channel", x)
			goto Error
		}
		if ch.Dir&ast.SEND == 0 {
			check.invalidArg(x.pos(), "%s must not be a receive-only channel", x)
			goto Error
		}
		x.mode = novalue

	case _Complex:
		if !check.complexArg(x) {
			goto Error
		}

		var y operand
		check.expr(&y, args[1], nil, iota)
		if y.mode == invalid {
			goto Error
		}
		if !check.complexArg(&y) {
			goto Error
		}

		check.convertUntyped(x, y.typ)
		if x.mode == invalid {
			goto Error
		}
		check.convertUntyped(&y, x.typ)
		if y.mode == invalid {
			goto Error
		}

		if !IsIdentical(x.typ, y.typ) {
			check.invalidArg(x.pos(), "mismatched types %s and %s", x.typ, y.typ)
			goto Error
		}

		typ := underlying(x.typ).(*Basic)
		if x.mode == constant && y.mode == constant {
			x.val = exact.BinaryOp(x.val, token.ADD, exact.MakeImag(y.val))
		} else {
			x.mode = value
		}

		switch typ.Kind {
		case Float32:
			x.typ = Typ[Complex64]
		case Float64:
			x.typ = Typ[Complex128]
		case UntypedInt, UntypedRune, UntypedFloat:
			if x.mode == constant {
				typ = defaultType(typ).(*Basic)
				x.typ = Typ[UntypedComplex]
			} else {
				// untyped but not constant; probably because one
				// operand is a non-constant shift of untyped lhs
				typ = Typ[Float64]
				x.typ = Typ[Complex128]
			}
		default:
			check.invalidArg(x.pos(), "float32 or float64 arguments expected")
			goto Error
		}

		if x.mode != constant {
			// The arguments have now their final types, which at run-
			// time will be materialized. Update the expression trees.
			// If the current types are untyped, the materialized type
			// is the respective default type.
			// (If the result is constant, the arguments are never
			// materialized and there is nothing to do.)
			check.updateExprType(args[0], typ, true)
			check.updateExprType(args[1], typ, true)
		}

	case _Copy:
		var y operand
		check.expr(&y, args[1], nil, iota)
		if y.mode == invalid {
			goto Error
		}

		var dst, src Type
		if t, ok := underlying(x.typ).(*Slice); ok {
			dst = t.Elt
		}
		switch t := underlying(y.typ).(type) {
		case *Basic:
			if isString(y.typ) {
				src = Typ[Byte]
			}
		case *Slice:
			src = t.Elt
		}

		if dst == nil || src == nil {
			check.invalidArg(x.pos(), "copy expects slice arguments; found %s and %s", x, &y)
			goto Error
		}

		if !IsIdentical(dst, src) {
			check.invalidArg(x.pos(), "arguments to copy %s and %s have different element types %s and %s", x, &y, dst, src)
			goto Error
		}

		x.mode = value
		x.typ = Typ[Int]

	case _Delete:
		m, ok := underlying(x.typ).(*Map)
		if !ok {
			check.invalidArg(x.pos(), "%s is not a map", x)
			goto Error
		}
		check.expr(x, args[1], nil, iota)
		if x.mode == invalid {
			goto Error
		}
		if !x.isAssignable(check.ctxt, m.Key) {
			check.invalidArg(x.pos(), "%s is not assignable to %s", x, m.Key)
			goto Error
		}
		x.mode = novalue

	case _Imag, _Real:
		if !isComplex(x.typ) {
			check.invalidArg(x.pos(), "%s must be a complex number", x)
			goto Error
		}
		if x.mode == constant {
			if id == _Real {
				x.val = exact.Real(x.val)
			} else {
				x.val = exact.Imag(x.val)
			}
		} else {
			x.mode = value
		}
		k := Invalid
		switch underlying(x.typ).(*Basic).Kind {
		case Complex64:
			k = Float32
		case Complex128:
			k = Float64
		case UntypedComplex:
			k = UntypedFloat
		default:
			unreachable()
		}
		x.typ = Typ[k]

	case _Make:
		resultTyp := check.typ(arg0, false)
		if resultTyp == Typ[Invalid] {
			goto Error
		}
		var min int // minimum number of arguments
		switch underlying(resultTyp).(type) {
		case *Slice:
			min = 2
		case *Map, *Chan:
			min = 1
		default:
			check.invalidArg(arg0.Pos(), "cannot make %s; type must be slice, map, or channel", arg0)
			goto Error
		}
		if n := len(args); n < min || min+1 < n {
			check.errorf(call.Pos(), "%s expects %d or %d arguments; found %d", call, min, min+1, n)
			goto Error
		}
		var sizes []int64 // constant integer arguments, if any
		for _, arg := range args[1:] {
			if s, ok := check.index(arg, -1, iota); ok && s >= 0 {
				sizes = append(sizes, s)
			}
		}
		if len(sizes) == 2 && sizes[0] > sizes[1] {
			check.invalidArg(args[1].Pos(), "length and capacity swapped")
			// safe to continue
		}
		x.mode = variable
		x.typ = resultTyp

	case _New:
		resultTyp := check.typ(arg0, false)
		if resultTyp == Typ[Invalid] {
			goto Error
		}
		x.mode = variable
		x.typ = &Pointer{Base: resultTyp}

	case _Panic:
		x.mode = novalue

	case _Print, _Println:
		for _, arg := range args {
			check.expr(x, arg, nil, -1)
			if x.mode == invalid {
				goto Error
			}
		}
		x.mode = novalue

	case _Recover:
		x.mode = value
		x.typ = new(Interface)

	case _Alignof:
		x.mode = constant
		x.val = exact.MakeInt64(check.ctxt.alignof(x.typ))
		x.typ = Typ[Uintptr]

	case _Offsetof:
		arg, ok := unparen(arg0).(*ast.SelectorExpr)
		if !ok {
			check.invalidArg(arg0.Pos(), "%s is not a selector expression", arg0)
			goto Error
		}
		check.expr(x, arg.X, nil, -1)
		if x.mode == invalid {
			goto Error
		}
		sel := arg.Sel.Name
		res := lookupField(x.typ, QualifiedName{check.pkg, arg.Sel.Name})
		if res.index == nil {
			check.invalidArg(x.pos(), "%s has no single field %s", x, sel)
			goto Error
		}
		offs := check.ctxt.offsetof(deref(x.typ), res.index)
		if offs < 0 {
			check.invalidArg(x.pos(), "field %s is embedded via a pointer in %s", sel, x)
			goto Error
		}
		x.mode = constant
		x.val = exact.MakeInt64(offs)
		x.typ = Typ[Uintptr]

	case _Sizeof:
		x.mode = constant
		x.val = exact.MakeInt64(check.ctxt.sizeof(x.typ))
		x.typ = Typ[Uintptr]

	case _Assert:
		// assert(pred) causes a typechecker error if pred is false.
		// The result of assert is the value of pred if there is no error.
		// Note: assert is only available in self-test mode.
		if x.mode != constant || !isBoolean(x.typ) {
			check.invalidArg(x.pos(), "%s is not a boolean constant", x)
			goto Error
		}
		if x.val.Kind() != exact.Bool {
			check.errorf(x.pos(), "internal error: value of %s should be a boolean constant", x)
			goto Error
		}
		if !exact.BoolVal(x.val) {
			check.errorf(call.Pos(), "%s failed", call)
			// compile-time assertion failure - safe to continue
		}

	case _Trace:
		// trace(x, y, z, ...) dumps the positions, expressions, and
		// values of its arguments. The result of trace is the value
		// of the first argument.
		// Note: trace is only available in self-test mode.
		if len(args) == 0 {
			check.dump("%s: trace() without arguments", call.Pos())
			x.mode = novalue
			x.expr = call
			return
		}
		var t operand
		x1 := x
		for _, arg := range args {
			check.rawExpr(x1, arg, nil, iota, true) // permit trace for types, e.g.: new(trace(T))
			check.dump("%s: %s", x1.pos(), x1)
			x1 = &t // use incoming x only for first argument
		}

	default:
		check.invalidAST(call.Pos(), "unknown builtin id %d", id)
		goto Error
	}

	x.expr = call
	return

Error:
	x.mode = invalid
	x.expr = call
}