// 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
}
// 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
}
// 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
}
// 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
}
// 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
}
// 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)
}
}
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")
}
}
// 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)
}
}
// 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))
}
}
}
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)
}
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)
}
// 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
}
// 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)
}
}
// 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)
}
}
}
}
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
}
// 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
}
// 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)
}
}
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"))
}
}
// 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)
}
}
}
}
// 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)
}
}
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}
}
// 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
}
// 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
}
// 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)
}
}
}
// 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
}
// 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
}