in libgo/go/go/types/builtins.go [20:758]
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(atPos(call.Ellipsis),
_InvalidDotDotDot,
"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 exprList because exprList evaluates
// all arguments.
if id == _Len || id == _Cap {
defer func(b bool) {
check.hasCallOrRecv = b
}(check.hasCallOrRecv)
check.hasCallOrRecv = false
}
// determine actual arguments
var arg func(*operand, int) // TODO(gri) remove use of arg getter in favor of using xlist directly
nargs := len(call.Args)
switch id {
default:
// make argument getter
xlist, _ := check.exprList(call.Args, false)
arg = func(x *operand, i int) { *x = *xlist[i]; x.typ = expand(x.typ) }
nargs = len(xlist)
// 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(inNode(call, call.Rparen), _WrongArgCount, "%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 := asSlice(S); s != nil {
T = s.elem
} else {
check.invalidArg(x, _InvalidAppend, "%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() {
if ok, _ := x.assignableTo(check, NewSlice(universeByte), nil); ok {
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
var xlist []*operand
// convert []operand to []*operand
for i := range alist {
xlist = append(xlist, &alist[i])
}
for i := len(alist); i < nargs; i++ {
var x operand
arg(&x, i)
xlist = append(xlist, &x)
}
check.arguments(call, sig, nil, xlist) // discard result (we know the result type)
// 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(optype(x.typ)); 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_
if t.len >= 0 {
val = constant.MakeInt64(t.len)
} else {
val = constant.MakeUnknown()
}
}
case *Slice, *Chan:
mode = value
case *Map:
if id == _Len {
mode = value
}
case *_Sum:
if t.is(func(t Type) bool {
switch t := under(t).(type) {
case *Basic:
if isString(t) && id == _Len {
return true
}
case *Array, *Slice, *Chan:
return true
case *Map:
if id == _Len {
return true
}
}
return false
}) {
mode = value
}
}
if mode == invalid && typ != Typ[Invalid] {
code := _InvalidCap
if id == _Len {
code = _InvalidLen
}
check.invalidArg(x, code, "%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 := asChan(x.typ)
if c == nil {
check.invalidArg(x, _InvalidClose, "%s is not a channel", x)
return
}
if c.dir == RecvOnly {
check.invalidArg(x, _InvalidClose, "%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 !check.identical(x.typ, y.typ) {
check.invalidArg(x, _InvalidComplex, "mismatched types %s and %s", x.typ, y.typ)
return
}
// the argument types must be of floating-point type
f := func(x Type) Type {
if t := asBasic(x); t != nil {
switch t.kind {
case Float32:
return Typ[Complex64]
case Float64:
return Typ[Complex128]
case UntypedFloat:
return Typ[UntypedComplex]
}
}
return nil
}
resTyp := check.applyTypeFunc(f, x.typ)
if resTyp == nil {
check.invalidArg(x, _InvalidComplex, "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
}
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 := asSlice(x.typ); t != nil {
dst = t.elem
}
var y operand
arg(&y, 1)
if y.mode == invalid {
return
}
var src Type
switch t := optype(y.typ).(type) {
case *Basic:
if isString(y.typ) {
src = universeByte
}
case *Slice:
src = t.elem
}
if dst == nil || src == nil {
check.invalidArg(x, _InvalidCopy, "copy expects slice arguments; found %s and %s", x, &y)
return
}
if !check.identical(dst, src) {
check.invalidArg(x, _InvalidCopy, "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 := asMap(x.typ)
if m == nil {
check.invalidArg(x, _InvalidDelete, "%s is not a map", x)
return
}
arg(x, 1) // k
if x.mode == invalid {
return
}
check.assignment(x, m.key, "argument to delete")
if x.mode == invalid {
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 always 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
f := func(x Type) Type {
if t := asBasic(x); t != nil {
switch t.kind {
case Complex64:
return Typ[Float32]
case Complex128:
return Typ[Float64]
case UntypedComplex:
return Typ[UntypedFloat]
}
}
return nil
}
resTyp := check.applyTypeFunc(f, x.typ)
if resTyp == nil {
code := _InvalidImag
if id == _Real {
code = _InvalidReal
}
check.invalidArg(x, code, "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
}
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.varType(arg0)
if T == Typ[Invalid] {
return
}
min, max := -1, 10
var valid func(t Type) bool
valid = func(t Type) bool {
var m int
switch t := optype(t).(type) {
case *Slice:
m = 2
case *Map, *Chan:
m = 1
case *_Sum:
return t.is(valid)
default:
return false
}
if m > min {
min = m
}
if m+1 < max {
max = m + 1
}
return true
}
if !valid(T) {
check.invalidArg(arg0, _InvalidMake, "cannot make %s; type must be slice, map, or channel", arg0)
return
}
if nargs < min || max < nargs {
if min == max {
check.errorf(call, _WrongArgCount, "%v expects %d arguments; found %d", call, min, nargs)
} else {
check.errorf(call, _WrongArgCount, "%v expects %d or %d arguments; found %d", call, min, max, nargs)
}
return
}
types := []Type{T}
var sizes []int64 // constant integer arguments, if any
for _, arg := range call.Args[1:] {
typ, size := check.index(arg, -1) // ok to continue with typ == Typ[Invalid]
types = append(types, typ)
if size >= 0 {
sizes = append(sizes, size)
}
}
if len(sizes) == 2 && sizes[0] > sizes[1] {
check.invalidArg(call.Args[1], _SwappedMakeArgs, "length and capacity swapped")
// safe to continue
}
x.mode = value
x.typ = T
if check.Types != nil {
check.recordBuiltinType(call.Fun, makeSig(x.typ, types...))
}
case _New:
// new(T)
// (no argument evaluated yet)
T := check.varType(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)
// record panic call if inside a function with result parameters
// (for use in Checker.isTerminating)
if check.sig != nil && check.sig.results.Len() > 0 {
// function has result parameters
p := check.isPanic
if p == nil {
// allocate lazily
p = make(map[*ast.CallExpr]bool)
check.isPanic = p
}
p[call] = true
}
check.assignment(x, &emptyInterface, "argument to panic")
if x.mode == invalid {
return
}
x.mode = novalue
if check.Types != nil {
check.recordBuiltinType(call.Fun, makeSig(nil, &emptyInterface))
}
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 = &emptyInterface
if check.Types != nil {
check.recordBuiltinType(call.Fun, makeSig(x.typ))
}
case _Add:
// unsafe.Add(ptr unsafe.Pointer, len IntegerType) unsafe.Pointer
if !check.allowVersion(check.pkg, 1, 17) {
check.errorf(call.Fun, _InvalidUnsafeAdd, "unsafe.Add requires go1.17 or later")
return
}
check.assignment(x, Typ[UnsafePointer], "argument to unsafe.Add")
if x.mode == invalid {
return
}
var y operand
arg(&y, 1)
if !check.isValidIndex(&y, _InvalidUnsafeAdd, "length", true) {
return
}
x.mode = value
x.typ = Typ[UnsafePointer]
if check.Types != nil {
check.recordBuiltinType(call.Fun, makeSig(x.typ, x.typ, y.typ))
}
case _Alignof:
// unsafe.Alignof(x T) uintptr
if asTypeParam(x.typ) != nil {
check.invalidOp(call, _Todo, "unsafe.Alignof undefined for %s", x)
return
}
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, _BadOffsetofSyntax, "%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 := check.lookupFieldOrMethod(base, false, check.pkg, sel)
switch obj.(type) {
case nil:
check.invalidArg(x, _MissingFieldOrMethod, "%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, _InvalidOffsetof, "%s is a method value", arg0)
return
}
if indirect {
check.invalidArg(x, _InvalidOffsetof, "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
if asTypeParam(x.typ) != nil {
check.invalidOp(call, _Todo, "unsafe.Sizeof undefined for %s", x)
return
}
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 _Slice:
// unsafe.Slice(ptr *T, len IntegerType) []T
if !check.allowVersion(check.pkg, 1, 17) {
check.errorf(call.Fun, _InvalidUnsafeSlice, "unsafe.Slice requires go1.17 or later")
return
}
typ := asPointer(x.typ)
if typ == nil {
check.invalidArg(x, _InvalidUnsafeSlice, "%s is not a pointer", x)
return
}
var y operand
arg(&y, 1)
if !check.isValidIndex(&y, _InvalidUnsafeSlice, "length", false) {
return
}
x.mode = value
x.typ = NewSlice(typ.base)
if check.Types != nil {
check.recordBuiltinType(call.Fun, makeSig(x.typ, typ, y.typ))
}
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, _Test, "%s is not a boolean constant", x)
return
}
if x.val.Kind() != constant.Bool {
check.errorf(x, _Test, "internal error: value of %s should be a boolean constant", x)
return
}
if !constant.BoolVal(x.val) {
check.errorf(call, _Test, "%v 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("%v: 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("%v: %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
}