// number = int_lit [ "p" int_lit ] .
//
func (p *parser) parseNumber() (typ *types.Basic, val exact.Value) {
// mantissa
mant := exact.MakeFromLiteral(p.parseInt(), token.INT)
if mant == nil {
panic("invalid mantissa")
}
if p.lit == "p" {
// exponent (base 2)
p.next()
exp, err := strconv.ParseInt(p.parseInt(), 10, 0)
if err != nil {
p.error(err)
}
if exp < 0 {
denom := exact.MakeInt64(1)
denom = exact.Shift(denom, token.SHL, uint(-exp))
typ = types.Typ[types.UntypedFloat]
val = exact.BinaryOp(mant, token.QUO, denom)
return
}
if exp > 0 {
mant = exact.Shift(mant, token.SHL, uint(exp))
}
typ = types.Typ[types.UntypedFloat]
val = mant
return
}
typ = types.Typ[types.UntypedInt]
val = mant
return
}
func (p *importer) ufloat() exact.Value {
exp := p.int()
x := exact.MakeFromBytes(p.bytes())
switch {
case exp < 0:
d := exact.Shift(exact.MakeInt64(1), token.SHL, uint(-exp))
x = exact.BinaryOp(x, token.QUO, d)
case exp > 0:
x = exact.Shift(x, token.SHL, uint(exp))
}
return x
}
func (p *importer) fraction() exact.Value {
sign := p.int()
if sign == 0 {
return exact.MakeInt64(0)
}
x := exact.BinaryOp(p.ufloat(), token.QUO, p.ufloat())
if sign < 0 {
x = exact.UnaryOp(token.SUB, x, 0)
}
return x
}
func (p *importer) value() exact.Value {
switch kind := exact.Kind(p.int()); kind {
case falseTag:
return exact.MakeBool(false)
case trueTag:
return exact.MakeBool(true)
case int64Tag:
return exact.MakeInt64(p.int64())
case floatTag:
return p.float()
case fractionTag:
return p.fraction()
case complexTag:
re := p.fraction()
im := p.fraction()
return exact.BinaryOp(re, token.ADD, exact.MakeImag(im))
case stringTag:
return exact.MakeString(p.string())
default:
panic(fmt.Sprintf("unexpected value kind %d", kind))
}
}
if isConst {
// Pass the value if constant. Cast it if it doesn't fit an int32.
call.Args[2*i+1] = castIfOverflow(ident)
} else {
// Pass a pointer if variable.
call.Args[2*i+1] = &ast.UnaryExpr{
Op: token.AND,
X: ident,
}
}
}
return expr
}
var (
minInt32 = exact.MakeInt64(math.MinInt32)
maxInt32 = exact.MakeInt64(math.MaxInt32)
)
func castIfOverflow(ident *ast.Ident) ast.Expr {
c, ok := defs[ident].(*types.Const)
if !ok || c == nil {
return ident
}
v := c.Val()
switch {
case v.Kind() != exact.Int:
return ident
case exact.Compare(v, token.LSS, minInt32):
return &ast.CallExpr{Fun: ast.NewIdent("int64"), Args: []ast.Expr{ident}}
case exact.Compare(v, token.GTR, maxInt32):
// collectObjects collects all file and package objects and inserts them
// into their respective scopes. It also performs imports and associates
// methods with receiver base type names.
func (check *Checker) collectObjects() {
pkg := check.pkg
importer := check.conf.Import
if importer == nil {
if DefaultImport != nil {
importer = DefaultImport
} else {
// Panic if we encounter an import.
importer = func(map[string]*Package, string) (*Package, error) {
panic(`no Config.Import or DefaultImport (missing import _ "golang.org/x/tools/go/gcimporter"?)`)
}
}
}
// pkgImports is the set of packages already imported by any package file seen
// so far. Used to avoid duplicate entries in pkg.imports. Allocate and populate
// it (pkg.imports may not be empty if we are checking test files incrementally).
var pkgImports = make(map[*Package]bool)
for _, imp := range pkg.imports {
pkgImports[imp] = true
}
for fileNo, file := range check.files {
// The package identifier denotes the current package,
// but there is no corresponding package object.
check.recordDef(file.Name, nil)
fileScope := NewScope(check.pkg.scope, check.filename(fileNo))
check.recordScope(file, fileScope)
for _, decl := range file.Decls {
switch d := decl.(type) {
case *ast.BadDecl:
// ignore
case *ast.GenDecl:
var last *ast.ValueSpec // last ValueSpec with type or init exprs seen
for iota, spec := range d.Specs {
switch s := spec.(type) {
case *ast.ImportSpec:
// import package
var imp *Package
path, err := validatedImportPath(s.Path.Value)
if err != nil {
check.errorf(s.Path.Pos(), "invalid import path (%s)", err)
continue
}
if path == "C" && check.conf.FakeImportC {
// TODO(gri) shouldn't create a new one each time
imp = NewPackage("C", "C")
imp.fake = true
} else {
var err error
imp, err = importer(check.conf.Packages, path)
if imp == nil && err == nil {
err = errors.New("Config.Import returned nil but no error")
}
if err != nil {
check.errorf(s.Path.Pos(), "could not import %s (%s)", path, err)
continue
}
}
// add package to list of explicit imports
// (this functionality is provided as a convenience
// for clients; it is not needed for type-checking)
if !pkgImports[imp] {
pkgImports[imp] = true
if imp != Unsafe {
pkg.imports = append(pkg.imports, imp)
}
}
// local name overrides imported package name
name := imp.name
if s.Name != nil {
name = s.Name.Name
if name == "init" {
check.errorf(s.Name.Pos(), "cannot declare init - must be func")
continue
}
}
obj := NewPkgName(s.Pos(), pkg, name, imp)
if s.Name != nil {
// in a dot-import, the dot represents the package
check.recordDef(s.Name, obj)
} else {
check.recordImplicit(s, obj)
}
// add import to file scope
if name == "." {
// merge imported scope with file scope
for _, obj := range imp.scope.elems {
// A package scope may contain non-exported objects,
// do not import them!
if obj.Exported() {
// TODO(gri) When we import a package, we create
// a new local package object. We should do the
// same for each dot-imported object. That way
// they can have correct position information.
// (We must not modify their existing position
// information because the same package - found
// via Config.Packages - may be dot-imported in
// another package!)
check.declare(fileScope, nil, obj)
check.recordImplicit(s, obj)
}
}
// add position to set of dot-import positions for this file
// (this is only needed for "imported but not used" errors)
check.addUnusedDotImport(fileScope, imp, s.Pos())
} else {
// declare imported package object in file scope
check.declare(fileScope, nil, obj)
}
case *ast.ValueSpec:
switch d.Tok {
case token.CONST:
// determine which initialization expressions to use
switch {
case s.Type != nil || len(s.Values) > 0:
last = s
case last == nil:
last = new(ast.ValueSpec) // make sure last exists
}
// declare all constants
for i, name := range s.Names {
obj := NewConst(name.Pos(), pkg, name.Name, nil, exact.MakeInt64(int64(iota)))
var init ast.Expr
if i < len(last.Values) {
init = last.Values[i]
}
d := &declInfo{file: fileScope, typ: last.Type, init: init}
check.declarePkgObj(name, obj, d)
}
check.arityMatch(s, last)
case token.VAR:
lhs := make([]*Var, len(s.Names))
// If there's exactly one rhs initializer, use
// the same declInfo d1 for all lhs variables
// so that each lhs variable depends on the same
// rhs initializer (n:1 var declaration).
var d1 *declInfo
if len(s.Values) == 1 {
// The lhs elements are only set up after the for loop below,
// but that's ok because declareVar only collects the declInfo
// for a later phase.
d1 = &declInfo{file: fileScope, lhs: lhs, typ: s.Type, init: s.Values[0]}
}
// declare all variables
for i, name := range s.Names {
obj := NewVar(name.Pos(), pkg, name.Name, nil)
lhs[i] = obj
d := d1
if d == nil {
// individual assignments
var init ast.Expr
if i < len(s.Values) {
init = s.Values[i]
}
d = &declInfo{file: fileScope, typ: s.Type, init: init}
}
check.declarePkgObj(name, obj, d)
}
check.arityMatch(s, nil)
default:
check.invalidAST(s.Pos(), "invalid token %s", d.Tok)
}
case *ast.TypeSpec:
obj := NewTypeName(s.Name.Pos(), pkg, s.Name.Name, nil)
check.declarePkgObj(s.Name, obj, &declInfo{file: fileScope, typ: s.Type})
default:
check.invalidAST(s.Pos(), "unknown ast.Spec node %T", s)
}
}
case *ast.FuncDecl:
name := d.Name.Name
obj := NewFunc(d.Name.Pos(), pkg, name, nil)
if d.Recv == nil {
// regular function
if name == "init" {
// don't declare init functions in the package scope - they are invisible
obj.parent = pkg.scope
check.recordDef(d.Name, obj)
// init functions must have a body
if d.Body == nil {
check.softErrorf(obj.pos, "missing function body")
}
} else {
check.declare(pkg.scope, d.Name, obj)
}
} else {
// method
check.recordDef(d.Name, obj)
// Associate method with receiver base type name, if possible.
// Ignore methods that have an invalid receiver, or a blank _
// receiver name. They will be type-checked later, with regular
// functions.
if list := d.Recv.List; len(list) > 0 {
typ := list[0].Type
if ptr, _ := typ.(*ast.StarExpr); ptr != nil {
typ = ptr.X
}
if base, _ := typ.(*ast.Ident); base != nil && base.Name != "_" {
check.assocMethod(base.Name, obj)
}
}
}
info := &declInfo{file: fileScope, fdecl: d}
check.objMap[obj] = info
obj.setOrder(uint32(len(check.objMap)))
default:
check.invalidAST(d.Pos(), "unknown ast.Decl node %T", d)
}
}
}
// verify that objects in package and file scopes have different names
for _, scope := range check.pkg.scope.children /* file scopes */ {
for _, obj := range scope.elems {
if alt := pkg.scope.Lookup(obj.Name()); alt != nil {
if pkg, ok := obj.(*PkgName); ok {
check.errorf(alt.Pos(), "%s already declared through import of %s", alt.Name(), pkg.Imported())
check.reportAltDecl(pkg)
} else {
check.errorf(alt.Pos(), "%s already declared through dot-import of %s", alt.Name(), obj.Pkg())
// TODO(gri) dot-imported objects don't have a position; reportAltDecl won't print anything
check.reportAltDecl(obj)
}
}
}
}
}
// 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.expr(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)) {
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 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.hasCallOrRecv {
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 == 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 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 !Identical(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 = 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) {
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)
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)
if !check.assignment(x, T) {
assert(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
}
if !check.assignment(x, nil) {
assert(x.mode == invalid)
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
if !check.assignment(x, nil) {
assert(x.mode == invalid)
return
}
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.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: http://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 = exact.MakeInt64(offs)
x.typ = Typ[Uintptr]
// result is constant - no need to record signature
case _Sizeof:
// unsafe.Sizeof(x T) uintptr
if !check.assignment(x, nil) {
assert(x.mode == invalid)
return
}
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
}
res := NewVar(token.NoPos, nil, "", Typ[String])
sig := &Signature{results: NewTuple(res)}
err := NewFunc(token.NoPos, nil, "Error", sig)
typ := &Named{underlying: NewInterface([]*Func{err}, nil).Complete()}
sig.recv = NewVar(token.NoPos, nil, "", typ)
def(NewTypeName(token.NoPos, nil, "error", typ))
}
var predeclaredConsts = [...]struct {
name string
kind BasicKind
val exact.Value
}{
{"true", UntypedBool, exact.MakeBool(true)},
{"false", UntypedBool, exact.MakeBool(false)},
{"iota", UntypedInt, exact.MakeInt64(0)},
}
func defPredeclaredConsts() {
for _, c := range predeclaredConsts {
def(NewConst(token.NoPos, nil, c.name, Typ[c.kind], c.val))
}
}
func defPredeclaredNil() {
def(&Nil{object{name: "nil", typ: Typ[UntypedNil]}})
}
// A builtinId is the id of a builtin function.
type builtinId int
func (check *Checker) declStmt(decl ast.Decl) {
pkg := check.pkg
switch d := decl.(type) {
case *ast.BadDecl:
// ignore
case *ast.GenDecl:
var last *ast.ValueSpec // last ValueSpec with type or init exprs seen
for iota, spec := range d.Specs {
switch s := spec.(type) {
case *ast.ValueSpec:
switch d.Tok {
case token.CONST:
// determine which init exprs to use
switch {
case s.Type != nil || len(s.Values) > 0:
last = s
case last == nil:
last = new(ast.ValueSpec) // make sure last exists
}
// declare all constants
lhs := make([]*Const, len(s.Names))
for i, name := range s.Names {
obj := NewConst(name.Pos(), pkg, name.Name, nil, exact.MakeInt64(int64(iota)))
lhs[i] = obj
var init ast.Expr
if i < len(last.Values) {
init = last.Values[i]
}
check.constDecl(obj, last.Type, init)
}
check.arityMatch(s, last)
for i, name := range s.Names {
check.declare(check.scope, name, lhs[i])
}
case token.VAR:
lhs0 := make([]*Var, len(s.Names))
for i, name := range s.Names {
lhs0[i] = NewVar(name.Pos(), pkg, name.Name, nil)
}
// initialize all variables
for i, obj := range lhs0 {
var lhs []*Var
var init ast.Expr
switch len(s.Values) {
case len(s.Names):
// lhs and rhs match
init = s.Values[i]
case 1:
// rhs is expected to be a multi-valued expression
lhs = lhs0
init = s.Values[0]
default:
if i < len(s.Values) {
init = s.Values[i]
}
}
check.varDecl(obj, lhs, s.Type, init)
if len(s.Values) == 1 {
// If we have a single lhs variable we are done either way.
// If we have a single rhs expression, it must be a multi-
// valued expression, in which case handling the first lhs
// variable will cause all lhs variables to have a type
// assigned, and we are done as well.
if debug {
for _, obj := range lhs0 {
assert(obj.typ != nil)
}
}
break
}
}
check.arityMatch(s, nil)
// declare all variables
// (only at this point are the variable scopes (parents) set)
for i, name := range s.Names {
check.declare(check.scope, name, lhs0[i])
}
default:
check.invalidAST(s.Pos(), "invalid token %s", d.Tok)
}
case *ast.TypeSpec:
obj := NewTypeName(s.Name.Pos(), pkg, s.Name.Name, nil)
check.declare(check.scope, s.Name, obj)
check.typeDecl(obj, s.Type, nil, nil)
default:
check.invalidAST(s.Pos(), "const, type, or var declaration expected")
}
}
default:
check.invalidAST(d.Pos(), "unknown ast.Decl node %T", d)
}
}