mirror of
https://github.com/golang/go
synced 2024-11-26 07:47:57 -07:00
go/types: factor out index/slice expr handling
This is a port of CL 308370 to go/types. There are some differences in the index checking code, but the methodology for moving the code was the same: replace `goto Error` with `x.mode = invalid; return`. Change-Id: I880f577a7720e6ad8a5b096207001fcf7620396d Reviewed-on: https://go-review.googlesource.com/c/go/+/312095 Trust: Robert Findley <rfindley@google.com> Run-TryBot: Robert Findley <rfindley@google.com> TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Robert Griesemer <gri@golang.org>
This commit is contained in:
Rob Findley
Robert Findley
parent
645cb62ee3
commit
214c8dd80c
@ -1002,121 +1002,6 @@ func (check *Checker) binary(x *operand, e ast.Expr, lhs, rhs ast.Expr, op token
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// x.typ is unchanged
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}
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// index checks an index expression for validity.
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// If max >= 0, it is the upper bound for index.
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// If the result typ is != Typ[Invalid], index is valid and typ is its (possibly named) integer type.
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// If the result val >= 0, index is valid and val is its constant int value.
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func (check *Checker) index(index ast.Expr, max int64) (typ Type, val int64) {
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typ = Typ[Invalid]
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val = -1
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var x operand
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check.expr(&x, index)
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if !check.isValidIndex(&x, _InvalidIndex, "index", false) {
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return
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}
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if x.mode != constant_ {
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return x.typ, -1
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}
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if x.val.Kind() == constant.Unknown {
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return
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}
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v, ok := constant.Int64Val(x.val)
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assert(ok)
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if max >= 0 && v >= max {
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check.invalidArg(&x, _InvalidIndex, "index %s is out of bounds", &x)
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return
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}
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// 0 <= v [ && v < max ]
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return x.typ, v
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}
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func (check *Checker) isValidIndex(x *operand, code errorCode, what string, allowNegative bool) bool {
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if x.mode == invalid {
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return false
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}
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// spec: "a constant index that is untyped is given type int"
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check.convertUntyped(x, Typ[Int])
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if x.mode == invalid {
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return false
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}
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// spec: "the index x must be of integer type or an untyped constant"
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if !isInteger(x.typ) {
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check.invalidArg(x, code, "%s %s must be integer", what, x)
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return false
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}
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if x.mode == constant_ {
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// spec: "a constant index must be non-negative ..."
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if !allowNegative && constant.Sign(x.val) < 0 {
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check.invalidArg(x, code, "%s %s must not be negative", what, x)
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return false
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}
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// spec: "... and representable by a value of type int"
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if !representableConst(x.val, check, Typ[Int], &x.val) {
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check.invalidArg(x, code, "%s %s overflows int", what, x)
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return false
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}
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}
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return true
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}
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// indexElts checks the elements (elts) of an array or slice composite literal
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// against the literal's element type (typ), and the element indices against
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// the literal length if known (length >= 0). It returns the length of the
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// literal (maximum index value + 1).
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//
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func (check *Checker) indexedElts(elts []ast.Expr, typ Type, length int64) int64 {
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visited := make(map[int64]bool, len(elts))
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var index, max int64
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for _, e := range elts {
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// determine and check index
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validIndex := false
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eval := e
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if kv, _ := e.(*ast.KeyValueExpr); kv != nil {
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if typ, i := check.index(kv.Key, length); typ != Typ[Invalid] {
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if i >= 0 {
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index = i
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validIndex = true
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} else {
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check.errorf(e, _InvalidLitIndex, "index %s must be integer constant", kv.Key)
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}
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}
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eval = kv.Value
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} else if length >= 0 && index >= length {
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check.errorf(e, _OversizeArrayLit, "index %d is out of bounds (>= %d)", index, length)
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} else {
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validIndex = true
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}
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// if we have a valid index, check for duplicate entries
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if validIndex {
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if visited[index] {
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check.errorf(e, _DuplicateLitKey, "duplicate index %d in array or slice literal", index)
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}
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visited[index] = true
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}
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index++
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if index > max {
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max = index
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}
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// check element against composite literal element type
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var x operand
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check.exprWithHint(&x, eval, typ)
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check.assignment(&x, typ, "array or slice literal")
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}
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return max
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}
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// exprKind describes the kind of an expression; the kind
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// determines if an expression is valid in 'statement context'.
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type exprKind int
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@ -1455,278 +1340,17 @@ func (check *Checker) exprInternal(x *operand, e ast.Expr, hint Type) exprKind {
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check.selector(x, e)
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case *ast.IndexExpr:
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check.exprOrType(x, e.X)
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check.indexExpr(x, e)
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if x.mode == invalid {
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check.use(typeparams.UnpackExpr(e.Index)...)
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goto Error
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}
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if x.mode == typexpr {
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// type instantiation
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x.mode = invalid
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x.typ = check.varType(e)
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if x.typ != Typ[Invalid] {
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x.mode = typexpr
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}
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return expression
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}
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if x.mode == value {
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if sig := asSignature(x.typ); sig != nil && len(sig.tparams) > 0 {
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check.funcInst(x, e)
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return expression
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}
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}
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valid := false
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length := int64(-1) // valid if >= 0
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switch typ := optype(x.typ).(type) {
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case *Basic:
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if isString(typ) {
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valid = true
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if x.mode == constant_ {
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length = int64(len(constant.StringVal(x.val)))
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}
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// an indexed string always yields a byte value
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// (not a constant) even if the string and the
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// index are constant
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x.mode = value
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x.typ = universeByte // use 'byte' name
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}
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case *Array:
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valid = true
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length = typ.len
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if x.mode != variable {
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x.mode = value
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}
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x.typ = typ.elem
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case *Pointer:
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if typ := asArray(typ.base); typ != nil {
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valid = true
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length = typ.len
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x.mode = variable
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x.typ = typ.elem
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}
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case *Slice:
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valid = true
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x.mode = variable
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x.typ = typ.elem
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case *Map:
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var key operand
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check.expr(&key, e.Index)
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check.assignment(&key, typ.key, "map index")
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// ok to continue even if indexing failed - map element type is known
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x.mode = mapindex
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x.typ = typ.elem
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x.expr = e
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return expression
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case *_Sum:
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// A sum type can be indexed if all of the sum's types
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// support indexing and have the same index and element
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// type. Special rules apply for maps in the sum type.
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var tkey, telem Type // key is for map types only
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nmaps := 0 // number of map types in sum type
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if typ.is(func(t Type) bool {
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var e Type
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switch t := under(t).(type) {
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case *Basic:
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if isString(t) {
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e = universeByte
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}
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case *Array:
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e = t.elem
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case *Pointer:
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if t := asArray(t.base); t != nil {
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e = t.elem
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}
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case *Slice:
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e = t.elem
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case *Map:
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// If there are multiple maps in the sum type,
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// they must have identical key types.
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// TODO(gri) We may be able to relax this rule
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// but it becomes complicated very quickly.
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if tkey != nil && !Identical(t.key, tkey) {
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return false
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}
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tkey = t.key
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e = t.elem
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nmaps++
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case *_TypeParam:
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check.errorf(x, 0, "type of %s contains a type parameter - cannot index (implementation restriction)", x)
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case *instance:
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panic("unimplemented")
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}
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if e == nil || telem != nil && !Identical(e, telem) {
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return false
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}
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telem = e
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return true
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}) {
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// If there are maps, the index expression must be assignable
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// to the map key type (as for simple map index expressions).
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if nmaps > 0 {
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var key operand
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check.expr(&key, e.Index)
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check.assignment(&key, tkey, "map index")
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// ok to continue even if indexing failed - map element type is known
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// If there are only maps, we are done.
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if nmaps == len(typ.types) {
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x.mode = mapindex
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x.typ = telem
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x.expr = e
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return expression
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}
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// Otherwise we have mix of maps and other types. For
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// now we require that the map key be an integer type.
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// TODO(gri) This is probably not good enough.
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valid = isInteger(tkey)
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// avoid 2nd indexing error if indexing failed above
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if !valid && key.mode == invalid {
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goto Error
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}
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x.mode = value // map index expressions are not addressable
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} else {
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// no maps
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valid = true
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x.mode = variable
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}
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x.typ = telem
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}
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}
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if !valid {
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check.invalidOp(x, _NonIndexableOperand, "cannot index %s", x)
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goto Error
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}
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if e.Index == nil {
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check.invalidAST(e, "missing index for %s", x)
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goto Error
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}
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// In pathological (invalid) cases (e.g.: type T1 [][[]T1{}[0][0]]T0)
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// the element type may be accessed before it's set. Make sure we have
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// a valid type.
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if x.typ == nil {
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x.typ = Typ[Invalid]
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}
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check.index(e.Index, length)
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// ok to continue
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case *ast.SliceExpr:
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check.expr(x, e.X)
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check.sliceExpr(x, e)
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if x.mode == invalid {
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check.use(e.Low, e.High, e.Max)
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goto Error
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}
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valid := false
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length := int64(-1) // valid if >= 0
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switch typ := optype(x.typ).(type) {
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case *Basic:
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if isString(typ) {
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if e.Slice3 {
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check.invalidOp(x, _InvalidSliceExpr, "3-index slice of string")
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goto Error
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}
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valid = true
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if x.mode == constant_ {
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length = int64(len(constant.StringVal(x.val)))
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}
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// spec: "For untyped string operands the result
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// is a non-constant value of type string."
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if typ.kind == UntypedString {
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x.typ = Typ[String]
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}
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}
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case *Array:
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valid = true
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length = typ.len
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if x.mode != variable {
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check.invalidOp(x, _NonSliceableOperand, "cannot slice %s (value not addressable)", x)
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goto Error
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}
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x.typ = &Slice{elem: typ.elem}
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case *Pointer:
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if typ := asArray(typ.base); typ != nil {
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valid = true
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length = typ.len
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x.typ = &Slice{elem: typ.elem}
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}
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case *Slice:
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valid = true
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// x.typ doesn't change
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case *_Sum, *_TypeParam:
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check.errorf(x, 0, "generic slice expressions not yet implemented")
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goto Error
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}
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if !valid {
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check.invalidOp(x, _NonSliceableOperand, "cannot slice %s", x)
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goto Error
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}
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x.mode = value
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// spec: "Only the first index may be omitted; it defaults to 0."
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if e.Slice3 && (e.High == nil || e.Max == nil) {
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check.invalidAST(inNode(e, e.Rbrack), "2nd and 3rd index required in 3-index slice")
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goto Error
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}
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// check indices
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var ind [3]int64
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for i, expr := range []ast.Expr{e.Low, e.High, e.Max} {
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x := int64(-1)
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switch {
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case expr != nil:
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// The "capacity" is only known statically for strings, arrays,
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// and pointers to arrays, and it is the same as the length for
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// those types.
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max := int64(-1)
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if length >= 0 {
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max = length + 1
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}
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if _, v := check.index(expr, max); v >= 0 {
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x = v
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}
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case i == 0:
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// default is 0 for the first index
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x = 0
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case length >= 0:
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// default is length (== capacity) otherwise
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x = length
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}
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ind[i] = x
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}
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// constant indices must be in range
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// (check.index already checks that existing indices >= 0)
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L:
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for i, x := range ind[:len(ind)-1] {
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if x > 0 {
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for _, y := range ind[i+1:] {
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if y >= 0 && x > y {
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check.errorf(inNode(e, e.Rbrack), _SwappedSliceIndices, "swapped slice indices: %d > %d", x, y)
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break L // only report one error, ok to continue
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}
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}
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}
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}
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case *ast.TypeAssertExpr:
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check.expr(x, e.X)
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if x.mode == invalid {
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410
src/go/types/index.go
Normal file
410
src/go/types/index.go
Normal file
@ -0,0 +1,410 @@
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// Copyright 2021 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// This file implements typechecking of index/slice expressions.
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package types
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import (
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"go/ast"
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"go/constant"
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"go/internal/typeparams"
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)
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func (check *Checker) indexExpr(x *operand, e *ast.IndexExpr) {
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check.exprOrType(x, e.X)
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if x.mode == invalid {
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check.use(typeparams.UnpackExpr(e.Index)...)
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return
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}
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if x.mode == typexpr {
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// type instantiation
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x.mode = invalid
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x.typ = check.varType(e)
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if x.typ != Typ[Invalid] {
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x.mode = typexpr
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}
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return
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}
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if x.mode == value {
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if sig := asSignature(x.typ); sig != nil && len(sig.tparams) > 0 {
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check.funcInst(x, e)
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return
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}
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}
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valid := false
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length := int64(-1) // valid if >= 0
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switch typ := optype(x.typ).(type) {
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case *Basic:
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if isString(typ) {
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valid = true
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if x.mode == constant_ {
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length = int64(len(constant.StringVal(x.val)))
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}
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// an indexed string always yields a byte value
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// (not a constant) even if the string and the
|
||||
// index are constant
|
||||
x.mode = value
|
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x.typ = universeByte // use 'byte' name
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}
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case *Array:
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valid = true
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length = typ.len
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if x.mode != variable {
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x.mode = value
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}
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x.typ = typ.elem
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case *Pointer:
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if typ := asArray(typ.base); typ != nil {
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valid = true
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length = typ.len
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x.mode = variable
|
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x.typ = typ.elem
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}
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case *Slice:
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valid = true
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x.mode = variable
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x.typ = typ.elem
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|
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case *Map:
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var key operand
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check.expr(&key, e.Index)
|
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check.assignment(&key, typ.key, "map index")
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// ok to continue even if indexing failed - map element type is known
|
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x.mode = mapindex
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x.typ = typ.elem
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x.expr = e
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return
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case *_Sum:
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// A sum type can be indexed if all of the sum's types
|
||||
// support indexing and have the same index and element
|
||||
// type. Special rules apply for maps in the sum type.
|
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var tkey, telem Type // key is for map types only
|
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nmaps := 0 // number of map types in sum type
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if typ.is(func(t Type) bool {
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var e Type
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switch t := under(t).(type) {
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case *Basic:
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if isString(t) {
|
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e = universeByte
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}
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case *Array:
|
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e = t.elem
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case *Pointer:
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if t := asArray(t.base); t != nil {
|
||||
e = t.elem
|
||||
}
|
||||
case *Slice:
|
||||
e = t.elem
|
||||
case *Map:
|
||||
// If there are multiple maps in the sum type,
|
||||
// they must have identical key types.
|
||||
// TODO(gri) We may be able to relax this rule
|
||||
// but it becomes complicated very quickly.
|
||||
if tkey != nil && !Identical(t.key, tkey) {
|
||||
return false
|
||||
}
|
||||
tkey = t.key
|
||||
e = t.elem
|
||||
nmaps++
|
||||
case *_TypeParam:
|
||||
check.errorf(x, 0, "type of %s contains a type parameter - cannot index (implementation restriction)", x)
|
||||
case *instance:
|
||||
panic("unimplemented")
|
||||
}
|
||||
if e == nil || telem != nil && !Identical(e, telem) {
|
||||
return false
|
||||
}
|
||||
telem = e
|
||||
return true
|
||||
}) {
|
||||
// If there are maps, the index expression must be assignable
|
||||
// to the map key type (as for simple map index expressions).
|
||||
if nmaps > 0 {
|
||||
var key operand
|
||||
check.expr(&key, e.Index)
|
||||
check.assignment(&key, tkey, "map index")
|
||||
// ok to continue even if indexing failed - map element type is known
|
||||
|
||||
// If there are only maps, we are done.
|
||||
if nmaps == len(typ.types) {
|
||||
x.mode = mapindex
|
||||
x.typ = telem
|
||||
x.expr = e
|
||||
return
|
||||
}
|
||||
|
||||
// Otherwise we have mix of maps and other types. For
|
||||
// now we require that the map key be an integer type.
|
||||
// TODO(gri) This is probably not good enough.
|
||||
valid = isInteger(tkey)
|
||||
// avoid 2nd indexing error if indexing failed above
|
||||
if !valid && key.mode == invalid {
|
||||
x.mode = invalid
|
||||
return
|
||||
}
|
||||
x.mode = value // map index expressions are not addressable
|
||||
} else {
|
||||
// no maps
|
||||
valid = true
|
||||
x.mode = variable
|
||||
}
|
||||
x.typ = telem
|
||||
}
|
||||
}
|
||||
|
||||
if !valid {
|
||||
check.invalidOp(x, _NonIndexableOperand, "cannot index %s", x)
|
||||
x.mode = invalid
|
||||
return
|
||||
}
|
||||
|
||||
if e.Index == nil {
|
||||
check.invalidAST(e, "missing index for %s", x)
|
||||
x.mode = invalid
|
||||
return
|
||||
}
|
||||
|
||||
// In pathological (invalid) cases (e.g.: type T1 [][[]T1{}[0][0]]T0)
|
||||
// the element type may be accessed before it's set. Make sure we have
|
||||
// a valid type.
|
||||
if x.typ == nil {
|
||||
x.typ = Typ[Invalid]
|
||||
}
|
||||
|
||||
check.index(e.Index, length)
|
||||
}
|
||||
|
||||
func (check *Checker) sliceExpr(x *operand, e *ast.SliceExpr) {
|
||||
check.expr(x, e.X)
|
||||
if x.mode == invalid {
|
||||
check.use(e.Low, e.High, e.Max)
|
||||
return
|
||||
}
|
||||
|
||||
valid := false
|
||||
length := int64(-1) // valid if >= 0
|
||||
switch typ := optype(x.typ).(type) {
|
||||
case *Basic:
|
||||
if isString(typ) {
|
||||
if e.Slice3 {
|
||||
check.invalidOp(x, _InvalidSliceExpr, "3-index slice of string")
|
||||
x.mode = invalid
|
||||
return
|
||||
}
|
||||
valid = true
|
||||
if x.mode == constant_ {
|
||||
length = int64(len(constant.StringVal(x.val)))
|
||||
}
|
||||
// spec: "For untyped string operands the result
|
||||
// is a non-constant value of type string."
|
||||
if typ.kind == UntypedString {
|
||||
x.typ = Typ[String]
|
||||
}
|
||||
}
|
||||
|
||||
case *Array:
|
||||
valid = true
|
||||
length = typ.len
|
||||
if x.mode != variable {
|
||||
check.invalidOp(x, _NonSliceableOperand, "cannot slice %s (value not addressable)", x)
|
||||
x.mode = invalid
|
||||
return
|
||||
}
|
||||
x.typ = &Slice{elem: typ.elem}
|
||||
|
||||
case *Pointer:
|
||||
if typ := asArray(typ.base); typ != nil {
|
||||
valid = true
|
||||
length = typ.len
|
||||
x.typ = &Slice{elem: typ.elem}
|
||||
}
|
||||
|
||||
case *Slice:
|
||||
valid = true
|
||||
// x.typ doesn't change
|
||||
|
||||
case *_Sum, *_TypeParam:
|
||||
check.errorf(x, 0, "generic slice expressions not yet implemented")
|
||||
x.mode = invalid
|
||||
return
|
||||
}
|
||||
|
||||
if !valid {
|
||||
check.invalidOp(x, _NonSliceableOperand, "cannot slice %s", x)
|
||||
x.mode = invalid
|
||||
return
|
||||
}
|
||||
|
||||
x.mode = value
|
||||
|
||||
// spec: "Only the first index may be omitted; it defaults to 0."
|
||||
if e.Slice3 && (e.High == nil || e.Max == nil) {
|
||||
check.invalidAST(inNode(e, e.Rbrack), "2nd and 3rd index required in 3-index slice")
|
||||
x.mode = invalid
|
||||
return
|
||||
}
|
||||
|
||||
// check indices
|
||||
var ind [3]int64
|
||||
for i, expr := range []ast.Expr{e.Low, e.High, e.Max} {
|
||||
x := int64(-1)
|
||||
switch {
|
||||
case expr != nil:
|
||||
// The "capacity" is only known statically for strings, arrays,
|
||||
// and pointers to arrays, and it is the same as the length for
|
||||
// those types.
|
||||
max := int64(-1)
|
||||
if length >= 0 {
|
||||
max = length + 1
|
||||
}
|
||||
if _, v := check.index(expr, max); v >= 0 {
|
||||
x = v
|
||||
}
|
||||
case i == 0:
|
||||
// default is 0 for the first index
|
||||
x = 0
|
||||
case length >= 0:
|
||||
// default is length (== capacity) otherwise
|
||||
x = length
|
||||
}
|
||||
ind[i] = x
|
||||
}
|
||||
|
||||
// constant indices must be in range
|
||||
// (check.index already checks that existing indices >= 0)
|
||||
L:
|
||||
for i, x := range ind[:len(ind)-1] {
|
||||
if x > 0 {
|
||||
for _, y := range ind[i+1:] {
|
||||
if y >= 0 && x > y {
|
||||
check.errorf(inNode(e, e.Rbrack), _SwappedSliceIndices, "swapped slice indices: %d > %d", x, y)
|
||||
break L // only report one error, ok to continue
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
// index checks an index expression for validity.
|
||||
// If max >= 0, it is the upper bound for index.
|
||||
// If the result typ is != Typ[Invalid], index is valid and typ is its (possibly named) integer type.
|
||||
// If the result val >= 0, index is valid and val is its constant int value.
|
||||
func (check *Checker) index(index ast.Expr, max int64) (typ Type, val int64) {
|
||||
typ = Typ[Invalid]
|
||||
val = -1
|
||||
|
||||
var x operand
|
||||
check.expr(&x, index)
|
||||
if !check.isValidIndex(&x, _InvalidIndex, "index", false) {
|
||||
return
|
||||
}
|
||||
|
||||
if x.mode != constant_ {
|
||||
return x.typ, -1
|
||||
}
|
||||
|
||||
if x.val.Kind() == constant.Unknown {
|
||||
return
|
||||
}
|
||||
|
||||
v, ok := constant.Int64Val(x.val)
|
||||
assert(ok)
|
||||
if max >= 0 && v >= max {
|
||||
check.invalidArg(&x, _InvalidIndex, "index %s is out of bounds", &x)
|
||||
return
|
||||
}
|
||||
|
||||
// 0 <= v [ && v < max ]
|
||||
return x.typ, v
|
||||
}
|
||||
|
||||
func (check *Checker) isValidIndex(x *operand, code errorCode, what string, allowNegative bool) bool {
|
||||
if x.mode == invalid {
|
||||
return false
|
||||
}
|
||||
|
||||
// spec: "a constant index that is untyped is given type int"
|
||||
check.convertUntyped(x, Typ[Int])
|
||||
if x.mode == invalid {
|
||||
return false
|
||||
}
|
||||
|
||||
// spec: "the index x must be of integer type or an untyped constant"
|
||||
if !isInteger(x.typ) {
|
||||
check.invalidArg(x, code, "%s %s must be integer", what, x)
|
||||
return false
|
||||
}
|
||||
|
||||
if x.mode == constant_ {
|
||||
// spec: "a constant index must be non-negative ..."
|
||||
if !allowNegative && constant.Sign(x.val) < 0 {
|
||||
check.invalidArg(x, code, "%s %s must not be negative", what, x)
|
||||
return false
|
||||
}
|
||||
|
||||
// spec: "... and representable by a value of type int"
|
||||
if !representableConst(x.val, check, Typ[Int], &x.val) {
|
||||
check.invalidArg(x, code, "%s %s overflows int", what, x)
|
||||
return false
|
||||
}
|
||||
}
|
||||
|
||||
return true
|
||||
}
|
||||
|
||||
// indexElts checks the elements (elts) of an array or slice composite literal
|
||||
// against the literal's element type (typ), and the element indices against
|
||||
// the literal length if known (length >= 0). It returns the length of the
|
||||
// literal (maximum index value + 1).
|
||||
//
|
||||
func (check *Checker) indexedElts(elts []ast.Expr, typ Type, length int64) int64 {
|
||||
visited := make(map[int64]bool, len(elts))
|
||||
var index, max int64
|
||||
for _, e := range elts {
|
||||
// determine and check index
|
||||
validIndex := false
|
||||
eval := e
|
||||
if kv, _ := e.(*ast.KeyValueExpr); kv != nil {
|
||||
if typ, i := check.index(kv.Key, length); typ != Typ[Invalid] {
|
||||
if i >= 0 {
|
||||
index = i
|
||||
validIndex = true
|
||||
} else {
|
||||
check.errorf(e, _InvalidLitIndex, "index %s must be integer constant", kv.Key)
|
||||
}
|
||||
}
|
||||
eval = kv.Value
|
||||
} else if length >= 0 && index >= length {
|
||||
check.errorf(e, _OversizeArrayLit, "index %d is out of bounds (>= %d)", index, length)
|
||||
} else {
|
||||
validIndex = true
|
||||
}
|
||||
|
||||
// if we have a valid index, check for duplicate entries
|
||||
if validIndex {
|
||||
if visited[index] {
|
||||
check.errorf(e, _DuplicateLitKey, "duplicate index %d in array or slice literal", index)
|
||||
}
|
||||
visited[index] = true
|
||||
}
|
||||
index++
|
||||
if index > max {
|
||||
max = index
|
||||
}
|
||||
|
||||
// check element against composite literal element type
|
||||
var x operand
|
||||
check.exprWithHint(&x, eval, typ)
|
||||
check.assignment(&x, typ, "array or slice literal")
|
||||
}
|
||||
return max
|
||||
}
|
||||
Loading…
Reference in New Issue
Block a user