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go/types: cleanup and fix Checker.index

A couple minor spec compliance issues: constant, typed index operands
must still be representable as type "int", but should also be recorded
as their original type.

Fixes #45667.

Change-Id: Iefeb29f20a8e48350af83a62c9ae0e92198c5ef7
Reviewed-on: https://go-review.googlesource.com/c/go/+/312591
Trust: Matthew Dempsky <mdempsky@google.com>
Trust: Robert Griesemer <gri@golang.org>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>
Reviewed-by: Robert Griesemer <gri@golang.org>
This commit is contained in:
Matthew Dempsky 2021-04-21 18:22:35 -07:00
parent cfe5d79c5c
commit f7afdfd483
3 changed files with 51 additions and 23 deletions

View File

@ -87,6 +87,9 @@ var builtinCalls = []struct {
{"make", `var c int32; _ = make([]float64 , 0, c)`, `func([]float64, int, int32) []float64`},
{"make", `var l, c uint ; _ = make([]complex128, l, c)`, `func([]complex128, uint, uint) []complex128`},
// issue #45667
{"make", `const l uint = 1; _ = make([]int, l)`, `func([]int, uint) []int`},
{"new", `_ = new(int)`, `func(int) *int`},
{"new", `type T struct{}; _ = new(T)`, `func(p.T) *p.T`},

View File

@ -203,7 +203,7 @@ func asGoVersion(s string) string {
return ""
}
func checkFiles(t *testing.T, goVersion string, filenames []string, srcs [][]byte) {
func checkFiles(t *testing.T, sizes Sizes, goVersion string, filenames []string, srcs [][]byte) {
if len(filenames) == 0 {
t.Fatal("no source files")
}
@ -239,6 +239,7 @@ func checkFiles(t *testing.T, goVersion string, filenames []string, srcs [][]byt
// typecheck and collect typechecker errors
var conf Config
conf.Sizes = sizes
conf.GoVersion = goVersion
// special case for importC.src
@ -310,7 +311,15 @@ func TestCheck(t *testing.T) {
func TestLongConstants(t *testing.T) {
format := "package longconst\n\nconst _ = %s\nconst _ = %s // ERROR excessively long constant"
src := fmt.Sprintf(format, strings.Repeat("1", 9999), strings.Repeat("1", 10001))
checkFiles(t, "", []string{"longconst.go"}, [][]byte{[]byte(src)})
checkFiles(t, nil, "", []string{"longconst.go"}, [][]byte{[]byte(src)})
}
// TestIndexRepresentability tests that constant index operands must
// be representable as int even if they already have a type that can
// represent larger values.
func TestIndexRepresentability(t *testing.T) {
const src = "package index\n\nvar s []byte\nvar _ = s[int64 /* ERROR \"int64\\(1\\) << 40 \\(.*\\) overflows int\" */ (1) << 40]"
checkFiles(t, &StdSizes{4, 4}, "", []string{"index.go"}, [][]byte{[]byte(src)})
}
func TestTestdata(t *testing.T) { DefPredeclaredTestFuncs(); testDir(t, "testdata") }
@ -358,5 +367,5 @@ func testPkg(t *testing.T, filenames []string, goVersion string) {
}
srcs[i] = src
}
checkFiles(t, goVersion, filenames, srcs)
checkFiles(t, nil, goVersion, filenames, srcs)
}

View File

@ -1012,19 +1012,7 @@ func (check *Checker) index(index ast.Expr, max int64) (typ Type, val int64) {
var x operand
check.expr(&x, index)
if x.mode == invalid {
return
}
// an untyped constant must be representable as Int
check.convertUntyped(&x, Typ[Int])
if x.mode == invalid {
return
}
// the index must be of integer type
if !isInteger(x.typ) {
check.invalidArg(&x, _InvalidIndex, "index %s must be integer", &x)
if !check.isValidIndex(&x, _InvalidIndex, "index", false) {
return
}
@ -1032,12 +1020,6 @@ func (check *Checker) index(index ast.Expr, max int64) (typ Type, val int64) {
return x.typ, -1
}
// a constant index i must be in bounds
if constant.Sign(x.val) < 0 {
check.invalidArg(&x, _InvalidIndex, "index %s must not be negative", &x)
return
}
v, valid := constant.Int64Val(constant.ToInt(x.val))
if !valid || max >= 0 && v >= max {
check.errorf(&x, _InvalidIndex, "index %s is out of bounds", &x)
@ -1045,7 +1027,41 @@ func (check *Checker) index(index ast.Expr, max int64) (typ Type, val int64) {
}
// 0 <= v [ && v < max ]
return Typ[Int], v
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