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cmd/compile/internal/typecheck: remove constant bounds check

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types2 handles all constant-related bounds checks in user Go code now,
so it's safe to remove the check from typecheck, avoid the inconsistency
with type parameter.

Fixes #65417

Change-Id: I82dd197b78e271725d132b5a20450ae3e90f9abc
Reviewed-on: https://go-review.googlesource.com/c/go/+/560575
Reviewed-by: Keith Randall <khr@google.com>
Auto-Submit: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Robert Griesemer <gri@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
This commit is contained in:
Cuong Manh Le 2024-02-02 09:35:07 +07:00 committed by Gopher Robot
parent 53708d86b0
commit 5428cc4f14
2 changed files with 42 additions and 13 deletions
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13
src/cmd/compile/internal/typecheck/expr.go
View File

@ -621,19 +621,6 @@ func tcIndex(n *ir.IndexExpr) ir.Node {
return n
}
if !n.Bounded() && ir.IsConst(n.Index, constant.Int) {
x := n.Index.Val()
if constant.Sign(x) < 0 {
base.Errorf("invalid %s index %v (index must be non-negative)", why, n.Index)
} else if t.IsArray() && constant.Compare(x, token.GEQ, constant.MakeInt64(t.NumElem())) {
base.Errorf("invalid array index %v (out of bounds for %d-element array)", n.Index, t.NumElem())
} else if ir.IsConst(n.X, constant.String) && constant.Compare(x, token.GEQ, constant.MakeInt64(int64(len(ir.StringVal(n.X))))) {
base.Errorf("invalid string index %v (out of bounds for %d-byte string)", n.Index, len(ir.StringVal(n.X)))
} else if ir.ConstOverflow(x, types.Types[types.TINT]) {
base.Errorf("invalid %s index %v (index too large)", why, n.Index)
}
}
case types.TMAP:
n.Index = AssignConv(n.Index, t.Key(), "map index")
n.SetType(t.Elem())

42
test/fixedbugs/issue65417.go Normal file
View File

@ -0,0 +1,42 @@
// run
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package main
import (
"strings"
"unsafe"
)
func main() {
shouldPanic("runtime error: index out of range", func() { f(0) })
shouldPanic("runtime error: index out of range", func() { g(0) })
}
func f[T byte](t T) {
const str = "a"
_ = str[unsafe.Sizeof(t)]
}
func g[T byte](t T) {
const str = "a"
_ = str[unsafe.Sizeof(t)+0]
}
func shouldPanic(str string, f func()) {
defer func() {
err := recover()
if err == nil {
panic("did not panic")
}
s := err.(error).Error()
if !strings.Contains(s, str) {
panic("got panic " + s + ", want " + str)
}
}()
f()
}