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go/test/fixedbugs/issue28797.go
David Chase ea6259d5e9 cmd/compile: check for negative upper bound to IsSliceInBounds
IsSliceInBounds(x, y) asserts that y is not negative, but
there were cases where this is not true.  Change code
generation to ensure that this is true when it's not obviously
true.  Prove phase cleans a few of these out.

With this change the compiler text section is 0.06% larger,
that is, not very much.  Benchmarking still TBD, may need
to wait for access to a benchmarking box (next week).

Also corrected run.go to handle '?' in -update_errors output.

Fixes #28797.

Change-Id: Ia8af90bc50a91ae6e934ef973def8d3f398fac7b
Reviewed-on: https://go-review.googlesource.com/c/152477
Run-TryBot: David Chase <drchase@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2018-12-07 23:04:58 +00:00

54 lines
900 B
Go

// run
// Copyright 2018 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 (
"fmt"
)
// test expects f to panic, but not to run out of memory,
// which is a non-panic fatal error. OOM results from failure
// to properly check negative limit.
func test(f func()) {
defer func() {
r := recover()
if r == nil {
panic("panic wasn't recoverable")
}
}()
f()
}
//go:noinline
func id(x int) int {
return x
}
func main() {
test(foo)
test(bar)
}
func foo() {
b := make([]byte, 0)
b = append(b, 1)
id(len(b))
id(len(b) - 2)
s := string(b[1 : len(b)-2])
fmt.Println(s)
}
func bar() {
b := make([]byte, 1)
b = append(b, 1)
i := id(-1)
if i < len(b) { // establish value is not too large.
s := string(b[1:i]) // should check for negative also.
fmt.Println(s)
}
}