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A few examples (for accessing a slice of length 3): s[-1] runtime error: index out of range [-1] s[3] runtime error: index out of range [3] with length 3 s[-1:0] runtime error: slice bounds out of range [-1:] s[3:0] runtime error: slice bounds out of range [3:0] s[3:-1] runtime error: slice bounds out of range [:-1] s[3:4] runtime error: slice bounds out of range [:4] with capacity 3 s[0:3:4] runtime error: slice bounds out of range [::4] with capacity 3 Note that in cases where there are multiple things wrong with the indexes (e.g. s[3:-1]), we report one of those errors kind of arbitrarily, currently the rightmost one. An exhaustive set of examples is in issue30116[u].out in the CL. The message text has the same prefix as the old message text. That leads to slightly awkward phrasing but hopefully minimizes the chance that code depending on the error text will break. Increases the size of the go binary by 0.5% (amd64). The panic functions take arguments in registers in order to keep the size of the compiled code as small as possible. Fixes #30116 Change-Id: Idb99a827b7888822ca34c240eca87b7e44a04fdd Reviewed-on: https://go-review.googlesource.com/c/go/+/161477 Run-TryBot: Keith Randall <khr@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: David Chase <drchase@google.com>
113 lines
2.2 KiB
Go
113 lines
2.2 KiB
Go
// run
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// Copyright 2019 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 test makes sure the text output for bounds check failures is as expected.
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package main
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import (
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"fmt"
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"os"
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"runtime"
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"text/tabwriter"
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)
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// Testing with length 3 slices, arrays, and strings.
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// Large (>1<<32) values are included to test 32-bit platforms.
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var indexes = []int64{-9876543210, -1, 0, 2, 3, 9876543210}
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var slices = []int64{-9876543210, -1, 0, 3, 4, 9876543210}
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var w *tabwriter.Writer
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func main() {
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w = tabwriter.NewWriter(os.Stdout, 0, 0, 1, ' ', tabwriter.AlignRight)
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defer w.Flush()
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doIndex()
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doSlice()
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doSlice3()
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}
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func doIndex() {
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a := []int{1, 2, 3}
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for _, i := range indexes {
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printPanic(fmt.Sprintf("slice[%d]", i), func() {
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_ = a[i]
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})
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}
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b := [3]int{1, 2, 3}
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for _, i := range indexes {
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printPanic(fmt.Sprintf("array[%d]", i), func() {
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_ = b[i]
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})
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}
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c := "123"
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for _, i := range indexes {
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printPanic(fmt.Sprintf("string[%d]", i), func() {
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_ = c[i]
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})
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}
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}
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func doSlice() {
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a := []int{1, 2, 3}
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for _, i := range slices {
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for _, j := range slices {
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printPanic(fmt.Sprintf("slice[%d:%d]", i, j), func() {
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_ = a[i:j]
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})
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}
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}
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b := [3]int{1, 2, 3}
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for _, i := range slices {
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for _, j := range slices {
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printPanic(fmt.Sprintf("array[%d:%d]", i, j), func() {
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_ = b[i:j]
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})
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}
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}
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c := "123"
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for _, i := range slices {
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for _, j := range slices {
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printPanic(fmt.Sprintf("string[%d:%d]", i, j), func() {
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_ = c[i:j]
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})
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}
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}
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}
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func doSlice3() {
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a := []int{1, 2, 3}
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for _, i := range slices {
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for _, j := range slices {
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for _, k := range slices {
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printPanic(fmt.Sprintf("slice[%d:%d:%d]", i, j, k), func() {
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_ = a[i:j:k]
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})
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}
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}
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}
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b := [3]int{1, 2, 3}
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for _, i := range slices {
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for _, j := range slices {
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for _, k := range slices {
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printPanic(fmt.Sprintf("array[%d:%d:%d]", i, j, k), func() {
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_ = b[i:j:k]
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})
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}
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}
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}
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}
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func printPanic(msg string, f func()) {
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defer func() {
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res := "no panic"
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if e := recover(); e != nil {
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res = e.(runtime.Error).Error()
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}
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fmt.Fprintf(w, "%s\t %s\n", msg, res)
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}()
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f()
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}
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