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author | Keith Randall <khr@golang.org> | 2023-08-23 15:19:15 -0700 |
---|---|---|
committer | Carlos Amedee <carlos@golang.org> | 2023-08-25 16:37:04 +0000 |
commit | 13339c75b80b906419e37596c0a1b6aeeca3f16c (patch) | |
tree | ccadfba90ebeb5708e383a4b69554a3d9a64a0e8 | |
parent | 29777098753015176fa4a596ef5c1b4ecb2ddb3b (diff) | |
download | go-13339c75b80b906419e37596c0a1b6aeeca3f16c.tar.gz go-13339c75b80b906419e37596c0a1b6aeeca3f16c.zip |
[release-branch.go1.21] runtime: fix maps.Clone bug when cloning a map mid-grow
Fixes #62204
Change-Id: I0459d3f481b0cd20102f6d9fd3ea84335a7739a8
Reviewed-on: https://go-review.googlesource.com/c/go/+/522317
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Keith Randall <khr@google.com>
Reviewed-by: Bryan Mills <bcmills@google.com>
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
(cherry picked from commit b303fb48558612e5c2a1f10acbc0b1accdb8f260)
Reviewed-on: https://go-review.googlesource.com/c/go/+/522936
Reviewed-by: Carlos Amedee <carlos@golang.org>
-rw-r--r-- | src/runtime/map.go | 2 | ||||
-rw-r--r-- | test/fixedbugs/issue62203.go | 32 |
2 files changed, 33 insertions, 1 deletions
diff --git a/src/runtime/map.go b/src/runtime/map.go index 7b954759f1..6b85681447 100644 --- a/src/runtime/map.go +++ b/src/runtime/map.go @@ -1553,7 +1553,7 @@ func mapclone2(t *maptype, src *hmap) *hmap { } if oldB >= dst.B { // main bucket bits in dst is less than oldB bits in src - dstBmap := (*bmap)(add(dst.buckets, uintptr(i)&bucketMask(dst.B))) + dstBmap := (*bmap)(add(dst.buckets, (uintptr(i)&bucketMask(dst.B))*uintptr(t.BucketSize))) for dstBmap.overflow(t) != nil { dstBmap = dstBmap.overflow(t) } diff --git a/test/fixedbugs/issue62203.go b/test/fixedbugs/issue62203.go new file mode 100644 index 0000000000..8c93d781ea --- /dev/null +++ b/test/fixedbugs/issue62203.go @@ -0,0 +1,32 @@ +// run + +// Copyright 2023 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" + "maps" +) + +func main() { + m := map[string]struct{}{} + + // Fill m up to the max for 4 buckets = 48 entries. + for i := 0; i < 48; i++ { + m[fmt.Sprintf("%d", i)] = struct{}{} + } + + // Add a 49th entry, to start a grow to 8 buckets. + m["foo"] = struct{}{} + + // Remove that 49th entry. m is still growing to 8 buckets, + // but a clone of m will only have 4 buckets because it + // only needs to fit 48 entries. + delete(m, "foo") + + // Clone an 8-bucket map to a 4-bucket map. + _ = maps.Clone(m) +} |