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go/test/fixedbugs/issue62203.go
Keith Randall b303fb4855 runtime: fix maps.Clone bug when cloning a map mid-grow
Fixes #62203

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>
2023-08-25 16:10:03 +00:00

33 lines
688 B
Go

// 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)
}