diff options
| author | Russ Cox <rsc@golang.org> | 2022-11-15 09:54:39 -0500 |
|---|---|---|
| committer | Russ Cox <rsc@golang.org> | 2022-11-15 18:14:39 +0000 |
| commit | b14cf3d93ae5c477dd35f13f6ba41044f01a7f7d (patch) | |
| tree | db7a421a387b59923ef3f6f0412809007bcf6492 /src/sync | |
| parent | 56d18207823d6e1c18ca46409180c40ae800230c (diff) | |
| download | go-b14cf3d93ae5c477dd35f13f6ba41044f01a7f7d.tar.gz go-b14cf3d93ae5c477dd35f13f6ba41044f01a7f7d.zip | |
sync/atomic: allow linked list of atomic pointers again
For #56603, CL 448275 added a _ [0]T field to atomic.Pointer,
so that different kinds of atomic.Pointer are not convertible.
Unfortunately, that breaks code like:
type List struct {
Next atomic.Pointer[List]
}
which should be valid, just as using Next *List is valid.
Instead, we get:
./atomic_test.go:2533:6: invalid recursive type List
./atomic_test.go:2533:6: List refers to
./atomic_test.go:2534:13: "sync/atomic".Pointer refers to
./atomic_test.go:2533:6: List
Fix by using _[0]*T instead.
Change-Id: Icc4c83c691d35961d20cb14b824223d6c779ac5e
Reviewed-on: https://go-review.googlesource.com/c/go/+/450655
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Diffstat (limited to 'src/sync')
| -rw-r--r-- | src/sync/atomic/atomic_test.go | 6 | ||||
| -rw-r--r-- | src/sync/atomic/type.go | 5 |
2 files changed, 9 insertions, 2 deletions
diff --git a/src/sync/atomic/atomic_test.go b/src/sync/atomic/atomic_test.go index 0cc9b06a6c..c3604ef0af 100644 --- a/src/sync/atomic/atomic_test.go +++ b/src/sync/atomic/atomic_test.go @@ -2526,3 +2526,9 @@ func TestNilDeref(t *testing.T) { }() } } + +// Test that this compiles. +// When atomic.Pointer used _ [0]T, it did not. +type List struct { + Next Pointer[List] +} diff --git a/src/sync/atomic/type.go b/src/sync/atomic/type.go index 4d466232f1..cc016833d1 100644 --- a/src/sync/atomic/type.go +++ b/src/sync/atomic/type.go @@ -41,9 +41,10 @@ var _ = &Pointer[int]{} // A Pointer is an atomic pointer of type *T. The zero value is a nil *T. type Pointer[T any] struct { - // Mention T in a field to disallow conversion between Pointer types. + // Mention *T in a field to disallow conversion between Pointer types. // See go.dev/issue/56603 for more details. - _ [0]T + // Use *T, not T, to avoid spurious recursive type definition errors. + _ [0]*T _ noCopy v unsafe.Pointer |