These new behaviors are only enabled when the main Go program
is in a module with a `go.mod` `go` line using Go 1.23.0 or later.
When Go 1.23 builds older programs, the old behaviors remain in effect.
The new [GODEBUG setting](/doc/godebug) [`asynctimerchan=1`](/pkg/time/#NewTimer)
can be used to revert back to asynchronous channel behaviors

`doc/next/*stdlib/*minor`.
The files should be in the subdirectory for the package with the new
API, and should be named after the issue number of the API proposal.
For example, if the directory `6-stdlib/99-minor` is present,
then an `api/next` file with the line

    pkg net/http, function F #12345

should have a corresponding file named `doc/next/6-stdlib/99-minor/net/http/12345.md`.

There are two modules, std and cmd, defined in src/go.mod and
src/cmd/go.mod. When a package outside std or cmd is imported
by a package inside std or cmd, the import path is interpreted
as if it had a "vendor/" prefix. For example, within "crypto/tls",
an import of "golang.org/x/crypto/cryptobyte" resolves to
"vendor/golang.org/x/crypto/cryptobyte". When a package with the
same path is imported from a package outside std or cmd, it will

  a new slice.
- [AppendSeq](/pkg/slices#AppendSeq) appends values from an iterator to
  an existing slice.
- [Sorted](/pkg/slices#Sorted) collects values from an iterator into a
  new slice, and then sorts the slice.
- [SortedFunc](/pkg/slices#SortedFunc) is like `Sorted` but with a
  comparison function.
- [SortedStableFunc](/pkg/slices#SortedStableFunc) is like `SortFunc`
  but uses a stable sort algorithm.

Using `panicnil=1` restores the behavior of Go 1.20 and earlier.

When compiling a work module or workspace that declares
an older Go version, the Go toolchain amends its defaults
to match that older Go version as closely as possible.
For example, when a Go 1.21 toolchain compiles a program,
if the work module's `go.mod` or the workspace's `go.work`
says `go` `1.20`, then the program defaults to `panicnil=1`,
matching Go 1.20 instead of Go 1.21.

<!-- TODO: Improve the wording. Mention the tlskyber GODEBUG. -->

### Trace {#trace}

<!-- go.dev/issue/65316 -->
The `trace` tool now better tolerates partially broken traces by attempting to
recover what trace data it can. This functionality is particularly helpful when
viewing a trace that was collected during a program crash, since the trace data
leading up to the crash will now [be recoverable](/issue/65319) under most

nnnnn.txt, after the issue number for the accepted proposal.
(The #nnnnn suffix must also appear at the end of each line in the file;
that will be preserved when next/*.txt is concatenated into go1.XX.txt.)

When you add a file to the api/next directory, you must add at least one file

<!-- go.dev/issue/65319 -->
The runtime now explicitly flushes trace data when a program crashes due to an
uncaught panic. This means that more complete trace data will be available in a

3DES cipher suites were removed from the default list used when
[Config.CipherSuites] is nil. The default can be reverted adding `tls3des=1` to