Each file is a list of API features, one per line.

go1.txt (and similarly named files) are frozen once a version has been
shipped. Each file adds new lines but does not remove any.

except.txt lists features that may disappear without breaking true
compatibility.

Starting with go1.19.txt, each API feature line must end in "#nnnnn"
giving the GitHub issue number of the proposal issue that accepted

pkg text/template/parse, type BreakNode struct
pkg text/template/parse, type BreakNode struct, Line int
pkg text/template/parse, type BreakNode struct, embedded NodeType
pkg text/template/parse, type BreakNode struct, embedded Pos
pkg text/template/parse, type ContinueNode struct
pkg text/template/parse, type ContinueNode struct, Line int
pkg text/template/parse, type ContinueNode struct, embedded NodeType

poll the length to decide whether a receive on the timer channel
will succeed.
Such code should use a non-blocking receive instead.

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)

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`.
At a minimum, that file should contain either a full sentence or a TODO,

The new type [KeepAliveConfig] permits fine-tuning the keep-alive
options for TCP connections, via a new [TCPConn.SetKeepAliveConfig]

`}}

Only differences from the base Go toolchain defaults are reported.

When testing a package, `//go:debug` lines in the `*_test.go`
files are treated as directives for the test's main package.
In any other context, `//go:debug` lines are ignored by the toolchain;
`go` `vet` reports such lines as misplaced.

## GODEBUG History {#history}

library packages begin with a dotless path element.

The module requirements of std and cmd do not influence version
selection in other modules. They are only considered when running
module commands like 'go get' and 'go mod vendor' from a directory
in GOROOT/src.

Maintaining vendor directories
==============================

Before updating vendor directories, ensure that module mode is enabled.

*.orig
*.rej
*.exe
.*.swp
core
*.cgo*.go
*.cgo*.c
_cgo_*
_obj
_test
_testmain.go

/VERSION.cache
/bin/
/build.out
/doc/articles/wiki/*.bin
/goinstall.log
/last-change
/misc/cgo/life/run.out
/misc/cgo/stdio/run.out
/misc/cgo/testso/main
/pkg/
/src/*.*/
/src/cmd/cgo/zdefaultcc.go
/src/cmd/dist/dist
/src/cmd/go/internal/cfg/zdefaultcc.go
/src/cmd/internal/objabi/zbootstrap.go

the code and data maintained as part of the IANA Time Zone Database.
The IANA asserts that the database is in the public domain.

For more information, see
https://www.iana.org/time-zones
ftp://ftp.iana.org/tz/code/tz-link.html
https://datatracker.ietf.org/doc/html/rfc6557

### New unique package

The new [unique](/pkg/unique) package provides facilities for
canonicalizing values (like "interning" or "hash-consing").

Any value of comparable type may be canonicalized with the new
`Make[T]` function, which produces a reference to a canonical copy of
the value in the form of a `Handle[T]`.
Two `Handle[T]` are equal if and only if the values used to produce the
handles are equal, allowing programs to deduplicate values and reduce