DRAFT RELEASE NOTES — Introduction to Go 1.20

Go 1.20 is not yet released. These are work-in-progress release notes. Go 1.20 is expected to be released in February 2023.

Changes to the language

TODO: complete this section

Ports

TODO: complete this section, or delete if not needed

Tools

Go command

TODO: https://go.dev/cl/421440: cmd/go: add go generate -skip flag

TODO: https://go.dev/issue/45454: provide build tags for architecture environment variables

When the main module is located within GOPATH/src, go install no longer installs libraries for non-main packages to GOPATH/pkg, and go list no longer reports a Target field for such packages. (In module mode, compiled packages are stored in the build cache only, but a bug had caused the GOPATH install targets to unexpectedly remain in effect.)

go version

The go version -m command now supports reading more types of Go binaries, most notably, Windows DLLs built with go build -buildmode=c-shared and Linux binaries without execute permission.

Vet

TODO: https://go.dev/issue/48801: check for time formats with 2006-02-01

Runtime

TODO: complete this section, or delete if not needed

Compiler

TODO: https://go.dev/issue/49390: clarify whether "-l" and "-N" compiler flags are actually supported

Linker

TODO: complete this section, or delete if not needed

Bootstrap

TODO: https://go.dev/issue/44505: adopt Go 1.17.13 as bootstrap toolchain for Go 1.20

Core library

New crypto/ecdh package

TODO: complete this section

Minor changes to the library

As always, there are various minor changes and updates to the library, made with the Go 1 promise of compatibility in mind. There are also various performance improvements, not enumerated here.

TODO: complete this section

bytes

TODO: https://go.dev/cl/407176: strings, bytes: add CutPrefix and CutSuffix

TODO: https://go.dev/cl/359675: bytes: add Clone function

crypto/elliptic

TODO: https://go.dev/issue/34648: automatically upgrade CurveParams for known curves and deprecate custom ones

crypto/subtle

TODO: https://go.dev/issue/53021: add XORBytes

TODO: https://go.dev/cl/421435: crypto/subtle: add XORBytes; modified api/next/53021.txt

debug/elf

TODO: https://go.dev/cl/420982: debug/elf: add new-style LoongArch reloc types; modified api/next/54222.txt

debug/pe

TODO: https://go.dev/cl/421357: debug/pe: add IMAGE_FILE_MACHINE_RISCV{32,64,128}; modified api/next/54251.txt

encoding/binary

TODO: https://go.dev/cl/420274: encoding/binary: ReadUvarint return io.ErrUnexpectedEOF when read at least 1 byte

encoding/xml

TODO: https://go.dev/issue/53346: Add (*Encoder).Close() to check for unclosed elements

TODO: https://go.dev/cl/424777: encoding/xml: add (*Encoder).Close

fmt

TODO: https://go.dev/issue/51668: add FormatString(State) string

TODO: https://go.dev/cl/400875: fmt: add a function to recover the original format string given a State; modified api/next/51668.txt

go/build

TODO: https://go.dev/cl/421434: go/build: add GO$GOARCH-based ToolTags

go/token

TODO: https://go.dev/cl/410114: go/token: add (*FileSet).RemoveFile(*File) method

io

TODO: https://go.dev/issue/45899: add OffsetWriter, NewOffsetWriter

TODO: https://go.dev/cl/406776: io: add OffsetWriter, NewOffsetWriter; modified api/next/45899.txt

net/http

TODO: https://go.dev/issue/41773: add Server.OptionsHandler to allow custom handling of OPTIONS *

TODO: https://go.dev/cl/356410: net/http: add Server.DisableOptionsHandler for custom handling of OPTIONS *; modified api/next/41773.txt

net/http/httputil

TODO: https://go.dev/issue/50465: add X-Forwarded-Proto and X-Forwarded-Host by default

TODO: https://go.dev/issue/53002: replace Director with Rewrite

TODO: https://go.dev/cl/407214: net/http/httputil: add ReverseProxy.Rewrite; modified api/next/53002.txt

TODO: https://go.dev/cl/407414: net/http/httputil: add X-Forwarded-{Host,Proto} headers in ReverseProxy

strconv

TODO: https://go.dev/cl/345488: strconv: optimize Parse for []byte arguments

strings

TODO: https://go.dev/issue/42537: add CutPrefix and CutSuffix

TODO: https://go.dev/issue/45038: bytes, strings: add Clone

syscall

TODO: https://go.dev/cl/407574: syscall: add new CLONE_ flags for Linux

time

TODO: https://go.dev/issue/52746: add DateTime, DateOnly, TimeOnly format constants

TODO: https://go.dev/cl/412495: time: add DateTime, DateOnly, and TimeOnly

unicode/utf16

TODO: https://go.dev/issue/51896: add AppendRune

TODO: https://go.dev/cl/409054: unicode/utf16: add AppendRune; modified api/next/51896.txt