DRAFT RELEASE NOTES - Introduction to Go 1.11

Go 1.11 is not yet released. These are work-in-progress release notes. Go 1.11 is expected to be released in August 2018.

The latest Go release, version 1.11, arrives six months after Go 1.10. Most of its changes are in the implementation of the toolchain, runtime, and libraries. As always, the release maintains the Go 1 promise of compatibility. We expect almost all Go programs to continue to compile and run as before.

Changes to the language

There are no changes to the language specification.

Ports

As announced in the Go 1.10 release notes, Go 1.11 now requires OpenBSD 6.2 or later, macOS 10.10 Yosemite or later, or Windows 7 or later; Support for previous versions of these operating systems has been removed.

There are known issues with NetBSD on i386 hardware.

TODO: PPC64LE race detector support

WebAssembly

Go 1.11 adds an experimental port to WebAssembly (js/wasm).

Go programs currently compile to one WebAssembly module that includes the Go runtime for goroutine scheduling, garbage collection, maps, etc. As a result, the resulting size is at minimum around 2 MB, or 500 KB compressed. Go programs can call into JavaScript using the new experimental syscall/js package. Binary size and interop with other languages has not yet been a priority but may be addressed in future releases.

As a result of the addition of the new GOOS value "js" and GOARCH value "wasm", Go files named *_js.go or *_wasm.go will now be ignored by Go tools except when those GOOS/GOARCH values are being used. If you have existing filenames matching those patterns, you will need to rename them.

Tools

Modules, package versioning, and dependency management

NOTE: This is not present in go1.11beta1 but will be available in future betas and subsequent releases. Go 1.11 adds experimental support for a new concept called “modules,” an alternative to GOPATH with integrated support for versioning and package distribution. Using modules, developers are no longer confined to working inside GOPATH, version dependency information is explicit yet lightweight, and builds are more reliable and reproducible.

Module support is considered experimental. Details are likely to change in response to feedback from Go 1.11 users, and we have more tools planned. Although the details of module support may change, projects that convert to modules using Go 1.11 will continue to work with Go 1.12 and later. If you encounter bugs using modules, please file issues so we can fix them.

TODO: Link to intro doc.

Import path restriction

Because Go module support assigns special meaning to the @ symbol in command line operations, the go command now disallows the use of import paths containing @ symbols. Such import paths were never allowed by go get, so this restriction can only affect users building custom GOPATH trees by other means.

Package loading

TODO: Note about go/build versus golang.org/x/tools/go/packages.

Build cache requirement

Go 1.11 will be the last release to support setting the environment variable GOCACHE=off to disable the build cache, introduced in Go 1.10. Starting in Go 1.12, the build cache will be required, as a step toward eliminating $GOPATH/pkg. The module and package loading support described above already require that the build cache be enabled. If you have disabled the build cache to avoid problems you encountered, please file an issue to let us know about them.

Core library

All of the changes to the standard library are minor.

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.

all

TODO: https://golang.org/cl/93875: enable c-shared/c-archive support for freebsd/amd64

TODO: https://golang.org/cl/94255: drop support for Windows Vista or below (Windows XP)

TODO: https://golang.org/cl/115038: remove support for macOS 10.9 and earlier

crypto: TODO: https://golang.org/cl/64451: randomly read an extra byte of randomness in some places.

crypto/cipher: TODO: https://golang.org/cl/48510: add NewGCMWithTagSize for custom tag sizes.

crypto/rsa: TODO: https://golang.org/cl/103876: add PublicKey.Size accessor

debug/elf: TODO: https://golang.org/cl/112115: add machine and OSABI constants

encoding/asn1: TODO: https://golang.org/cl/110561: allow Marshaling and Unmarshaling private tag class

encoding/base32: TODO: https://golang.org/cl/112516: handle surplus padding consistently

encoding/csv: TODO: https://golang.org/cl/99696: disallow quote for use as Comma

go/build, runtime/internal/sys: TODO: https://golang.org/cl/106256: reserve RISC-V arch names

go/scanner: TODO: https://golang.org/cl/100235: report errors for incorrect line directives

html/template: TODO: https://golang.org/cl/121815: ignore untyped nil arguments to default escapers

http/http/httputil: TODO: https://golang.org/cl/77410: add ReverseProxy.ErrorHandler

http/httpproxy: TODO: https://golang.org/cl/115255: support CIDR notation and ports with NO_PROXY

image/gif: TODO: https://golang.org/cl/93076: support non-looping animated gifs (LoopCount=-1)

io/ioutil: TODO: https://golang.org/cl/105675: change TempFile prefix to a pattern

math/big: TODO: https://golang.org/cl/74851: speed-up addMulVVW on amd64

mime/multipart: TODO: https://golang.org/cl/121055: restore 1.9 handling of missing/empty form-data file name

mime/quotedprintable: To support invalid input found in the wild, the package now permits non-ASCII bytes but does not validate their encoding.

net

The new ListenConfig type and the new Dialer.Control field permit setting socket options before accepting and creating connections, respectively.

TODO: https://golang.org/cl/76391: implement (*syscall.RawConn).Read/Write on Windows

The net package now automatically uses the splice system call on Linux when calling copying data between TCP connections in TCPConn.ReadFrom, as called by io.Copy. The result is faster, more efficient TCP proxying.

TODO: https://golang.org/cl/108297: calling File leaves the socket in nonblocking mode

net/http

The Transport has a new MaxConnsPerHost option that permits limiting the maximum number of connections per host.

The Cookie type has a new The SameSite field (of new type also named SameSite) to represent the new cookie attribute recently supported by most browsers. The net/http's Transport does not use the SameSite attribute itself, but the package supports parsing and serializing the attribute for browsers to use.

It is no longer allowed to reuse a Server after a call to Shutdown or Close. It was never officially supported in the past and had often surprising behavior. Now, all future calls to the server's Serve methods will return errors after a shutdown or close.

The HTTP server will no longer automatically set the Content-Type if a Handler sets the "X-Content-Type-Options" header to "nosniff".

The constant StatusMisdirectedRequest is now defined for HTTP status code 421.

The HTTP server will no longer cancel contexts or send on CloseNotifier channels upon receiving pipelined HTTP/1.1 requests. Browsers do not use HTTP pipelining, but some clients (such as Debian's apt) may be configured to do so.

os

TODO: https://golang.org/cl/78835: add UserCacheDir

TODO: https://golang.org/cl/94856: add ModeIrregular flag

TODO: https://golang.org/cl/99337: enable symlink creation on Windows 10

TODO: https://golang.org/cl/100077: use poller when NewFile is called with a blocking descriptor.

os/signal: TODO: https://golang.org/cl/108376: add func Ignored(sig Signal) bool

os/user: The os/user package can now be built in pure Go mode using the build tag "osusergo", independent of the use of the environment variable CGO_ENABLED=0. Previously the only way to use the package's pure Go implementation was to disable cgo support across the entire program.

runtime

TODO: https://golang.org/cl/85887: use sparse mappings for the heap

TODO: https://golang.org/cl/94076: use native CAS and memory barrier on ARMv7

TODO: https://golang.org/cl/106156: use fixed TLS offsets on darwin/amd64 and darwin/386

TODO: https://golang.org/cl/109255: enable memory sanitizer on arm64

TODO: https://golang.org/cl/109699: support for debugger function calls

TODO: https://golang.org/cl/121657: remap stack spans with MAP_STACK on OpenBSD

runtime,cmd/ld: TODO: https://golang.org/cl/108679: on darwin, create theads using libc

runtime/pprof: TODO: https://golang.org/cl/102696: introduce "allocs" profile

runtime/race: TODO: https://golang.org/cl/107935: implement race detector for ppc64le

runtime/trace: TODO: https://golang.org/cl/63274: user annotation API

runtime/traceback: TODO: https://golang.org/cl/70993: support tracking goroutine ancestor tracebacks with GODEBUG="tracebackancestors=N"

sync: TODO: https://golang.org/cl/87095: enable profiling of RWMutex

syscall

TODO: https://golang.org/cl/106275: introduce Pointer type and use it instead of uintptr

TODO: https://golang.org/cl/118658: check Fchmodat flags parameter on Linux

text/scanner: TODO: https://golang.org/cl/112037: return RawString token rather than String for raw string literals

text/template

TODO: https://golang.org/cl/84480: add variable assignments

TODO: https://golang.org/cl/95215: differentiate nil from missing arg

time: TODO: https://golang.org/cl/98157: add support for parsing timezones denoted by sign and offset