Go 1.19 is not yet released. These are work-in-progress release notes. Go 1.19 is expected to be released in August 2022.
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The -trimpath flag, if set, is now included in the build settings
stamped into Go binaries by go build, and can be
examined using
go version -m
or debug.ReadBuildInfo.
go generate now sets the GOROOT
environment variable explicitly in the generator's environment, so that
generators can locate the correct GOROOT even if built
with -trimpath.
unix build constraint
The build constraint unix is now recognized
in //go:build lines. The constraint is satisfied
if the target operating system, also known as GOOS, is
a Unix or Unix-like system. For the 1.19 release it is satisfied
if GOOS is one of
aix, android, darwin,
dragonfly, freebsd, hurd,
illumos, ios, linux,
netbsd, openbsd, or solaris.
In future releases the unix constraint may match
additional newly supported operating systems.
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The compiler now uses
a jump
table to implement large integer and string switch statements.
Performance improvements for the switch statement vary but can be
on the order of 20% faster.
(GOARCH=amd64 and GOARCH=arm64 only)
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As always, there are various minor changes and updates to the library, made with the Go 1 promise of compatibility in mind.
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The tls10default GODEBUG option has been
removed. It is still possible to enable TLS 1.0 client-side by setting
Config.MinVersion.
Draw with the Src operator preserves
non-premultiplied-alpha colors when destination and source images are
both *image.NRGBA (or both *image.NRGBA64).
This reverts a behavior change accidentally introduced by a Go 1.18
library optimization, to match the behavior in Go 1.17 and earlier.
The pure Go resolver will now use EDNS(0) to include a suggested
maximum reply packet length, permitting reply packets to contain
up to 1232 bytes (the previous maximum was 512).
In the unlikely event that this causes problems with a local DNS
resolver, setting the environment variable
GODEBUG=netdns=cgo to use the cgo-based resolver
should work.
Please report any such problems on the
issue tracker.
When a net package function or method returns an "I/O timeout"
error, the error will now satisfy errors.Is(err,
context.DeadlineExceeded). When a net package function
returns an "operation was canceled" error, the error will now
satisfy errors.Is(err, context.Canceled).
These changes are intended to make it easier for code to test
for cases in which a context cancellation or timeout causes a net
package function or method to return an error, while preserving
backward compatibility for error messages.
An exec.Cmd with a non-empty Dir and a
nil Env now implicitly sets the PWD environment
variable for the subprocess to match Dir.
The new method (*exec.Cmd).Environ reports the
environment that would be used to run the command, including the
aforementioned PWD variable.
reflect.SliceHeader
and reflect.StringHeader
are now deprecated, and their use should be avoided.
The GOROOT function now returns the empty string
(instead of "go") when the binary was built with
the -trimpath flag set and the GOROOT
variable is not set in the process environment.
The race detector has been updgraded to use thread sanitizer version v3.
strconv.Quote
and related functions now quote the rune 007F as \x7f,
not \u007f.