Go 1.14 is not yet released. These are work-in-progress release notes. Go 1.14 is expected to be released in February 2020.
TODO
TODO: https://golang.org/cl/187519: allow embedding overlapping interfaces
TODO: is Dragonfly passing? On both Dragonfly release & tip? (ABI change happened) Does the net package's interface APIs work on both? https://golang.org/issue/34368.
TODO: is Illumos up with a builder and passing? https://golang.org/issue/15581.
TODO: announce something about the Go Solaris port? Solaris itself is unmaintained? The builder is still running at Oracle, but the employee who set it up left the company and we have no way to maintain it.
Go 1.14 is the last Go release to support 32-bit binaries on
macOS (the darwin/386 port). They are no longer
supported by macOS, starting with macOS 10.15 (Catalina).
Go continues to support the 64-bit darwin/amd64 port.
Go 1.14 will likely be the last Go release to support 32-bit
binaries on iOS, iPadOS, watchOS, and tvOS
(the darwin/arm port). Go continues to support the
64-bit darwin/arm64 port.
Go binaries on Windows now have DEP (Data Execution Prevention) enabled.
JavaScript values referenced from Go via js.Value
objects can now be garbage collected.
js.Value values can no longer be compared using
the == operator, and instead must be compared using
their Equal method.
js.Value now
has IsUndefined, IsNull,
and IsNaN methods.
Go now supports the 64-bit ARM architecture on FreeBSD (the
freebsd/arm64 port).
As announced in the Go 1.13 release notes,
Go 1.14 drops support for the Native Client platform (GOOS=nacl).
The runtime now respects zone CPU caps
(the zone.cpu-cap resource control)
for runtime.NumCPU and the default value
of GOMAXPROCS.
TODO
When the main module contains a top-level vendor directory and
its go.mod file specifies go 1.14 or
higher, the go command now defaults to -mod=vendor
for operations that accept that flag. A new value for that flag,
-mod=mod, causes the go command to instead load
modules from the module cache (as when no vendor directory is
present).
When -mod=vendor is set (explicitly or by default), the
go command now verifies that the main module's
vendor/modules.txt file is consistent with its
go.mod file.
go list -m no longer silently omits
transitive dependencies that do not provide packages in
the vendor directory. It now fails explicitly if
-mod=vendor is set.
The go get command no longer accepts
the -mod flag. Previously, the flag's setting either
was ignored or
caused the build to fail.
-mod=readonly is now set by default when the go.mod
file is read-only and no top-level vendor directory is present.
-modcacherw is a new flag that instructs the go
command to leave newly-created directories in the module cache at their
default permissions rather than making them read-only.
The use of this flag makes it more likely that tests or other tools will
accidentally add files not included in the module's verified checksum.
However, it allows the use of rm -rf
(instead of go clean -modcache)
to remove the module cache.
-modfile=file is a new flag that instructs the go
command to read (and possibly write) an alternate go.mod file instead of the
one in the module root directory. A file named "go.mod" must still be present
in order to determine the module root directory, but it is not
accessed. When -modfile is specified, an alternate go.sum file
is also used: its path is derived from the -modfile flag by
trimming the ".mod" extension and appending ".sum".
+incompatible versions
If the latest version of a module contains a go.mod file,
go get will no longer upgrade to an
incompatible
major version of that module unless such a version is requested explicitly
or is already required.
go list also omits incompatible major versions
for such a module when fetching directly from version control, but may
include them if reported by a proxy.
go.mod file maintenance
go commands other than
go mod tidy no longer
remove a require directive that specifies a version of an indirect dependency
that is already implied by other (transitive) dependencies of the main
module.
go commands other than
go mod tidy no longer
edit the go.mod file if the changes are only cosmetic.
When -mod=readonly is set, go commands will no
longer fail due to a missing go directive or erroneous
// indirect comment.
The go command now supports Subversion repositories in module mode.
The go command now includes snippets of plain-text error messages
from module proxies and other HTTP servers.
An error message will only be shown if it is valid UTF-8 and consists of only
graphic characters and spaces.
This release improves the performance of most uses
of defer to incur almost zero overhead compared to
calling the deferred function directly.
As a result, defer can now be used in
performance-critical code without overhead concerns.
Goroutines are now asynchronously preemptible.
As a result, loops without function calls no longer potentially
deadlock the scheduler or significantly delay garbage collection.
This is supported on all platforms except windows/arm,
darwin/arm, js/wasm, and
plan9/*.
A consequence of the implementation of preemption is that on Unix
systems, including Linux and macOS systems, programs built with Go
1.14 will receive more signals than programs built with earlier
releases.
This means that programs that use packages
like syscall
or golang.org/x/sys/unix
will see more slow system calls fail with EINTR errors.
Those programs will have to handle those errors in some way, most
likely looping to try the system call again. For more
information about this
see man
7 signal for Linux systems or similar documentation for
other systems.
The page allocator is more efficient and incurs significantly less
lock contention at high values of GOMAXPROCS.
This is most noticeable as lower latency and higher throughput for
large allocations being done in parallel and at a high rate.
Internal timers, used by
time.After,
time.Tick,
net.Conn.SetDeadline,
and friends, are more efficient, with less lock contention and fewer
context switches.
This is a performance improvement that should not cause any user
visible changes.
This release adds -d=checkptr as a compile-time option
for adding instrumentation to check that Go code is following
unsafe.Pointer safety rules dynamically.
This option is enabled by default with the -race
or -msan flags, and can be disabled
with -gcflags=-all=-d=checkptr=0.
Specifically, -d=checkptr checks the following:
unsafe.Pointer to *T,
the resulting pointer must be aligned appropriately
for T.
unsafe.Pointer-typed operands must point
into the same object.
The compiler can now emit machine-readable logs of key optimizations
using the -json flag, including inlining, escape
analysis, bounds-check elimination, and nil-check elimination
Detailed escape analysis diagnostics (-m=2) now work again.
This had been dropped from the new escape analysis implementation in
the previous release.
All Go symbols in macOS binaries now begin with an underscore, following platform conventions.
This release includes experimental support for compiler-inserted coverage instrumentation for fuzzing. See the issue for more details. This API may change in future releases.
TODO
TODO: https://golang.org/cl/186877: add hashing package for bytes and strings
TODO: https://golang.org/cl/191976: remove SSLv3 support
TODO: https://golang.org/cl/191999: remove TLS 1.3 opt-out
The tls package no longer supports NPN and now only
supports ALPN. In previous releases it supported both. There are
no API changes and code should function identically as before.
Most other clients & servers have already removed NPN support in
favor of the standardized ALPN.
TODO: https://golang.org/cl/126624: handle ASN1's string type BMPString
TODO: https://golang.org/cl/186927: update type of .js and .mjs files to text/javascript
The new FMA function
computes x*y+z in floating point with no
intermediate rounding of the x*y
computation. Several architectures implement this computation
using dedicated hardware instructions for additional performance.
The plugin package now supports freebsd/amd64.
StructOf now
supports creating struct types with unexported fields, by
setting the PkgPath field in
a StructField element.
runtime.Goexit can no longer be aborted by a
recursive panic/recover.
On macOS, SIGPIPE is no longer forwarded to signal
handlers installed before the Go runtime is initialized.
This is necessary because macOS delivers SIGPIPE
to the main thread
rather than the thread writing to the closed pipe.
On Windows,
the CTRL_CLOSE_EVENT, CTRL_LOGOFF_EVENT,
and CTRL_SHUTDOWN_EVENT events now generate
a syscall.SIGTERM signal, similar to how Control-C
and Control-Break generate a syscall.SIGINT signal.
Unlocking a highly contended Mutex now directly
yields the CPU to the next goroutine waiting for
that Mutex. This significantly improves the
performance of highly contended mutexes on high CPU count
machines.
The testing package now supports cleanup functions, called after
a test or benchmark has finished, by calling
T.Cleanup or
B.Cleanup respectively.
As always, there are various minor changes and updates to the library, made with the Go 1 promise of compatibility in mind.
TODO