mirror of
https://github.com/golang/go
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![Filippo Valsorda](/assets/img/avatar_default.png)
Most of the issues that led to the decision on #30055 were related to incompatibility with or faulty support for RSA-PSS (#29831, #29779, v1.5 signatures). RSA-PSS is required by TLS 1.3, but is also available to be negotiated in TLS 1.2. Altering TLS 1.2 behavior based on GODEBUG=tls13=1 feels surprising, so just disable RSA-PSS entirely in TLS 1.2 until TLS 1.3 is on by default, so breakage happens all at once. Updates #30055 Change-Id: Iee90454a20ded8895e5302e8bcbcd32e4e3031c2 Reviewed-on: https://go-review.googlesource.com/c/160998 Run-TryBot: Filippo Valsorda <filippo@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Adam Langley <agl@golang.org>
923 lines
36 KiB
HTML
923 lines
36 KiB
HTML
<!--{
|
||
"Title": "Go 1.12 Release Notes",
|
||
"Path": "/doc/go1.12",
|
||
"Template": true
|
||
}-->
|
||
|
||
<!--
|
||
NOTE: In this document and others in this directory, the convention is to
|
||
set fixed-width phrases with non-fixed-width spaces, as in
|
||
<code>hello</code> <code>world</code>.
|
||
Do not send CLs removing the interior tags from such phrases.
|
||
-->
|
||
|
||
<style>
|
||
ul li { margin: 0.5em 0; }
|
||
</style>
|
||
|
||
<h2 id="introduction">DRAFT RELEASE NOTES - Introduction to Go 1.12</h2>
|
||
|
||
<p>
|
||
<strong>
|
||
Go 1.12 is not yet released. These are work-in-progress
|
||
release notes. Go 1.12 is expected to be released in February 2019.
|
||
</strong>
|
||
</p>
|
||
|
||
<p>
|
||
The latest Go release, version 1.12, arrives six months after <a href="go1.11">Go 1.11</a>.
|
||
Most of its changes are in the implementation of the toolchain, runtime, and libraries.
|
||
As always, the release maintains the Go 1 <a href="/doc/go1compat">promise of compatibility</a>.
|
||
We expect almost all Go programs to continue to compile and run as before.
|
||
</p>
|
||
|
||
<h2 id="language">Changes to the language</h2>
|
||
|
||
<p>
|
||
There are no changes to the language specification.
|
||
</p>
|
||
|
||
<h2 id="ports">Ports</h2>
|
||
|
||
<p><!-- CL 138675 -->
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||
The race detector is now supported on <code>linux/arm64</code>.
|
||
</p>
|
||
|
||
<p id="freebsd">
|
||
Go 1.12 is the last release that is supported on FreeBSD 10.x, which has
|
||
already reached end-of-life. Go 1.13 will require FreeBSD 11.2+ or FreeBSD
|
||
12.0+.
|
||
FreeBSD 12.0+ requires a kernel with the COMPAT_FREEBSD11 option set (this is the default).
|
||
</p>
|
||
|
||
<p><!-- CL 146898 -->
|
||
cgo is now supported on <code>linux/ppc64</code>.
|
||
</p>
|
||
|
||
<p id="hurd"><!-- CL 146023 -->
|
||
<code>hurd</code> is now a recognized value for <code>GOOS</code>, reserved
|
||
for the GNU/Hurd system for use with <code>gccgo</code>.
|
||
</p>
|
||
|
||
<h3 id="windows">Windows</h3>
|
||
|
||
<p>
|
||
Go's new <code>windows/arm</code> port supports running Go on Windows 10
|
||
IoT Core on 32-bit ARM chips such as the Raspberry Pi 3.
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||
</p>
|
||
|
||
<h3 id="aix">AIX</h3>
|
||
|
||
<p>
|
||
Go now supports AIX 7.2 and later on POWER8 architectures (<code>aix/ppc64</code>). External linking, cgo, pprof and the race detector aren't yet supported.
|
||
</p>
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||
|
||
<h3 id="darwin">Darwin</h3>
|
||
|
||
<p>
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||
Go 1.12 is the last release that will run on macOS 10.10 Yosemite.
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||
Go 1.13 will require macOS 10.11 El Capitan or later.
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||
</p>
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||
|
||
<p><!-- CL 141639 -->
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||
<code>libSystem</code> is now used when making syscalls on Darwin,
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||
ensuring forward-compatibility with future versions of macOS and iOS.
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||
<!-- CL 153338 -->
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||
The switch to <code>libSystem</code> triggered additional App Store
|
||
checks for private API usage. Since it is considered private,
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||
<code>syscall.Getdirentries</code> now always fails with
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||
<code>ENOSYS</code> on iOS.
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||
</p>
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|
||
<h2 id="tools">Tools</h2>
|
||
|
||
<h3 id="vet"><code>go tool vet</code> no longer supported</h3>
|
||
|
||
<p>
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||
The <code>go vet</code> command has been rewritten to serve as the
|
||
base for a range of different source code analysis tools. See
|
||
the <a href="https://godoc.org/golang.org/x/tools/go/analysis">golang.org/x/tools/go/analysis</a>
|
||
package for details. A side-effect is that <code>go tool vet</code>
|
||
is no longer supported. External tools that use <code>go tool
|
||
vet</code> must be changed to use <code>go
|
||
vet</code>. Using <code>go vet</code> instead of <code>go tool
|
||
vet</code> should work with all supported versions of Go.
|
||
</p>
|
||
|
||
<p>
|
||
As part of this change, the experimental <code>-shadow</code> option
|
||
is no longer available with <code>go vet</code>. Checking for
|
||
variable shadowing may now be done using
|
||
<pre>
|
||
go install golang.org/x/tools/go/analysis/passes/shadow/cmd/shadow
|
||
go vet -vettool=$(which shadow)
|
||
</pre>
|
||
</p>
|
||
|
||
<h3 id="tour">Tour</h3>
|
||
|
||
<p> <!-- CL 152657 -->
|
||
The Go tour is no longer included in the main binary distribution. To
|
||
run the tour locally, instead of running <code>go</code> <code>tool</code> <code>tour</code>,
|
||
manually install it:
|
||
<pre>
|
||
go install golang.org/x/tour
|
||
tour
|
||
</pre>
|
||
</p>
|
||
|
||
<h3 id="gocache">Build cache requirement</h3>
|
||
|
||
<p>
|
||
The <a href="/cmd/go/#hdr-Build_and_test_caching">build cache</a> is now
|
||
required as a step toward eliminating
|
||
<code>$GOPATH/pkg</code>. Setting the environment variable
|
||
<code>GOCACHE=off</code> will cause <code>go</code> commands that write to the
|
||
cache to fail.
|
||
</p>
|
||
|
||
<h3 id="binary-only">Binary-only packages</h3>
|
||
|
||
<p>
|
||
Go 1.12 is the last release that will support binary-only packages.
|
||
</p>
|
||
|
||
<h3 id="cgo">Cgo</h3>
|
||
|
||
<p>
|
||
Go 1.12 will translate the C type <code>EGLDisplay</code> to the Go type <code>uintptr</code>.
|
||
This change is similar to how Go 1.10 and newer treats Darwin's CoreFoundation
|
||
and Java's JNI types. See the
|
||
<a href="/cmd/cgo/#hdr-Special_cases">cgo documentation</a>
|
||
for more information.
|
||
</p>
|
||
|
||
<p><!-- CL 152657 -->
|
||
Mangled C names are no longer accepted in packages that use Cgo. Use the Cgo
|
||
names instead. For example, use the documented cgo name <code>C.char</code>
|
||
rather than the mangled name <code>_Ctype_char</code> that cgo generates.
|
||
</p>
|
||
|
||
<h3 id="modules">Modules</h3>
|
||
|
||
<p><!-- CL 148517 -->
|
||
When <code>GO111MODULE</code> is set to <code>on</code>, the <code>go</code>
|
||
command now supports module-aware operations outside of a module directory,
|
||
provided that those operations do not need to resolve import paths relative to
|
||
the current directory or explicitly edit the <code>go.mod</code> file.
|
||
Commands such as <code>go</code> <code>get</code>,
|
||
<code>go</code> <code>list</code>, and
|
||
<code>go</code> <code>mod</code> <code>download</code> behave as if in a
|
||
module with initially-empty requirements.
|
||
In this mode, <code>go</code> <code>env</code> <code>GOMOD</code> reports
|
||
the system's null device (<code>/dev/null</code> or <code>NUL</code>).
|
||
</p>
|
||
|
||
<p><!-- CL 146382 -->
|
||
<code>go</code> commands that download and extract modules are now safe to
|
||
invoke concurrently.
|
||
The module cache (<code>GOPATH/pkg/mod</code>) must reside in a filesystem that
|
||
supports file locking.
|
||
</p>
|
||
|
||
<p><!-- CL 147282, 147281 -->
|
||
The <code>go</code> directive in a <code>go.mod</code> file now indicates the
|
||
version of the language used by the files within that module.
|
||
It will be set to the current release
|
||
(<code>go</code> <code>1.12</code>) if no existing version is
|
||
present.
|
||
If the <code>go</code> directive for a module specifies a
|
||
version <em>newer</em> than the toolchain in use, the <code>go</code> command
|
||
will attempt to build the packages regardless, and will note the mismatch only if
|
||
that build fails.
|
||
</p>
|
||
|
||
<p><!-- CL 152739 -->
|
||
When an import cannot be resolved using the active modules,
|
||
the <code>go</code> command will now try to use the modules mentioned in the
|
||
main module's <code>replace</code> directives before consulting the module
|
||
cache and the usual network sources.
|
||
If a matching replacement is found but the <code>replace</code> directive does
|
||
not specify a version, the <code>go</code> command uses a pseudo-version
|
||
derived from the zero <code>time.Time</code> (such
|
||
as <code>v0.0.0-00010101000000-000000000000</code>).
|
||
</p>
|
||
|
||
<h3 id="compiler">Compiler toolchain</h3>
|
||
|
||
<p><!-- CL 134155, 134156 -->
|
||
The compiler's live variable analysis has improved. This may mean that
|
||
finalizers will be executed sooner in this release than in previous
|
||
releases. If that is a problem, consider the appropriate addition of a
|
||
<a href="/pkg/runtime/#KeepAlive"><code>runtime.KeepAlive</code></a> call.
|
||
</p>
|
||
|
||
<p><!-- CL 147361 -->
|
||
More functions are now eligible for inlining by default, including
|
||
functions that do nothing but call another function.
|
||
This extra inlining makes it additionally important to use
|
||
<a href="/pkg/runtime/#CallersFrames"><code>runtime.CallersFrames</code></a>
|
||
instead of iterating over the result of
|
||
<a href="/pkg/runtime/#Callers"><code>runtime.Callers</code></a> directly.
|
||
<pre>
|
||
// Old code which no longer works correctly (it will miss inlined call frames).
|
||
var pcs [10]uintptr
|
||
n := runtime.Callers(1, pcs[:])
|
||
for _, pc := range pcs[:n] {
|
||
f := runtime.FuncForPC(pc)
|
||
if f != nil {
|
||
fmt.Println(f.Name())
|
||
}
|
||
}
|
||
</pre>
|
||
<pre>
|
||
// New code which will work correctly.
|
||
var pcs [10]uintptr
|
||
n := runtime.Callers(1, pcs[:])
|
||
frames := runtime.CallersFrames(pcs[:n])
|
||
for {
|
||
frame, more := frames.Next()
|
||
fmt.Println(frame.Function)
|
||
if !more {
|
||
break
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||
}
|
||
}
|
||
</pre>
|
||
</p>
|
||
|
||
<p><!-- CL 153477 -->
|
||
Wrappers generated by the compiler to implement method expressions
|
||
are no longer reported
|
||
by <a href="/pkg/runtime/#CallersFrames"><code>runtime.CallersFrames</code></a>
|
||
and <a href="/pkg/runtime/#Stack"><code>runtime.Stack</code></a>. They
|
||
are also not printed in panic stack traces.
|
||
|
||
This change aligns the <code>gc</code> toolchain to match
|
||
the <code>gccgo</code> toolchain, which already elided such wrappers
|
||
from stack traces.
|
||
|
||
Clients of these APIs might need to adjust for the missing
|
||
frames. For code that must interoperate between 1.11 and 1.12
|
||
releases, you can replace the method expression <code>x.M</code>
|
||
with the function literal <code>func (...) { x.M(...) } </code>.
|
||
</p>
|
||
|
||
<p><!-- CL 144340 -->
|
||
The compiler now accepts a <code>-lang</code> flag to set the Go language
|
||
version to use. For example, <code>-lang=go1.8</code> causes the compiler to
|
||
emit an error if the program uses type aliases, which were added in Go 1.9.
|
||
Language changes made before Go 1.12 are not consistently enforced.
|
||
</p>
|
||
|
||
<p><!-- CL 147160 -->
|
||
The compiler toolchain now uses different conventions to call Go
|
||
functions and assembly functions. This should be invisible to users,
|
||
except for calls that simultaneously cross between Go and
|
||
assembly <em>and</em> cross a package boundary. If linking results
|
||
in an error like "relocation target not defined for ABIInternal (but
|
||
is defined for ABI0)", please refer to the
|
||
<a href="https://github.com/golang/proposal/blob/master/design/27539-internal-abi.md#compatibility">compatibility section</a>
|
||
of the ABI design document.
|
||
</p>
|
||
|
||
<p><!-- CL 145179 -->
|
||
There have been many improvements to the DWARF debug information
|
||
produced by the compiler, including improvements to argument
|
||
printing and variable location information.
|
||
</p>
|
||
|
||
<p><!-- CL 61511 -->
|
||
Go programs now also maintain stack frame pointers on <code>linux/arm64</code>
|
||
for the benefit of profiling tools like <code>perf</code>. The frame pointer
|
||
maintenance has a small run-time overhead that varies but averages around 3%.
|
||
To build a toolchain that does not use frame pointers, set
|
||
<code>GOEXPERIMENT=noframepointer</code> when running <code>make.bash</code>.
|
||
</p>
|
||
|
||
<p><!-- CL 142717 -->
|
||
The obsolete "safe" compiler mode (enabled by the <code>-u</code> gcflag) has been removed.
|
||
</p>
|
||
|
||
<h3 id="godoc"><code>godoc</code> and <code>go</code> <code>doc</code></h3>
|
||
|
||
<p>
|
||
In Go 1.12, <code>godoc</code> no longer has a command-line interface and
|
||
is only a web server. Users should use <code>go</code> <code>doc</code>
|
||
for command-line help output instead.
|
||
</p>
|
||
|
||
<p><!-- CL 141977 -->
|
||
<code>go</code> <code>doc</code> now supports the <code>-all</code> flag,
|
||
which will cause it to print all exported APIs and their documentation,
|
||
as the <code>godoc</code> command line used to do.
|
||
</p>
|
||
|
||
<p><!-- CL 140959 -->
|
||
<code>go</code> <code>doc</code> also now includes the <code>-src</code> flag,
|
||
which will show the target's source code.
|
||
</p>
|
||
|
||
<h3 id="trace">Trace</h3>
|
||
|
||
<p><!-- CL 60790 -->
|
||
The trace tool now supports plotting mutator utilization curves,
|
||
including cross-references to the execution trace. These are useful
|
||
for analyzing the impact of the garbage collector on application
|
||
latency and throughput.
|
||
</p>
|
||
|
||
<h3 id="assembler">Assembler</h3>
|
||
|
||
<p><!-- CL 147218 -->
|
||
On <code>arm64</code>, the platform register was renamed from
|
||
<code>R18</code> to <code>R18_PLATFORM</code> to prevent accidental
|
||
use, as the OS could choose to reserve this register.
|
||
</p>
|
||
|
||
<h2 id="runtime">Runtime</h2>
|
||
|
||
<p><!-- CL 138959 -->
|
||
Go 1.12 significantly improves the performance of sweeping when a
|
||
large fraction of the heap remains live. This reduces allocation
|
||
latency immediately following a garbage collection.
|
||
</p>
|
||
|
||
<p><!-- CL 139719 -->
|
||
The Go runtime now releases memory back to the operating system more
|
||
aggressively, particularly in response to large allocations that
|
||
can't reuse existing heap space.
|
||
</p>
|
||
|
||
<p><!-- CL 146342, CL 146340, CL 146345, CL 146339, CL 146343, CL 146337, CL 146341, CL 146338 -->
|
||
The Go runtime's timer and deadline code is faster and scales better
|
||
with higher numbers of CPUs. In particular, this improves the
|
||
performance of manipulating network connection deadlines.
|
||
</p>
|
||
|
||
<p><!-- CL 135395 -->
|
||
On Linux, the runtime now uses <code>MADV_FREE</code> to release unused
|
||
memory. This is more efficient but may result in higher reported
|
||
RSS. The kernel will reclaim the unused data when it is needed.
|
||
To revert to the Go 1.11 behavior (<code>MADV_DONTNEED</code>), set the
|
||
environment variable <code>GODEBUG=madvdontneed=1</code>.
|
||
</p>
|
||
|
||
<p><!-- CL 149578 -->
|
||
Adding cpu.<em>extension</em>=off to the
|
||
<a href="/doc/diagnostics.html#godebug">GODEBUG</a> environment
|
||
variable now disables the use of optional CPU instruction
|
||
set extensions in the standard library and runtime. This is not
|
||
yet supported on Windows.
|
||
</p>
|
||
|
||
<p><!-- CL 158337 -->
|
||
Go 1.12 improves the accuracy of memory profiles by fixing
|
||
overcounting of large heap allocations.
|
||
</p>
|
||
|
||
<p><!-- CL 159717 -->
|
||
Tracebacks, <code>runtime.Caller</code>,
|
||
and <code>runtime.Callers</code> no longer include
|
||
compiler-generated initialization functions. Doing a traceback
|
||
during the initialization of a global variable will now show a
|
||
function named <code>PKG.init.ializers</code>.
|
||
</p>
|
||
|
||
<h2 id="library">Core library</h2>
|
||
|
||
<h3 id="tls_1_3">TLS 1.3</h3>
|
||
|
||
<p>
|
||
Go 1.12 adds opt-in support for TLS 1.3 in the <code>crypto/tls</code> package as
|
||
specified by <a href="https://www.rfc-editor.org/info/rfc8446">RFC 8446</a>. It can
|
||
be enabled by adding the value <code>tls13=1</code> to the <code>GODEBUG</code>
|
||
environment variable. It will be enabled by default in Go 1.13.
|
||
</p>
|
||
|
||
<p>
|
||
To negotiate TLS 1.3, make sure you do not set an explicit <code>MaxVersion</code> in
|
||
<a href="/pkg/crypto/tls/#Config"><code>Config</code></a> and run your program with
|
||
the environment variable <code>GODEBUG=tls13=1</code> set.
|
||
</p>
|
||
|
||
<p>
|
||
All TLS 1.2 features except <code>TLSUnique</code> in
|
||
<a href="/pkg/crypto/tls/#ConnectionState"><code>ConnectionState</code></a>
|
||
and renegotiation are available in TLS 1.3 and provide equivalent or
|
||
better security and performance. Note that even though TLS 1.3 is backwards
|
||
compatible with previous versions, certain legacy systems might not work
|
||
correctly when attempting to negotiate it. RSA certificate keys too small
|
||
to be secure (including 512-bit keys) will not work with TLS 1.3.
|
||
</p>
|
||
|
||
<p>
|
||
TLS 1.3 cipher suites are not configurable. All supported cipher suites are
|
||
safe, and if <code>PreferServerCipherSuites</code> is set in
|
||
<a href="/pkg/crypto/tls/#Config"><code>Config</code></a> the preference order
|
||
is based on the available hardware.
|
||
</p>
|
||
|
||
<p>
|
||
Early data (also called "0-RTT mode") is not currently supported as a
|
||
client or server. Additionally, a Go 1.12 server does not support skipping
|
||
unexpected early data if a client sends it. Since TLS 1.3 0-RTT mode
|
||
involves clients keeping state regarding which servers support 0-RTT,
|
||
a Go 1.12 server cannot be part of a load-balancing pool where some other
|
||
servers do support 0-RTT. If switching a domain from a server that supported
|
||
0-RTT to a Go 1.12 server, 0-RTT would have to be disabled for at least the
|
||
lifetime of the issued session tickets before the switch to ensure
|
||
uninterrupted operation.
|
||
</p>
|
||
|
||
<p>
|
||
In TLS 1.3 the client is the last one to speak in the handshake, so if it causes
|
||
an error to occur on the server, it will be returned on the client by the first
|
||
<a href="/pkg/crypto/tls/#Conn.Read"><code>Read</code></a>, not by
|
||
<a href="/pkg/crypto/tls/#Conn.Handshake"><code>Handshake</code></a>. For
|
||
example, that will be the case if the server rejects the client certificate.
|
||
Similarly, session tickets are now post-handshake messages, so are only
|
||
received by the client upon its first
|
||
<a href="/pkg/crypto/tls/#Conn.Read"><code>Read</code></a>.
|
||
</p>
|
||
|
||
<h3 id="minor_library_changes">Minor changes to the library</h3>
|
||
|
||
<p>
|
||
As always, there are various minor changes and updates to the library,
|
||
made with the Go 1 <a href="/doc/go1compat">promise of compatibility</a>
|
||
in mind.
|
||
</p>
|
||
|
||
<!-- TODO: CL 115677: https://golang.org/cl/115677: cmd/vet: check embedded field tags too -->
|
||
|
||
<dl id="bufio"><dt><a href="/pkg/bufio/">bufio</a></dt>
|
||
<dd>
|
||
<p><!-- CL 149297 -->
|
||
<code>Reader</code>'s <a href="/pkg/bufio/#Reader.UnreadRune"><code>UnreadRune</code></a> and
|
||
<a href="/pkg/bufio/#Reader.UnreadByte"><code>UnreadByte</code></a> methods will now return an error
|
||
if they are called after <a href="/pkg/bufio/#Reader.Peek"><code>Peek</code></a>.
|
||
</p>
|
||
|
||
</dl><!-- bufio -->
|
||
|
||
<dl id="bytes"><dt><a href="/pkg/bytes/">bytes</a></dt>
|
||
<dd>
|
||
<p><!-- CL 137855 -->
|
||
The new function <a href="/pkg/bytes/#ReplaceAll"><code>ReplaceAll</code></a> returns a copy of
|
||
a byte slice with all non-overlapping instances of a value replaced by another.
|
||
</p>
|
||
|
||
<p><!-- CL 145098 -->
|
||
A pointer to a zero-value <a href="/pkg/bytes/#Reader"><code>Reader</code></a> is now
|
||
functionally equivalent to <a href="/pkg/bytes/#NewReader"><code>NewReader</code></a><code>(nil)</code>.
|
||
Prior to Go 1.12, the former could not be used as a substitute for the latter in all cases.
|
||
</p>
|
||
|
||
</dl><!-- bytes -->
|
||
|
||
<dl id="crypto/rand"><dt><a href="/pkg/crypto/rand/">crypto/rand</a></dt>
|
||
<dd>
|
||
<p><!-- CL 139419 -->
|
||
A warning will now be printed to standard error the first time
|
||
<code>Reader.Read</code> is blocked for more than 60 seconds waiting
|
||
to read entropy from the kernel.
|
||
</p>
|
||
|
||
<p><!-- CL 120055 -->
|
||
On FreeBSD, <code>Reader</code> now uses the <code>getrandom</code>
|
||
system call if available, <code>/dev/urandom</code> otherwise.
|
||
</p>
|
||
|
||
</dl><!-- crypto/rand -->
|
||
|
||
<dl id="crypto/rc4"><dt><a href="/pkg/crypto/rc4/">crypto/rc4</a></dt>
|
||
<dd>
|
||
<p><!-- CL 130397 -->
|
||
This release removes the optimized assembly implementations. RC4 is insecure
|
||
and should only be used for compatibility with legacy systems.
|
||
</p>
|
||
|
||
</dl><!-- crypto/rc4 -->
|
||
|
||
<dl id="crypto/tls"><dt><a href="/pkg/crypto/tls/">crypto/tls</a></dt>
|
||
<dd>
|
||
<p><!-- CL 143177 -->
|
||
If a client sends an initial message that does not look like TLS, the server
|
||
will no longer reply with an alert, and it will expose the underlying
|
||
<code>net.Conn</code> in the new field <code>Conn</code> of
|
||
<a href="/pkg/crypto/tls/#RecordHeaderError"><code>RecordHeaderError</code></a>.
|
||
</p>
|
||
|
||
</dl><!-- crypto/tls -->
|
||
|
||
<dl id="database/sql"><dt><a href="/pkg/database/sql/">database/sql</a></dt>
|
||
<dd>
|
||
<p><!-- CL 145738 -->
|
||
A query cursor can now be obtained by passing a
|
||
<a href="/pkg/database/sql/#Rows"><code>*Rows</code></a>
|
||
value to the <a href="/pkg/database/sql/#Row.Scan"><code>Row.Scan</code></a> method.
|
||
</p>
|
||
|
||
</dl><!-- database/sql -->
|
||
|
||
<dl id="expvar"><dt><a href="/pkg/expvar/">expvar</a></dt>
|
||
<dd>
|
||
<p><!-- CL 139537 -->
|
||
The new <a href="/pkg/expvar/#Map.Delete"><code>Delete</code></a> method allows
|
||
for deletion of key/value pairs from a <a href="/pkg/expvar/#Map"><code>Map</code></a>.
|
||
</p>
|
||
|
||
</dl><!-- expvar -->
|
||
|
||
<dl id="fmt"><dt><a href="/pkg/fmt/">fmt</a></dt>
|
||
<dd>
|
||
<p><!-- CL 142737 -->
|
||
Maps are now printed in key-sorted order to ease testing. The ordering rules are:
|
||
<ul>
|
||
<li>When applicable, nil compares low
|
||
<li>ints, floats, and strings order by <
|
||
<li>NaN compares less than non-NaN floats
|
||
<li>bool compares false before true
|
||
<li>Complex compares real, then imaginary
|
||
<li>Pointers compare by machine address
|
||
<li>Channel values compare by machine address
|
||
<li>Structs compare each field in turn
|
||
<li>Arrays compare each element in turn
|
||
<li>Interface values compare first by <code>reflect.Type</code> describing the concrete type
|
||
and then by concrete value as described in the previous rules.
|
||
</ul>
|
||
</p>
|
||
|
||
<p><!-- CL 129777 -->
|
||
When printing maps, non-reflexive key values like <code>NaN</code> were previously
|
||
displayed as <code><nil></code>. As of this release, the correct values are printed.
|
||
</p>
|
||
|
||
</dl><!-- fmt -->
|
||
|
||
<dl id="go/doc"><dt><a href="/pkg/go/doc/">go/doc</a></dt>
|
||
<dd>
|
||
<p><!-- CL 140958 -->
|
||
To address some outstanding issues in <a href="/cmd/doc/"><code>cmd/doc</code></a>,
|
||
this package has a new <a href="/pkg/go/doc/#Mode"><code>Mode</code></a> bit,
|
||
<code>PreserveAST</code>, which controls whether AST data is cleared.
|
||
</p>
|
||
|
||
</dl><!-- go/doc -->
|
||
|
||
<dl id="go/token"><dt><a href="/pkg/go/token/">go/token</a></dt>
|
||
<dd>
|
||
<p><!-- CL 134075 -->
|
||
The <a href="/pkg/go/token#File"><code>File</code></a> type has a new
|
||
<a href="/pkg/go/token#File.LineStart"><code>LineStart</code></a> field,
|
||
which returns the position of the start of a given line. This is especially useful
|
||
in programs that occasionally handle non-Go files, such as assembly, but wish to use
|
||
the <code>token.Pos</code> mechanism to identify file positions.
|
||
</p>
|
||
|
||
</dl><!-- go/token -->
|
||
|
||
<dl id="image"><dt><a href="/pkg/image/">image</a></dt>
|
||
<dd>
|
||
<p><!-- CL 118755 -->
|
||
The <a href="/pkg/image/#RegisterFormat"><code>RegisterFormat</code></a> function is now safe for concurrent use.
|
||
</p>
|
||
|
||
</dl><!-- image -->
|
||
|
||
<dl id="image/png"><dt><a href="/pkg/image/png/">image/png</a></dt>
|
||
<dd>
|
||
<p><!-- CL 134235 -->
|
||
Paletted images with fewer than 16 colors now encode to smaller outputs.
|
||
</p>
|
||
|
||
</dl><!-- image/png -->
|
||
|
||
<dl id="io"><dt><a href="/pkg/io/">io</a></dt>
|
||
<dd>
|
||
<p><!-- CL 139457 -->
|
||
The new <a href="/pkg/io#StringWriter"><code>StringWriter</code></a> interface wraps the
|
||
<a href="/pkg/io/#WriteString"><code>WriteString</code></a> function.
|
||
</p>
|
||
|
||
</dl><!-- io -->
|
||
|
||
<dl id="lib/time"><dt><a href="/pkg/lib/time/">lib/time</a></dt>
|
||
<dd>
|
||
<p><!-- CL 151299 -->
|
||
The time zone database in <code>$GOROOT/lib/time/zoneinfo.zip</code>
|
||
has been updated to version 2018i. Note that this ZIP file is
|
||
only used if a time zone database is not provided by the operating
|
||
system.
|
||
</p>
|
||
|
||
</dl><!-- lib/time -->
|
||
|
||
<dl id="math"><dt><a href="/pkg/math/">math</a></dt>
|
||
<dd>
|
||
<p><!-- CL 153059 -->
|
||
The functions
|
||
<a href="/pkg/math/#Sin"><code>Sin</code></a>,
|
||
<a href="/pkg/math/#Cos"><code>Cos</code></a>,
|
||
<a href="/pkg/math/#Tan"><code>Tan</code></a>,
|
||
and <a href="/pkg/math/#Sincos"><code>Sincos</code></a> now
|
||
apply Payne-Hanek range reduction to huge arguments. This
|
||
produces more accurate answers, but they will not be bit-for-bit
|
||
identical with the results in earlier releases.
|
||
</p>
|
||
</dl><!-- math -->
|
||
|
||
<dl id="math/bits"><dt><a href="/pkg/math/bits/">math/bits</a></dt>
|
||
<dd>
|
||
<p><!-- CL 123157 -->
|
||
New extended precision operations <a href="/pkg/math/bits/#Add"><code>Add</code></a>, <a href="/pkg/math/bits/#Sub"><code>Sub</code></a>, <a href="/pkg/math/bits/#Mul"><code>Mul</code></a>, and <a href="/pkg/math/bits/#Div"><code>Div</code></a> are available in <code>uint</code>, <code>uint32</code>, and <code>uint64</code> versions.
|
||
</p>
|
||
|
||
</dl><!-- math/bits -->
|
||
|
||
<dl id="net"><dt><a href="/pkg/net/">net</a></dt>
|
||
<dd>
|
||
<p><!-- CL 146659 -->
|
||
The
|
||
<a href="/pkg/net/#Dialer.DualStack"><code>Dialer.DualStack</code></a> setting is now ignored and deprecated;
|
||
RFC 6555 Fast Fallback ("Happy Eyeballs") is now enabled by default. To disable, set
|
||
<a href="/pkg/net/#Dialer.FallbackDelay"><code>Dialer.FallbackDelay</code></a> to a negative value.
|
||
</p>
|
||
|
||
<p><!-- CL 107196 -->
|
||
Similarly, TCP keep-alives are now enabled by default if
|
||
<a href="/pkg/net/#Dialer.KeepAlive"><code>Dialer.KeepAlive</code></a> is zero.
|
||
To disable, set it to a negative value.
|
||
</p>
|
||
|
||
<p><!-- CL 113997 -->
|
||
On Linux, the <a href="http://man7.org/linux/man-pages/man2/splice.2.html"><code>splice</code> system call</a> is now used when copying from a
|
||
<a href="/pkg/net/#UnixConn"><code>UnixConn</code></a> to a
|
||
<a href="/pkg/net/#TCPConn"><code>TCPConn</code></a>.
|
||
</p>
|
||
</dl><!-- net -->
|
||
|
||
<dl id="net/http"><dt><a href="/pkg/net/http/">net/http</a></dt>
|
||
<dd>
|
||
<p><!-- CL 143177 -->
|
||
The HTTP server now rejects misdirected HTTP requests to HTTPS servers with a plaintext "400 Bad Request" response.
|
||
</p>
|
||
|
||
<p><!-- CL 130115 -->
|
||
The new <a href="/pkg/net/http/#Client.CloseIdleConnections"><code>Client.CloseIdleConnections</code></a>
|
||
method calls the <code>Client</code>'s underlying <code>Transport</code>'s <code>CloseIdleConnections</code>
|
||
if it has one.
|
||
</p>
|
||
|
||
<p><!-- CL 145398 -->
|
||
The <a href="/pkg/net/http/#Transport"><code>Transport</code></a> no longer rejects HTTP responses which declare
|
||
HTTP Trailers but don't use chunked encoding. Instead, the declared trailers are now just ignored.
|
||
</p>
|
||
|
||
<p><!-- CL 152080 --> <!-- CL 151857 -->
|
||
The <a href="/pkg/net/http/#Transport"><code>Transport</code></a> no longer handles <code>MAX_CONCURRENT_STREAMS</code> values
|
||
advertised from HTTP/2 servers as strictly as it did during Go 1.10 and Go 1.11. The default behavior is now back
|
||
to how it was in Go 1.9: each connection to a server can have up to <code>MAX_CONCURRENT_STREAMS</code> requests
|
||
active and then new TCP connections are created as needed. In Go 1.10 and Go 1.11 the <code>http2</code> package
|
||
would block and wait for requests to finish instead of creating new connections.
|
||
To get the stricter behavior back, import the
|
||
<a href="https://godoc.org/golang.org/x/net/http2"><code>golang.org/x/net/http2</code></a> package
|
||
directly and set
|
||
<a href="https://godoc.org/golang.org/x/net/http2#Transport.StrictMaxConcurrentStreams"><code>Transport.StrictMaxConcurrentStreams</code></a> to
|
||
<code>true</code>.
|
||
</p>
|
||
|
||
</dl><!-- net/http -->
|
||
|
||
<dl id="net/http/httputil"><dt><a href="/pkg/net/http/httputil/">net/http/httputil</a></dt>
|
||
<dd>
|
||
<p><!-- CL 146437 -->
|
||
The <a href="/pkg/net/http/httputil/#ReverseProxy"><code>ReverseProxy</code></a> now automatically
|
||
proxies WebSocket requests.
|
||
</p>
|
||
|
||
</dl><!-- net/http/httputil -->
|
||
|
||
<dl id="os"><dt><a href="/pkg/os/">os</a></dt>
|
||
<dd>
|
||
<p><!-- CL 125443 -->
|
||
The new <a href="/pkg/os/#ProcessState.ExitCode"><code>ProcessState.ExitCode</code></a> method
|
||
returns the process's exit code.
|
||
</p>
|
||
|
||
<p><!-- CL 135075 -->
|
||
<code>ModeCharDevice</code> has been added to the <code>ModeType</code> bitmask, allowing for
|
||
<code>ModeDevice | ModeCharDevice</code> to be recovered when masking a
|
||
<a href="/pkg/os/#FileMode"><code>FileMode</code></a> with <code>ModeType</code>.
|
||
</p>
|
||
|
||
<p><!-- CL 139418 -->
|
||
The new function <a href="/pkg/os/#UserHomeDir"><code>UserHomeDir</code></a> returns the
|
||
current user's home directory.
|
||
</p>
|
||
|
||
<p><!-- CL 146020 -->
|
||
<a href="/pkg/os/#RemoveAll"><code>RemoveAll</code></a> now supports paths longer than 4096 characters
|
||
on most Unix systems.
|
||
</p>
|
||
|
||
<p><!-- CL 130676 -->
|
||
<a href="/pkg/os/#File.Sync"><code>File.Sync</code></a> now uses <code>F_FULLFSYNC</code> on macOS
|
||
to correctly flush the file contents to permanent storage.
|
||
This may cause the method to run more slowly than in previous releases.
|
||
</p>
|
||
|
||
<p><!--CL 155517 -->
|
||
<a href="/pkg/os/#File"><code>File</code></a> now supports
|
||
a <a href="/pkg/os/#File.SyscallConn"><code>SyscallConn</code></a>
|
||
method returning
|
||
a <a href="/pkg/syscall/#RawConn"><code>syscall.RawConn</code></a>
|
||
interface value. This may be used to invoke system-specific
|
||
operations on the underlying file descriptor.
|
||
</p>
|
||
|
||
</dl><!-- os -->
|
||
|
||
<dl id="path/filepath"><dt><a href="/pkg/path/filepath/">path/filepath</a></dt>
|
||
<dd>
|
||
<p><!-- CL 145220 -->
|
||
The <a href="/pkg/path/filepath/#IsAbs"><code>IsAbs</code></a> function now returns true when passed
|
||
a reserved filename on Windows such as <code>NUL</code>.
|
||
<a href="https://docs.microsoft.com/en-us/windows/desktop/fileio/naming-a-file#naming-conventions">List of reserved names.</a>
|
||
</p>
|
||
|
||
</dl><!-- path/filepath -->
|
||
|
||
<dl id="reflect"><dt><a href="/pkg/reflect/">reflect</a></dt>
|
||
<dd>
|
||
<p><!-- CL 33572 -->
|
||
A new <a href="/pkg/reflect#MapIter"><code>MapIter</code></a> type is
|
||
an iterator for ranging over a map. This type is exposed through the
|
||
<a href="/pkg/reflect#Value"><code>Value</code></a> type's new
|
||
<a href="/pkg/reflect#Value.MapRange"><code>MapRange</code></a> method.
|
||
This follows the same iteration semantics as a range statement, with <code>Next</code>
|
||
to advance the iterator, and <code>Key</code>/<code>Value</code> to access each entry.
|
||
</p>
|
||
|
||
</dl><!-- reflect -->
|
||
|
||
<dl id="regexp"><dt><a href="/pkg/regexp/">regexp</a></dt>
|
||
<dd>
|
||
<p><!-- CL 139784 -->
|
||
<a href="/pkg/regexp/#Regexp.Copy"><code>Copy</code></a> is no longer necessary
|
||
to avoid lock contention, so it has been given a partial deprecation comment.
|
||
<a href="/pkg/regexp/#Regexp.Copy"><code>Copy</code></a>
|
||
may still be appropriate if the reason for its use is to make two copies with
|
||
different <a href="/pkg/regexp/#Regexp.Longest"><code>Longest</code></a> settings.
|
||
</p>
|
||
|
||
</dl><!-- regexp -->
|
||
|
||
<dl id="runtime/debug"><dt><a href="/pkg/runtime/debug/">runtime/debug</a></dt>
|
||
<dd>
|
||
<p><!-- CL 144220 -->
|
||
A new <a href="/pkg/runtime/debug/#BuildInfo"><code>BuildInfo</code></a> type
|
||
exposes the build information read from the running binary, available only in
|
||
binaries built with module support. This includes the main package path, main
|
||
module information, and the module dependencies. This type is given though the
|
||
<a href="/pkg/runtime/debug/#ReadBuildInfo"><code>ReadBuildInfo</code></a> function
|
||
on <a href="/pkg/runtime/debug/#BuildInfo"><code>BuildInfo</code></a>.
|
||
</p>
|
||
|
||
</dl><!-- runtime/debug -->
|
||
|
||
<dl id="strings"><dt><a href="/pkg/strings/">strings</a></dt>
|
||
<dd>
|
||
<p><!-- CL 137855 -->
|
||
The new function <a href="/pkg/strings/#ReplaceAll"><code>ReplaceAll</code></a> returns a copy of
|
||
a string with all non-overlapping instances of a value replaced by another.
|
||
</p>
|
||
|
||
<p><!-- CL 145098 -->
|
||
A pointer to a zero-value <a href="/pkg/strings/#Reader"><code>Reader</code></a> is now
|
||
functionally equivalent to <a href="/pkg/strings/#NewReader"><code>NewReader</code></a><code>(nil)</code>.
|
||
Prior to Go 1.12, the former could not be used as a substitute for the latter in all cases.
|
||
</p>
|
||
|
||
<p><!-- CL 122835 -->
|
||
The new <a href="/pkg/strings/#Builder.Cap"><code>Builder.Cap</code></a> method returns the capacity of the builder's underlying byte slice.
|
||
</p>
|
||
|
||
<p><!-- CL 131495 -->
|
||
The character mapping functions <a href="/pkg/strings/#Map"><code>Map</code></a>,
|
||
<a href="/pkg/strings/#Title"><code>Title</code></a>,
|
||
<a href="/pkg/strings/#ToLower"><code>ToLower</code></a>,
|
||
<a href="/pkg/strings/#ToLowerSpecial"><code>ToLowerSpecial</code></a>,
|
||
<a href="/pkg/strings/#ToTitle"><code>ToTitle</code></a>,
|
||
<a href="/pkg/strings/#ToTitleSpecial"><code>ToTitleSpecial</code></a>,
|
||
<a href="/pkg/strings/#ToUpper"><code>ToUpper</code></a>, and
|
||
<a href="/pkg/strings/#ToUpperSpecial"><code>ToUpperSpecial</code></a>
|
||
now always guarantee to return valid UTF-8. In earlier releases, if the input was invalid UTF-8 but no character replacements
|
||
needed to be applied, these routines incorrectly returned the invalid UTF-8 unmodified.
|
||
</p>
|
||
|
||
</dl><!-- strings -->
|
||
|
||
<dl id="syscall"><dt><a href="/pkg/syscall/">syscall</a></dt>
|
||
<dd>
|
||
<p><!-- CL 138595 -->
|
||
64-bit inodes are now supported on FreeBSD 12. Some types have been adjusted accordingly.
|
||
</p>
|
||
|
||
<p><!-- CL 125456 -->
|
||
The Unix socket
|
||
(<a href="https://blogs.msdn.microsoft.com/commandline/2017/12/19/af_unix-comes-to-windows/"><code>AF_UNIX</code></a>)
|
||
address family is now supported for compatible versions of Windows.
|
||
</p>
|
||
|
||
<p><!-- CL 147117 -->
|
||
The new function <a href="/pkg/syscall/?GOOS=windows&GOARCH=amd64#Syscall18"><code>Syscall18</code></a>
|
||
has been introduced for Windows, allowing for calls with up to 18 arguments.
|
||
</p>
|
||
|
||
</dl><!-- syscall -->
|
||
|
||
<dl id="syscall/js"><dt><a href="/pkg/syscall/js/">syscall/js</a></dt>
|
||
<dd>
|
||
<p><!-- CL 153559 -->
|
||
<p>
|
||
The <code>Callback</code> type and <code>NewCallback</code> function have been renamed;
|
||
they are now called
|
||
<a href="/pkg/syscall/js/?GOOS=js&GOARCH=wasm#Func"><code>Func</code></a> and
|
||
<a href="/pkg/syscall/js/?GOOS=js&GOARCH=wasm#FuncOf"><code>FuncOf</code></a>, respectively.
|
||
This is a breaking change, but WebAssembly support is still experimental
|
||
and not yet subject to the
|
||
<a href="/doc/go1compat">Go 1 compatibility promise</a>. Any code using the
|
||
old names will need to be updated.
|
||
</p>
|
||
|
||
<p><!-- CL 141644 -->
|
||
If a type implements the new
|
||
<a href="/pkg/syscall/js/?GOOS=js&GOARCH=wasm#Wrapper"><code>Wrapper</code></a>
|
||
interface,
|
||
<a href="/pkg/syscall/js/?GOOS=js&GOARCH=wasm#ValueOf"><code>ValueOf</code></a>
|
||
will use it to return the JavaScript value for that type.
|
||
</p>
|
||
|
||
<p><!-- CL 143137 -->
|
||
The meaning of the zero
|
||
<a href="/pkg/syscall/js/?GOOS=js&GOARCH=wasm#Value"><code>Value</code></a>
|
||
has changed. It now represents the JavaScript <code>undefined</code> value
|
||
instead of the number zero.
|
||
This is a breaking change, but WebAssembly support is still experimental
|
||
and not yet subject to the
|
||
<a href="/doc/go1compat">Go 1 compatibility promise</a>. Any code relying on
|
||
the zero <a href="/pkg/syscall/js/?GOOS=js&GOARCH=wasm#Value"><code>Value</code></a>
|
||
to mean the number zero will need to be updated.
|
||
</p>
|
||
|
||
<p><!-- CL 144384 -->
|
||
The new
|
||
<a href="/pkg/syscall/js/?GOOS=js&GOARCH=wasm#Value.Truthy"><code>Value.Truthy</code></a>
|
||
method reports the
|
||
<a href="https://developer.mozilla.org/en-US/docs/Glossary/Truthy">JavaScript "truthiness"</a>
|
||
of a given value.
|
||
</p>
|
||
|
||
</dl><!-- syscall/js -->
|
||
|
||
<dl id="testing"><dt><a href="/pkg/testing/">testing</a></dt>
|
||
<dd>
|
||
<p><!-- CL 139258 -->
|
||
The <a href="/cmd/go/#hdr-Testing_flags"><code>-benchtime</code></a> flag now supports setting an explicit iteration count instead of a time when the value ends with an "<code>x</code>". For example, <code>-benchtime=100x</code> runs the benchmark 100 times.
|
||
</p>
|
||
|
||
</dl><!-- testing -->
|
||
|
||
<dl id="text/template"><dt><a href="/pkg/text/template/">text/template</a></dt>
|
||
<dd>
|
||
<p><!-- CL 142217 -->
|
||
When executing a template, long context values are no longer truncated in errors.
|
||
</p>
|
||
<p>
|
||
<code>executing "tmpl" at <.very.deep.context.v...>: map has no entry for key "notpresent"</code>
|
||
</p>
|
||
<p>
|
||
is now
|
||
</p>
|
||
<p>
|
||
<code>executing "tmpl" at <.very.deep.context.value.notpresent>: map has no entry for key "notpresent"</code>
|
||
</p>
|
||
|
||
<dd>
|
||
<p><!-- CL 143097 -->
|
||
If a user-defined function called by a template panics, the
|
||
panic is now caught and returned as an error by
|
||
the <code>Execute</code> or <code>ExecuteTemplate</code> method.
|
||
</p>
|
||
</dl><!-- text/template -->
|
||
|
||
<dl id="unsafe"><dt><a href="/pkg/unsafe/">unsafe</a></dt>
|
||
<dd>
|
||
<p><!-- CL 146058 -->
|
||
It is invalid to convert a nil <code>unsafe.Pointer</code> to <code>uintptr</code> and back with arithmetic.
|
||
(This was already invalid, but will now cause the compiler to misbehave.)
|
||
</p>
|
||
|
||
</dl><!-- unsafe -->
|