<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 TODO.
+ 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>
+<p>
+ There is a <a href="https://golang.org/issue/27993"><strong>known issue</strong> in
+ the garbage collector</a> that can cause rare crashes. It is being investigated.
+ Please <a href="https://golang.org/issue/new">report</a> any issues you encounter.
+</p>
+
<h2 id="language">Changes to the language</h2>
<p>
<h2 id="ports">Ports</h2>
-<h3 id="freebsd">FreeBSD</h3>
+<p><!-- CL 138675 -->
+ The race detector is now supported on <code>linux/arm64</code>.
+</p>
-<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+.
</p>
-<h3 id="darwin">Darwin</h3>
-
-<p>
-Go 1.12 is the last release that will run on macOS 10.10 Yosemite.
-Go 1.13 will require macOS 10.11 El Capitan or later.
+<p><!-- CL 146898 -->
+ cgo is now supported on <code>linux/ppc64</code>.
</p>
-<p><!-- CL 141639 -->
- <code>libSystem</code> is now used when making syscalls on Darwin, ensuring forward-compatibility
- with future versions of macOS.
+<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>
- TODO: status of ARM32 port?
+ 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.
</p>
<h3 id="aix">AIX</h3>
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>
-<h3 id="hurd">Hurd</h3>
+<h3 id="darwin">Darwin</h3>
-<p><!-- 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>
+ Go 1.12 is the last release that will run on macOS 10.10 Yosemite.
+ Go 1.13 will require macOS 10.11 El Capitan or later.
+</p>
+
+<p><!-- CL 141639 -->
+ <code>libSystem</code> is now used when making syscalls on Darwin,
+ ensuring forward-compatibility with future versions of macOS and iOS.
</p>
<h2 id="tools">Tools</h2>
in an error like "relocation target not defined for ABIInternal (but
is defined for ABI0)", please refer to help section of the ABI
design document.
- TODO(austin): Link to the design doc.
+ <!-- TODO(austin): Link to the design doc. -->
</p>
<p><!-- CL 145179 -->
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>
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 -->
in mind.
</p>
-<!-- CL 147218: https://golang.org/cl/147218: cmd/asm: rename R18 to R18_PLATFORM on ARM64 -->
-<!-- CL 116275: https://golang.org/cl/116275: cmd/compile: avoid string allocations when map key is struct or array literal -->
-<!-- CL 142717: https://golang.org/cl/142717: cmd/compile: remove obsolete "safe" mode -->
-<!-- CL 146058: https://golang.org/cl/146058: It is invalid to convert a nil unsafe.Pointer to uintptr and back, with arithmetic.: cmd/compile: assume unsafe pointer arithmetic generates non-nil results -->
-<!-- CL 146898: https://golang.org/cl/146898: cmd/link, runtime: add initial cgo support for ppc64 -->
-<!-- CL 115677: https://golang.org/cl/115677: cmd/vet: check embedded field tags too -->
+<!-- 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 -->
</dl><!-- bufio -->
-<dl id="build"><dt><a href="/pkg/build/">build</a></dt>
- <dd>
- <p><!-- CL 61511 -->
- TODO: <a href="https://golang.org/cl/61511">https://golang.org/cl/61511</a>: support frame-pointer for arm64
- </p>
-
-</dl><!-- build -->
-
<dl id="bytes"><dt><a href="/pkg/bytes/">bytes</a></dt>
<dd>
<p><!-- CL 137855 -->
</dl><!-- bytes -->
-<dl id="cmd,runtime"><dt><a href="/pkg/cmd,runtime/">cmd,runtime</a></dt>
- <dd>
- <p><!-- CL 138675 -->
- TODO: <a href="https://golang.org/cl/138675">https://golang.org/cl/138675</a>: enable race detector on arm64
- </p>
-
-</dl><!-- cmd,runtime -->
-
<dl id="crypto/rand"><dt><a href="/pkg/crypto/rand/">crypto/rand</a></dt>
<dd>
<p><!-- CL 139419 -->
</dl><!-- image/png -->
-<dl id="internal/poll"><dt><a href="/pkg/internal/poll/">internal/poll</a></dt>
- <dd>
- <p><!-- CL 130676 -->
- TODO: <a href="https://golang.org/cl/130676">https://golang.org/cl/130676</a>: use F_FULLFSYNC fcntl for FD.Fsync on OS X
- </p>
-
-</dl><!-- internal/poll -->
-
<dl id="io"><dt><a href="/pkg/io/">io</a></dt>
<dd>
<p><!-- CL 139457 -->
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 properly flush content to permanent storage. Note that this might have a negative performance impact.
+ </p>
+
</dl><!-- os -->
<dl id="path/filepath"><dt><a href="/pkg/path/filepath/">path/filepath</a></dt>
</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 -->