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<!--{
"Title": "Go 1.18 Release Notes",
"Path": "/doc/go1.18"
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<h2 id="introduction">DRAFT RELEASE NOTES — Introduction to Go 1.18</h2>
<p>
<strong>
Go 1.18 is not yet released. These are work-in-progress
release notes. Go 1.18 is expected to be released in February 2022.
</strong>
</p>
<h2 id="language">Changes to the language</h2>
<p>
TODO: complete this section
</p>
<h2 id="ports">Ports</h2>
<p id="freebsd">
Go 1.18 is the last release that is supported on FreeBSD 11.x, which has
already reached end-of-life. Go 1.19 will require FreeBSD 12.2+ or FreeBSD
13.0+.
FreeBSD 13.0+ will require a kernel with the COMPAT_FREEBSD12 option set (this is the default).
</p>
<h2 id="tools">Tools</h2>
<p>
TODO: complete this section, or delete if not needed
</p>
<h3 id="go-command">Go command</h3>
<p><!-- golang.org/issue/43684 -->
<code>go</code> <code>get</code> no longer builds or installs packages in
module-aware mode. <code>go</code> <code>get</code> is now dedicated to
adjusting dependencies in <code>go.mod</code>. Effectively, the
<code>-d</code> flag is always enabled. To install the latest version
of an executable outside the context of the current module, use
<a href="https://golang.org/ref/mod#go-install"><code>go</code>
<code>install</code> <code>example.com/cmd@latest</code></a>. Any
<a href="https://golang.org/ref/mod#version-queries">version query</a>
may be used instead of <code>latest</code>. This form of <code>go</code>
<code>install</code> was added in Go 1.16, so projects supporting older
versions may need to provide install instructions for both <code>go</code>
<code>install</code> and <code>go</code> <code>get</code>. <code>go</code>
<code>get</code> now reports an error when used outside a module, since there
is no <code>go.mod</code> file to update. In GOPATH mode (with
<code>GO111MODULE=off</code>), <code>go</code> <code>get</code> still builds
and installs packages, as before.
</p>
<p><!-- golang.org/issue/37475 -->
The <code>go</code> command now embeds version control information in
binaries including the currently checked-out revision and a flag indicating
whether edited or untracked files are present. Version control information
is embedded if the <code>go</code> command is invoked in a directory within a
Git or Mercurial repository, and the <code>main</code> package and its
containing main module are in the same repository. This information may be
omitted using the flag <code>-buildvcs=false</code>.
</p>
<p><!-- golang.org/issue/37475 -->
Additionally, the <code>go</code> command embeds information about the build
including build and tool tags (set with <code>-tags</code>), compiler,
assembler, and linker flags (like <code>-gcflags</code>), whether cgo was
enabled, and if it was, the values of the cgo environment variables
(like <code>CGO_CFLAGS</code>). This information may be omitted using the
flag <code>-buildinfo=false</code>. Both VCS and build information may be
read together with module information using <code>go</code>
<code>version</code> <code>-m</code> <code>file</code> or
<code>runtime/debug.ReadBuildInfo</code> (for the currently running binary)
or the new <a href="#debug/buildinfo"><code>debug/buildinfo</code></a>
package.
</p>
<p><!-- golang.org/issue/47788 -->
The <code>go</code> command no longer supports <code>-linkshared</code>
and <code>-buildmode=shared</code>.
(<code>shared<code> building and linking has never worked in module mode or
when <code>GOROOT</code> is not writable.)
<p>
<p>
TODO: complete this section, or delete if not needed
</p>
<h3 id="gofmt"><code>gofmt</code></h3>
<p><!-- https://golang.org/issue/43566 -->
<code>gofmt</code> now reads and formats input files concurrently, with a
memory limit proportional to <code>GOMAXPROCS</code>. On a machine with
multiple CPUs, <code>gofmt</code> should now be significantly faster.
</p>
<h2 id="runtime">Runtime</h2>
<p>
TODO: complete this section, or delete if not needed
</p>
<h2 id="compiler">Compiler</h2>
<p>
TODO: complete this section, or delete if not needed
</p>
<h2 id="linker">Linker</h2>
<p>
TODO: complete this section, or delete if not needed
</p>
<h2 id="library">Core library</h2>
<p>
TODO: complete this section
</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>
<p>
TODO: complete this section
</p>
<dl id="debug/buildinfo"><dt><a href="/pkg/debug/buildinfo">debug/buildinfo</a></dt>
<dd>
<p><!-- golang.org/issue/39301 -->
This new package provides access to module versions, version control
information, and build flags embedded in executable files built by
the <code>go</code> command. The same information is also available via
<a href="/pkg/runtime/debug#ReadBuildInfo"><code>runtime/debug.ReadBuildInfo</code></a>
for the currently running binary and via <code>go</code>
<code>version</code> <code>-m</code> on the command line.
</p>
</dd>
</dl>
<dl id="image/draw"><dt><a href="/pkg/image/draw/">image/draw</a></dt>
<dd>
<p><!-- CL 340049 -->
The <code>Draw</code> and <code>DrawMask</code> fallback implementations
(used when the arguments are not the most common image types) are now
faster when those arguments implement the optional
<a href="/pkg/image/draw/#RGBA64Image"><code>draw.RGBA64Image</code></a>
and <a href="/pkg/image/#RGBA64Image"><code>image.RGBA64Image</code></a>
interfaces that were added in Go 1.17.
</p>
</dd>
</dl><!-- image/draw -->
<dl id="reflect"><dt><a href="/pkg/reflect/">reflect</a></dt>
<dd>
<p><!-- CL 356049, 320929 -->
The new
<a href="/pkg/reflect/#Value.SetIterKey"><code>Value.SetIterKey</code></a>
and <a href="/pkg/reflect/#Value.SetIterValue"><code>Value.SetIterValue</code></a>
methods set a Value using a map iterator as the source. They are equivalent to
<code>Value.Set(iter.Key())</code> and <code>Value.Set(iter.Value())</code> but
do fewer allocations.
</p>
</dd>
<dd>
<p><!-- CL 350691 -->
The new
<a href="/pkg/reflect/#Value.UnsafePointer"><code>Value.UnsafePointer</code></a>
method returns the Value's value as an <a href="/pkg/unsafe/#Pointer"><code>unsafe.Pointer</code></a>.
This allows callers to migrate from <a href="/pkg/reflect/#Value.UnsafeAddr"><code>Value.UnsafeAddr</code></a>
and <a href="/pkg/reflect/#Value.Pointer"><code>Value.Pointer</code></a>
to eliminate the need to perform uintptr to unsafe.Pointer conversions at the callsite (as unsafe.Pointer rules require).
</p>
</dd>
</dl><!-- reflect -->
<dl id="syscall"><dt><a href="/pkg/syscall/">syscall</a></dt>
<dd>
<p><!-- CL 336550 -->
The new function <a href="/pkg/syscall/?GOOS=windows#SyscallN"><code>SyscallN</code></a>
has been introduced for Windows, allowing for calls with arbitrary number
of arguments. As a result,
<a href="/pkg/syscall/?GOOS=windows#Syscall"><code>Syscall</code></a>,
<a href="/pkg/syscall/?GOOS=windows#Syscall6"><code>Syscall6</code></a>,
<a href="/pkg/syscall/?GOOS=windows#Syscall9"><code>Syscall9</code></a>,
<a href="/pkg/syscall/?GOOS=windows#Syscall12"><code>Syscall12</code></a>,
<a href="/pkg/syscall/?GOOS=windows#Syscall15"><code>Syscall15</code></a>, and
<a href="/pkg/syscall/?GOOS=windows#Syscall18"><code>Syscall18</code></a> are
deprecated in favor of <a href="/pkg/syscall/?GOOS=windows#SyscallN"><code>SyscallN</code></a>.
</p>
</dd>
</dl><!-- syscall -->