<!--{
        "Title": "Go 1.12 Release Notes",
        "Path":  "/doc/go1.12",
        "Template": true
}-->

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<style>
  ul li { margin: 0.5em 0; }
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<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 TODO.
  As always, the release maintains the Go 1 <a href="/doc/go1compat.html">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>

<h3 id="freebsd">FreeBSD</h3>

<p>
  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>

<h2 id="tools">Tools</h2>

<h3 id="gocache">Build cache requirement</h3>

<p>
  The build cache is now required as a step toward eliminating
  <code>$GOPATH/pkg</code>. Setting the environment variable
  <code>GOCACHE=off</code> to disable the
  <a href="/cmd/go/#hdr-Build_and_test_caching">build cache</a>
  has no effect in Go 1.12.
</p>

<h3 id="godoc">Godoc</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>

<h2 id="library">Core library</h2>

<p>
  All of the changes to the standard library are minor.
</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>

<!-- CL 142717: https://golang.org/cl/142717: cmd/compile: remove obsolete "safe" mode -->
<!-- CL 144340: https://golang.org/cl/144340: cmd/compile: add -lang flag to specify language version -->
<!-- CL 141977: https://golang.org/cl/141977: cmd/doc: add -all flag to print all documentation for package -->
<!-- CL 126656: https://golang.org/cl/126656: cmd/go: add $GOFLAGS environment variable -->
<!-- CL 115677: https://golang.org/cl/115677: cmd/vet: check embedded field tags too -->
<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, strings"><dt><a href="/pkg/bytes, strings/">bytes, strings</a></dt>
  <dd>
    <p><!-- CL 137855 -->
      TODO: <a href="https://golang.org/cl/137855">https://golang.org/cl/137855</a>: add ReplaceAll
    </p>

    <p><!-- CL 145098 -->
      TODO: <a href="https://golang.org/cl/145098">https://golang.org/cl/145098</a>: fix Reader.UnreadRune returning without error on a zero Reader
    </p>

</dl><!-- bytes, strings -->

<dl id="crypto/tls, net/http"><dt><a href="/pkg/crypto/tls, net/http/">crypto/tls, net/http</a></dt>
  <dd>
    <p><!-- CL 143177 -->
      TODO: <a href="https://golang.org/cl/143177">https://golang.org/cl/143177</a>: reject HTTP requests to HTTPS server
    </p>

</dl><!-- crypto/tls, net/http -->

<dl id="expvar"><dt><a href="/pkg/expvar/">expvar</a></dt>
  <dd>
    <p><!-- CL 139537 -->
      TODO: <a href="https://golang.org/cl/139537">https://golang.org/cl/139537</a>: add Map.Delete
    </p>

</dl><!-- expvar -->

<dl id="fmt"><dt><a href="/pkg/fmt/">fmt</a></dt>
  <dd>
    <p><!-- CL 142737 -->
      TODO: <a href="https://golang.org/cl/142737">https://golang.org/cl/142737</a>: print maps in key-sorted order
    </p>

</dl><!-- fmt -->

<dl id="go/build, cmd/go"><dt><a href="/pkg/go/build, cmd/go/">go/build, cmd/go</a></dt>
  <dd>
    <p><!-- CL 146023 -->
      TODO: <a href="https://golang.org/cl/146023">https://golang.org/cl/146023</a>: add &#34;hurd&#34; as a GOOS value
    </p>

</dl><!-- go/build, cmd/go -->

<dl id="go/doc"><dt><a href="/pkg/go/doc/">go/doc</a></dt>
  <dd>
    <p><!-- CL 140958 -->
      TODO: <a href="https://golang.org/cl/140958">https://golang.org/cl/140958</a>: add new mode bit PreserveAST to control clearing of data in AST
    </p>

</dl><!-- go/doc -->

<dl id="godoc, cmd/godoc"><dt><a href="/pkg/godoc, cmd/godoc/">godoc, cmd/godoc</a></dt>
  <dd>
    <p><!-- CL 141397 -->
      TODO: <a href="https://golang.org/cl/141397">https://golang.org/cl/141397</a>: remove CLI support
    </p>

</dl><!-- godoc, cmd/godoc -->

<dl id="image"><dt><a href="/pkg/image/">image</a></dt>
  <dd>
    <p><!-- CL 118755 -->
      TODO: <a href="https://golang.org/cl/118755">https://golang.org/cl/118755</a>: make RegisterFormat 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 -->
      TODO: <a href="https://golang.org/cl/134235">https://golang.org/cl/134235</a>: pack image data for small bitdepth paletted images
    </p>

</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 -->
      TODO: <a href="https://golang.org/cl/139457">https://golang.org/cl/139457</a>: export StringWriter
    </p>

</dl><!-- io -->

<dl id="math/bits"><dt><a href="/pkg/math/bits/">math/bits</a></dt>
  <dd>
    <p><!-- CL 123157 -->
      TODO: <a href="https://golang.org/cl/123157">https://golang.org/cl/123157</a>: add extended precision Add, Sub, Mul, Div
    </p>

</dl><!-- math/bits -->

<dl id="net"><dt><a href="/pkg/net/">net</a></dt>
  <dd>
    <p><!-- CL 113997 -->
      TODO: <a href="https://golang.org/cl/113997">https://golang.org/cl/113997</a>: use splice(2) on Linux when reading from UnixConn, rework splice tests
    </p>

</dl><!-- net -->

<dl id="net/http"><dt><a href="/pkg/net/http/">net/http</a></dt>
  <dd>
    <p><!-- CL 130115 -->
      TODO: <a href="https://golang.org/cl/130115">https://golang.org/cl/130115</a>: add Client.CloseIdleConnections
    </p>

    <p><!-- CL 145398 -->
      TODO: <a href="https://golang.org/cl/145398">https://golang.org/cl/145398</a>: in Transport, don&#39;t error on non-chunked response with Trailer header
    </p>

</dl><!-- net/http -->

<dl id="os"><dt><a href="/pkg/os/">os</a></dt>
  <dd>
    <p><!-- CL 125443 -->
      TODO: <a href="https://golang.org/cl/125443">https://golang.org/cl/125443</a>: add ExitCode method to ProcessState
    </p>

    <p><!-- CL 135075 -->
      TODO: <a href="https://golang.org/cl/135075">https://golang.org/cl/135075</a>: add ModeCharDevice to ModeType
    </p>

    <p><!-- CL 139418 -->
      TODO: <a href="https://golang.org/cl/139418">https://golang.org/cl/139418</a>: add UserHomeDir
    </p>

</dl><!-- os -->

<dl id="reflect"><dt><a href="/pkg/reflect/">reflect</a></dt>
  <dd>
    <p><!-- CL 33572 -->
      TODO: <a href="https://golang.org/cl/33572">https://golang.org/cl/33572</a>: add Value.MapRange method and MapIter type
    </p>

</dl><!-- reflect -->

<dl id="runtime"><dt><a href="/pkg/runtime/">runtime</a></dt>
  <dd>
    <p><!-- CL 135395 -->
      TODO: <a href="https://golang.org/cl/135395">https://golang.org/cl/135395</a>: use MADV_FREE on Linux if available
    </p>

</dl><!-- runtime -->

<dl id="strings"><dt><a href="/pkg/strings/">strings</a></dt>
  <dd>
    <p><!-- CL 122835 -->
      TODO: <a href="https://golang.org/cl/122835">https://golang.org/cl/122835</a>: add Builder.Cap
    </p>

</dl><!-- strings -->

<dl id="syscall"><dt><a href="/pkg/syscall/">syscall</a></dt>
  <dd>
    <p><!-- CL 125456 -->
      TODO: <a href="https://golang.org/cl/125456">https://golang.org/cl/125456</a>: implement Unix Socket for Windows
    </p>

    <p><!-- CL 138595 -->
      TODO: <a href="https://golang.org/cl/138595">https://golang.org/cl/138595</a>: FreeBSD 12 ino64 support
    </p>

</dl><!-- syscall -->

<dl id="syscall/js"><dt><a href="/pkg/syscall/js/">syscall/js</a></dt>
  <dd>
    <p><!-- CL 141644 -->
      TODO: <a href="https://golang.org/cl/141644">https://golang.org/cl/141644</a>: add Wrapper interface to support external Value wrapper types
    </p>

    <p><!-- CL 143137 -->
      TODO: <a href="https://golang.org/cl/143137">https://golang.org/cl/143137</a>: make zero js.Value represent &#34;undefined&#34;
    </p>

    <p><!-- CL 144384 -->
      TODO: <a href="https://golang.org/cl/144384">https://golang.org/cl/144384</a>: add the Value.Truthy method
    </p>

</dl><!-- syscall/js -->

<dl id="testing"><dt><a href="/pkg/testing/">testing</a></dt>
  <dd>
    <p><!-- CL 139258 -->
      TODO: <a href="https://golang.org/cl/139258">https://golang.org/cl/139258</a>: implement -benchtime=100x
    </p>

</dl><!-- testing -->