<p>
When explicitly converting structs, tags are now ignored for structural type identity.
- See <a href="https://golang.org/cl/24190">change 24190</a> for details.
+ See <a href="/ref/spec#Conversions">language specification</a> for details.
</p>
<p> <!-- CL 17711 -->
The language specification now only requires that implementations
- support up to 16-bit exponents in constants. This does not affect
+ support up to 16-bit exponents in floating-point constants. This does not affect
either the <code>gc</code> or <code>gccgo</code> compilers, both of
which still support 32-bit exponents.
</p>
<p>
For 64-bit PPC systems, the common vector scalar instructions have been
-added. See <a href="https://golang.org/cl/30510">change 30510</a>.
+added:
+<code>LXS</code>,
+<code>LXSDX</code>,
+<code>LXSI</code>,
+<code>LXSIWAX</code>,
+<code>LXSIWZX</code>,
+<code>LXV</code>,
+<code>LXVD2X</code>,
+<code>LXVDSX</code>,
+<code>LXVW4X</code>,
+<code>MFVSR</code>,
+<code>MFVSRD</code>,
+<code>MFVSRWZ</code>,
+<code>MTVSR</code>,
+<code>MTVSRD</code>,
+<code>MTVSRWA</code>,
+<code>MTVSRWZ</code>,
+<code>STXS</code>,
+<code>STXSDX</code>,
+<code>STXSI</code>,
+<code>STXSIWX</code>,
+<code>STXV</code>,
+<code>STXVD2X</code>,
+<code>STXVW4X</code>,
+<code>XSCV</code>,
+<code>XSCVDPSP</code>,
+<code>XSCVDPSPN</code>,
+<code>XSCVDPSXDS</code>,
+<code>XSCVDPSXWS</code>,
+<code>XSCVDPUXDS</code>,
+<code>XSCVDPUXWS</code>,
+<code>XSCVSPDP</code>,
+<code>XSCVSPDPN</code>,
+<code>XSCVSXDDP</code>,
+<code>XSCVSXDSP</code>,
+<code>XSCVUXDDP</code>,
+<code>XSCVUXDSP</code>,
+<code>XSCVX</code>,
+<code>XSCVXP</code>,
+<code>XVCV</code>,
+<code>XVCVDPSP</code>,
+<code>XVCVDPSXDS</code>,
+<code>XVCVDPSXWS</code>,
+<code>XVCVDPUXDS</code>,
+<code>XVCVDPUXWS</code>,
+<code>XVCVSPDP</code>,
+<code>XVCVSPSXDS</code>,
+<code>XVCVSPSXWS</code>,
+<code>XVCVSPUXDS</code>,
+<code>XVCVSPUXWS</code>,
+<code>XVCVSXDDP</code>,
+<code>XVCVSXDSP</code>,
+<code>XVCVSXWDP</code>,
+<code>XVCVSXWSP</code>,
+<code>XVCVUXDDP</code>,
+<code>XVCVUXDSP</code>,
+<code>XVCVUXWDP</code>,
+<code>XVCVUXWSP</code>,
+<code>XVCVX</code>,
+<code>XVCVXP</code>,
+<code>XXLAND</code>,
+<code>XXLANDC</code>,
+<code>XXLANDQ</code>,
+<code>XXLEQV</code>,
+<code>XXLNAND</code>,
+<code>XXLNOR</code>,
+<code>XXLOR</code>,
+<code>XXLORC</code>,
+<code>XXLORQ</code>,
+<code>XXLXOR</code>,
+<code>XXMRG</code>,
+<code>XXMRGHW</code>,
+<code>XXMRGLW</code>,
+<code>XXPERM</code>,
+<code>XXPERMDI</code>,
+<code>XXSEL</code>,
+<code>XXSI</code>,
+<code>XXSLDWI</code>,
+<code>XXSPLT</code>, and
+<code>XXSPLTW</code>.
</p>
<h3 id="tool_yacc">Yacc</h3>
<p> <!-- CL 27324, CL 27325 -->
-The <code>yacc</code> (previously available via
+The <code>yacc</code> tool (previously available via
“<code>go</code> <code>tool</code> <code>yacc</code>”)
has been removed. As of Go 1.7 it was no longer used by the Go compiler.
It has moved to the “tools” repository and is and is available via
-<code>go
get <a href="https://godoc.org/golang.org/x/tools/cmd/goyacc">golang.org/x/tools/cmd/goyacc</a></code>.
+<code>go
</code> <code>get</code> <code><a href="https://godoc.org/golang.org/x/tools/cmd/goyacc">golang.org/x/tools/cmd/goyacc</a></code>.
</p>
<h3 id="compiler">Compiler Toolchain</h3>
</p>
<p>
-The temporary <code>-ssa=0</code> flag introduced in Go 1.7 to disable
-the new backend has been removed in Go 1.8.
+ The temporary <code>-ssa=0</code> compiler flag introduced in Go 1.7
+ to disable the new backend has been removed in Go 1.8.
</p>
<p>
</p>
<p>
-A new “<code>go</code> <code>bug</code>” command helps users file bug reports.
+ A new
+ “<a href="/cmd/go/#hdr-Print_information_for_bug_reports"><code>go</code>
+ <code>bug</code></a>” command helps users file bug reports.
</p>
<h3 id="cmd_doc">Go doc</h3>
<p> <!-- CL 25419 -->
- The “<code>go</code> <code>doc</code>” command
+ The
+ “<a href="/cmd/go/#hdr-Show_documentation_for_package_or_symbol"><code>go</code>
+ <code>doc</code></a>” command
now groups constants and variables with their type,
following the behavior of
<a href="/cmd/godoc/"><code>godoc</code></a>.
explicitly.
</p>
-<h3 id="plugin">Plug-ins</h3>
+<h3 id="plugin">Plugins</h3>
<p>
Go now supports a “<code>plugin</code>” build mode for generating
- plug-ins written in Go, and a
+ plugins written in Go, and a
new <a href="/pkg/plugin/"><code>plugin</code></a> package for
- loading such plug-ins at run time. Plug-ins support is only currently
- available on Linux and Darwin.
+ loading such plugins at run time. Plugin support is only currently
+ available on Linux and macOS.
</p>
<h2 id="runtime">Runtime</h2>
<h3 id="gc">Garbage Collector</h3>
<p>
-Garbage collection pauses should be significantly shorter than they
-were in Go 1.7, often as low as 10 microseconds and usually under 100
-microseconds.
-See the
-<a href="https://github.com/golang/proposal/blob/master/design/17503-eliminate-rescan.md">
-document on eliminating stop-the-world stack re-scanning</a> for details.
-More work remains for Go 1.9.
+ Garbage collection pauses should be significantly shorter than they
+ were in Go 1.7, often as low as 10 microseconds and usually under 100
+ microseconds.
+ See the
+ <a href="https://github.com/golang/proposal/blob/master/design/17503-eliminate-rescan.md"
+ >document on eliminating stop-the-world stack re-scanning</a>
+ for details. More work remains for Go 1.9.
</p>
<h3 id="defer">Defer</h3>
<!-- CL 29656, CL 29656 -->
-<p><code>defer</code> calls are now about twice as fast.</p>
+<p>
+ The overhead of <a href="/ref/spec/#Defer_statements">deferred
+ function calls</a> has been reduced by half.
+</p>
<h3 id="cgoperf">Cgo</h3>
The encoder, when operating in
<a href="/pkg/compress/flate/#NoCompression"><code>NoCompression</code></a>
mode, now produces a consistent output that is not dependent on
- the size of the input buffer to the
+ the size of the slices passed to the
<a href="/pkg/compress/flate/#Writer.Write"><code>Write</code></a>
method.
</p>
field is the zero value.
In previous releases of Go, the <code>Writer</code> would encode
- a non-sensible value.
+ a nonsensical value.
Similarly,
the <a href="/pkg/compress/gzip/#Reader"><code>Reader</code></a>
<dl id="encoding_base64"><dt><a href="/pkg/encoding/base64/">encoding/base64</a></dt>
<dd>
<p> <!-- CL 24964 -->
- The new <a href="/pkg/encoding/base64/#Encoding.Strict"><code>Encoding.Strict</code></a> method returns an <code>Encoding</code> that causes the decoder to return an error when the trailing padding bits are not zero.
+ The new
+ <a href="/pkg/encoding/base64/#Encoding.Strict"><code>Encoding.Strict</code></a>
+ method returns an <code>Encoding</code> that causes the decoder
+ to return an error when the trailing padding bits are not zero.
</p>
</dd>
</dl>
</p>
<p> <!-- CL 30371 -->
- Numbers are now formatted in the same floating point format as they are in ES6.
+ Marshal encodes floating-point numbers using the same format as in ES6,
+ preferring decimal (not exponential) notation for a wider range of values.
+ In particular, all floating-point integers up to 2<sup>64</sup> format the
+ same as the equivalent <code>int64</code> representation.
</p>
<p> <!-- CL 30944 -->
Implementations
of <a href="/pkg/encoding/json/#Unmarshaler"><code>Unmarshaler</code></a>
are now called with the literal "<code>null</code>" and can
- decide what to do with it.
+ decide how to handle it.
</p>
</dd>
<dl id="math_rand"><dt><a href="/pkg/math/rand/">math/rand</a></dt>
<dd>
- <p>
- There is a new
- method <a href="/pkg/math/rand/#Rand.Uint64"><code>Rand.Uint64</code></a>
- to return <code>uint64</code> values. <!-- CL 27253 -->
+ <p><!-- CL 27253, CL 33456 -->
+ The new <a href="/pkg/math/rand/#Rand.Uint64"><code>Rand.Uint64</code></a>
+ method returns <code>uint64</code> values. The
+ new <a href="/pkg/math/rand/#Rand.Source64"><code>Rand.Source64</code></a>
+ interface describes sources capable of generating such values
+ directly; otherwise the <code>Rand.Uint64</code> method
+ constructs a <code>uint64</code> from two calls
+ to <code>Rand.Source</code>'s <code>Int63</code> method.
</p>
</dd>
<li>The server now supports graceful shutdown support, <a href="#http_shutdown">mentioned above</a>.</li>
<li> <!-- CL 32024 -->
- The <a href="/pkg/net/http/#Server"><code>Server</code></a> now
- has new configuration options
- <code>ReadHeaderTimeout</code> and <code>IdleTimeout</code>.
- The previously ill-defined <code>WriteTimeout</code> is now
- documented.
+ The <a href="/pkg/net/http/#Server"><code>Server</code></a>
+ adds configuration options
+ <code>ReadHeaderTimeout</code> and <code>IdleTimeout</code>
+ and documents <code>WriteTimeout</code>.
</li>
<li> <!-- CL 32014 -->
support.
</li>
- <li><!-- CL 32479 --> There is now a second way to serve trailers
- for when the trailer name is not known before the headers are
- written (via a call to
- to <code>ResponseWriter.WriteHeader</code>). The old way
- continues to work, but when the trailer is only known after the
- header has been written, see the
- new <a href="/pkg/net/http/#TrailerPrefix"><code>TrailerPrefix</code></a>.</li>
+ <li><!-- CL 32479 -->
+ To serve trailers known after the header has been written,
+ see the new
+ <a href="/pkg/net/http/#TrailerPrefix"><code>TrailerPrefix</code></a>
+ mechanism.
+ </li>
<li><!-- CL 33099 -->
- A <code>Handler</code> now has a supported mechanism to abort a
- response: panicking with
+ A <code>Handler</code> can now abort a response by panicking
+ with the error
<a href="/pkg/net/http/#ErrAbortHandler"><code>ErrAbortHandler</code></a>.
</li>
<li><!-- CL 30812 -->
- There is now a supported mechanism to test whether a
- <code>ResponseWriter</code> has been hijacked: <code>Write</code> zero bytes to it.
- While this previously returned
- <a href="/pkg/net/http/#ErrHijacked"><code>ErrHijacked</code></a>, now
- it also does so without spamming the server's error log.
+ A <code>Write</code> of zero bytes to a
+ <a href="/pkg/net/http/#ResponseWriter"><code>ResponseWriter</code></a>
+ is now defined as a
+ way to test whether a <code>ResponseWriter</code> has been hijacked:
+ if so, the <code>Write</code> returns
+ <a href="/pkg/net/http/#ErrHijacked"><code>ErrHijacked</code></a>
+ without printing an error
+ to the server's error log.
</li>
</ul>
<p>Client & Transport changes:</p>
<ul>
<li><!-- CL 28930 -->
- The <code>Client</code> now copies request headers on redirect.
+ The <a href="/pkg/net/http/#Client"><code>Client</code></a>
+ now copies most request headers on redirect. Authentication-specific
+ headers are only sent to the same origin or subdomains thereof.
+ Cookies are not sent again, unless they were set explicitly.
+ TODO: verify this, and link to docs once https://github.com/golang/go/issues/18096
+ is fixed.
</li>
<li><!-- CL 29072 -->
- The <code>Transport</code> now supports international domain names.
+ The <a href="/pkg/net/http/#Transport"><code>Transport</code></a>
+ now supports international domain names. Consequently, so do
+ <a href="/pkg/net/http/#Get">Get</a> and other helpers.
</li>
<li><!-- CL 31733, CL 29852 -->
The <code>Client</code> now supports 307 and 308 redirects.
- If the redirect involves re-sending the request body,
+ If the redirect requires resending the request body,
the request must have the new
<a href="/pkg/net/http/#Request"><code>Request.GetBody</code></a>
field defined.
<li> <!-- CL 28077 -->
The <a href="/pkg/net/http/#DefaultTransport"><code>DefaultTransport.Dialer</code></a>
- now enables <code>DualStack</code> ("Happy Eyeballs") support,
+ now enables <code>DualStack</code> ("<a href="https://tools.ietf.org/html/rfc6555">Happy Eyeballs</a>") support,
to use IPv4 as a backup if it looks like IPv6 might be
failing.
</li>
<dd>
<p> <!-- CL 32176 -->
- Empty quoted strings are now allowed in the name part of an
- address. That is, this is now a legal address:
- <code>"" <gopher@example.com></code>
+ Empty quoted strings are once again allowed in the name part of
+ an address. That is, Go 1.4 and earlier accepted
+ <code>"" <gopher@example.com></code>,
+ but Go 1.5 introduced a bug that rejected this address.
+ The address is recognized again.
</p>
<p> <!-- CL 31581 -->
- The <a href="/pkg/net/mail/#ParseDate"><code>ParseDate</code></a>
- function has been exported.
+ The
+ <a href="/pkg/net/mail/#Header.Date"><code>Header.Date</code></a>
+ method has always provided a way to parse
+ the <code>Date:</code> header.
+ A new function
+ <a href="/pkg/net/mail/#ParseDate"><code>ParseDate</code></a>
+ allows parsing dates found in other
+ header lines, such as the <code>Resent-Date:</code> header.
</p>
</dd>
<dd>
<p> <!-- CL 33143 -->
- If implementations of the <a href="/pkg/net/smtp/#Auth"><code>Auth</code></a>
- interface return an empty <code>toServer</code> value, the package
- no longer sends trailing whitespace after the SMTP <code>AUTH</code>
- command, which some servers rejected.
+ If an implementation of
+ the <a href="/pkg/net/smtp/#Auth"><code>Auth</code></a>
+ interface's <code>Start</code> method returns an
+ empty <code>toServer</code> value, the package no longer sends
+ trailing whitespace in the SMTP <code>AUTH</code> command,
+ which some servers rejected.
</p>
</dd>
and
<a href="/pkg/net/url/#PathUnescape"><code>PathUnescape</code></a>
are similar to the query escaping and unescaping functions but
- don't treat spaces specially.</p>
+ for path elements.</p>
<p> <!-- CL 28933 --> The new methods
<a href="/pkg/net/url/#URL.Hostname"><code>URL.Hostname</code></a>
<p> <!-- CL 31467 -->
The <code>URL</code> type now implements
<a href="/pkg/encoding/#BinaryMarshaler"><code>encoding.BinaryMarshaler</code></a> and
- <a href="/pkg/encoding/#BinaryUnmarshaler"><code>encoding.BinaryUnmarshaler</code></a>.
+ <a href="/pkg/encoding/#BinaryUnmarshaler"><code>encoding.BinaryUnmarshaler</code></a>,
+ making it possible to process URLs in <a href="/pkg/encoding/gob/">gob data</a>.
</p>
<p> <!-- CL 29610, CL 31582 -->
- <code>Parse</code> now rejects relative URLs containing a "<code>:</code>" in
- the first path segment. Such paths should be prefixed with "<code>./</code>".
- The <code>URL.String</code> method now prepends "<code>./</code>" to such paths.
+ Following RFC 3986,
+ <a href="/pkg/net/url/#Parse"><code>Parse</code></a>
+ now rejects URLs like <code>this_that:other/thing</code> instead of
+ interpreting them as relative paths (<code>this_that</code> is not a valid scheme).
+ To force interpretation as a relative path,
+ such URLs should be prefixed with <code>"./"</code>.
+ The <code>URL.String</code> method now inserts this prefix as needed.
</p>
</dd>
<p> <!-- CL 30088 -->
The new function
<a href="/pkg/reflect/#Swapper"><code>Swapper</code></a> was
- added to support
- the <a href="#sortslice">new <code>sort.Slice</code>
- support</a>.
+ added to support <a href="#sortslice"><code>sort.Slice</code></a>.
</p>
</dd>
</dl>
<p> <!-- CL 31210 -->
The <a href="/pkg/strconv/#Unquote"><code>Unquote</code></a>
function now strips carriage returns (<code>\r</code>) in
- backquoted raw strings.
+ backquoted raw strings, following the
+ <a href="/ref/spec#String_literals">Go language semantics</a>.
</p>
</dd>
</dl>
the analogous <code>Since</code> function.
</p>
- <p> <!-- CL 29338 --> <code>ParseDuration</code> now accepts long fractional parts.</p>
+ <p> <!-- CL 29338 -->
+ <a href="/pkg/time/#ParseDuration"><code>ParseDuration</code></a>
+ now accepts long fractional parts.
+ </p>
<p> <!-- CL 33429 -->
<code>Parse</code> now validates days that are too small, in
<p><!-- CL 32483 -->
The new function
<a href="/pkg/testing/#CoverMode"><code>CoverMode</code></a>
- reports what the test coverage mode is set to.
+ reports the test coverage mode.
</p>
<p><!-- CL 32615 -->
Tests and benchmarks are now marked as failed if the race
detector is enabled and a data race occurs during execution.
+ Previously, individual test cases would appear to pass,
+ and only the overall execution of the test binary would fail.
</p>
</dd>
<p><!-- CL 30935 -->
<code>SimpleFold</code> now returns its argument unchanged
if the provided input was an invalid rune.
- </p>
- </dd>
-</dl>
-
-
-
-
-<dl id="foo"><dt><a href="/pkg/foo/">foo</a></dt>
- <dd>
- <p> <!-- CL nnn -->
-
+ Previously, the implementation failed with an index bounds check panic.
</p>
</dd>
</dl>