_content/doc: add Go 1.17 release notes
Copied from Go commit 20a620fd9f7bc35739c1af3602d53808d0430814.
deleted there in CL 342070.
Updates golang/go#44513
Change-Id: I435253feb47b222423a453c51d0c1ced30e86633
Reviewed-on: https://go-review.googlesource.com/c/website/+/342089
Trust: Carlos Amedee <carlos@golang.org>
Run-TryBot: Carlos Amedee <carlos@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
diff --git a/_content/doc/go1.17.html b/_content/doc/go1.17.html
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+<!--{
+ "Title": "Go 1.17 Release Notes",
+ "Path": "/doc/go1.17"
+}-->
+
+<!--
+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>
+ main ul li { margin: 0.5em 0; }
+</style>
+
+<h2 id="introduction">Introduction to Go 1.17</h2>
+
+<p>
+ The latest Go release, version 1.17, arrives six months after <a href="/doc/go1.16">Go 1.16</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>
+ Go 1.17 includes three small enhancements to the language.
+</p>
+
+<ul>
+ <li><!-- CL 216424; issue 395 -->
+ <a href="/ref/spec#Conversions_from_slice_to_array_pointer">Conversions
+ from slice to array pointer</a>: An expression <code>s</code> of
+ type <code>[]T</code> may now be converted to array pointer type
+ <code>*[N]T</code>. If <code>a</code> is the result of such a
+ conversion, then corresponding indices that are in range refer to
+ the same underlying elements: <code>&a[i] == &s[i]</code>
+ for <code>0 <= i < N</code>. The conversion panics if
+ <code>len(s)</code> is less than <code>N</code>.
+ </li>
+
+ <li><!-- CL 312212; issue 40481 -->
+ <a href="/pkg/unsafe#Add"><code>unsafe.Add</code></a>:
+ <code>unsafe.Add(ptr, len)</code> adds <code>len</code>
+ to <code>ptr</code> and returns the updated pointer
+ <code>unsafe.Pointer(uintptr(ptr) + uintptr(len))</code>.
+ </li>
+
+ <li><!-- CL 312212; issue 19367 -->
+ <a href="/pkg/unsafe#Slice"><code>unsafe.Slice</code></a>:
+ For expression <code>ptr</code> of type <code>*T</code>,
+ <code>unsafe.Slice(ptr, len)</code> returns a slice of
+ type <code>[]T</code> whose underlying array starts
+ at <code>ptr</code> and whose length and capacity
+ are <code>len</code>.
+ </li>
+</ul>
+
+<p>
+ The package unsafe enhancements were added to simplify writing code that conforms
+ to <code>unsafe.Pointer</code>'s <a href="/pkg/unsafe/#Pointer">safety
+ rules</a>, but the rules remain unchanged. In particular, existing
+ programs that correctly use <code>unsafe.Pointer</code> remain
+ valid, and new programs must still follow the rules when
+ using <code>unsafe.Add</code> or <code>unsafe.Slice</code>.
+</p>
+
+
+<p>
+ Note that the new conversion from slice to array pointer is the
+ first case in which a type conversion can panic at run time.
+ Analysis tools that assume type conversions can never panic
+ should be updated to consider this possibility.
+</p>
+
+<h2 id="ports">Ports</h2>
+
+<h3 id="darwin">Darwin</h3>
+
+<p><!-- golang.org/issue/23011 -->
+ As <a href="go1.16#darwin">announced</a> in the Go 1.16 release
+ notes, Go 1.17 requires macOS 10.13 High Sierra or later; support
+ for previous versions has been discontinued.
+</p>
+
+<h3 id="windows">Windows</h3>
+
+<p><!-- golang.org/issue/36439 -->
+ Go 1.17 adds support of 64-bit ARM architecture on Windows (the
+ <code>windows/arm64</code> port). This port supports cgo.
+</p>
+
+<h3 id="openbsd">OpenBSD</h3>
+
+<p><!-- golang.org/issue/43005 -->
+ The 64-bit MIPS architecture on OpenBSD (the <code>openbsd/mips64</code>
+ port) now supports cgo.
+</p>
+
+<p><!-- golang.org/issue/36435 -->
+ In Go 1.16, on the 64-bit x86 and 64-bit ARM architectures on
+ OpenBSD (the <code>openbsd/amd64</code> and <code>openbsd/arm64</code>
+ ports) system calls are made through <code>libc</code>, instead
+ of directly using machine instructions. In Go 1.17, this is also
+ done on the 32-bit x86 and 32-bit ARM architectures on OpenBSD
+ (the <code>openbsd/386</code> and <code>openbsd/arm</code> ports).
+ This ensures compatibility with OpenBSD 6.9 onwards, which require
+ system calls to be made through <code>libc</code> for non-static
+ Go binaries.
+</p>
+
+<h3 id="arm64">ARM64</h3>
+
+<p><!-- CL 288814 -->
+ Go programs now maintain stack frame pointers on the 64-bit ARM
+ architecture on all operating systems. Previously it maintained
+ stack frame pointers only on Linux, macOS, and iOS.
+</p>
+
+<h3 id="loong64">loong64 GOARCH value reserved</h3>
+
+<p><!-- CL 333909 -->
+ The main Go compiler does not yet support the LoongArch
+ architecture, but we've reserved the <code>GOARCH</code> value
+ "<code>loong64</code>".
+ This means that Go files named <code>*_loong64.go</code> will now
+ be <a href="/pkg/go/build/#hdr-Build_Constraints">ignored by Go
+ tools</a> except when that GOARCH value is being used.
+</p>
+
+<h2 id="tools">Tools</h2>
+
+<h3 id="go-command">Go command</h3>
+
+<a id="lazy-loading"><!-- for existing links only --></a>
+<h4 id="graph-pruning">Pruned module graphs in <code>go 1.17</code> modules</h4>
+
+<p><!-- golang.org/issue/36460 -->
+ If a module specifies <code>go</code> <code>1.17</code> or higher, the module
+ graph includes only the <em>immediate</em> dependencies of
+ other <code>go</code> <code>1.17</code> modules, not their full transitive
+ dependencies. (See <a href="/ref/mod#graph-pruning">Module graph pruning</a>
+ for more detail.)
+</p>
+
+<p>
+ For the <code>go</code> command to correctly resolve transitive imports using
+ the pruned module graph, the <code>go.mod</code> file for each module needs to
+ include more detail about the transitive dependencies relevant to that module.
+ If a module specifies <code>go</code> <code>1.17</code> or higher in its
+ <code>go.mod</code> file, its <code>go.mod</code> file now contains an
+ explicit <a href="/ref/mod#go-mod-file-require"><code>require</code>
+ directive</a> for every module that provides a transitively-imported package.
+ (In previous versions, the <code>go.mod</code> file typically only included
+ explicit requirements for <em>directly</em>-imported packages.)
+<p>
+
+<p>
+ Since the expanded <code>go.mod</code> file needed for module graph pruning
+ includes all of the dependencies needed to load the imports of any package in
+ the main module, if the main module specifies
+ <code>go</code> <code>1.17</code> or higher the <code>go</code> tool no longer
+ reads (or even downloads) <code>go.mod</code> files for dependencies if they
+ are not needed in order to complete the requested command.
+ (See <a href="/ref/mod#lazy-loading">Lazy loading</a>.)
+</p>
+
+<p><!-- golang.org/issue/45965 -->
+ Because the number of explicit requirements may be substantially larger in an
+ expanded Go 1.17 <code>go.mod</code> file, the newly-added requirements
+ on <em>indirect</em> dependencies in a <code>go</code> <code>1.17</code>
+ module are maintained in a separate <code>require</code> block from the block
+ containing direct dependencies.
+</p>
+
+<p><!-- golang.org/issue/45094 -->
+ To facilitate the upgrade to Go 1.17 pruned module graphs, the
+ <a href="/ref/mod#go-mod-tidy"><code>go</code> <code>mod</code> <code>tidy</code></a>
+ subcommand now supports a <code>-go</code> flag to set or change
+ the <code>go</code> version in the <code>go.mod</code> file. To convert
+ the <code>go.mod</code> file for an existing module to Go 1.17 without
+ changing the selected versions of its dependencies, run:
+</p>
+
+<pre>
+ go mod tidy -go=1.17
+</pre>
+
+<p><!-- golang.org/issue/46141 -->
+ By default, <code>go</code> <code>mod</code> <code>tidy</code> verifies that
+ the selected versions of dependencies relevant to the main module are the same
+ versions that would be used by the prior Go release (Go 1.16 for a module that
+ specifies <code>go</code> <code>1.17</code>), and preserves
+ the <code>go.sum</code> entries needed by that release even for dependencies
+ that are not normally needed by other commands.
+</p>
+
+<p>
+ The <code>-compat</code> flag allows that version to be overridden to support
+ older (or only newer) versions, up to the version specified by
+ the <code>go</code> directive in the <code>go.mod</code> file. To tidy
+ a <code>go</code> <code>1.17</code> module for Go 1.17 only, without saving
+ checksums for (or checking for consistency with) Go 1.16:
+</p>
+
+<pre>
+ go mod tidy -compat=1.17
+</pre>
+
+<p>
+ Note that even if the main module is tidied with <code>-compat=1.17</code>,
+ users who <code>require</code> the module from a
+ <code>go</code> <code>1.16</code> or earlier module will still be able to
+ use it, provided that the packages use only compatible language and library
+ features.
+</p>
+
+<p><!-- golang.org/issue/46366 -->
+ The <a href="/ref/mod#go-mod-graph"><code>go</code> <code>mod</code> <code>graph</code></a>
+ subcommand also supports the <code>-go</code> flag, which causes it to report
+ the graph as seen by the indicated Go version, showing dependencies that may
+ otherwise be pruned out.
+</p>
+
+<h4 id="module-deprecation-comments">Module deprecation comments</h4>
+
+<p><!-- golang.org/issue/40357 -->
+ Module authors may deprecate a module by adding a
+ <a href="/ref/mod#go-mod-file-module-deprecation"><code>// Deprecated:</code>
+ comment</a> to <code>go.mod</code>, then tagging a new version.
+ <code>go</code> <code>get</code> now prints a warning if a module needed to
+ build packages named on the command line is deprecated. <code>go</code>
+ <code>list</code> <code>-m</code> <code>-u</code> prints deprecations for all
+ dependencies (use <code>-f</code> or <code>-json</code> to show the full
+ message). The <code>go</code> command considers different major versions to
+ be distinct modules, so this mechanism may be used, for example, to provide
+ users with migration instructions for a new major version.
+</p>
+
+<h4 id="go-get"><code>go</code> <code>get</code></h4>
+
+<p><!-- golang.org/issue/37519 -->
+ The <code>go</code> <code>get</code> <code>-insecure</code> flag is
+ deprecated and has been removed. To permit the use of insecure schemes
+ when fetching dependencies, please use the <code>GOINSECURE</code>
+ environment variable. The <code>-insecure</code> flag also bypassed module
+ sum validation, use <code>GOPRIVATE</code> or <code>GONOSUMDB</code> if
+ you need that functionality. See <code>go</code> <code>help</code>
+ <code>environment</code> for details.
+</p>
+
+<p><!-- golang.org/issue/43684 -->
+ <code>go</code> <code>get</code> prints a deprecation warning when installing
+ commands outside the main module (without the <code>-d</code> flag).
+ <code>go</code> <code>install</code> <code>cmd@version</code> should be used
+ instead to install a command at a specific version, using a suffix like
+ <code>@latest</code> or <code>@v1.2.3</code>. In Go 1.18, the <code>-d</code>
+ flag will always be enabled, and <code>go</code> <code>get</code> will only
+ be used to change dependencies in <code>go.mod</code>.
+</p>
+
+<h4 id="missing-go-directive"><code>go.mod</code> files missing <code>go</code> directives</h4>
+
+<p><!-- golang.org/issue/44976 -->
+ If the main module's <code>go.mod</code> file does not contain
+ a <a href="/doc/modules/gomod-ref#go"><code>go</code> directive</a> and
+ the <code>go</code> command cannot update the <code>go.mod</code> file, the
+ <code>go</code> command now assumes <code>go 1.11</code> instead of the
+ current release. (<code>go</code> <code>mod</code> <code>init</code> has added
+ <code>go</code> directives automatically <a href="/doc/go1.12#modules">since
+ Go 1.12</a>.)
+</p>
+
+<p><!-- golang.org/issue/44976 -->
+ If a module dependency lacks an explicit <code>go.mod</code> file, or
+ its <code>go.mod</code> file does not contain
+ a <a href="/doc/modules/gomod-ref#go"><code>go</code> directive</a>,
+ the <code>go</code> command now assumes <code>go 1.16</code> for that
+ dependency instead of the current release. (Dependencies developed in GOPATH
+ mode may lack a <code>go.mod</code> file, and
+ the <code>vendor/modules.txt</code> has to date never recorded
+ the <code>go</code> versions indicated by dependencies' <code>go.mod</code>
+ files.)
+</p>
+
+<h4 id="vendor"><code>vendor</code> contents</h4>
+
+<p><!-- golang.org/issue/36876 -->
+ If the main module specifies <code>go</code> <code>1.17</code> or higher,
+ <a href="/ref/mod#go-mod-vendor"><code>go</code> <code>mod</code> <code>vendor</code></a>
+ now annotates
+ <code>vendor/modules.txt</code> with the <code>go</code> version indicated by
+ each vendored module in its own <code>go.mod</code> file. The annotated
+ version is used when building the module's packages from vendored source code.
+</p>
+
+<p><!-- golang.org/issue/42970 -->
+ If the main module specifies <code>go</code> <code>1.17</code> or higher,
+ <code>go</code> <code>mod</code> <code>vendor</code> now omits <code>go.mod</code>
+ and <code>go.sum</code> files for vendored dependencies, which can otherwise
+ interfere with the ability of the <code>go</code> command to identify the correct
+ module root when invoked within the <code>vendor</code> tree.
+</p>
+
+<h4 id="password-prompts">Password prompts</h4>
+
+<p><!-- golang.org/issue/44904 -->
+ The <code>go</code> command by default now suppresses SSH password prompts and
+ Git Credential Manager prompts when fetching Git repositories using SSH, as it
+ already did previously for other Git password prompts. Users authenticating to
+ private Git repos with password-protected SSH may configure
+ an <code>ssh-agent</code> to enable the <code>go</code> command to use
+ password-protected SSH keys.
+</p>
+
+<h4 id="go-mod-download"><code>go</code> <code>mod</code> <code>download</code></h4>
+
+<p><!-- golang.org/issue/45332 -->
+ When <code>go</code> <code>mod</code> <code>download</code> is invoked without
+ arguments, it will no longer save sums for downloaded module content to
+ <code>go.sum</code>. It may still make changes to <code>go.mod</code> and
+ <code>go.sum</code> needed to load the build list. This is the same as the
+ behavior in Go 1.15. To save sums for all modules, use <code>go</code>
+ <code>mod</code> <code>download</code> <code>all</code>.
+</p>
+
+<h4 id="build-lines"><code>//go:build</code> lines</h4>
+
+<p>
+ The <code>go</code> command now understands <code>//go:build</code> lines
+ and prefers them over <code>// +build</code> lines. The new syntax uses
+ boolean expressions, just like Go, and should be less error-prone.
+ As of this release, the new syntax is fully supported, and all Go files
+ should be updated to have both forms with the same meaning. To aid in
+ migration, <a href="#gofmt"><code>gofmt</code></a> now automatically
+ synchronizes the two forms. For more details on the syntax and migration plan,
+ see
+ <a href="https://golang.org/design/draft-gobuild">https://golang.org/design/draft-gobuild</a>.
+</p>
+
+<h4 id="go run"><code>go</code> <code>run</code></h4>
+
+<p><!-- golang.org/issue/42088 -->
+ <code>go</code> <code>run</code> now accepts arguments with version suffixes
+ (for example, <code>go</code> <code>run</code>
+ <code>example.com/cmd@v1.0.0</code>). This causes <code>go</code>
+ <code>run</code> to build and run packages in module-aware mode, ignoring the
+ <code>go.mod</code> file in the current directory or any parent directory, if
+ there is one. This is useful for running executables without installing them or
+ without changing dependencies of the current module.
+</p>
+
+<h3 id="gofmt">Gofmt</h3>
+
+<p>
+ <code>gofmt</code> (and <code>go</code> <code>fmt</code>) now synchronizes
+ <code>//go:build</code> lines with <code>// +build</code> lines. If a file
+ only has <code>// +build</code> lines, they will be moved to the appropriate
+ location in the file, and matching <code>//go:build</code> lines will be
+ added. Otherwise, <code>// +build</code> lines will be overwritten based on
+ any existing <code>//go:build</code> lines. For more information, see
+ <a href="https://golang.org/design/draft-gobuild">https://golang.org/design/draft-gobuild</a>.
+</p>
+
+<h3 id="vet">Vet</h3>
+
+<h4 id="vet-buildtags">New warning for mismatched <code>//go:build</code> and <code>// +build</code> lines</h4>
+
+<p><!-- CL 240609 -->
+ The <code>vet</code> tool now verifies that <code>//go:build</code> and
+ <code>// +build</code> lines are in the correct part of the file and
+ synchronized with each other. If they aren't,
+ <a href="#gofmt"><code>gofmt</code></a> can be used to fix them. For more
+ information, see
+ <a href="https://golang.org/design/draft-gobuild">https://golang.org/design/draft-gobuild</a>.
+</p>
+
+<h4 id="vet-sigchanyzer">New warning for calling <code>signal.Notify</code> on unbuffered channels</h4>
+
+<p><!-- CL 299532 -->
+ The vet tool now warns about calls to <a href="/pkg/os/signal/#Notify">signal.Notify</a>
+ with incoming signals being sent to an unbuffered channel. Using an unbuffered channel
+ risks missing signals sent on them as <code>signal.Notify</code> does not block when
+ sending to a channel. For example:
+</p>
+
+<pre>
+c := make(chan os.Signal)
+// signals are sent on c before the channel is read from.
+// This signal may be dropped as c is unbuffered.
+signal.Notify(c, os.Interrupt)
+</pre>
+
+<p>
+ Users of <code>signal.Notify</code> should use channels with sufficient buffer space to keep up with the
+ expected signal rate.
+</p>
+
+<h4 id="vet-error-stdmethods">New warnings for Is, As and Unwrap methods</h4>
+
+<p><!-- CL 321389 -->
+ The vet tool now warns about methods named <code>As</code>, <code>Is</code> or <code>Unwrap</code>
+ on types implementing the <code>error</code> interface that have a different signature than the
+ one expected by the <code>errors</code> package. The <code>errors.{As,Is,Unwrap}</code> functions
+ expect such methods to implement either <code>Is(error)</code> <code>bool</code>,
+ <code>As(interface{})</code> <code>bool</code>, or <code>Unwrap()</code> <code>error</code>
+ respectively. The functions <code>errors.{As,Is,Unwrap}</code> will ignore methods with the same
+ names but a different signature. For example:
+</p>
+
+<pre>
+type MyError struct { hint string }
+func (m MyError) Error() string { ... } // MyError implements error.
+func (MyError) Is(target interface{}) bool { ... } // target is interface{} instead of error.
+func Foo() bool {
+ x, y := MyError{"A"}, MyError{"B"}
+ return errors.Is(x, y) // returns false as x != y and MyError does not have an `Is(error) bool` function.
+}
+</pre>
+
+<h3 id="cover">Cover</h3>
+
+<p><!-- CL 249759 -->
+ The <code>cover</code> tool now uses an optimized parser
+ from <code>golang.org/x/tools/cover</code>, which may be noticeably faster
+ when parsing large coverage profiles.
+</p>
+
+<h2 id="compiler">Compiler</h2>
+
+<p><!-- golang.org/issue/40724 -->
+ Go 1.17 implements a new way of passing function arguments and results using
+ registers instead of the stack.
+ Benchmarks for a representative set of Go packages and programs show
+ performance improvements of about 5%, and a typical reduction in
+ binary size of about 2%.
+ This is currently enabled for Linux, macOS, and Windows on the
+ 64-bit x86 architecture (the <code>linux/amd64</code>,
+ <code>darwin/amd64</code>, and <code>windows/amd64</code> ports).
+</p>
+
+<p>
+ This change does not affect the functionality of any safe Go code
+ and is designed to have no impact on most assembly code.
+ It may affect code that violates
+ the <a href="/pkg/unsafe#Pointer"><code>unsafe.Pointer</code></a>
+ rules when accessing function arguments, or that depends on
+ undocumented behavior involving comparing function code pointers.
+ To maintain compatibility with existing assembly functions, the
+ compiler generates adapter functions that convert between the new
+ register-based calling convention and the previous stack-based
+ calling convention.
+ These adapters are typically invisible to users, except that taking
+ the address of a Go function in assembly code or taking the address
+ of an assembly function in Go code
+ using <code>reflect.ValueOf(fn).Pointer()</code>
+ or <code>unsafe.Pointer</code> will now return the address of the
+ adapter.
+ Code that depends on the value of these code pointers may no longer
+ behave as expected.
+ Adapters also may cause a very small performance overhead in two
+ cases: calling an assembly function indirectly from Go via
+ a <code>func</code> value, and calling Go functions from assembly.
+</p>
+
+<p><!-- CL 304470 -->
+ The format of stack traces from the runtime (printed when an uncaught panic
+ occurs, or when <code>runtime.Stack</code> is called) is improved. Previously,
+ the function arguments were printed as hexadecimal words based on the memory
+ layout. Now each argument in the source code is printed separately, separated
+ by commas. Aggregate-typed (struct, array, string, slice, interface, and complex)
+ arguments are delimited by curly braces. A caveat is that the value of an
+ argument that only lives in a register and is not stored to memory may be
+ inaccurate. Function return values (which were usually inaccurate) are no longer
+ printed.
+</p>
+
+<p><!-- CL 283112, golang.org/issue/28727 -->
+ Functions containing closures can now be inlined.
+ One effect of this change is that a function with a closure may
+ produce a distinct closure code pointer for each place that the
+ function is inlined.
+ Go function values are not directly comparable, but this change
+ could reveal bugs in code that uses <code>reflect</code>
+ or <code>unsafe.Pointer</code> to bypass this language restriction
+ and compare functions by code pointer.
+</p>
+
+<h3 id="link">Linker</h3>
+
+<p><!-- CL 310349 -->
+ When the linker uses external linking mode, which is the default
+ when linking a program that uses cgo, and the linker is invoked
+ with a <code>-I</code> option, the option will now be passed to the
+ external linker as a <code>-Wl,--dynamic-linker</code> option.
+</p>
+
+<h2 id="library">Core library</h2>
+
+<h3 id="runtime/cgo"><a href="/pkg/runtime/cgo">Cgo</a></h3>
+
+<p>
+ The <a href="/pkg/runtime/cgo">runtime/cgo</a> package now provides a
+ new facility that allows to turn any Go values to a safe representation
+ that can be used to pass values between C and Go safely. See
+ <a href="/pkg/runtime/cgo#Handle">runtime/cgo.Handle</a> for more information.
+</p>
+
+<h3 id="semicolons">URL query parsing</h3>
+<!-- CL 325697, CL 326309 -->
+
+<p>
+ The <code>net/url</code> and <code>net/http</code> packages used to accept
+ <code>";"</code> (semicolon) as a setting separator in URL queries, in
+ addition to <code>"&"</code> (ampersand). Now, settings with non-percent-encoded
+ semicolons are rejected and <code>net/http</code> servers will log a warning to
+ <a href="/pkg/net/http#Server.ErrorLog"><code>Server.ErrorLog</code></a>
+ when encountering one in a request URL.
+</p>
+
+<p>
+ For example, before Go 1.17 the <a href="/pkg/net/url#URL.Query"><code>Query</code></a>
+ method of the URL <code>example?a=1;b=2&c=3</code> would have returned
+ <code>map[a:[1] b:[2] c:[3]]</code>, while now it returns <code>map[c:[3]]</code>.
+</p>
+
+<p>
+ When encountering such a query string,
+ <a href="/pkg/net/url#URL.Query"><code>URL.Query</code></a>
+ and
+ <a href="/pkg/net/http#Request.FormValue"><code>Request.FormValue</code></a>
+ ignore any settings that contain a semicolon,
+ <a href="/pkg/net/url#ParseQuery"><code>ParseQuery</code></a>
+ returns the remaining settings and an error, and
+ <a href="/pkg/net/http#Request.ParseForm"><code>Request.ParseForm</code></a>
+ and
+ <a href="/pkg/net/http#Request.ParseMultipartForm"><code>Request.ParseMultipartForm</code></a>
+ return an error but still set <code>Request</code> fields based on the
+ remaining settings.
+</p>
+
+<p>
+ <code>net/http</code> users can restore the original behavior by using the new
+ <a href="/pkg/net/http#AllowQuerySemicolons"><code>AllowQuerySemicolons</code></a>
+ handler wrapper. This will also suppress the <code>ErrorLog</code> warning.
+ Note that accepting semicolons as query separators can lead to security issues
+ if different systems interpret cache keys differently.
+ See <a href="https://golang.org/issue/25192">issue 25192</a> for more information.
+</p>
+
+<h3 id="ALPN">TLS strict ALPN</h3>
+<!-- CL 289209, CL 325432 -->
+
+<p>
+ When <a href="/pkg/crypto/tls#Config.NextProtos"><code>Config.NextProtos</code></a>
+ is set, servers now enforce that there is an overlap between the configured
+ protocols and the ALPN protocols advertised by the client, if any. If there is
+ no mutually supported protocol, the connection is closed with the
+ <code>no_application_protocol</code> alert, as required by RFC 7301. This
+ helps mitigate <a href="https://alpaca-attack.com/">the ALPACA cross-protocol attack</a>.
+</p>
+
+<p>
+ As an exception, when the value <code>"h2"</code> is included in the server's
+ <code>Config.NextProtos</code>, HTTP/1.1 clients will be allowed to connect as
+ if they didn't support ALPN.
+ See <a href="https://golang.org/issue/46310">issue 46310</a> for more information.
+</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>
+
+<dl id="archive/zip"><dt><a href="/pkg/archive/zip/">archive/zip</a></dt>
+ <dd>
+ <p><!-- CL 312310 -->
+ The new methods <a href="/pkg/archive/zip#File.OpenRaw"><code>File.OpenRaw</code></a>, <a href="/pkg/archive/zip#Writer.CreateRaw"><code>Writer.CreateRaw</code></a>, <a href="/pkg/archive/zip#Writer.Copy"><code>Writer.Copy</code></a> provide support for cases where performance is a primary concern.
+ </p>
+ </dd>
+</dl><!-- archive/zip -->
+
+<dl id="bufio"><dt><a href="/pkg/bufio/">bufio</a></dt>
+ <dd>
+ <p><!-- CL 280492 -->
+ The <a href="/pkg/bufio/#Writer.WriteRune"><code>Writer.WriteRune</code></a> method
+ now writes the replacement character U+FFFD for negative rune values,
+ as it does for other invalid runes.
+ </p>
+ </dd>
+</dl><!-- bufio -->
+
+<dl id="bytes"><dt><a href="/pkg/bytes/">bytes</a></dt>
+ <dd>
+ <p><!-- CL 280492 -->
+ The <a href="/pkg/bytes/#Buffer.WriteRune"><code>Buffer.WriteRune</code></a> method
+ now writes the replacement character U+FFFD for negative rune values,
+ as it does for other invalid runes.
+ </p>
+ </dd>
+</dl><!-- bytes -->
+
+<dl id="compress/lzw"><dt><a href="/pkg/compress/lzw/">compress/lzw</a></dt>
+ <dd>
+ <p><!-- CL 273667 -->
+ The <a href="/pkg/compress/lzw/#NewReader"><code>NewReader</code></a>
+ function is guaranteed to return a value of the new
+ type <a href="/pkg/compress/lzw/#Reader"><code>Reader</code></a>,
+ and similarly <a href="/pkg/compress/lzw/#NewWriter"><code>NewWriter</code></a>
+ is guaranteed to return a value of the new
+ type <a href="/pkg/compress/lzw/#Writer"><code>Writer</code></a>.
+ These new types both implement a <code>Reset</code> method
+ (<a href="/pkg/compress/lzw/#Reader.Reset"><code>Reader.Reset</code></a>,
+ <a href="/pkg/compress/lzw/#Writer.Reset"><code>Writer.Reset</code></a>)
+ that allows reuse of the <code>Reader</code> or <code>Writer</code>.
+ </p>
+ </dd>
+</dl><!-- compress/lzw -->
+
+<dl id="crypto/ed25519"><dt><a href="/pkg/crypto/ed25519/">crypto/ed25519</a></dt>
+ <dd>
+ <p><!-- CL 276272 -->
+ The <code>crypto/ed25519</code> package has been rewritten, and all
+ operations are now approximately twice as fast on amd64 and arm64.
+ The observable behavior has not otherwise changed.
+ </p>
+ </dd>
+</dl><!-- crypto/ed25519 -->
+
+<dl id="crypto/elliptic"><dt><a href="/pkg/crypto/elliptic/">crypto/elliptic</a></dt>
+ <dd>
+ <p><!-- CL 233939 -->
+ <a href="/pkg/crypto/elliptic#CurveParams"><code>CurveParams</code></a>
+ methods now automatically invoke faster and safer dedicated
+ implementations for known curves (P-224, P-256, and P-521) when
+ available. Note that this is a best-effort approach and applications
+ should avoid using the generic, not constant-time <code>CurveParams</code>
+ methods and instead use dedicated
+ <a href="/pkg/crypto/elliptic#Curve"><code>Curve</code></a> implementations
+ such as <a href="/pkg/crypto/elliptic#P256"><code>P256</code></a>.
+ </p>
+
+ <p><!-- CL 315271, CL 315274 -->
+ The <a href="/pkg/crypto/elliptic#P521"><code>P521</code></a> curve
+ implementation has been rewritten using code generated by the
+ <a href="https://github.com/mit-plv/fiat-crypto">fiat-crypto project</a>,
+ which is based on a formally-verified model of the arithmetic
+ operations. It is now constant-time and three times faster on amd64 and
+ arm64. The observable behavior has not otherwise changed.
+ </p>
+ </dd>
+</dl><!-- crypto/elliptic -->
+
+<dl id="crypto/rand"><dt><a href="/pkg/crypto/rand/">crypto/rand</a></dt>
+ <dd>
+ <p><!-- CL 302489, CL 299134, CL 269999 -->
+ The <code>crypto/rand</code> package now uses the <code>getentropy</code>
+ syscall on macOS and the <code>getrandom</code> syscall on Solaris,
+ Illumos, and DragonFlyBSD.
+ </p>
+ </dd>
+</dl><!-- crypto/rand -->
+
+<dl id="crypto/tls"><dt><a href="/pkg/crypto/tls/">crypto/tls</a></dt>
+ <dd>
+ <p><!-- CL 295370 -->
+ The new <a href="/pkg/crypto/tls#Conn.HandshakeContext"><code>Conn.HandshakeContext</code></a>
+ method allows the user to control cancellation of an in-progress TLS
+ handshake. The provided context is accessible from various callbacks through the new
+ <a href="/pkg/crypto/tls#ClientHelloInfo.Context"><code>ClientHelloInfo.Context</code></a> and
+ <a href="/pkg/crypto/tls#CertificateRequestInfo.Context"><code>CertificateRequestInfo.Context</code></a>
+ methods. Canceling the context after the handshake has finished has no effect.
+ </p>
+
+ <p><!-- CL 314609 -->
+ Cipher suite ordering is now handled entirely by the
+ <code>crypto/tls</code> package. Currently, cipher suites are sorted based
+ on their security, performance, and hardware support taking into account
+ both the local and peer's hardware. The order of the
+ <a href="/pkg/crypto/tls#Config.CipherSuites"><code>Config.CipherSuites</code></a>
+ field is now ignored, as well as the
+ <a href="/pkg/crypto/tls#Config.PreferServerCipherSuites"><code>Config.PreferServerCipherSuites</code></a>
+ field. Note that <code>Config.CipherSuites</code> still allows
+ applications to choose what TLS 1.0–1.2 cipher suites to enable.
+ </p>
+
+ <p>
+ The 3DES cipher suites have been moved to
+ <a href="/pkg/crypto/tls#InsecureCipherSuites"><code>InsecureCipherSuites</code></a>
+ due to <a href="https://sweet32.info/">fundamental block size-related
+ weakness</a>. They are still enabled by default but only as a last resort,
+ thanks to the cipher suite ordering change above.
+ </p>
+
+ <p><!-- golang.org/issue/45428 -->
+ Beginning in the next release, Go 1.18, the
+ <a href="/pkg/crypto/tls/#Config.MinVersion"><code>Config.MinVersion</code></a>
+ for <code>crypto/tls</code> clients will default to TLS 1.2, disabling TLS 1.0
+ and TLS 1.1 by default. Applications will be able to override the change by
+ explicitly setting <code>Config.MinVersion</code>.
+ This will not affect <code>crypto/tls</code> servers.
+ </p>
+ </dd>
+</dl><!-- crypto/tls -->
+
+<dl id="crypto/x509"><dt><a href="/pkg/crypto/x509/">crypto/x509</a></dt>
+ <dd>
+ <p><!-- CL 224157 -->
+ <a href="/pkg/crypto/x509/#CreateCertificate"><code>CreateCertificate</code></a>
+ now returns an error if the provided private key doesn't match the
+ parent's public key, if any. The resulting certificate would have failed
+ to verify.
+ </p>
+
+ <p><!-- CL 315209 -->
+ The temporary <code>GODEBUG=x509ignoreCN=0</code> flag has been removed.
+ </p>
+
+ <p><!-- CL 274234 -->
+ <a href="/pkg/crypto/x509/#ParseCertificate"><code>ParseCertificate</code></a>
+ has been rewritten, and now consumes ~70% fewer resources. The observable
+ behavior has not otherwise changed, except for error messages.
+ </p>
+
+ <p><!-- CL 321190 -->
+ On BSD systems, <code>/etc/ssl/certs</code> is now searched for trusted
+ roots. This adds support for the new system trusted certificate store in
+ FreeBSD 12.2+.
+ </p>
+
+ <p><!-- golang.org/issue/41682 -->
+ Beginning in the next release, Go 1.18, <code>crypto/x509</code> will
+ reject certificates signed with the SHA-1 hash function. This doesn't
+ apply to self-signed root certificates. Practical attacks against SHA-1
+ <a href="https://shattered.io/">have been demonstrated in 2017</a> and publicly
+ trusted Certificate Authorities have not issued SHA-1 certificates since 2015.
+ </p>
+ </dd>
+</dl><!-- crypto/x509 -->
+
+<dl id="database/sql"><dt><a href="/pkg/database/sql/">database/sql</a></dt>
+ <dd>
+ <p><!-- CL 258360 -->
+ The <a href="/pkg/database/sql/#DB.Close"><code>DB.Close</code></a> method now closes
+ the <code>connector</code> field if the type in this field implements the
+ <a href="/pkg/io/#Closer"><code>io.Closer</code></a> interface.
+ </p>
+
+ <p><!-- CL 311572 -->
+ The new
+ <a href="/pkg/database/sql/#NullInt16"><code>NullInt16</code></a>
+ and
+ <a href="/pkg/database/sql/#NullByte"><code>NullByte</code></a>
+ structs represent the int16 and byte values that may be null. These can be used as
+ destinations of the <a href="/pkg/database/sql/#Scan"><code>Scan</code></a> method,
+ similar to NullString.
+ </p>
+ </dd>
+</dl><!-- database/sql -->
+
+<dl id="debug/elf"><dt><a href="/pkg/debug/elf/">debug/elf</a></dt>
+ <dd>
+ <p><!-- CL 239217 -->
+ The <a href="/pkg/debug/elf/#SHT_MIPS_ABIFLAGS"><code>SHT_MIPS_ABIFLAGS</code></a>
+ constant has been added.
+ </p>
+ </dd>
+</dl><!-- debug/elf -->
+
+<dl id="encoding/binary"><dt><a href="/pkg/encoding/binary/">encoding/binary</a></dt>
+ <dd>
+ <p><!-- CL 299531 -->
+ <code>binary.Uvarint</code> will stop reading after <code>10 bytes</code> to avoid
+ wasted computations. If more than <code>10 bytes</code> are needed, the byte count returned is <code>-11</code>.
+ <br />
+ Previous Go versions could return larger negative counts when reading incorrectly encoded varints.
+ </p>
+ </dd>
+</dl><!-- encoding/binary -->
+
+<dl id="encoding/csv"><dt><a href="/pkg/encoding/csv/">encoding/csv</a></dt>
+ <dd>
+ <p><!-- CL 291290 -->
+ The new
+ <a href="/pkg/encoding/csv/#Reader.FieldPos"><code>Reader.FieldPos</code></a>
+ method returns the line and column corresponding to the start of
+ a given field in the record most recently returned by
+ <a href="/pkg/encoding/csv/#Reader.Read"><code>Read</code></a>.
+ </p>
+ </dd>
+</dl><!-- encoding/csv -->
+
+<dl id="encoding/xml"><dt><a href="/pkg/encoding/xml/">encoding/xml</a></dt>
+ <dd>
+ <p><!-- CL 277893 -->
+ When a comment appears within a
+ <a href="/pkg/encoding/xml/#Directive"><code>Directive</code></a>, it is now replaced
+ with a single space instead of being completely elided.
+ </p>
+
+ <p>
+ Invalid element or attribute names with leading, trailing, or multiple
+ colons are now stored unmodified into the
+ <a href="/pkg/encoding/xml/#Name"><code>Name.Local</code></a> field.
+ </p>
+ </dd>
+</dl><!-- encoding/xml -->
+
+<dl id="flag"><dt><a href="/pkg/flag/">flag</a></dt>
+ <dd>
+ <p><!-- CL 271788 -->
+ Flag declarations now panic if an invalid name is specified.
+ </p>
+ </dd>
+</dl><!-- flag -->
+
+<dl id="go/build"><dt><a href="/pkg/go/build/">go/build</a></dt>
+ <dd>
+ <p><!-- CL 310732 -->
+ The new
+ <a href="/pkg/go/build/#Context.ToolTags"><code>Context.ToolTags</code></a>
+ field holds the build tags appropriate to the current Go
+ toolchain configuration.
+ </p>
+ </dd>
+</dl><!-- go/build -->
+
+<dl id="go/format"><dt><a href="/pkg/go/format/">go/format</a></dt>
+ <dd>
+ <p>
+ The <a href="/pkg/go/format/#Source"><code>Source</code></a> and
+ <a href="/pkg/go/format/#Node"><code>Node</code></a> functions now
+ synchronize <code>//go:build</code> lines with <code>// +build</code>
+ lines. If a file only has <code>// +build</code> lines, they will be
+ moved to the appropriate location in the file, and matching
+ <code>//go:build</code> lines will be added. Otherwise,
+ <code>// +build</code> lines will be overwritten based on any existing
+ <code>//go:build</code> lines. For more information, see
+ <a href="https://golang.org/design/draft-gobuild">https://golang.org/design/draft-gobuild</a>.
+ </p>
+ </dd>
+</dl><!-- go/format -->
+
+<dl id="go/parser"><dt><a href="/pkg/go/parser/">go/parser</a></dt>
+ <dd>
+ <p><!-- CL 306149 -->
+ The new <a href="/pkg/go/parser/#SkipObjectResolution"><code>SkipObjectResolution</code></a>
+ <code>Mode</code> value instructs the parser not to resolve identifiers to
+ their declaration. This may improve parsing speed.
+ </p>
+ </dd>
+</dl><!-- go/parser -->
+
+<dl id="image"><dt><a href="/pkg/image/">image</a></dt>
+ <dd>
+ <p><!-- CL 311129 -->
+ The concrete image types (<code>RGBA</code>, <code>Gray16</code> and so on)
+ now implement a new <a href="/pkg/image/#RGBA64Image"><code>RGBA64Image</code></a>
+ interface. The concrete types that previously implemented
+ <a href="/pkg/image/draw/#Image"><code>draw.Image</code></a> now also implement
+ <a href="/pkg/image/draw/#RGBA64Image"><code>draw.RGBA64Image</code></a>, a
+ new interface in the <code>image/draw</code> package.
+ </p>
+ </dd>
+</dl><!-- image -->
+
+<dl id="io/fs"><dt><a href="/pkg/io/fs/">io/fs</a></dt>
+ <dd>
+ <p><!-- CL 293649 -->
+ The new <a href="/pkg/io/fs/#FileInfoToDirEntry"><code>FileInfoToDirEntry</code></a> function converts a <code>FileInfo</code> to a <code>DirEntry</code>.
+ </p>
+ </dd>
+</dl><!-- io/fs -->
+
+<dl id="math"><dt><a href="/pkg/math/">math</a></dt>
+ <dd>
+ <p><!-- CL 247058 -->
+ The math package now defines three more constants: <code>MaxUint</code>, <code>MaxInt</code> and <code>MinInt</code>.
+ For 32-bit systems their values are <code>2^32 - 1</code>, <code>2^31 - 1</code> and <code>-2^31</code>, respectively.
+ For 64-bit systems their values are <code>2^64 - 1</code>, <code>2^63 - 1</code> and <code>-2^63</code>, respectively.
+ </p>
+ </dd>
+</dl><!-- math -->
+
+<dl id="mime"><dt><a href="/pkg/mime/">mime</a></dt>
+ <dd>
+ <p><!-- CL 305230 -->
+ On Unix systems, the table of MIME types is now read from the local system's
+ <a href="https://specifications.freedesktop.org/shared-mime-info-spec/shared-mime-info-spec-0.21.html">Shared MIME-info Database</a>
+ when available.
+ </p>
+ </dd>
+</dl><!-- mime -->
+
+<dl id="mime/multipart"><dt><a href="/pkg/mime/multipart/">mime/multipart</a></dt>
+ <dd>
+ <p><!-- CL 313809 -->
+ <a href="/pkg/mime/multipart/#Part.FileName"><code>Part.FileName</code></a>
+ now applies
+ <a href="/pkg/path/filepath/#Base"><code>filepath.Base</code></a> to the
+ return value. This mitigates potential path traversal vulnerabilities in
+ applications that accept multipart messages, such as <code>net/http</code>
+ servers that call
+ <a href="/pkg/net/http/#Request.FormFile"><code>Request.FormFile</code></a>.
+ </p>
+ </dd>
+</dl><!-- mime/multipart -->
+
+<dl id="net"><dt><a href="/pkg/net/">net</a></dt>
+ <dd>
+ <p><!-- CL 272668 -->
+ The new method <a href="/pkg/net/#IP.IsPrivate"><code>IP.IsPrivate</code></a> reports whether an address is
+ a private IPv4 address according to <a href="https://datatracker.ietf.org/doc/rfc1918">RFC 1918</a>
+ or a local IPv6 address according <a href="https://datatracker.ietf.org/doc/rfc4193">RFC 4193</a>.
+ </p>
+
+ <p><!-- CL 301709 -->
+ The Go DNS resolver now only sends one DNS query when resolving an address for an IPv4-only or IPv6-only network,
+ rather than querying for both address families.
+ </p>
+
+ <p><!-- CL 307030 -->
+ The <a href="/pkg/net/#ErrClosed"><code>ErrClosed</code></a> sentinel error and
+ <a href="/pkg/net/#ParseError"><code>ParseError</code></a> error type now implement
+ the <a href="/pkg/net/#Error"><code>net.Error</code></a> interface.
+ </p>
+
+ <p><!-- CL 325829 -->
+ The <a href="/pkg/net/#ParseIP"><code>ParseIP</code></a> and <a href="/pkg/net/#ParseCIDR"><code>ParseCIDR</code></a>
+ functions now reject IPv4 addresses which contain decimal components with leading zeros.
+
+ These components were always interpreted as decimal, but some operating systems treat them as octal.
+ This mismatch could hypothetically lead to security issues if a Go application was used to validate IP addresses
+ which were then used in their original form with non-Go applications which interpreted components as octal. Generally,
+ it is advisable to always re-encode values after validation, which avoids this class of parser misalignment issues.
+ </p>
+ </dd>
+</dl><!-- net -->
+
+<dl id="net/http"><dt><a href="/pkg/net/http/">net/http</a></dt>
+ <dd>
+ <p><!-- CL 295370 -->
+ The <a href="/pkg/net/http/"><code>net/http</code></a> package now uses the new
+ <a href="/pkg/crypto/tls#Conn.HandshakeContext"><code>(*tls.Conn).HandshakeContext</code></a>
+ with the <a href="/pkg/net/http/#Request"><code>Request</code></a> context
+ when performing TLS handshakes in the client or server.
+ </p>
+
+ <p><!-- CL 235437 -->
+ Setting the <a href="/pkg/net/http/#Server"><code>Server</code></a>
+ <code>ReadTimeout</code> or <code>WriteTimeout</code> fields to a negative value now indicates no timeout
+ rather than an immediate timeout.
+ </p>
+
+ <p><!-- CL 308952 -->
+ The <a href="/pkg/net/http/#ReadRequest"><code>ReadRequest</code></a> function
+ now returns an error when the request has multiple Host headers.
+ </p>
+
+ <p><!-- CL 313950 -->
+ When producing a redirect to the cleaned version of a URL,
+ <a href="/pkg/net/http/#ServeMux"><code>ServeMux</code></a> now always
+ uses relative URLs in the <code>Location</code> header. Previously it
+ would echo the full URL of the request, which could lead to unintended
+ redirects if the client could be made to send an absolute request URL.
+ </p>
+
+ <p><!-- CL 308009, CL 313489 -->
+ When interpreting certain HTTP headers handled by <code>net/http</code>,
+ non-ASCII characters are now ignored or rejected.
+ </p>
+
+ <p><!-- CL 325697 -->
+ If
+ <a href="/pkg/net/http/#Request.ParseForm"><code>Request.ParseForm</code></a>
+ returns an error when called by
+ <a href="/pkg/net/http/#Request.ParseMultipartForm"><code>Request.ParseMultipartForm</code></a>,
+ the latter now continues populating
+ <a href="/pkg/net/http/#Request.MultipartForm"><code>Request.MultipartForm</code></a>
+ before returning it.
+ </p>
+ </dd>
+</dl><!-- net/http -->
+
+<dl id="net/http/httptest"><dt><a href="/pkg/net/http/httptest/">net/http/httptest</a></dt>
+ <dd>
+ <p><!-- CL 308950 -->
+ <a href="/pkg/net/http/httptest/#ResponseRecorder.WriteHeader"><code>ResponseRecorder.WriteHeader</code></a>
+ now panics when the provided code is not a valid three-digit HTTP status code.
+ This matches the behavior of <a href="/pkg/net/http/#ResponseWriter"><code>ResponseWriter</code></a>
+ implementations in the <a href="/pkg/net/http/"><code>net/http</code></a> package.
+ </p>
+ </dd>
+</dl><!-- net/http/httptest -->
+
+<dl id="net/url"><dt><a href="/pkg/net/url/">net/url</a></dt>
+ <dd>
+ <p><!-- CL 314850 -->
+ The new method <a href="/pkg/net/url/#Values.Has"><code>Values.Has</code></a>
+ reports whether a query parameter is set.
+ </p>
+ </dd>
+</dl><!-- net/url -->
+
+<dl id="os"><dt><a href="/pkg/os/">os</a></dt>
+ <dd>
+ <p><!-- CL 268020 -->
+ The <a href="/pkg/os/#File.WriteString"><code>File.WriteString</code></a> method
+ has been optimized to not make a copy of the input string.
+ </p>
+ </dd>
+</dl><!-- os -->
+
+<dl id="reflect"><dt><a href="/pkg/reflect/">reflect</a></dt>
+ <dd>
+ <p><!-- CL 334669 -->
+ The new
+ <a href="/pkg/reflect/#Value.CanConvert"><code>Value.CanConvert</code></a>
+ method reports whether a value can be converted to a type.
+ This may be used to avoid a panic when converting a slice to an
+ array pointer type if the slice is too short.
+ Previously it was sufficient to use
+ <a href="/pkg/reflect/#Type.ConvertibleTo"><code>Type.ConvertibleTo</code></a>
+ for this, but the newly permitted conversion from slice to array
+ pointer type can panic even if the types are convertible.
+ </p>
+
+ <p><!-- CL 266197 -->
+ The new
+ <a href="/pkg/reflect/#StructField.IsExported"><code>StructField.IsExported</code></a>
+ and
+ <a href="/pkg/reflect/#Method.IsExported"><code>Method.IsExported</code></a>
+ methods report whether a struct field or type method is exported.
+ They provide a more readable alternative to checking whether <code>PkgPath</code>
+ is empty.
+ </p>
+
+ <p><!-- CL 281233 -->
+ The new <a href="/pkg/reflect/#VisibleFields"><code>VisibleFields</code></a> function
+ returns all the visible fields in a struct type, including fields inside anonymous struct members.
+ </p>
+
+ <p><!-- CL 284136 -->
+ The <a href="/pkg/reflect/#ArrayOf"><code>ArrayOf</code></a> function now panics when
+ called with a negative length.
+ </p>
+
+ <p><!-- CL 301652 -->
+ Checking the <a href="/pkg/reflect/#Type"><code>Type.ConvertibleTo</code></a> method
+ is no longer sufficient to guarantee that a call to
+ <a href="/pkg/reflect/#Value.Convert"><code>Value.Convert</code></a> will not panic.
+ It may panic when converting `[]T` to `*[N]T` if the slice's length is less than N.
+ See the <a href="#language">language changes</a> section above.
+ </p>
+ </dd>
+</dl><!-- reflect -->
+
+<dl id="runtime/metrics"><dt><a href="/pkg/runtime/metrics">runtime/metrics</a></dt>
+ <dd>
+ <p><!-- CL 308933, CL 312431, CL 312909 -->
+ New metrics were added that track total bytes and objects allocated and freed.
+ A new metric tracking the distribution of goroutine scheduling latencies was
+ also added.
+ </p>
+ </dd>
+</dl><!-- runtime/metrics -->
+
+<dl id="runtime/pprof"><dt><a href="/pkg/runtime/pprof">runtime/pprof</a></dt>
+ <dd>
+ <p><!-- CL 299991 -->
+ Block profiles are no longer biased to favor infrequent long events over
+ frequent short events.
+ </p>
+ </dd>
+</dl><!-- runtime/pprof -->
+
+<dl id="strconv"><dt><a href="/pkg/strconv/">strconv</a></dt>
+ <dd>
+ <p><!-- CL 170079, CL 170080 -->
+ The <code>strconv</code> package now uses Ulf Adams's Ryū algorithm for formatting floating-point numbers.
+ This algorithm improves performance on most inputs and is more than 99% faster on worst-case inputs.
+ </p>
+
+ <p><!-- CL 314775 -->
+ The new <a href="/pkg/strconv/#QuotedPrefix"><code>QuotedPrefix</code></a> function
+ returns the quoted string (as understood by
+ <a href="/pkg/strconv/#Unquote"><code>Unquote</code></a>)
+ at the start of input.
+ </p>
+ </dd>
+</dl><!-- strconv -->
+
+<dl id="strings"><dt><a href="/pkg/strings/">strings</a></dt>
+ <dd>
+ <p><!-- CL 280492 -->
+ The <a href="/pkg/strings/#Builder.WriteRune"><code>Builder.WriteRune</code></a> method
+ now writes the replacement character U+FFFD for negative rune values,
+ as it does for other invalid runes.
+ </p>
+ </dd>
+</dl><!-- strings -->
+
+<dl id="sync/atomic"><dt><a href="/pkg/sync/atomic/">sync/atomic</a></dt>
+ <dd>
+ <p><!-- CL 241678 -->
+ <code>atomic.Value</code> now has <a href="/pkg/sync/atomic/#Value.Swap"><code>Swap</code></a> and
+ <a href="/pkg/sync/atomic/#Value.CompareAndSwap"><code>CompareAndSwap</code></a> methods that provide
+ additional atomic operations.
+ </p>
+ </dd>
+</dl><!-- sync/atomic -->
+
+<dl id="syscall"><dt><a href="/pkg/syscall/">syscall</a></dt>
+ <dd>
+ <p><!-- CL 295371 -->
+ <p>
+ The <a href="/pkg/syscall/#GetQueuedCompletionStatus"><code>GetQueuedCompletionStatus</code></a> and
+ <a href="/pkg/syscall/#PostQueuedCompletionStatus"><code>PostQueuedCompletionStatus</code></a>
+ functions are now deprecated. These functions have incorrect signatures and are superseded by
+ equivalents in the <a href="https://godoc.org/golang.org/x/sys/windows"><code>golang.org/x/sys/windows</code></a> package.
+ </p>
+
+ <p><!-- CL 313653 -->
+ On Unix-like systems, the process group of a child process is now set with signals blocked.
+ This avoids sending a <code>SIGTTOU</code> to the child when the parent is in a background process group.
+ </p>
+
+ <p><!-- CL 288298, CL 288300 -->
+ The Windows version of
+ <a href="/pkg/syscall/#SysProcAttr"><code>SysProcAttr</code></a>
+ has two new fields. <code>AdditionalInheritedHandles</code> is
+ a list of additional handles to be inherited by the new child
+ process. <code>ParentProcess</code> permits specifying the
+ parent process of the new process.
+
+ <p><!-- CL 311570 -->
+ The constant <code>MSG_CMSG_CLOEXEC</code> is now defined on
+ DragonFly and all OpenBSD systems (it was already defined on
+ some OpenBSD systems and all FreeBSD, NetBSD, and Linux systems).
+ </p>
+
+ <p><!-- CL 315281 -->
+ The constants <code>SYS_WAIT6</code> and <code>WEXITED</code>
+ are now defined on NetBSD systems (<code>SYS_WAIT6</code> was
+ already defined on DragonFly and FreeBSD systems;
+ <code>WEXITED</code> was already defined on Darwin, DragonFly,
+ FreeBSD, Linux, and Solaris systems).
+ </p>
+ </dd>
+</dl><!-- syscall -->
+
+<dl id="testing"><dt><a href="/pkg/testing/">testing</a></dt>
+ <dd>
+ <p><!-- CL 310033 -->
+ Added a new <a href="/cmd/go/#hdr-Testing_flags">testing flag</a> <code>-shuffle</code> which controls the execution order of tests and benchmarks.
+ </p>
+ <p><!-- CL 260577 -->
+ The new
+ <a href="/pkg/testing/#T.Setenv"><code>T.Setenv</code></a>
+ and <a href="/pkg/testing/#B.Setenv"><code>B.Setenv</code></a>
+ methods support setting an environment variable for the duration
+ of the test or benchmark.
+ </p>
+ </dd>
+</dl><!-- testing -->
+
+<dl id="text/template/parse"><dt><a href="/pkg/text/template/parse/">text/template/parse</a></dt>
+ <dd>
+ <p><!-- CL 301493 -->
+ The new <a href="/pkg/text/template/parse/#Mode"><code>SkipFuncCheck</code></a> <a href=><code>Mode</code></a>
+ value changes the template parser to not verify that functions are defined.
+ </p>
+ </dd>
+</dl><!-- text/template/parse -->
+
+<dl id="time"><dt><a href="/pkg/time/">time</a></dt>
+ <dd>
+ <p><!-- CL 260858 -->
+ The <a href="/pkg/time/#Time"><code>Time</code></a> type now has a
+ <a href="/pkg/time/#Time.GoString"><code>GoString</code></a> method that
+ will return a more useful value for times when printed with the
+ <code>%#v</code> format specifier in the <code>fmt</code> package.
+ </p>
+
+ <p><!-- CL 264077 -->
+ The new <a href="/pkg/time/#Time.IsDST"><code>Time.IsDST</code></a> method can be used to check whether the time
+ is in Daylight Savings Time in its configured location.
+ </p>
+
+ <p><!-- CL 293349 -->
+ The new <a href="/pkg/time/#Time.UnixMilli"><code>Time.UnixMilli</code></a> and
+ <a href="/pkg/time/#Time.UnixMicro"><code>Time.UnixMicro</code></a>
+ methods return the number of milliseconds and microseconds elapsed since
+ January 1, 1970 UTC respectively.
+ <br />
+ The new <a href="/pkg/time/#UnixMilli"><code>UnixMilli</code></a> and
+ <a href="/pkg/time/#UnixMicro"><code>UnixMicro</code></a> functions
+ return the local <code>Time</code> corresponding to the given Unix time.
+ </p>
+
+ <p><!-- CL 300996 -->
+ The package now accepts comma "," as a separator for fractional seconds when parsing and formatting time.
+ For example, the following time layouts are now accepted:
+ <ul>
+ <li>2006-01-02 15:04:05,999999999 -0700 MST</li>
+ <li>Mon Jan _2 15:04:05,000000 2006</li>
+ <li>Monday, January 2 15:04:05,000 2006</li>
+ </ul>
+ </p>
+
+ <p><!-- CL 320252 -->
+ The new constant <a href="/pkg/time/#Layout"><code>Layout</code></a>
+ defines the reference time.
+ </p>
+ </dd>
+</dl><!-- time -->
+
+<dl id="unicode"><dt><a href="/pkg/unicode/">unicode</a></dt>
+ <dd>
+ <p><!-- CL 280493 -->
+ The <a href="/pkg/unicode/#Is"><code>Is</code></a>,
+ <a href="/pkg/unicode/#IsGraphic"><code>IsGraphic</code></a>,
+ <a href="/pkg/unicode/#IsLetter"><code>IsLetter</code></a>,
+ <a href="/pkg/unicode/#IsLower"><code>IsLower</code></a>,
+ <a href="/pkg/unicode/#IsMark"><code>IsMark</code></a>,
+ <a href="/pkg/unicode/#IsNumber"><code>IsNumber</code></a>,
+ <a href="/pkg/unicode/#IsPrint"><code>IsPrint</code></a>,
+ <a href="/pkg/unicode/#IsPunct"><code>IsPunct</code></a>,
+ <a href="/pkg/unicode/#IsSpace"><code>IsSpace</code></a>,
+ <a href="/pkg/unicode/#IsSymbol"><code>IsSymbol</code></a>, and
+ <a href="/pkg/unicode/#IsUpper"><code>IsUpper</code></a> functions
+ now return <code>false</code> on negative rune values, as they do for other invalid runes.
+ </p>
+ </dd>
+</dl><!-- unicode -->
