doc/go1.16.html - go - Git at Google

 <!--{
 	"Title": "Go 1.16 Release Notes",
 	"Path":  "/doc/go1.16"
 }-->

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 <code>hello</code> <code>world</code>.
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 <h2 id="introduction">DRAFT RELEASE NOTES — Introduction to Go 1.16</h2>

 <p>
   <strong>
     Go 1.16 is not yet released. These are work-in-progress
     release notes. Go 1.16 is expected to be released in February 2021.
   </strong>
 </p>

 <h2 id="language">Changes to the language</h2>

 <p>
   TODO
 </p>

 <h2 id="ports">Ports</h2>

 <h3 id="netbsd">NetBSD</h3>

 <p><!-- golang.org/issue/30824 -->
   Go now supports the 64-bit ARM architecture on NetBSD (the
   <code>netbsd/arm64</code> port).
 </p>

 <h3 id="386">386</h3>

 <p><!-- golang.org/issue/40255, golang.org/issue/41848, CL 258957, and CL 260017 -->
   As <a href="go1.15#386">announced</a> in the Go 1.15 release notes,
   Go 1.16 drops support for x87 mode compilation (<code>GO386=387</code>).
   Support for non-SSE2 processors is now available using soft float
   mode (<code>GO386=softfloat</code>).
   Users running on non-SSE2 processors should replace <code>GO386=387</code>
   with <code>GO386=softfloat</code>.
 </p>

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

 <p>
   TODO
 </p>

 <h3 id="go-command">Go command</h3>

 <h4 id="modules">Modules</h4>

 <p><!-- golang.org/issue/40276 -->
   <code>go</code> <code>install</code> now accepts arguments with
   version suffixes (for example, <code>go</code> <code>install</code>
   <code>example.com/cmd@v1.0.0</code>). This causes <code>go</code>
   <code>install</code> to build and install 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 installing executables without
   affecting the dependencies of the main module.<br>
   TODO: write and link to section in golang.org/ref/mod<br>
   TODO: write and link to blog post
 </p>

 <p><!-- golang.org/issue/24031 -->
   <code>retract</code> directives may now be used in a <code>go.mod</code> file
   to indicate that certain published versions of the module should not be used
   by other modules. A module author may retract a version after a severe problem
   is discovered or if the version was published unintentionally.<br>
   TODO: write and link to section in golang.org/ref/mod<br>
   TODO: write and link to tutorial or blog post
 </p>

 <p><!-- golang.org/issue/26603 -->
   The <code>go</code> <code>mod</code> <code>vendor</code>
   and <code>go</code> <code>mod</code> <code>tidy</code> subcommands now accept
   the <code>-e</code> flag, which instructs them to proceed despite errors in
   resolving missing packages.
 </p>

 <h4 id="go-test"><code>go</code> <code>test</code></h4>

 <p><!-- golang.org/issue/29062 -->
   When using <code>go</code> <code>test</code>, a test that
   calls <code>os.Exit(0)</code> during execution of a test function
   will now be considered to fail.
   This will help catch cases in which a test calls code that calls
   <code>os.Exit(0)</code> and thereby stops running all future tests.
   If a <code>TestMain</code> function calls <code>os.Exit(0)</code>
   that is still considered to be a passing test.
 </p>

 <p><!-- golang.org/issue/37519 -->
   The <code>go</code> <code>get</code> <code>-insecure</code> flag is
   deprecated and will be removed in a future version. This flag permits
   fetching from repositories and resolving custom domains using insecure
   schemes such as HTTP, and also bypassess module sum validation using the
   checksum database. To permit the use of insecure schemes, use the
   <code>GOINSECURE</code> environment variable instead. To bypass module
   sum validation, use <code>GOPRIVATE</code> or <code>GONOSUMDB</code>.
   See <code>go</code> <code>help</code> <code>environment</code> for details.
 </p>

 <h4 id="all-pattern">The <code>all</code> pattern</h4>

 <p><!-- golang.org/cl/240623 -->
   When the main module's <code>go.mod</code> file
   declares <code>go</code> <code>1.16</code> or higher, the <code>all</code>
   package pattern now matches only those packages that are transitively imported
   by a package or test found in the main module. (Packages imported by <em>tests
   of</em> packages imported by the main module are no longer included.) This is
   the same set of packages retained
   by <code>go</code> <code>mod</code> <code>vendor</code> since Go 1.11.
 </p>

 <h4 id="toolexec">The <code>-toolexec</code> build flag</h4>

 <p><!-- golang.org/cl/263357 -->
   When the <code>-toolexec</code> build flag is specified to use a program when
   invoking toolchain programs like compile or asm, the environment variable
   <code>TOOLEXEC_IMPORTPATH</code> is now set to the import path of the package
   being built.
 </p>

 <h3 id="cgo">Cgo</h3>

 <p> <!-- CL 252378 -->
   The <a href="/cmd/cgo">cgo</a> tool will no longer try to translate
   C struct bitfields into Go struct fields, even if their size can be
   represented in Go. The order in which C bitfields appear in memory
   is implementation dependent, so in some cases the cgo tool produced
   results that were silently incorrect.
 </p>

 <p>
   TODO
 </p>

 <h2 id="runtime">Runtime</h2>

 <p>
   TODO
 </p>

 <h2 id="compiler">Compiler</h2>

 <p>
   TODO
 </p>

 <h2 id="linker">Linker</h2>

 <p>
   This release includes additional improvements to the Go linker,
   reducing linker resource usage (both time and memory) and improving
   code robustness/maintainability. These changes form the second half
   of a two-release project to
   <a href="https://golang.org/s/better-linker">modernize the Go
   linker</a>.
 </p>

 <p>
   The linker changes in 1.16 extend the 1.15 improvements to all
   supported architecture/OS combinations (the 1.15 performance improvements
   were primarily focused on <code>ELF</code>-based OSes and
   <code>amd64</code> architectures).  For a representative set of
   large Go programs, linking is 20-35% faster than 1.15 and requires
   5-15% less memory on average for <code>linux/amd64</code>, with larger
   improvements for other architectures and OSes.
 </p>

 <p>
   TODO: update with final numbers later in the release.
 </p>

 <p> <!-- CL 255259 -->
   On Windows, <code>go build -buildmode=c-shared</code> now generates Windows
   ASLR DLLs by default. ASLR can be disabled with <code>--ldflags=-aslr=false</code>.
 </p>

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

 <p>
   TODO
 </p>

 <h3 id="crypto/hmac"><a href="/pkg/crypto/hmac">crypto/hmac</a></h3>

 <p><!-- CL 261960 -->
   <a href="/pkg/crypto/hmac/#New">New</a> will now panic if separate calls to
   the hash generation function fail to return new values. Previously, the
   behavior was undefined and invalid outputs were sometimes generated.
 </p>

 <h3 id="crypto/tls"><a href="/pkg/crypto/tls">crypto/tls</a></h3>

 <p><!-- CL 256897 -->
   I/O operations on closing or closed TLS connections can now be detected using
   the new <a href="/pkg/net/#ErrClosed">ErrClosed</a> error.  A typical use
   would be <code>errors.Is(err, net.ErrClosed)</code>.  In earlier releases
   the only way to reliably detect this case was to match the string returned
   by the <code>Error</code> method with <code>"tls: use of closed connection"</code>.
 </p>

 <h3 id="crypto/x509"><a href="/pkg/crypto/x509">crypto/x509</a></h3>

 <p><!-- CL 235078 -->
   <a href="/pkg/crypto/x509/#ParseCertificate">ParseCertificate</a> and
   <a href="/pkg/crypto/x509/#CreateCertificate">CreateCertificate</a> both
   now enforce string encoding restrictions for the fields <code>DNSNames</code>,
   <code>EmailAddresses</code>, and <code>URIs</code>. These fields can only
   contain strings with characters within the ASCII range.
 </p>

 <p><!-- CL 259697 -->
   <a href="/pkg/crypto/x509/#CreateCertificate">CreateCertificate</a> now
   verifies the generated certificate's signature using the signer's
   public key. If the signature is invalid, an error is returned, instead
   of a malformed certificate.
 </p>

 <h3 id="encoding/json"><a href="/pkg/encoding/json">encoding/json</a></h3>

 <p><!-- CL 263619 -->
   The error message for
   <a href="/pkg/encoding/json/#SyntaxError">SyntaxError</a>
   now begins with "json: ", matching the other errors in the package.
 </p>

 <h3 id="net"><a href="/pkg/net/">net</a></h3>

 <p><!-- CL 250357 -->
   The case of I/O on a closed network connection, or I/O on a network
   connection that is closed before any of the I/O completes, can now
   be detected using the new <a href="/pkg/net/#ErrClosed">ErrClosed</a> error.
   A typical use would be <code>errors.Is(err, net.ErrClosed)</code>.
   In earlier releases the only way to reliably detect this case was to
   match the string returned by the <code>Error</code> method
   with <code>"use of closed network connection"</code>.
 </p>

 <p><!-- CL 255898 -->
   In previous Go releases the default TCP listener backlog size on Linux systems,
   set by <code>/proc/sys/net/core/somaxconn</code>, was limited to a maximum of <code>65535</code>.
   On Linux kernel version 4.1 and above, the maximum is now <code>4294967295</code>.
 </p>

 <h3 id="reflect"><a href="/pkg/reflect/">reflect</a></h3>

 <p><!-- CL 259237, golang.org/issue/22075 -->
   For interface types and values, <a href="/pkg/reflect/#Value.Method">Method</a>,
   <a href="/pkg/reflect/#Value.MethodByName">MethodByName</a>, and
   <a href="/pkg/reflect/#Value.NumMethod">NumMethod</a> now
   operate on the interface's exported method set, rather than its full method set.
 </p>

 <h3 id="text/template/parse"><a href="/pkg/text/template/parse/">text/template/parse</a></h3>

 <p><!-- CL 229398, golang.org/issue/34652 -->
   A new <a href="/pkg/text/template/parse/#CommentNode"><code>CommentNode</code></a>
   was added to the parse tree. The <a href="/pkg/text/template/parse/#Mode"><code>Mode</code></a>
   field in the <code>parse.Tree</code> enables access to it.
 </p>
 <!-- text/template/parse -->

 <h3 id="unicode"><a href="/pkg/unicode/">unicode</a></h3>

 <p><!-- CL 248765 -->
   The <a href="/pkg/unicode/"><code>unicode</code></a> package and associated
   support throughout the system has been upgraded from Unicode 12.0.0 to
   <a href="https://www.unicode.org/versions/Unicode13.0.0/">Unicode 13.0.0</a>,
   which adds 5,930 new characters, including four new scripts, and 55 new emoji.
   Unicode 13.0.0 also designates plane 3 (U+30000-U+3FFFF) as the tertiary
   ideographic plane.
 </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
 </p>

 <dl id="crypto/dsa"><dt><a href="/pkg/crypto/dsa/">crypto/dsa</a></dt>
   <dd>
     <p><!-- CL 257939 -->
       The <a href="/pkg/crypto/dsa/"><code>crypto/dsa</code></a> package is now deprecated.
       See <a href="https://golang.org/issue/40337">issue #40337</a>.
     </p>
   </dd>
 </dl><!-- crypto/dsa -->

 <dl id="crypto/x509"><dt><a href="/pkg/crypto/x509/">crypto/x509</a></dt>
   <dd>
     <p><!-- CL 257939 -->
       DSA signature verification is no longer supported. Note that DSA signature
       generation was never supported.
       See <a href="https://golang.org/issue/40337">issue #40337</a>.
     </p>
   </dd>
 </dl><!-- crypto/x509 -->

 <dl id="encoding/xml"><dt><a href="/pkg/encoding/xml/">encoding/xml</a></dt>
   <dd>
     <p><!-- CL 264024 -->
       The encoder has always taken care to avoid using namespace prefixes
       beginning with <code>xml</code>, which are reserved by the XML
       specification.
       Now, following the specification more closely, that check is
       case-insensitive, so that prefixes beginning
       with <code>XML</code>, <code>XmL</code>, and so on are also
       avoided.
     </p>
   </dd>
 </dl><!-- encoding/xml -->

 <dl id="net/http"><dt><a href="/pkg/net/http/">net/http</a></dt>
   <dd>
     <p><!-- CL 233637 -->
       In the <a href="/pkg/net/http/"><code>net/http</code></a> package, the
       behavior of <a href="/pkg/net/http/#StripPrefix"><code>StripPrefix</code></a>
       has been changed to strip the prefix from the request URL's
       <code>RawPath</code> field in addition to its <code>Path</code> field.
       In past releases, only the <code>Path</code> field was trimmed, and so if the
       request URL contained any escaped characters the URL would be modified to
       have mismatched <code>Path</code> and <code>RawPath</code> fields.
       In Go 1.16, <code>StripPrefix</code> trims both fields.
       If there are escaped characters in the prefix part of the request URL the
       handler serves a 404 instead of its previous behavior of invoking the
       underlying handler with a mismatched <code>Path</code>/<code>RawPath</code> pair.
     </p>

     <p><!-- CL 252497 -->
      The <a href="/pkg/net/http/"><code>net/http</code></a> package now rejects HTTP range requests
      of the form <code>"Range": "bytes=--N"</code> where <code>"-N"</code> is a negative suffix length, for
      example <code>"Range": "bytes=--2"</code>. It now replies with a <code>416 "Range Not Satisfiable"</code> response.
     </p>

     <p><!-- CL 256498, golang.org/issue/36990 -->
     Cookies set with <code>SameSiteDefaultMode</code> now behave according to the current
     spec (no attribute is set) instead of generating a SameSite key without a value.
     </p>
   </dd>
 </dl><!-- net/http -->

 <dl id="runtime/debug"><dt><a href="/pkg/runtime/debug/">runtime/debug</a></dt>
   <dd>
     <p><!-- CL 249677 -->
       TODO: <a href="https://golang.org/cl/249677">https://golang.org/cl/249677</a>: provide Addr method for errors from SetPanicOnFault
     </p>
   </dd>
 </dl><!-- runtime/debug -->

 <dl id="strconv"><dt><a href="/pkg/strconv/">strconv</a></dt>
   <dd>
     <p><!-- CL 260858 -->
       <a href="/pkg/strconv/#ParseFloat"><code>ParseFloat</code></a> now uses
       the <a
       href="https://nigeltao.github.io/blog/2020/eisel-lemire.html">Eisel-Lemire
       algorithm</a>, improving performance by up to a factor of 2. This can
       also speed up decoding textual formats like <a
       href="/pkg/encoding/json/"><code>encoding/json</code></a>.
     </p>
   </dd>
 </dl><!-- strconv -->
	<!--{
	"Title": "Go 1.16 Release Notes",
	"Path": "/doc/go1.16"
	}-->

	<!--
	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">DRAFT RELEASE NOTES — Introduction to Go 1.16</h2>

	<p>
	<strong>
	Go 1.16 is not yet released. These are work-in-progress
	release notes. Go 1.16 is expected to be released in February 2021.
	</strong>
	</p>

	<h2 id="language">Changes to the language</h2>

	<p>
	TODO
	</p>

	<h2 id="ports">Ports</h2>

	<h3 id="netbsd">NetBSD</h3>

	<p><!-- golang.org/issue/30824 -->
	Go now supports the 64-bit ARM architecture on NetBSD (the
	<code>netbsd/arm64</code> port).
	</p>

	<h3 id="386">386</h3>

	<p><!-- golang.org/issue/40255, golang.org/issue/41848, CL 258957, and CL 260017 -->
	As <a href="go1.15#386">announced</a> in the Go 1.15 release notes,
	Go 1.16 drops support for x87 mode compilation (<code>GO386=387</code>).
	Support for non-SSE2 processors is now available using soft float
	mode (<code>GO386=softfloat</code>).
	Users running on non-SSE2 processors should replace <code>GO386=387</code>
	with <code>GO386=softfloat</code>.
	</p>

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

	<p>
	TODO
	</p>

	<h3 id="go-command">Go command</h3>

	<h4 id="modules">Modules</h4>

	<p><!-- golang.org/issue/40276 -->
	<code>go</code> <code>install</code> now accepts arguments with
	version suffixes (for example, <code>go</code> <code>install</code>
	<code>example.com/cmd@v1.0.0</code>). This causes <code>go</code>
	<code>install</code> to build and install 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 installing executables without
	affecting the dependencies of the main module.<br>
	TODO: write and link to section in golang.org/ref/mod<br>
	TODO: write and link to blog post
	</p>

	<p><!-- golang.org/issue/24031 -->
	<code>retract</code> directives may now be used in a <code>go.mod</code> file
	to indicate that certain published versions of the module should not be used
	by other modules. A module author may retract a version after a severe problem
	is discovered or if the version was published unintentionally.<br>
	TODO: write and link to section in golang.org/ref/mod<br>
	TODO: write and link to tutorial or blog post
	</p>

	<p><!-- golang.org/issue/26603 -->
	The <code>go</code> <code>mod</code> <code>vendor</code>
	and <code>go</code> <code>mod</code> <code>tidy</code> subcommands now accept
	the <code>-e</code> flag, which instructs them to proceed despite errors in
	resolving missing packages.
	</p>

	<h4 id="go-test"><code>go</code> <code>test</code></h4>

	<p><!-- golang.org/issue/29062 -->
	When using <code>go</code> <code>test</code>, a test that
	calls <code>os.Exit(0)</code> during execution of a test function
	will now be considered to fail.
	This will help catch cases in which a test calls code that calls
	<code>os.Exit(0)</code> and thereby stops running all future tests.
	If a <code>TestMain</code> function calls <code>os.Exit(0)</code>
	that is still considered to be a passing test.
	</p>

	<p><!-- golang.org/issue/37519 -->
	The <code>go</code> <code>get</code> <code>-insecure</code> flag is
	deprecated and will be removed in a future version. This flag permits
	fetching from repositories and resolving custom domains using insecure
	schemes such as HTTP, and also bypassess module sum validation using the
	checksum database. To permit the use of insecure schemes, use the
	<code>GOINSECURE</code> environment variable instead. To bypass module
	sum validation, use <code>GOPRIVATE</code> or <code>GONOSUMDB</code>.
	See <code>go</code> <code>help</code> <code>environment</code> for details.
	</p>

	<h4 id="all-pattern">The <code>all</code> pattern</h4>

	<p><!-- golang.org/cl/240623 -->
	When the main module's <code>go.mod</code> file
	declares <code>go</code> <code>1.16</code> or higher, the <code>all</code>
	package pattern now matches only those packages that are transitively imported
	by a package or test found in the main module. (Packages imported by <em>tests
	of</em> packages imported by the main module are no longer included.) This is
	the same set of packages retained
	by <code>go</code> <code>mod</code> <code>vendor</code> since Go 1.11.
	</p>

	<h4 id="toolexec">The <code>-toolexec</code> build flag</h4>

	<p><!-- golang.org/cl/263357 -->
	When the <code>-toolexec</code> build flag is specified to use a program when
	invoking toolchain programs like compile or asm, the environment variable
	<code>TOOLEXEC_IMPORTPATH</code> is now set to the import path of the package
	being built.
	</p>

	<h3 id="cgo">Cgo</h3>

	<p> <!-- CL 252378 -->
	The <a href="/cmd/cgo">cgo</a> tool will no longer try to translate
	C struct bitfields into Go struct fields, even if their size can be
	represented in Go. The order in which C bitfields appear in memory
	is implementation dependent, so in some cases the cgo tool produced
	results that were silently incorrect.
	</p>

	<p>
	TODO
	</p>

	<h2 id="runtime">Runtime</h2>

	<p>
	TODO
	</p>

	<h2 id="compiler">Compiler</h2>

	<p>
	TODO
	</p>

	<h2 id="linker">Linker</h2>

	<p>
	This release includes additional improvements to the Go linker,
	reducing linker resource usage (both time and memory) and improving
	code robustness/maintainability. These changes form the second half
	of a two-release project to
	<a href="https://golang.org/s/better-linker">modernize the Go
	linker</a>.
	</p>

	<p>
	The linker changes in 1.16 extend the 1.15 improvements to all
	supported architecture/OS combinations (the 1.15 performance improvements
	were primarily focused on <code>ELF</code>-based OSes and
	<code>amd64</code> architectures). For a representative set of
	large Go programs, linking is 20-35% faster than 1.15 and requires
	5-15% less memory on average for <code>linux/amd64</code>, with larger
	improvements for other architectures and OSes.
	</p>

	<p>
	TODO: update with final numbers later in the release.
	</p>

	<p> <!-- CL 255259 -->
	On Windows, <code>go build -buildmode=c-shared</code> now generates Windows
	ASLR DLLs by default. ASLR can be disabled with <code>--ldflags=-aslr=false</code>.
	</p>

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

	<p>
	TODO
	</p>

	<h3 id="crypto/hmac"><a href="/pkg/crypto/hmac">crypto/hmac</a></h3>

	<p><!-- CL 261960 -->
	<a href="/pkg/crypto/hmac/#New">New</a> will now panic if separate calls to
	the hash generation function fail to return new values. Previously, the
	behavior was undefined and invalid outputs were sometimes generated.
	</p>

	<h3 id="crypto/tls"><a href="/pkg/crypto/tls">crypto/tls</a></h3>

	<p><!-- CL 256897 -->
	I/O operations on closing or closed TLS connections can now be detected using
	the new <a href="/pkg/net/#ErrClosed">ErrClosed</a> error. A typical use
	would be <code>errors.Is(err, net.ErrClosed)</code>. In earlier releases
	the only way to reliably detect this case was to match the string returned
	by the <code>Error</code> method with <code>"tls: use of closed connection"</code>.
	</p>

	<h3 id="crypto/x509"><a href="/pkg/crypto/x509">crypto/x509</a></h3>

	<p><!-- CL 235078 -->
	<a href="/pkg/crypto/x509/#ParseCertificate">ParseCertificate</a> and
	<a href="/pkg/crypto/x509/#CreateCertificate">CreateCertificate</a> both
	now enforce string encoding restrictions for the fields <code>DNSNames</code>,
	<code>EmailAddresses</code>, and <code>URIs</code>. These fields can only
	contain strings with characters within the ASCII range.
	</p>

	<p><!-- CL 259697 -->
	<a href="/pkg/crypto/x509/#CreateCertificate">CreateCertificate</a> now
	verifies the generated certificate's signature using the signer's
	public key. If the signature is invalid, an error is returned, instead
	of a malformed certificate.
	</p>

	<h3 id="encoding/json"><a href="/pkg/encoding/json">encoding/json</a></h3>

	<p><!-- CL 263619 -->
	The error message for
	<a href="/pkg/encoding/json/#SyntaxError">SyntaxError</a>
	now begins with "json: ", matching the other errors in the package.
	</p>

	<h3 id="net"><a href="/pkg/net/">net</a></h3>

	<p><!-- CL 250357 -->
	The case of I/O on a closed network connection, or I/O on a network
	connection that is closed before any of the I/O completes, can now
	be detected using the new <a href="/pkg/net/#ErrClosed">ErrClosed</a> error.
	A typical use would be <code>errors.Is(err, net.ErrClosed)</code>.
	In earlier releases the only way to reliably detect this case was to
	match the string returned by the <code>Error</code> method
	with <code>"use of closed network connection"</code>.
	</p>

	<p><!-- CL 255898 -->
	In previous Go releases the default TCP listener backlog size on Linux systems,
	set by <code>/proc/sys/net/core/somaxconn</code>, was limited to a maximum of <code>65535</code>.
	On Linux kernel version 4.1 and above, the maximum is now <code>4294967295</code>.
	</p>

	<h3 id="reflect"><a href="/pkg/reflect/">reflect</a></h3>

	<p><!-- CL 259237, golang.org/issue/22075 -->
	For interface types and values, <a href="/pkg/reflect/#Value.Method">Method</a>,
	<a href="/pkg/reflect/#Value.MethodByName">MethodByName</a>, and
	<a href="/pkg/reflect/#Value.NumMethod">NumMethod</a> now
	operate on the interface's exported method set, rather than its full method set.
	</p>

	<h3 id="text/template/parse"><a href="/pkg/text/template/parse/">text/template/parse</a></h3>

	<p><!-- CL 229398, golang.org/issue/34652 -->
	A new <a href="/pkg/text/template/parse/#CommentNode"><code>CommentNode</code></a>
	was added to the parse tree. The <a href="/pkg/text/template/parse/#Mode"><code>Mode</code></a>
	field in the <code>parse.Tree</code> enables access to it.
	</p>
	<!-- text/template/parse -->

	<h3 id="unicode"><a href="/pkg/unicode/">unicode</a></h3>

	<p><!-- CL 248765 -->
	The <a href="/pkg/unicode/"><code>unicode</code></a> package and associated
	support throughout the system has been upgraded from Unicode 12.0.0 to
	<a href="https://www.unicode.org/versions/Unicode13.0.0/">Unicode 13.0.0</a>,
	which adds 5,930 new characters, including four new scripts, and 55 new emoji.
	Unicode 13.0.0 also designates plane 3 (U+30000-U+3FFFF) as the tertiary
	ideographic plane.
	</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
	</p>

	<dl id="crypto/dsa"><dt><a href="/pkg/crypto/dsa/">crypto/dsa</a></dt>
	<dd>
	<p><!-- CL 257939 -->
	The <a href="/pkg/crypto/dsa/"><code>crypto/dsa</code></a> package is now deprecated.
	See <a href="https://golang.org/issue/40337">issue #40337</a>.
	</p>
	</dd>
	</dl><!-- crypto/dsa -->

	<dl id="crypto/x509"><dt><a href="/pkg/crypto/x509/">crypto/x509</a></dt>
	<dd>
	<p><!-- CL 257939 -->
	DSA signature verification is no longer supported. Note that DSA signature
	generation was never supported.
	See <a href="https://golang.org/issue/40337">issue #40337</a>.
	</p>
	</dd>
	</dl><!-- crypto/x509 -->

	<dl id="encoding/xml"><dt><a href="/pkg/encoding/xml/">encoding/xml</a></dt>
	<dd>
	<p><!-- CL 264024 -->
	The encoder has always taken care to avoid using namespace prefixes
	beginning with <code>xml</code>, which are reserved by the XML
	specification.
	Now, following the specification more closely, that check is
	case-insensitive, so that prefixes beginning
	with <code>XML</code>, <code>XmL</code>, and so on are also
	avoided.
	</p>
	</dd>
	</dl><!-- encoding/xml -->

	<dl id="net/http"><dt><a href="/pkg/net/http/">net/http</a></dt>
	<dd>
	<p><!-- CL 233637 -->
	In the <a href="/pkg/net/http/"><code>net/http</code></a> package, the
	behavior of <a href="/pkg/net/http/#StripPrefix"><code>StripPrefix</code></a>
	has been changed to strip the prefix from the request URL's
	<code>RawPath</code> field in addition to its <code>Path</code> field.
	In past releases, only the <code>Path</code> field was trimmed, and so if the
	request URL contained any escaped characters the URL would be modified to
	have mismatched <code>Path</code> and <code>RawPath</code> fields.
	In Go 1.16, <code>StripPrefix</code> trims both fields.
	If there are escaped characters in the prefix part of the request URL the
	handler serves a 404 instead of its previous behavior of invoking the
	underlying handler with a mismatched <code>Path</code>/<code>RawPath</code> pair.
	</p>

	<p><!-- CL 252497 -->
	The <a href="/pkg/net/http/"><code>net/http</code></a> package now rejects HTTP range requests
	of the form <code>"Range": "bytes=--N"</code> where <code>"-N"</code> is a negative suffix length, for
	example <code>"Range": "bytes=--2"</code>. It now replies with a <code>416 "Range Not Satisfiable"</code> response.
	</p>

	<p><!-- CL 256498, golang.org/issue/36990 -->
	Cookies set with <code>SameSiteDefaultMode</code> now behave according to the current
	spec (no attribute is set) instead of generating a SameSite key without a value.
	</p>
	</dd>
	</dl><!-- net/http -->

	<dl id="runtime/debug"><dt><a href="/pkg/runtime/debug/">runtime/debug</a></dt>
	<dd>
	<p><!-- CL 249677 -->
	TODO: <a href="https://golang.org/cl/249677">https://golang.org/cl/249677</a>: provide Addr method for errors from SetPanicOnFault
	</p>
	</dd>
	</dl><!-- runtime/debug -->

	<dl id="strconv"><dt><a href="/pkg/strconv/">strconv</a></dt>
	<dd>
	<p><!-- CL 260858 -->
	<a href="/pkg/strconv/#ParseFloat"><code>ParseFloat</code></a> now uses
	the <a
	href="https://nigeltao.github.io/blog/2020/eisel-lemire.html">Eisel-Lemire
	algorithm</a>, improving performance by up to a factor of 2. This can
	also speed up decoding textual formats like <a
	href="/pkg/encoding/json/"><code>encoding/json</code></a>.
	</p>
	</dd>
	</dl><!-- strconv -->