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doc/go1.16: consolidate stdlib changes in "Minor changes" section
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Many of the standard library changes that were added before CL 272871
ended up in the "Core library" section. That section is meant for
major changes like new packages, and most of these aren't.

Consolidate all changes in the "Minor changes to the library" section
for now, so that it's easier to get a complete picture of changes for
each package, along with the remaining TODOs. Add a TODO to read them
over at the end and factor out items that are worth highlighting.

Apply minor other fixups to improve consistency.

For #40700.

Change-Id: I7dc2e7ebf2ea3385fce0c207bae4ce467998a717
Reviewed-on: https://go-review.googlesource.com/c/go/+/273267
Trust: Dmitri Shuralyov <dmitshur@golang.org>
Run-TryBot: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Katie Hockman <katie@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
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@dmitshur
dmitshur committed Nov 25, 2020
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Showing 1 changed file with 153 additions and 150 deletions.
303 changes: 153 additions & 150 deletions doc/go1.16.html
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Original file line number Diff line number Diff line change
Expand Up @@ -216,7 +216,7 @@ <h4 id="list-buildid">The <code>list</code> command</h4>

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

<p> <!-- CL 252378 -->
<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
Expand Down Expand Up @@ -281,143 +281,21 @@ <h2 id="linker">Linker</h2>
TODO: update with final numbers later in the release.
</p>

<p> <!-- CL 255259 -->
<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>

<p><!-- CL 266037 -->
A default deadline is set in <a href="/pkg/crypto/tls/#Conn.Close">Close</a>
before sending the close notify alert, in order to prevent blocking
indefinitely.
</p>

<p><!-- CL 246338 -->
<a href="/pkg/crypto/tls#Conn.HandshakeContext">(*Conn).HandshakeContext</a> was added to
allow the user to control cancellation of an in-progress TLS Handshake.
The context provided is propagated into the
<a href="/pkg/crypto/tls#ClientHelloInfo">ClientHelloInfo</a>
and <a href="/pkg/crypto/tls#CertificateRequestInfo">CertificateRequestInfo</a>
structs and accessible through the new
<a href="/pkg/crypto/tls#ClientHelloInfo.Context">(*ClientHelloInfo).Context</a>
and
<a href="/pkg/crypto/tls#CertificateRequestInfo.Context">
(*CertificateRequestInfo).Context
</a> methods respectively. Canceling the context after the handshake has finished
has no effect.
</p>

<p><!-- CL 239748 -->
Clients now ensure that the server selects
<a href="/pkg/crypto/tls/#ConnectionState.NegotiatedProtocol">
an ALPN protocol</a> from
<a href="/pkg/crypto/tls/#Config.NextProtos">
the list advertised by the client</a>.
</p>

<p><!-- CL 262857 -->
TLS servers will now prefer other AEAD cipher suites (such as ChaCha20Poly1305)
over AES-GCM cipher suites if either the client or server doesn't have AES hardware
support, unless the application set both
<a href="/pkg/crypto/tls/#Config.PreferServerCipherSuites"><code>Config.PreferServerCipherSuites</code></a>
and <a href="/pkg/crypto/tls/#Config.CipherSuites"><code>Config.CipherSuites</code></a>
or there are no other AEAD cipher suites supported.
The client is assumed not to have AES hardware support if it does not signal a
preference for AES-GCM cipher suites.
</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.
TODO: mention significant additions like new packages (<code>io/fs</code>),
new proposal-scoped features (<code>//go:embed</code>), and so on
</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>

<p><!-- CL 233163 -->
A number of additional fields have been added to the
<a href="/pkg/crypto/x509/#CertificateRequest">CertificateRequest</a> type.
These fields are now parsed in <a href="/pkg/crypto/x509/#ParseCertificateRequest">ParseCertificateRequest</a>
and marshalled in <a href="/pkg/crypto/x509/#CreateCertificateRequest">CreateCertificateRequest</a>.
</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="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>
TODO: when the "Minor changes to the library" section is close to completion,
decide if any changes are worth factoring out and highlighting in "Core library"
</p>

<h3 id="minor_library_changes">Minor changes to the library</h3>
Expand All @@ -429,7 +307,7 @@ <h3 id="minor_library_changes">Minor changes to the library</h3>
</p>

<p>
TODO
TODO: complete this section, resolve TODOs below, add missing entries
</p>

<dl id="crypto/dsa"><dt><a href="/pkg/crypto/dsa/">crypto/dsa</a></dt>
Expand All @@ -441,8 +319,66 @@ <h3 id="minor_library_changes">Minor changes to the library</h3>
</dd>
</dl><!-- crypto/dsa -->

<dl id="crypto/hmac"><dt><a href="/pkg/crypto/hmac/">crypto/hmac</a></dt>
<dd>
<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>
</dd>
</dl><!-- crypto/hmac -->

<dl id="crypto/tls"><dt><a href="/pkg/crypto/tls/">crypto/tls</a></dt>
<dd>
<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>

<p><!-- CL 266037 -->
A default deadline is set in <a href="/pkg/crypto/tls/#Conn.Close">Close</a>
before sending the close notify alert, in order to prevent blocking
indefinitely.
</p>

<p><!-- CL 246338 -->
<a href="/pkg/crypto/tls#Conn.HandshakeContext">(*Conn).HandshakeContext</a> was added to
allow the user to control cancellation of an in-progress TLS Handshake.
The context provided is propagated into the
<a href="/pkg/crypto/tls#ClientHelloInfo">ClientHelloInfo</a>
and <a href="/pkg/crypto/tls#CertificateRequestInfo">CertificateRequestInfo</a>
structs and accessible through the new
<a href="/pkg/crypto/tls#ClientHelloInfo.Context">(*ClientHelloInfo).Context</a>
and
<a href="/pkg/crypto/tls#CertificateRequestInfo.Context">
(*CertificateRequestInfo).Context
</a> methods respectively. Canceling the context after the handshake has finished
has no effect.
</p>

<p><!-- CL 239748 -->
Clients now ensure that the server selects
<a href="/pkg/crypto/tls/#ConnectionState.NegotiatedProtocol">
an ALPN protocol</a> from
<a href="/pkg/crypto/tls/#Config.NextProtos">
the list advertised by the client</a>.
</p>

<p><!-- CL 262857 -->
TLS servers will now prefer other AEAD cipher suites (such as ChaCha20Poly1305)
over AES-GCM cipher suites if either the client or server doesn't have AES hardware
support, unless the application set both
<a href="/pkg/crypto/tls/#Config.PreferServerCipherSuites"><code>Config.PreferServerCipherSuites</code></a>
and <a href="/pkg/crypto/tls/#Config.CipherSuites"><code>Config.CipherSuites</code></a>
or there are no other AEAD cipher suites supported.
The client is assumed not to have AES hardware support if it does not signal a
preference for AES-GCM cipher suites.
</p>

<p><!-- CL 246637 -->
TODO: <a href="https://golang.org/cl/246637">https://golang.org/cl/246637</a>: make config.Clone return nil if the source is nil
</p>
Expand All @@ -451,6 +387,28 @@ <h3 id="minor_library_changes">Minor changes to the library</h3>

<dl id="crypto/x509"><dt><a href="/pkg/crypto/x509/">crypto/x509</a></dt>
<dd>
<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>

<p><!-- CL 233163 -->
A number of additional fields have been added to the
<a href="/pkg/crypto/x509/#CertificateRequest">CertificateRequest</a> type.
These fields are now parsed in <a href="/pkg/crypto/x509/#ParseCertificateRequest">ParseCertificateRequest</a>
and marshalled in <a href="/pkg/crypto/x509/#CreateCertificateRequest">CreateCertificateRequest</a>.
</p>

<p><!-- CL 257939 -->
DSA signature verification is no longer supported. Note that DSA signature
generation was never supported.
Expand All @@ -469,6 +427,12 @@ <h3 id="minor_library_changes">Minor changes to the library</h3>

<dl id="encoding/json"><dt><a href="/pkg/encoding/json/">encoding/json</a></dt>
<dd>
<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>

<p><!-- CL 234818 -->
TODO: <a href="https://golang.org/cl/234818">https://golang.org/cl/234818</a>: allow semicolon in field key / struct tag
</p>
Expand Down Expand Up @@ -531,6 +495,22 @@ <h3 id="minor_library_changes">Minor changes to the library</h3>

<dl id="net"><dt><a href="/pkg/net/">net</a></dt>
<dd>
<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>

<p><!-- CL 238629 -->
TODO: <a href="https://golang.org/cl/238629">https://golang.org/cl/238629</a>: prefer /etc/hosts over DNS when no /etc/nsswitch.conf is present
</p>
Expand All @@ -554,14 +534,14 @@ <h3 id="minor_library_changes">Minor changes to the library</h3>
</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.
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.
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>

<p><!-- CL 246338 -->
Expand Down Expand Up @@ -661,6 +641,19 @@ <h3 id="minor_library_changes">Minor changes to the library</h3>
</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 -->

<dl id="syscall"><dt><a href="/pkg/syscall/">syscall</a></dt>
<dd>
<p><!-- CL 261917 -->
Expand All @@ -677,19 +670,6 @@ <h3 id="minor_library_changes">Minor changes to the library</h3>
</dd>
</dl><!-- syscall -->

<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 -->

<dl id="text/template"><dt><a href="/pkg/text/template/">text/template</a></dt>
<dd>
<p><!-- CL 254257 -->
Expand All @@ -698,12 +678,35 @@ <h3 id="minor_library_changes">Minor changes to the library</h3>
</dd>
</dl><!-- text/template -->

<dl id="text/template/parse"><dt><a href="/pkg/text/template/parse/">text/template/parse</a></dt>
<dd>
<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>
</dd>
</dl><!-- text/template/parse -->

<dl id="time/tzdata"><dt><a href="/pkg/time/tzdata/">time/tzdata</a></dt>
<dd>
<p><!-- CL 261877 -->
The slim timezone data format is now used for the time zone database in
The slim timezone data format is now used for the timezone database in
<code>$GOROOT/lib/time/zoneinfo.zip</code> and the embedded copy in this
package. This reduces the size of the time zone database by about 350 KB.
package. This reduces the size of the timezone database by about 350 KB.
</p>
</dd>
</dl><!-- time/tzdata -->

<dl id="unicode"><dt><a href="/pkg/unicode/">unicode</a></dt>
<dd>
<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>
</dd>
</dl><!-- unicode -->

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