Commit 7119f4b0 authored by Robert Griesemer's avatar Robert Griesemer

doc/go1.13: add release notes for language changes

Change-Id: I17b156e77f279e1387ad27ab0e41ae8f50c9a325
Reviewed-on: https://go-review.googlesource.com/c/go/+/182857Reviewed-by: default avatarIan Lance Taylor <iant@golang.org>
Reviewed-by: default avatarAustin Clements <austin@google.com>
parent 9f68d2fa
......@@ -41,13 +41,69 @@ TODO
<h2 id="language">Changes to the language</h2>
<p>
TODO
Per the <a href="https://github.com/golang/proposal/blob/master/design/19308-number-literals.md">number literal proposal</a>,
Go 1.13 supports a more uniform and modernized set of number literal prefixes.
<ul>
<li>
<a href="https://golang.org/ref/spec#Integer_literals">Binary integer literals</a>:
The prefix <code>0b</code> or <code>0B</code> indicates a binary integer literal
such as <code>0b1011</code>.
</li>
<li>
<a href="https://golang.org/ref/spec#Integer_literals">Octal integer literals</a>:
The prefix <code>0o</code> or <code>0O</code> indicates an octal integer literal
such as <code>0o660</code>.
The existing octal notation indicated by a leading <code>0</code> followed by
octal digits remains valid.
</li>
<li>
<a href="https://golang.org/ref/spec#Floating-point_literals">Hexadecimal floating point literals</a>:
The prefix <code>0x</code> or <code>0X</code> may now be used to express the mantissa of a
floating-point number in hexadecimal format such as <code>0x1.0p-1021</code>.
A hexadecimal floating-point number must always have an exponent, written as the letter
<code>p</code> or <code>P</code> followed by an exponent in decimal. The exponent scales
the mantissa by 2 to the power of the exponent.
</li>
<li>
<a href="https://golang.org/ref/spec#Imaginary_literals">Imaginary literals</a>:
The imaginary suffix <code>i</code> may now be used with any (binary, decimal, hexadecimal)
integer or floating-point literal.
</li>
<li>
Digit separators:
The digits of any number literal may now be separated (grouped) using underscores, such as
in <code>1_000_000</code>, <code>0b_1010_0110</code>, or <code>3.1415_9265</code>.
An underscore may appear between any two digits or the literal prefix and the first digit.
</li>
</ul>
</p>
<p><!-- CL 158719 -->
TODO: <a href="https://golang.org/cl/158797">https://golang.org/cl/158797</a>: implement shifts by signed amounts
<p>
Per the <a href="https://github.com/golang/proposal/blob/master/design/19113-signed-shift-counts.md">signed shift counts proposal</a>
Go 1.13 removes the restriction that a <a href="https://golang.org/ref/spec#Operators">shift count</a>
must be unsigned. This change eliminates the need for many artificial <code>uint</code> conversions,
solely introduced to satisfy this (now removed) restriction of the <code>&lt;&lt;</code> and <code>&gt;&gt;</code> operators.
</p>
<p>
These language changes were implemented by changes to the compiler, and corresponding internal changes to the library
packages <code><a href="https://golang.org/pkg/go/scanner">go/scanner</a></code> and
<code><a href="https://golang.org/pkg/text/scanner">text/scanner</a></code> (number literals),
and <code><a href="https://golang.org/pkg/go/types">go/types</a></code> (signed shift counts).
</p>
<p>
If your code uses modules and your <code>go.mod</code> files specifies a language version, be sure
it is set to at least <code>1.13</code> to get access to these language changes.
You can do this by editing the <code>go.mod</code> file directly, or you can run
<code>go mod edit -go=1.13</code>.
</p>
<h2 id="ports">Ports</h2>
<p>
......
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