doc/go1.2.html: first cut

Lay out the doc and write text for the minor changes.
(I left the net ones for someone who understands them better,
or for someone to describe them to me better so I can write them.)
Much still to do.

Delete go1.2.txt so there's only one thing to update.

R=golang-dev, adg
CC=golang-dev
https://golang.org/cl/13597044
This commit is contained in:
Rob Pike 2013-09-09 13:29:08 +10:00
parent a789ae9e8e
commit 5863b7d2ce
2 changed files with 577 additions and 82 deletions

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<!--{
"Title": "Go 1.2 Release Notes",
"Path": "/doc/go1.2",
"Template": true
}-->
<h2 id="introduction">Introduction to Go 1.2</h2>
<p>
RED TEXT IS FROM THE 1.1 DOC AND NEEDS TO BE UPDATED. (It is here for
formatting and style reference.)
<p>
<font color=red>
The release of <a href="/doc/go1.html">Go version 1</a> (Go 1 or Go 1.0 for short)
in March of 2012 introduced a new period
of stability in the Go language and libraries.
That stability has helped nourish a growing community of Go users
and systems around the world.
Several "point" releases since
then—1.0.1, 1.0.2, and 1.0.3—have been issued.
These point releases fixed known bugs but made
no non-critical changes to the implementation.
</font>
</p>
<p>
<font color=red>
This new release, Go 1.1, keeps the <a href="/doc/go1compat.html">promise
of compatibility</a> but adds a couple of significant
(backwards-compatible, of course) language changes, has a long list
of (again, compatible) library changes, and
includes major work on the implementation of the compilers,
libraries, and run-time.
The focus is on performance.
Benchmarking is an inexact science at best, but we see significant,
sometimes dramatic speedups for many of our test programs.
We trust that many of our users' programs will also see improvements
just by updating their Go installation and recompiling.
</font>
</p>
<p>
<font color=red>
This document summarizes the changes between Go 1 and Go 1.2.
Very little if any code will need modification to run with Go 1.1,
although a couple of rare error cases surface with this release
and need to be addressed if they arise.
Details appear below; see the discussion of XXX.
</font>
</p>
<h2 id="language">Changes to the language</h2>
<p>
<font color=red>
<a href="/doc/go1compat.html">The Go compatibility document</a> promises
that programs written to the Go 1 language specification will continue to operate,
and those promises are maintained.
In the interest of firming up the specification, though, there are
details about some error cases that have been clarified.
There are also some new language features.
</font>
</p>
<h3 id="threeindex">Three-index slices</h3>
<p>
cmd/gc: three-index slicing to set cap as well as length (CL 10743046).
</p>
<h2 id="impl">Changes to the implementations and tools</h2>
<ul>
<li>
runtime: preemption of goroutines at function entry (CL 12371043).
</li>
<li>
go/build: support including C++ code with cgo (CL 8248043).
</li>
</ul>
<h3 id="gccgo">Status of gccgo</h3>
<p>
<font color=red>
The GCC release schedule does not coincide with the Go release schedule, so some skew is inevitable in
<code>gccgo</code>'s releases.
The 4.8.0 version of GCC shipped in March, 2013 and includes a nearly-Go 1.1 version of <code>gccgo</code>.
Its library is a little behind the release, but the biggest difference is that method values are not implemented.
Sometime around July 2013, we expect 4.8.2 of GCC to ship with a <code>gccgo</code>
providing a complete Go 1.1 implementaiton.
</font>
</p>
<h3 id="gc_changes">TODO</h3>
<p>
TODO: write prose
</p>
<ul>
<li>cmd/5a: removed support for R9/R10 (use m/g instead) (CL 9840043).
</li>
<li>cmd/5l: add MOVBS, MOVHS etc for sub-word moves (CL 12682043).
</li>
<li>cmd/5l: support for external linking for linux/arm (CL 12871044).
</li>
<li>cmd/cgo, cmd/go: support including C++ code with cgo (CL 8248043).
</li>
<li>cmd/gc: make missing package error fatal (CL 12677043).
</li>
</ul>
<h3 id="gocmd">Changes to the go command</h3>
<ul>
<li>cmd/go: test coverage (CL 10413044).
</li>
<li>cmd/go: add -t flag to 'go get' to download test dependencies (CL 12566046).
</li>
<li>cmd/go: delete 'go doc' (CL 12974043).
</li>
</ul>
<h3 id="platforms">Additional platforms</h3>
<p>
<font color=red>
The Go 1.1 tool chain adds experimental support for <code>freebsd/arm</code>,
<code>netbsd/386</code>, <code>netbsd/amd64</code>, <code>netbsd/arm</code>,
<code>openbsd/386</code> and <code>openbsd/amd64</code> platforms.
</font>
</p>
<p>
<font color=red>
An ARMv6 or later processor is required for <code>freebsd/arm</code> or
<code>netbsd/arm</code>.
</font>
</p>
<p>
<font color=red>
Go 1.1 adds experimental support for <code>cgo</code> on <code>linux/arm</code>.
</font>
</p>
<h2 id="performance">Performance</h2>
<p>
<font color=red>
The performance of code compiled with the Go 1.1 gc tool suite should be noticeably
better for most Go programs.
Typical improvements relative to Go 1.0 seem to be about 30%-40%, sometimes
much more, but occasionally less or even non-existent.
There are too many small performance-driven tweaks through the tools and libraries
to list them all here, but the following major changes are worth noting:
</font>
</p>
<ul>
<li>compress/bzip2: faster decompression by 30% (CL 9915043).
</li>
<li>crypto/des: 5x faster encoding/decoding (CL 11874043, 12072045).
</li>
<li>encoding/json: faster encoding (CL 9129044).
</li>
<li>net: improve windows performance by up to 30% (CL 8670044).
</li>
<li>net: improve performance on BSD by up to 30% (CL 8264043, 12927048, 13080043).
</li>
</ul>
<h2 id="library">Changes to the standard library</h2>
<h3 id="foo_bar">foo.Bar</h3>
<p>
TODO: choose which to call out
<font color=red>
The various routines to scan textual input in the
<a href="/pkg/bufio/"><code>bufio</code></a>
package,
<a href="/pkg/bufio/#Reader.ReadBytes"><code>ReadBytes</code></a>,
<a href="/pkg/bufio/#Reader.ReadString"><code>ReadString</code></a>
and particularly
<a href="/pkg/bufio/#Reader.ReadLine"><code>ReadLine</code></a>,
are needlessly complex to use for simple purposes.
In Go 1.1, a new type,
<a href="/pkg/bufio/#Scanner"><code>Scanner</code></a>,
has been added to make it easier to do simple tasks such as
read the input as a sequence of lines or space-delimited words.
It simplifies the problem by terminating the scan on problematic
input such as pathologically long lines, and having a simple
default: line-oriented input, with each line stripped of its terminator.
Here is code to reproduce the input a line at a time:
</font>
<p>
<font color=red>
<em>Updating</em>:
To correct breakage caused by the new struct field,
<code>go fix</code> will rewrite code to add tags for these types.
More generally, <code>go vet</code> will identify composite literals that
should be revised to use field tags.
</font>
</p>
<ul>
<li>
Breaking change:
archive/tar,archive/zip: fix os.FileInfo implementation to provide base name only (CL 13118043).
</li>
<li>
fmt: indexed access to arguments in Printf etc. (CL 9680043).
</li>
<li>
encoding: new package defining generic encoding interfaces (CL 12541051).
</li>
<li>
sync/atomic: add Swap functions (CL 12670045).
</li>
<li>
text/template: add comparison functions (CL 13091045).
</li>
<li>
text/template: allow {{"{{"}}else if ... {{"}}"}} to simplify if chains (CL 13327043).
</li>
</ul>
<h3 id="exp_old">Exp and old subtrees moved to go.exp and go.text subrepositories</h3>
<p>
<font color=red>
To make it easier for binary distributions to access them if desired, the <code>exp</code>
and <code>old</code> source subtrees, which are not included in binary distributions,
have been moved to the new <code>go.exp</code> subrepository at
<code>code.google.com/p/go.exp</code>. To access the <code>ssa</code> package,
for example, run
</font>
</p>
<h3 id="new_packages">New packages</h3>
<p>
<font color=red>
There are three new packages.
</font>
</p>
<ul>
<li>
<font color=red>
The <a href="/pkg/go/format/"><code>go/format</code></a> package provides
a convenient way for a program to access the formatting capabilities of the
<a href="/cmd/go/#hdr-Run_gofmt_on_package_sources"><code>go fmt</code></a> command.
It has two functions,
<a href="/pkg/go/format/#Node"><code>Node</code></a> to format a Go parser
<a href="/pkg/go/ast/#Node"><code>Node</code></a>,
and
<a href="/pkg/go/format/#Source"><code>Source</code></a>
to reformat arbitrary Go source code into the standard format as provided by the
<a href="/cmd/go/#hdr-Run_gofmt_on_package_sources"><code>go fmt</code></a> command.
</font>
</li>
</ul>
<h3 id="minor_library_changes">Minor changes to the library</h3>
<p>
The following list summarizes a number of minor changes to the library, mostly additions.
See the relevant package documentation for more information about each change.
</p>
<ul>
<li>
The <a href="/pkg/archive/zip/"><code>archive/zip</code></a> package
adds the
<a href="/pkg/archive/zip/#File.DataOffset"><code>DataOffset</code></a> accessor
to return the offset of a file's (possibly compressed) data within the archive.
</li>
<li>
The <a href="/pkg/bufio/"><code>bufio</code></a> package
adds <a href="/pkg/bufio/#Reader.Reset"><code>Reset</code></a>
methods to <a href="/pkg/bufio/#Reader"><code>Reader</code></a> and
<a href="/pkg/bufio/#Writer"><code>Writer</code></a>.
These methods allow the <a href="/pkg/Reader/"><code>Readers</code></a>
and <a href="/pkg/Writer/"><code>Writers</code></a>
to be re-used on new input and output readers and writers, saving
allocation overhead.
</li>
<li>
The <a href="/pkg/compress/bzip2/"><code>compress/bzip2</code></a>
can now decompress concatenated archives.
</li>
<li>
The <a href="/pkg/compress/flate/"><code>compress/flate</code></a>
package adds a <a href="/pkg/compress/flate/#Reset"><code>Reset</code></a>
method on the <a href="/pkg/compress/flate/#Writer"><code>Writer</code></a>,
allowing compression of one file to start with another's dictionary.
</li>
<li>
compress/gzip: add Reset method on Writer (CL 13435043).
</li>
<li>
The <a href="/pkg/container/heap/"><code>container/heap</code></a> package
adds a <a href="/pkg/container/heap/#Fix"><code>Fix</code></a>
method to provide a more efficient way to update an item's position in the heap.
</li>
<li>
The <a href="/pkg/container/list/"><code>container/list</code></a> package
adds the <a href="/pkg/container/list/#MoveBefore"><code>MoveBefore</code></a>
and
<a href="/pkg/container/list/#MoveAfter"><code>MoveAfter</code></a>
methods, which implement the obvious rearrangement.
</li>
<li>
The <a href="/pkg/crypto/cipher/"><code>crypto/cipher</code></a> package
adds the a new GCM mode (Galois Counter Mode), which is almost always
used with AES encryption.
</li>
<li>
The
<a href="/pkg/crypto/md5/"><code>crypto/md5</code></a> package
adds a new <a href="/pkg/crypto/md5/#Sum"><code>Sum</code></a> function
to simplify hashing without sacrificing performance.
</li>
<li>
Similarly, the
<a href="/pkg/crypto/md5/"><code>crypto/sha1</code></a> package
adds a new <a href="/pkg/crypto/sha1/#Sum"><code>Sum</code></a> function.
</li>
<li>
Also, the
<a href="/pkg/crypto/sha256/"><code>crypto/sha256</code></a> package
adds <a href="/pkg/crypto/sha256/#Sum256"><code>Sum256</code></a>
and <a href="/pkg/crypto/sha256/#Sum224"><code>Sum224</code></a> functions.
</li>
<li>
Finally, the <a href="/pkg/crypto/sha512/"><code>crypto/sha512</code></a> package
adds <a href="/pkg/crypto/sha512/#Sum512"><code>Sum512</code></a> and
<a href="/pkg/crypto/sha512/#Sum384"><code>Sum384</code></a> functions.
</li>
<li>
The <a href="/pkg/crypto/x509/"><code>crypto/x509</code></a> package
adds support for reading and writing arbitrary extensions.
</li>
<li>
The <a href="/pkg/crypto/tls/"><code>crypto/tls</code></a> package adds
support for TLS 1.1, 1.2 and AES-GCM.
</li>
<li>
The <a href="/pkg/database/sql/"><code>database/sql</code></a> package adds a
<a href="/pkg/database/sql/#DB.SetMaxOpenConns"><code>SetMaxOpenConns</code></a>
method on <a href="/pkg/database/sql/#DB"><code>DB</code></a> to limit the
number of open connections to the database.
</li>
<li>
The <a href="/pkg/encoding/csv/"><code>encoding/csv</code></a> package
now always allows trailing commas on fields.
</li>
<li>
The <a href="/pkg/encoding/gob/"><code>encoding/gob</code></a> package
now supports the generic encoding interfaces of the
<a href="/pkg/encoding/"><code>encoding</code></a> package
described above.
</li>
<li>
The <a href="/pkg/encoding/json/"><code>encoding/json</code></a> package
now will alway escape ampersands as "\u0026" when printing strings.
It will now accept but correct invalid UTF-8 in
<a href="/pkg/encoding/json/#Marshal"><code>Marshal</code></a>
(such input was previously rejected).
Finally, it now supports the generic encoding interfaces of the
<a href="/pkg/encoding/"><code>encoding</code></a> package
described above.
</li>
<li>
The <a href="/pkg/encoding/xml/"><code>encoding/xml</code></a> package
now allows attributes stored in pointers to be marshaled.
It also supports the generic encoding interfaces of the
<a href="/pkg/encoding/"><code>encoding</code></a> package
described above through the new
<a href="/pkg/encoding/xml/#Marshaler"><code>Marshaler</code></a>,
<a href="/pkg/encoding/xml/#UnMarshaler"><code>UnMarshaler</code></a>,
and related
<a href="/pkg/encoding/xml/#MarshalerAttr"><code>MarshalerAttr</code></a> and
<a href="/pkg/encoding/xml/#UnmarshalerAttr"><code>UnmarshalerAttr</code></a>
interfaces.
</li>
<li>
The <a href="/pkg/flag/"><code>flag</code></a> package now
has a <a href="/pkg/flag/#Getter"><code>Getter</code></a> interface
to allow the value of a flag to be retrieved. Due to the
Go 1 compatibility guidelines, this method cannot be added to the existing
<a href="/pkg/flag/#Value"><code>Value</code></a>
interface, but all the existing standard flag types implement it.
The package also now exports the <a href="/pkg/flag/#CommandLine"><code>CommandLine</code></a>
flag set, which holds the flags from the command line.
</li>
<li>
The <a href="/pkg/go/build/"><code>go/build</code></a> package adds
the <a href="/pkg/go/build/#Package.AllTags"><code>AllTags</code></a> field
to the <a href="/pkg/go/build/#Package"><code>Package</code></a> type,
to make it easier to process build tags.
</li>
<li>
The <a href="/pkg/image/draw/"><code>image/draw</code></a> package now
exports an interface, <a href="/pkg/image/draw/#Drawer"><code>Drawer</code></a>,
that wraps the standard <a href="/pkg/image/draw/#Draw"><code>Draw</code></a> method.
The Porter-Duff operators now implement this interface, in effect binding an operation to
the draw operator rather than providing it explicitly.
Given a paletted image as its destination, the new
<a href="/pkg/image/draw/#FloydSteinberg"><code>FloydSteinberg</code></a>
implementation of the
<a href="/pkg/image/draw/#Drawer"><code>Drawer</code></a>
interface will use the Floyd-Steinberg error diffusion algorithm to draw the image.
To create palettes suitable for such processing, the new
<a href="/pkg/image/draw/#Quantizer"><code>Quantizer</code></a> interface
represents implementations of quantization algorithms that choose a palette
given a full-color image.
There are no implementations of this interface in the library.
</li>
<li>
The <a href="/pkg/image/gif/"><code>image/gif</code></a> package
can now create GIF files using the new
<a href="/pkg/image/gif/#Encode"><code>Encode</code></a>
and <a href="/pkg/image/gif/#EncodeAll"><code>EncodeAll</code></a>
functions.
Their options argument allows specification of an image
<a href="/pkg/image/draw/#Quantizer"><code>Quantizer</code></a> to use;
if it is <code>nil</code>, the generated GIF will use the
<a href="/pkg/image/color/palette/#Plan9"><code>Plan9</code></a>
color map (palette) defined in the new
<a href="/pkg/image/color/palette/"><code>image/color/palette</code></a> package.
The options also specify a
<a href="/pkg/image/draw/#Drawer"><code>Drawer</code></a>
to use to create the output image;
if it is <code>nil</code>, Floyd-Steinberg error diffusion is used.
</li>
<li>
The<a href="/pkg/io/#Copy"><code>Copy</code></a> method of the
<a href="/pkg/io/"><code>io</code></a> package now prioritizes its
arguments differently.
If one argument implements <a href="/pkg/io/#WriterTo"><code>WriterTo</code></a>
and the other implements i<a href="/pkg/o/#ReaderFrom"><code>ReaderFrom</code></a>,
<a href="/pkg/io/#Copy"><code>Copy</code></a> will now invoke
<a href="/pkg/io/#WriterTo"><code>WriterTo</code></a> to do the work,
so that less intermediate buffering is required in general.
</li>
<li>
net: new build tag netgo for building a pure Go net package (CL 7100050).
</li>
<li>
net/http: don't allow sending invalid cookie lines (CL 12204043).
</li>
<li>
net/http: allow ReadResponse with nil *Request parameter (CL 9821043).
</li>
<li>
net/http: allow responses to HEAD requests, detect type and length (CL 12583043).
</li>
<li>
The <a href="/pkg/runtime/"><code>runtime</code></a> package relaxes
the constraints on finalizer functions in
<a href="/pkg/runtime/#SetFinalizer"><code>SetFinalizer</code></a>: the
actual argument can now be any type that is assignable to the formal type of
the function, as is the case for any normal function call in Go.
</li>
<li>
The <a href="/pkg/sort/"><code>sort</code></a> package has a new
<a href="/pkg/sort/#Stable"><code>Stable</code></a> function that implements
stable sorting. It is less efficient than the normal sort algorithm, however.
</li>
<li>
The <a href="/pkg/strings/"><code>strings</code></a> package adds
an <a href="/pkg/strings/#IndexByte"><code>IndexByte</code></a>
function for consistency with the <a href="/pkg/bytes/"><code>bytes</code></a> package.
</li>
<li>
syscall: implemented Sendfile for Darwin, added Syscall9 for Darwin/amd64 (CL 10980043).
</li>
<li>
The <a href="/pkg/testing/"><code>testing</code></a> package
now exports the<a href="/pkg/testing/#TB"><code>TB</code></a> interface.
It records the methods in common with the
<a href="/pkg/testing/#T"><code>T</code></a>
and
<a href="/pkg/testing/#B"><code>B</code></a> types,
to make it easier to share code between tests and benchmarks.
Also, the
<a href="/pkg/testing/#AllocsPerRun"><code>AllocsPerRun</code></a>
function now quantizes the return value to an integer (although it
still has type <code>float64</code>), to round off any error caused by
initialization and make the result more repeatable.
</li>
<li>
The <a href="/pkg/text/template/"><code>text/template</code></a> package
now automatically dereferences pointer values when evaluating the arguments
to "escape" functions such as "html", to bring the behavior of such functions
in agreement with that of other printing functions such as "printf".
</li>
<li>
In the <a href="/pkg/time/"><code>time</code></a> package, the
<a href="/pkg/time/#Parse"><code>Parse</code></a> function
and
<a href="/pkg/time/#Format"><code>Format</code></a>
method
now handle time zone offsets with seconds, such as in the historical
date "1871-01-01T05:33:02+00:34:08".
Also, pattern matching in the formats for those routines is stricter: a non-lowercase letter
must now follow the standard words such as "Jan" and "Mon".
</li>
<li>
The <a href="/pkg/unicode/"><code>unicode</code></a> package
adds <a href="/pkg/unicode/#In"><code>In</code></a>,
a nicer-to-use but equivalent version of the original
<a href="/pkg/unicode/#IsOneOf"><code>IsOneOf</code></a>,
to see whether a character is a member of a Unicode category.
</li>
</ul>

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@ -1,82 +0,0 @@
This file collects notes about what has changed since Go 1.1
and should be mentioned in the Go 1.2 release notes.
During the Go 1.2 release process it will be necessary to convert
it to HTML, similar to go1.1.html, but for now it is a text file,
to make the process of keeping it up-to-date more lightweight.
Please keep the descriptions to a single line, starting with the
package or cmd/xxx directory name, and ending in a CL number.
Please keep the list sorted (as in sort.Strings of the lines).
Performance:
compress/bzip2: faster decompression by 30% (CL 9915043).
crypto/des: 5x faster encoding/decoding (CL 11874043, 12072045).
encoding/json: faster encoding (CL 9129044).
net: improve windows performance by up to 30% (CL 8670044).
net: improve performance on BSD by up to 30% (CL 8264043, 12927048, 13080043).
Breaking change:
archive/tar,archive/zip: fix os.FileInfo implementation to provide base name only (CL 13118043).
cmd/5a: removed support for R9/R10 (use m/g instead) (CL 9840043).
cmd/5l: add MOVBS, MOVHS etc for sub-word moves (CL 12682043).
cmd/5l: support for external linking for linux/arm (CL 12871044).
cmd/cgo, cmd/go: support including C++ code with cgo (CL 8248043).
cmd/gc: three-index slicing to set cap as well as length (CL 10743046).
cmd/gc: make missing package error fatal (CL 12677043).
cmd/go: test coverage (CL 10413044).
cmd/go: add -t flag to 'go get' to download test dependencies (CL 12566046).
cmd/go: delete 'go doc' (CL 12974043).
archive/zip: add File.DataOffset accessor (CL 12784045).
bufio: add Reset methods to Reader and Writer (CL 12603049).
compress/bzip2: support concatenated files (CL 12387044).
compress/flate: add Reset method on Writer (CL 12265043).
compress/gzip: add Reset method on Writer (CL 13435043).
container/heap: added Fix (CL 12265043).
container/list: added MoveBefore and MoveAfter (CL 12021044).
crypto/cipher: AES-GCM mode (CL 12375043).
crypto/md5: Sum function to simplify hashing (CL10624044).
crypto/sha1: Sum function to simplify hashing (CL 10571043).
crypto/sha256: Sum256 and Sum224 functions to simplify hashing (CL 10629043).
crypto/sha512: Sum512 and Sum384 functions to simplify hashing (CL 10630043).
crypto/x509: add support for reading and writing arbitrary extensions (CL 12056043).
crypto/tls: add support for TLS 1.1, 1.2 and AES-GCM. (CL 7872043, 10762044 and 13249044).
database/sql: add SetMaxOpenConns method on DB (CL 10726044).
encoding: new package defining generic encoding interfaces (CL 12541051).
encoding/csv: always allow trailing commas (CL 12294043).
encoding/gob: support generic encoding interfaces (CL 12681044).
encoding/json: accept but correct invalid UTF-8 in Marshal (CL 11211045).
encoding/json: always escape ampersands (CL 12708044).
encoding/json: support generic encoding interfaces (CL 12703043).
encoding/xml: allow attributes stored in pointers to be marshaled (CL 8653047).
encoding/xml: add Marshaler, MarshalerAttr interfaces (CL 12919043).
encoding/xml: add Unmarshaler, UnmarshalerAttr interfaces (CL 12556043).
encoding/xml: support generic encoding interfaces (CL 12751045).
flag: add Getter interface (CL 10472043).
flag: export commandLine (now CommandLine) (CL 12587043).
fmt: indexed access to arguments in Printf etc. (CL 9680043).
go/build: support including C++ code with cgo (CL 8248043).
go/build: add Package.AllTags (CL 12703044).
image/draw: added Drawer, FloydSteinberg and the op.Draw method (CL 10977043).
image/draw: added Quantizer type (CL 11148043).
image/gif: added Encode and EncodeAll (CL 10896043).
io: Copy prioritizes WriterTo over ReaderFrom (CL 9462044).
net: new build tag netgo for building a pure Go net package (CL 7100050).
net/http: don't allow sending invalid cookie lines (CL 12204043).
net/http: allow ReadResponse with nil *Request parameter (CL 9821043).
net/http: allow responses to HEAD requests, detect type and length (CL 12583043).
runtime: relax constraint on finalizer func in SetFinalizer (CL 12895043).
runtime: preemption of goroutines at function entry (CL 12371043).
sort: new Stable function provides stable sort (CL 9612044).
strings: add IndexByte, for consistency with bytes package (CL 12214044).
sync/atomic: add Swap functions (CL 12670045).
syscall: implemented Sendfile for Darwin, added Syscall9 for Darwin/amd64 (CL 10980043).
testing: AllocsPerRun is now quantized to an integer (the type is still float64) (CL 9837049).
testing: add TB interface (intersection of T and B's methods) (CL 12962043).
text/template: add comparison functions (CL 13091045).
text/template: dereference pointer values when evaluating args escape funcs (CL 13257043).
text/template: allow {{else if ... }} to simplify if chains (CL 13327043).
time: Allow Parse and Format to handle time zone offsets with seconds (CL 8132044)
time: patterns require non-lowercase letter to follow Mon, Jan etc (CL 12448044).
unicode: add In, a nicer-to-use but equivalent version of IsOneOf (CL 11672044).