mirror of
https://github.com/golang/go
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75d7a02e86
Fixes #21603 Change-Id: I42fb7ea2dd7f6d6a201171055beaeda68c26b823 Reviewed-on: https://go-review.googlesource.com/59530 Reviewed-by: Ian Lance Taylor <iant@golang.org>
1025 lines
37 KiB
HTML
1025 lines
37 KiB
HTML
<!--{
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"Title": "Go 1.9 Release Notes",
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"Path": "/doc/go1.9",
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"Template": true
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}-->
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<!--
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NOTE: In this document and others in this directory, the convention is to
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set fixed-width phrases with non-fixed-width spaces, as in
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<code>hello</code> <code>world</code>.
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Do not send CLs removing the interior tags from such phrases.
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-->
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<style>
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ul li { margin: 0.5em 0; }
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</style>
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<h2 id="introduction">Introduction to Go 1.9</h2>
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<p>
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The latest Go release, version 1.9, arrives six months
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after <a href="go1.8">Go 1.8</a> and is the tenth release in
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the <a href="https://golang.org/doc/devel/release.html">Go 1.x
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series</a>.
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There are two <a href="#language">changes to the language</a>:
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adding support for type aliases and defining when implementations
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may fuse floating point operations.
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Most of the changes are in the implementation of the toolchain,
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runtime, and libraries.
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As always, the release maintains the Go 1
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<a href="/doc/go1compat.html">promise of compatibility</a>.
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We expect almost all Go programs to continue to compile and run as
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before.
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</p>
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<p>
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The release
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adds <a href="#monotonic-time">transparent monotonic time support</a>,
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<a href="#parallel-compile">parallelizes compilation of functions</a> within a package,
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better supports <a href="#test-helper">test helper functions</a>,
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includes a new <a href="#math-bits">bit manipulation package</a>,
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and has a new <a href="#sync-map">concurrent map type</a>.
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</p>
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<h2 id="language">Changes to the language</h2>
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<p>
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There are two changes to the language.
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</p>
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<p>
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Go now supports type aliases to support gradual code repair while
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moving a type between packages.
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The <a href="https://golang.org/design/18130-type-alias">type alias
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design document</a>
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and <a href="https://talks.golang.org/2016/refactor.article">an
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article on refactoring</a> cover the problem in detail.
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In short, a type alias declaration has the form:
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</p>
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<pre>
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type T1 = T2
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</pre>
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<p>
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This declaration introduces an alias name <code>T1</code>—an
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alternate spelling—for the type denoted by <code>T2</code>; that is,
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both <code>T1</code> and <code>T2</code> denote the same type.
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</p>
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<p> <!-- CL 40391 -->
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A smaller language change is that the
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<a href="/ref/spec#Floating_point_operators">language specification
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now states</a> when implementations are allowed to fuse floating
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point operations together, such as by using an architecture's "fused
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multiply and add" (FMA) instruction to compute <code>x*y</code> <code>+</code> <code>z</code>
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without rounding the intermediate result <code>x*y</code>.
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To force the intermediate rounding, write <code>float64(x*y)</code> <code>+</code> <code>z</code>.
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</p>
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<h2 id="ports">Ports</h2>
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<p>
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There are no new supported operating systems or processor
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architectures in this release.
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</p>
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<h3 id="power8">ppc64x requires POWER8</h3>
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<p> <!-- CL 36725, CL 36832 -->
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Both <code>GOARCH=ppc64</code> and <code>GOARCH=ppc64le</code> now
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require at least POWER8 support. In previous releases,
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only <code>GOARCH=ppc64le</code> required POWER8 and the big
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endian <code>ppc64</code> architecture supported older
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hardware.
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<p>
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<h3 id="freebsd">FreeBSD</h3>
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<p>
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Go 1.9 is the last release that will run on FreeBSD 9.3,
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which is already
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<a href="https://www.freebsd.org/security/unsupported.html">unsupported by FreeBSD</a>.
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Go 1.10 will require FreeBSD 10.3+.
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</p>
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<h3 id="openbsd">OpenBSD 6.0</h3>
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<p> <!-- CL 40331 -->
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Go 1.9 now enables PT_TLS generation for cgo binaries and thus
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requires OpenBSD 6.0 or newer. Go 1.9 no longer supports
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OpenBSD 5.9.
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<p>
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<h3 id="known_issues">Known Issues</h3>
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<p>
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There are some instabilities on FreeBSD that are known but not understood.
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These can lead to program crashes in rare cases.
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See <a href="https://golang.org/issue/15658">issue 15658</a>.
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Any help in solving this FreeBSD-specific issue would be appreciated.
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</p>
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<p>
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Go stopped running NetBSD builders during the Go 1.9 development
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cycle due to NetBSD kernel crashes, up to and including NetBSD 7.1.
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As Go 1.9 is being released, NetBSD 7.1.1 is being released with a fix.
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However, at this time we have no NetBSD builders passing our test suite.
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Any help investigating the
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<a href="https://github.com/golang/go/labels/OS-NetBSD">various NetBSD issues</a>
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would be appreciated.
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</p>
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<h2 id="tools">Tools</h2>
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<h3 id="parallel-compile">Parallel Compilation</h3>
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<p>
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The Go compiler now supports compiling a package's functions in parallel, taking
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advantage of multiple cores. This is in addition to the <code>go</code> command's
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existing support for parallel compilation of separate packages.
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Parallel compilation is on by default, but it can be disabled by setting the
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environment variable <code>GO19CONCURRENTCOMPILATION</code> to <code>0</code>.
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</p>
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<h3 id="vendor-dotdotdot">Vendor matching with ./...</h3>
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<p><!-- CL 38745 -->
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By popular request, <code>./...</code> no longer matches packages
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in <code>vendor</code> directories in tools accepting package names,
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such as <code>go</code> <code>test</code>. To match vendor
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directories, write <code>./vendor/...</code>.
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</p>
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<h3 id="goroot">Moved GOROOT</h3>
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<p><!-- CL 42533 -->
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The <a href="/cmd/go/">go tool</a> will now use the path from which it
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was invoked to attempt to locate the root of the Go install tree.
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This means that if the entire Go installation is moved to a new
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location, the go tool should continue to work as usual.
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This may be overridden by setting <code>GOROOT</code> in the environment,
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which should only be done in unusual circumstances.
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Note that this does not affect the result of
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the <a href="/pkg/runtime/#GOROOT">runtime.GOROOT</a> function, which
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will continue to report the original installation location;
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this may be fixed in later releases.
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</p>
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<h3 id="compiler">Compiler Toolchain</h3>
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<p><!-- CL 37441 -->
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Complex division is now C99-compatible. This has always been the
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case in gccgo and is now fixed in the gc toolchain.
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</p>
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<p> <!-- CL 36983 -->
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The linker will now generate DWARF information for cgo executables on Windows.
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</p>
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<p> <!-- CL 44210, CL 40095 -->
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The compiler now includes lexical scopes in the generated DWARF if the
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<code>-N -l</code> flags are provided, allowing
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debuggers to hide variables that are not in scope. The <code>.debug_info</code>
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section is now DWARF version 4.
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</p>
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<p> <!-- CL 43855 -->
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The values of <code>GOARM</code> and <code>GO386</code> now affect a
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compiled package's build ID, as used by the <code>go</code> tool's
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dependency caching.
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</p>
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<h3 id="asm">Assembler</h3>
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<p> <!-- CL 42028 -->
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The four-operand ARM <code>MULA</code> instruction is now assembled correctly,
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with the addend register as the third argument and the result
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register as the fourth and final argument.
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In previous releases, the two meanings were reversed.
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The three-operand form, in which the fourth argument is implicitly
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the same as the third, is unaffected.
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Code using four-operand <code>MULA</code> instructions
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will need to be updated, but we believe this form is very rarely used.
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<code>MULAWT</code> and <code>MULAWB</code> were already
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using the correct order in all forms and are unchanged.
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</p>
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<p> <!-- CL 42990 -->
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The assembler now supports <code>ADDSUBPS/PD</code>, completing the
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two missing x86 SSE3 instructions.
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</p>
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<h3 id="go-doc">Doc</h3>
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<p><!-- CL 36031 -->
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Long lists of arguments are now truncated. This improves the readability
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of <code>go</code> <code>doc</code> on some generated code.
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</p>
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<p><!-- CL 38438 -->
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Viewing documentation on struct fields is now supported.
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For example, <code>go</code> <code>doc</code> <code>http.Client.Jar</code>.
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</p>
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<h3 id="go-env-json">Env</h3>
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<p> <!-- CL 38757 -->
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The new <code>go</code> <code>env</code> <code>-json</code> flag
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enables JSON output, instead of the default OS-specific output
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format.
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</p>
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<h3 id="go-test-list">Test</h3>
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<p> <!-- CL 41195 -->
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The <a href="/cmd/go/#hdr-Description_of_testing_flags"><code>go</code> <code>test</code></a>
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command accepts a new <code>-list</code> flag, which takes a regular
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expression as an argument and prints to stdout the name of any
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tests, benchmarks, or examples that match it, without running them.
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</p>
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<h3 id="go-tool-pprof">Pprof</h3>
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<p> <!-- CL 34192 -->
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Profiles produced by the <code>runtime/pprof</code> package now
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include symbol information, so they can be viewed
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in <code>go</code> <code>tool</code> <code>pprof</code>
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without the binary that produced the profile.
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</p>
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<p> <!-- CL 38343 -->
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The <code>go</code> <code>tool</code> <code>pprof</code> command now
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uses the HTTP proxy information defined in the environment, using
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<a href="/pkg/net/http/#ProxyFromEnvironment"><code>http.ProxyFromEnvironment</code></a>.
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</p>
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<h3 id="vet">Vet</h3>
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<!-- CL 40112 -->
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<p>
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The <a href="/cmd/vet/"><code>vet</code> command</a>
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has been better integrated into the
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<a href="/cmd/go/"><code>go</code> tool</a>,
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so <code>go</code> <code>vet</code> now supports all standard build
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flags while <code>vet</code>'s own flags are now available
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from <code>go</code> <code>vet</code> as well as
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from <code>go</code> <code>tool</code> <code>vet</code>.
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</p>
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<h3 id="gccgo">Gccgo</h3>
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<p>
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Due to the alignment of Go's semiannual release schedule with GCC's
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annual release schedule,
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GCC release 7 contains the Go 1.8.3 version of gccgo.
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We expect that the next release, GCC 8, will contain the Go 1.10
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version of gccgo.
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</p>
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<h2 id="runtime">Runtime</h2>
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<h3 id="callersframes">Call stacks with inlined frames</h3>
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<p>
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Users of
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<a href="/pkg/runtime#Callers"><code>runtime.Callers</code></a>
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should avoid directly inspecting the resulting PC slice and instead use
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<a href="/pkg/runtime#CallersFrames"><code>runtime.CallersFrames</code></a>
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to get a complete view of the call stack, or
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<a href="/pkg/runtime#Caller"><code>runtime.Caller</code></a>
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to get information about a single caller.
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This is because an individual element of the PC slice cannot account
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for inlined frames or other nuances of the call stack.
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</p>
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<p>
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Specifically, code that directly iterates over the PC slice and uses
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functions such as
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<a href="/pkg/runtime#FuncForPC"><code>runtime.FuncForPC</code></a>
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to resolve each PC individually will miss inlined frames.
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To get a complete view of the stack, such code should instead use
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<code>CallersFrames</code>.
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Likewise, code should not assume that the length returned by
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<code>Callers</code> is any indication of the call depth.
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It should instead count the number of frames returned by
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<code>CallersFrames</code>.
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</p>
|
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<p>
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Code that queries a single caller at a specific depth should use
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<code>Caller</code> rather than passing a slice of length 1 to
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<code>Callers</code>.
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</p>
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<p>
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<a href="/pkg/runtime#CallersFrames"><code>runtime.CallersFrames</code></a>
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has been available since Go 1.7, so code can be updated prior to
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upgrading to Go 1.9.
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</p>
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<h2 id="performance">Performance</h2>
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<p>
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As always, the changes are so general and varied that precise
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statements about performance are difficult to make. Most programs
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should run a bit faster, due to speedups in the garbage collector,
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better generated code, and optimizations in the core library.
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</p>
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<h3 id="gc">Garbage Collector</h3>
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<p> <!-- CL 37520 -->
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Library functions that used to trigger stop-the-world garbage
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collection now trigger concurrent garbage collection.
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Specifically, <a href="/pkg/runtime/#GC"><code>runtime.GC</code></a>,
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<a href="/pkg/runtime/debug/#SetGCPercent"><code>debug.SetGCPercent</code></a>,
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and
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<a href="/pkg/runtime/debug/#FreeOSMemory"><code>debug.FreeOSMemory</code></a>,
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now trigger concurrent garbage collection, blocking only the calling
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goroutine until the garbage collection is done.
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</p>
|
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<p> <!-- CL 34103, CL 39835 -->
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The
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<a href="/pkg/runtime/debug/#SetGCPercent"><code>debug.SetGCPercent</code></a>
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function only triggers a garbage collection if one is immediately
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necessary because of the new GOGC value.
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This makes it possible to adjust GOGC on-the-fly.
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</p>
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<p> <!-- CL 38732 -->
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Large object allocation performance is significantly improved in
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applications using large (>50GB) heaps containing many large
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objects.
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</p>
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<p> <!-- CL 34937 -->
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The <a href="/pkg/runtime/#ReadMemStats"><code>runtime.ReadMemStats</code></a>
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function now takes less than 100µs even for very large heaps.
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</p>
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<h2 id="library">Core library</h2>
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<h3 id="monotonic-time">Transparent Monotonic Time support</h3>
|
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<p> <!-- CL 36255 -->
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The <a href="/pkg/time/"><code>time</code></a> package now transparently
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tracks monotonic time in each <a href="/pkg/time/#Time"><code>Time</code></a>
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value, making computing durations between two <code>Time</code> values
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a safe operation in the presence of wall clock adjustments.
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See the <a href="/pkg/time/#hdr-Monotonic_Clocks">package docs</a> and
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<a href="https://golang.org/design/12914-monotonic">design document</a>
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for details.
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</p>
|
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<h3 id="math-bits">New bit manipulation package</h3>
|
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<p> <!-- CL 36315 -->
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Go 1.9 includes a new package,
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<a href="/pkg/math/bits/"><code>math/bits</code></a>, with optimized
|
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implementations for manipulating bits. On most architectures,
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functions in this package are additionally recognized by the
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compiler and treated as intrinsics for additional performance.
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</p>
|
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<h3 id="test-helper">Test Helper Functions</h3>
|
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<p> <!-- CL 38796 -->
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The
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new <a href="/pkg/testing/#T.Helper"><code>(*T).Helper</code></a>
|
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and <a href="/pkg/testing/#B.Helper"><code>(*B).Helper</code></a>
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methods mark the calling function as a test helper function. When
|
|
printing file and line information, that function will be skipped.
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This permits writing test helper functions while still having useful
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|
line numbers for users.
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</p>
|
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|
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<h3 id="sync-map">Concurrent Map</h3>
|
|
|
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<p> <!-- CL 36617 -->
|
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The new <a href="/pkg/sync/#Map"><code>Map</code></a> type
|
|
in the <a href="/pkg/sync/"><code>sync</code></a> package
|
|
is a concurrent map with amortized-constant-time loads, stores, and
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|
deletes. It is safe for multiple goroutines to call a <code>Map</code>'s methods
|
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concurrently.
|
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</p>
|
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|
|
<h3 id="pprof-labels">Profiler Labels</h3>
|
|
|
|
<p><!-- CL 34198 -->
|
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The <a href="/pkg/runtime/pprof"><code>runtime/pprof</code> package</a>
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now supports adding labels to <code>pprof</code> profiler records.
|
|
Labels form a key-value map that is used to distinguish calls of the
|
|
same function in different contexts when looking at profiles
|
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with the <a href="/cmd/pprof/"><code>pprof</code> command</a>.
|
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The <code>pprof</code> package's
|
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new <a href="/pkg/runtime/pprof/#Do"><code>Do</code> function</a>
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runs code associated with some provided labels. Other new functions
|
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in the package help work with labels.
|
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</p>
|
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</dl><!-- runtime/pprof -->
|
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|
|
|
|
<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 39570 -->
|
|
The
|
|
ZIP <a href="/pkg/archive/zip/#Writer"><code>Writer</code></a>
|
|
now sets the UTF-8 bit in
|
|
the <a href="/pkg/archive/zip/#FileHeader.Flags"><code>FileHeader.Flags</code></a>
|
|
when appropriate.
|
|
</p>
|
|
|
|
</dl><!-- archive/zip -->
|
|
|
|
<dl id="crypto/rand"><dt><a href="/pkg/crypto/rand/">crypto/rand</a></dt>
|
|
<dd>
|
|
<p><!-- CL 43852 -->
|
|
On Linux, Go now calls the <code>getrandom</code> system call
|
|
without the <code>GRND_NONBLOCK</code> flag; it will now block
|
|
until the kernel has sufficient randomness. On kernels predating
|
|
the <code>getrandom</code> system call, Go continues to read
|
|
from <code>/dev/urandom</code>.
|
|
</p>
|
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|
|
</dl><!-- crypto/rand -->
|
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|
|
<dl id="crypto/x509"><dt><a href="/pkg/crypto/x509/">crypto/x509</a></dt>
|
|
<dd>
|
|
<p><!-- CL 36093 -->
|
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|
|
On Unix systems the environment
|
|
variables <code>SSL_CERT_FILE</code>
|
|
and <code>SSL_CERT_DIR</code> can now be used to override the
|
|
system default locations for the SSL certificate file and SSL
|
|
certificate files directory, respectively.
|
|
</p>
|
|
|
|
<p>The FreeBSD file <code>/usr/local/etc/ssl/cert.pem</code> is
|
|
now included in the certificate search path.
|
|
</p>
|
|
|
|
<p><!-- CL 36900 -->
|
|
|
|
The package now supports excluded domains in name constraints.
|
|
In addition to enforcing such constraints,
|
|
<a href="/pkg/crypto/x509/#CreateCertificate"><code>CreateCertificate</code></a>
|
|
will create certificates with excluded name constraints
|
|
if the provided template certificate has the new
|
|
field
|
|
<a href="/pkg/crypto/x509/#Certificate.ExcludedDNSDomains"><code>ExcludedDNSDomains</code></a>
|
|
populated.
|
|
</p>
|
|
|
|
<p><!-- CL 36696 -->
|
|
|
|
If any SAN extension, including with no DNS names, is present
|
|
in the certificate, then the Common Name from
|
|
<a href="/pkg/crypto/x509/#Certificate.Subject"><code>Subject</code></a> is ignored.
|
|
In previous releases, the code tested only whether DNS-name SANs were
|
|
present in a certificate.
|
|
</p>
|
|
|
|
</dl><!-- crypto/x509 -->
|
|
|
|
<dl id="database/sql"><dt><a href="/pkg/database/sql/">database/sql</a></dt>
|
|
<dd>
|
|
<p><!-- CL 35476 -->
|
|
The package will now use a cached <a href="/pkg/database/sql/#Stmt"><code>Stmt</code></a> if
|
|
available in <a href="/pkg/database/sql/#Tx.Stmt"><code>Tx.Stmt</code></a>.
|
|
This prevents statements from being re-prepared each time
|
|
<a href="/pkg/database/sql/#Tx.Stmt"><code>Tx.Stmt</code></a> is called.
|
|
</p>
|
|
|
|
<p><!-- CL 38533 -->
|
|
The package now allows drivers to implement their own argument checkers by implementing
|
|
<a href="/pkg/database/sql/driver/#NamedValueChecker"><code>driver.NamedValueChecker</code></a>.
|
|
This also allows drivers to support <code>OUTPUT</code> and <code>INOUT</code> parameter types.
|
|
<a href="/pkg/database/sql/#Out"><code>Out</code></a> should be used to return output parameters
|
|
when supported by the driver.
|
|
</p>
|
|
|
|
<p><!-- CL 39031 -->
|
|
<a href="/pkg/database/sql/#Rows.Scan"><code>Rows.Scan</code></a> can now scan user-defined string types.
|
|
Previously the package supported scanning into numeric types like <code>type</code> <code>Int</code> <code>int64</code>. It now also supports
|
|
scanning into string types like <code>type</code> <code>String</code> <code>string</code>.
|
|
</p>
|
|
|
|
<p><!-- CL 40694 -->
|
|
The new <a href="/pkg/database/sql/#DB.Conn"><code>DB.Conn</code></a> method returns the new
|
|
<a href="/pkg/database/sql/#Conn"><code>Conn</code></a> type representing an
|
|
exclusive connection to the database from the connection pool. All queries run on
|
|
a <a href="/pkg/database/sql/#Conn"><code>Conn</code></a> will use the same underlying
|
|
connection until <a href="/pkg/database/sql/#Conn.Close"><code>Conn.Close</code></a> is called
|
|
to return the connection to the connection pool.
|
|
</p>
|
|
|
|
</dl><!-- database/sql -->
|
|
|
|
<dl id="encoding/asn1"><dt><a href="/pkg/encoding/asn1/">encoding/asn1</a></dt>
|
|
<dd>
|
|
<p><!-- CL 38660 -->
|
|
The new
|
|
<a href="/pkg/encoding/asn1/#NullBytes"><code>NullBytes</code></a>
|
|
and
|
|
<a href="/pkg/encoding/asn1/#NullRawValue"><code>NullRawValue</code></a>
|
|
represent the ASN.1 NULL type.
|
|
</p>
|
|
|
|
</dl><!-- encoding/asn1 -->
|
|
|
|
<dl id="encoding/base32"><dt><a href="/pkg/encoding/base32/">encoding/base32</a></dt>
|
|
<dd>
|
|
<p><!-- CL 38634 -->
|
|
The new <a href="/pkg/encoding/base32/#Encoding.WithPadding">Encoding.WithPadding</a>
|
|
method adds support for custom padding characters and disabling padding.
|
|
</p>
|
|
|
|
</dl><!-- encoding/base32 -->
|
|
|
|
<dl id="encoding/csv"><dt><a href="/pkg/encoding/csv/">encoding/csv</a></dt>
|
|
<dd>
|
|
<p><!-- CL 41730 -->
|
|
The new field
|
|
<a href="/pkg/encoding/csv/#Reader.ReuseRecord"><code>Reader.ReuseRecord</code></a>
|
|
controls whether calls to
|
|
<a href="/pkg/encoding/csv/#Reader.Read"><code>Read</code></a>
|
|
may return a slice sharing the backing array of the previous
|
|
call's returned slice for improved performance.
|
|
</p>
|
|
|
|
</dl><!-- encoding/csv -->
|
|
|
|
<dl id="fmt"><dt><a href="/pkg/fmt/">fmt</a></dt>
|
|
<dd>
|
|
<p><!-- CL 37051 -->
|
|
The sharp flag ('<code>#</code>') is now supported when printing
|
|
floating point and complex numbers. It will always print a
|
|
decimal point
|
|
for <code>%e</code>, <code>%E</code>, <code>%f</code>, <code>%F</code>, <code>%g</code>
|
|
and <code>%G</code>; it will not remove trailing zeros
|
|
for <code>%g</code> and <code>%G</code>.
|
|
</p>
|
|
|
|
</dl><!-- fmt -->
|
|
|
|
<dl id="hash/fnv"><dt><a href="/pkg/hash/fnv/">hash/fnv</a></dt>
|
|
<dd>
|
|
<p><!-- CL 38356 -->
|
|
The package now includes 128-bit FNV-1 and FNV-1a hash support with
|
|
<a href="/pkg/hash/fnv/#New128"><code>New128</code></a> and
|
|
<a href="/pkg/hash/fnv/#New128a"><code>New128a</code></a>, respectively.
|
|
</p>
|
|
|
|
</dl><!-- hash/fnv -->
|
|
|
|
<dl id="html/template"><dt><a href="/pkg/html/template/">html/template</a></dt>
|
|
<dd>
|
|
<p><!-- CL 37880, CL 40936 -->
|
|
The package now reports an error if a predefined escaper (one of
|
|
"html", "urlquery" and "js") is found in a pipeline and does not match
|
|
what the auto-escaper would have decided on its own.
|
|
This avoids certain security or correctness issues.
|
|
Now use of one of these escapers is always either a no-op or an error.
|
|
(The no-op case eases migration from <a href="/pkg/text/template/">text/template</a>.)
|
|
</p>
|
|
|
|
</dl><!-- html/template -->
|
|
|
|
<dl id="image"><dt><a href="/pkg/image/">image</a></dt>
|
|
<dd>
|
|
<p><!-- CL 36734 -->
|
|
The <a href="/pkg/image/#Rectangle.Intersect"><code>Rectangle.Intersect</code></a>
|
|
method now returns a zero <code>Rectangle</code> when called on
|
|
adjacent but non-overlapping rectangles, as documented. In
|
|
earlier releases it would incorrectly return an empty but
|
|
non-zero <code>Rectangle</code>.
|
|
</p>
|
|
|
|
</dl><!-- image -->
|
|
|
|
<dl id="image/color"><dt><a href="/pkg/image/color/">image/color</a></dt>
|
|
<dd>
|
|
<p><!-- CL 36732 -->
|
|
The YCbCr to RGBA conversion formula has been tweaked to ensure
|
|
that rounding adjustments span the complete [0, 0xffff] RGBA
|
|
range.
|
|
</p>
|
|
|
|
</dl><!-- image/color -->
|
|
|
|
<dl id="image/png"><dt><a href="/pkg/image/png/">image/png</a></dt>
|
|
<dd>
|
|
<p><!-- CL 34150 -->
|
|
The new <a href="/pkg/image/png/#Encoder.BufferPool"><code>Encoder.BufferPool</code></a>
|
|
field allows specifying an <a href="/pkg/image/png/#EncoderBufferPool"><code>EncoderBufferPool</code></a>,
|
|
that will be used by the encoder to get temporary <code>EncoderBuffer</code>
|
|
buffers when encoding a PNG image.
|
|
|
|
The use of a <code>BufferPool</code> reduces the number of
|
|
memory allocations performed while encoding multiple images.
|
|
</p>
|
|
|
|
<p><!-- CL 38271 -->
|
|
The package now supports the decoding of transparent 8-bit
|
|
grayscale ("Gray8") images.
|
|
</p>
|
|
|
|
</dl><!-- image/png -->
|
|
|
|
<dl id="math/big"><dt><a href="/pkg/math/big/">math/big</a></dt>
|
|
<dd>
|
|
<p><!-- CL 36487 -->
|
|
The new
|
|
<a href="/pkg/math/big/#Int.IsInt64"><code>IsInt64</code></a>
|
|
and
|
|
<a href="/pkg/math/big/#Int.IsUint64"><code>IsUint64</code></a>
|
|
methods report whether an <code>Int</code>
|
|
may be represented as an <code>int64</code> or <code>uint64</code>
|
|
value.
|
|
</p>
|
|
|
|
</dl><!-- math/big -->
|
|
|
|
<dl id="mime/multipart"><dt><a href="/pkg/mime/multipart/">mime/multipart</a></dt>
|
|
<dd>
|
|
<p><!-- CL 39223 -->
|
|
The new
|
|
<a href="/pkg/mime/multipart/#FileHeader.Size"><code>FileHeader.Size</code></a>
|
|
field describes the size of a file in a multipart message.
|
|
</p>
|
|
|
|
</dl><!-- mime/multipart -->
|
|
|
|
<dl id="net"><dt><a href="/pkg/net/">net</a></dt>
|
|
<dd>
|
|
<p><!-- CL 32572 -->
|
|
The new
|
|
<a href="/pkg/net/#Resolver.StrictErrors"><code>Resolver.StrictErrors</code></a>
|
|
provides control over how Go's built-in DNS resolver handles
|
|
temporary errors during queries composed of multiple sub-queries,
|
|
such as an A+AAAA address lookup.
|
|
</p>
|
|
|
|
<p><!-- CL 37260 -->
|
|
The new
|
|
<a href="/pkg/net/#Resolver.Dial"><code>Resolver.Dial</code></a>
|
|
allows a <code>Resolver</code> to use a custom dial function.
|
|
</p>
|
|
|
|
<p><!-- CL 40510 -->
|
|
<a href="/pkg/net/#JoinHostPort"><code>JoinHostPort</code></a> now only places an address in square brackets if the host contains a colon.
|
|
In previous releases it would also wrap addresses in square brackets if they contained a percent ('<code>%</code>') sign.
|
|
</p>
|
|
|
|
<p><!-- CL 37913 -->
|
|
The new methods
|
|
<a href="/pkg/net/#TCPConn.SyscallConn"><code>TCPConn.SyscallConn</code></a>,
|
|
<a href="/pkg/net/#IPConn.SyscallConn"><code>IPConn.SyscallConn</code></a>,
|
|
<a href="/pkg/net/#UDPConn.SyscallConn"><code>UDPConn.SyscallConn</code></a>,
|
|
and
|
|
<a href="/pkg/net/#UnixConn.SyscallConn"><code>UnixConn.SyscallConn</code></a>
|
|
provide access to the connections' underlying file descriptors.
|
|
</p>
|
|
|
|
<p><!-- 45088 -->
|
|
It is now safe to call <a href="/pkg/net/#Dial"><code>Dial</code></a> with the address obtained from
|
|
<code>(*TCPListener).String()</code> after creating the listener with
|
|
<code><a href="/pkg/net/#Listen">Listen</a>("tcp", ":0")</code>.
|
|
Previously it failed on some machines with half-configured IPv6 stacks.
|
|
</p>
|
|
|
|
</dl><!-- net -->
|
|
|
|
<dl id="net/http"><dt><a href="/pkg/net/http/">net/http</a></dt>
|
|
<dd>
|
|
|
|
<p><!-- CL 37328 -->
|
|
The <a href="/pkg/net/http/#Cookie.String"><code>Cookie.String</code></a> method, used for
|
|
<code>Cookie</code> and <code>Set-Cookie</code> headers, now encloses values in double quotes
|
|
if the value contains either a space or a comma.
|
|
</p>
|
|
|
|
<p>Server changes:</p>
|
|
<ul>
|
|
<li><!-- CL 38194 -->
|
|
<a href="/pkg/net/http/#ServeMux"><code>ServeMux</code></a> now ignores ports in the host
|
|
header when matching handlers. The host is matched unmodified for <code>CONNECT</code> requests.
|
|
</li>
|
|
|
|
<li><!-- CL 44074 -->
|
|
The new <a href="/pkg/net/http/#Server.ServeTLS"><code>Server.ServeTLS</code></a> method wraps
|
|
<a href="/pkg/net/http/#Server.Serve"><code>Server.Serve</code></a> with added TLS support.
|
|
</li>
|
|
|
|
<li><!-- CL 34727 -->
|
|
<a href="/pkg/net/http/#Server.WriteTimeout"><code>Server.WriteTimeout</code></a>
|
|
now applies to HTTP/2 connections and is enforced per-stream.
|
|
</li>
|
|
|
|
<li><!-- CL 43231 -->
|
|
HTTP/2 now uses the priority write scheduler by default.
|
|
Frames are scheduled by following HTTP/2 priorities as described in
|
|
<a href="https://tools.ietf.org/html/rfc7540#section-5.3">RFC 7540 Section 5.3</a>.
|
|
</li>
|
|
|
|
<li><!-- CL 36483 -->
|
|
The HTTP handler returned by <a href="/pkg/net/http/#StripPrefix"><code>StripPrefix</code></a>
|
|
now calls its provided handler with a modified clone of the original <code>*http.Request</code>.
|
|
Any code storing per-request state in maps keyed by <code>*http.Request</code> should
|
|
use
|
|
<a href="/pkg/net/http/#Request.Context"><code>Request.Context</code></a>,
|
|
<a href="/pkg/net/http/#Request.WithContext"><code>Request.WithContext</code></a>,
|
|
and
|
|
<a href="/pkg/context/#WithValue"><code>context.WithValue</code></a> instead.
|
|
</li>
|
|
|
|
<li><!-- CL 35490 -->
|
|
<a href="/pkg/net/http/#LocalAddrContextKey"><code>LocalAddrContextKey</code></a> now contains
|
|
the connection's actual network address instead of the interface address used by the listener.
|
|
</li>
|
|
</ul>
|
|
|
|
<p>Client & Transport changes:</p>
|
|
<ul>
|
|
<li><!-- CL 35488 -->
|
|
The <a href="/pkg/net/http/#Transport"><code>Transport</code></a>
|
|
now supports making requests via SOCKS5 proxy when the URL returned by
|
|
<a href="/pkg/net/http/#Transport.Proxy"><code>Transport.Proxy</code></a>
|
|
has the scheme <code>socks5</code>.
|
|
</li>
|
|
</ul>
|
|
|
|
</dl><!-- net/http -->
|
|
|
|
<dl id="net/http/fcgi"><dt><a href="/pkg/net/http/fcgi/">net/http/fcgi</a></dt>
|
|
<dd>
|
|
<p><!-- CL 40012 -->
|
|
The new
|
|
<a href="/pkg/net/http/fcgi/#ProcessEnv"><code>ProcessEnv</code></a>
|
|
function returns FastCGI environment variables associated with an HTTP request
|
|
for which there are no appropriate
|
|
<a href="/pkg/net/http/#Request"><code>http.Request</code></a>
|
|
fields, such as <code>REMOTE_USER</code>.
|
|
</p>
|
|
|
|
</dl><!-- net/http/fcgi -->
|
|
|
|
<dl id="net/http/httptest"><dt><a href="/pkg/net/http/httptest/">net/http/httptest</a></dt>
|
|
<dd>
|
|
<p><!-- CL 34639 -->
|
|
The new
|
|
<a href="/pkg/net/http/httptest/#Server.Client"><code>Server.Client</code></a>
|
|
method returns an HTTP client configured for making requests to the test server.
|
|
</p>
|
|
|
|
<p>
|
|
The new
|
|
<a href="/pkg/net/http/httptest/#Server.Certificate"><code>Server.Certificate</code></a>
|
|
method returns the test server's TLS certificate, if any.
|
|
</p>
|
|
|
|
</dl><!-- net/http/httptest -->
|
|
|
|
<dl id="net/http/httputil"><dt><a href="/pkg/net/http/httputil/">net/http/httputil</a></dt>
|
|
<dd>
|
|
<p><!-- CL 43712 -->
|
|
The <a href="/pkg/net/http/httputil/#ReverseProxy"><code>ReverseProxy</code></a>
|
|
now proxies all HTTP/2 response trailers, even those not declared in the initial response
|
|
header. Such undeclared trailers are used by the gRPC protocol.
|
|
</p>
|
|
|
|
</dl><!-- net/http/httputil -->
|
|
|
|
<dl id="os"><dt><a href="/pkg/os/">os</a></dt>
|
|
<dd>
|
|
<p><!-- CL 36800 -->
|
|
The <code>os</code> package now uses the internal runtime poller
|
|
for file I/O.
|
|
This reduces the number of threads required for read/write
|
|
operations on pipes, and it eliminates races when one goroutine
|
|
closes a file while another is using the file for I/O.
|
|
</p>
|
|
|
|
<dd>
|
|
<p><!-- CL 37915 -->
|
|
On Windows,
|
|
<a href="/pkg/os/#Args"><code>Args</code></a>
|
|
is now populated without <code>shell32.dll</code>, improving process start-up time by 1-7 ms.
|
|
</p>
|
|
|
|
</dl><!-- os -->
|
|
|
|
<dl id="os/exec"><dt><a href="/pkg/os/exec/">os/exec</a></dt>
|
|
<dd>
|
|
<p><!-- CL 37586 -->
|
|
The <code>os/exec</code> package now prevents child processes from being created with
|
|
any duplicate environment variables.
|
|
If <a href="/pkg/os/exec/#Cmd.Env"><code>Cmd.Env</code></a>
|
|
contains duplicate environment keys, only the last
|
|
value in the slice for each duplicate key is used.
|
|
</p>
|
|
|
|
</dl><!-- os/exec -->
|
|
|
|
<dl id="os/user"><dt><a href="/pkg/os/user/">os/user</a></dt>
|
|
<dd>
|
|
<p><!-- CL 37664 -->
|
|
<a href="/pkg/os/user/#Lookup"><code>Lookup</code></a> and
|
|
<a href="/pkg/os/user/#LookupId"><code>LookupId</code></a> now
|
|
work on Unix systems when <code>CGO_ENABLED=0</code> by reading
|
|
the <code>/etc/passwd</code> file.
|
|
</p>
|
|
|
|
<p><!-- CL 33713 -->
|
|
<a href="/pkg/os/user/#LookupGroup"><code>LookupGroup</code></a> and
|
|
<a href="/pkg/os/user/#LookupGroupId"><code>LookupGroupId</code></a> now
|
|
work on Unix systems when <code>CGO_ENABLED=0</code> by reading
|
|
the <code>/etc/group</code> file.
|
|
</p>
|
|
|
|
</dl><!-- os/user -->
|
|
|
|
<dl id="reflect"><dt><a href="/pkg/reflect/">reflect</a></dt>
|
|
<dd>
|
|
<p><!-- CL 38335 -->
|
|
The new
|
|
<a href="/pkg/reflect/#MakeMapWithSize"><code>MakeMapWithSize</code></a>
|
|
function creates a map with a capacity hint.
|
|
</p>
|
|
|
|
</dl><!-- reflect -->
|
|
|
|
<dl id="runtime"><dt><a href="/pkg/runtime/">runtime</a></dt>
|
|
<dd>
|
|
<p><!-- CL 37233, CL 37726 -->
|
|
Tracebacks generated by the runtime and recorded in profiles are
|
|
now accurate in the presence of inlining.
|
|
To retrieve tracebacks programmatically, applications should use
|
|
<a href="/pkg/runtime/#CallersFrames"><code>runtime.CallersFrames</code></a>
|
|
rather than directly iterating over the results of
|
|
<a href="/pkg/runtime/#Callers"><code>runtime.Callers</code></a>.
|
|
</p>
|
|
|
|
<p><!-- CL 38403 -->
|
|
On Windows, Go no longer forces the system timer to run at high
|
|
resolution when the program is idle.
|
|
This should reduce the impact of Go programs on battery life.
|
|
</p>
|
|
|
|
<p><!-- CL 29341 -->
|
|
On FreeBSD, <code>GOMAXPROCS</code> and
|
|
<a href="/pkg/runtime/#NumCPU"><code>runtime.NumCPU</code></a>
|
|
are now based on the process' CPU mask, rather than the total
|
|
number of CPUs.
|
|
</p>
|
|
|
|
<p><!-- CL 43641 -->
|
|
The runtime has preliminary support for Android O.
|
|
</p>
|
|
|
|
</dl><!-- runtime -->
|
|
|
|
<dl id="runtime/debug"><dt><a href="/pkg/runtime/debug/">runtime/debug</a></dt>
|
|
<dd>
|
|
<p><!-- CL 34013 -->
|
|
Calling
|
|
<a href="/pkg/runtime/debug/#SetGCPercent"><code>SetGCPercent</code></a>
|
|
with a negative value no longer runs an immediate garbage collection.
|
|
</p>
|
|
|
|
</dl><!-- runtime/debug -->
|
|
|
|
<dl id="runtime/trace"><dt><a href="/pkg/runtime/trace/">runtime/trace</a></dt>
|
|
<dd>
|
|
<p><!-- CL 36015 -->
|
|
The execution trace now displays mark assist events, which
|
|
indicate when an application goroutine is forced to assist
|
|
garbage collection because it is allocating too quickly.
|
|
</p>
|
|
|
|
<p><!-- CL 40810 -->
|
|
"Sweep" events now encompass the entire process of finding free
|
|
space for an allocation, rather than recording each individual
|
|
span that is swept.
|
|
This reduces allocation latency when tracing allocation-heavy
|
|
programs.
|
|
The sweep event shows how many bytes were swept and how many
|
|
were reclaimed.
|
|
</p>
|
|
|
|
</dl><!-- runtime/trace -->
|
|
|
|
<dl id="sync"><dt><a href="/pkg/sync/">sync</a></dt>
|
|
<dd>
|
|
<p><!-- CL 34310 -->
|
|
<a href="/pkg/sync/#Mutex"><code>Mutex</code></a> is now more fair.
|
|
</p>
|
|
|
|
</dl><!-- sync -->
|
|
|
|
<dl id="syscall"><dt><a href="/pkg/syscall/">syscall</a></dt>
|
|
<dd>
|
|
<p><!-- CL 36697 -->
|
|
The new field
|
|
<a href="/pkg/syscall/#Credential.NoSetGroups"><code>Credential.NoSetGroups</code></a>
|
|
controls whether Unix systems make a <code>setgroups</code> system call
|
|
to set supplementary groups when starting a new process.
|
|
</p>
|
|
|
|
<p><!-- CL 43512 -->
|
|
The new field
|
|
<a href="/pkg/syscall/#SysProcAttr.AmbientCaps"><code>SysProcAttr.AmbientCaps</code></a>
|
|
allows setting ambient capabilities on Linux 4.3+ when creating
|
|
a new process.
|
|
</p>
|
|
|
|
<p><!-- CL 37439 -->
|
|
On 64-bit x86 Linux, process creation latency has been optimized with
|
|
use of <code>CLONE_VFORK</code> and <code>CLONE_VM</code>.
|
|
</p>
|
|
|
|
<p><!-- CL 37913 -->
|
|
The new
|
|
<a href="/pkg/syscall/#Conn"><code>Conn</code></a>
|
|
interface describes some types in the
|
|
<a href="/pkg/net/"><code>net</code></a>
|
|
package that can provide access to their underlying file descriptor
|
|
using the new
|
|
<a href="/pkg/syscall/#RawConn"><code>RawConn</code></a>
|
|
interface.
|
|
</p>
|
|
|
|
</dl><!-- syscall -->
|
|
|
|
|
|
<dl id="testing/quick"><dt><a href="/pkg/testing/quick/">testing/quick</a></dt>
|
|
<dd>
|
|
<p><!-- CL 39152 -->
|
|
The package now chooses values in the full range when
|
|
generating <code>int64</code> and <code>uint64</code> random
|
|
numbers; in earlier releases generated values were always
|
|
limited to the [-2<sup>62</sup>, 2<sup>62</sup>) range.
|
|
</p>
|
|
|
|
<p>
|
|
In previous releases, using a nil
|
|
<a href="/pkg/testing/quick/#Config.Rand"><code>Config.Rand</code></a>
|
|
value caused a fixed deterministic random number generator to be used.
|
|
It now uses a random number generator seeded with the current time.
|
|
For the old behavior, set <code>Config.Rand</code> to <code>rand.New(rand.NewSource(0))</code>.
|
|
</p>
|
|
|
|
</dl><!-- testing/quick -->
|
|
|
|
<dl id="text/template"><dt><a href="/pkg/text/template/">text/template</a></dt>
|
|
<dd>
|
|
<p><!-- CL 38420 -->
|
|
The handling of empty blocks, which was broken by a Go 1.8
|
|
change that made the result dependent on the order of templates,
|
|
has been fixed, restoring the old Go 1.7 behavior.
|
|
</p>
|
|
|
|
</dl><!-- text/template -->
|
|
|
|
<dl id="time"><dt><a href="/pkg/time/">time</a></dt>
|
|
<dd>
|
|
<p><!-- CL 36615 -->
|
|
The new methods
|
|
<a href="/pkg/time/#Duration.Round"><code>Duration.Round</code></a>
|
|
and
|
|
<a href="/pkg/time/#Duration.Truncate"><code>Duration.Truncate</code></a>
|
|
handle rounding and truncating durations to multiples of a given duration.
|
|
</p>
|
|
|
|
<p><!-- CL 35710 -->
|
|
Retrieving the time and sleeping now work correctly under Wine.
|
|
</p>
|
|
|
|
<p>
|
|
If a <code>Time</code> value has a monotonic clock reading, its
|
|
string representation (as returned by <code>String</code>) now includes a
|
|
final field <code>"m=±value"</code>, where <code>value</code> is the
|
|
monotonic clock reading formatted as a decimal number of seconds.
|
|
</p>
|
|
|
|
<p><!-- CL 44832 -->
|
|
The included <code>tzdata</code> timezone database has been
|
|
updated to version 2017b. As always, it is only used if the
|
|
system does not already have the database available.
|
|
</p>
|
|
|
|
</dl><!-- time -->
|