mirror of
https://github.com/golang/go
synced 2024-11-23 10:30:03 -07:00
33d058308f
Change-Id: I67aac387359378cf7aa8f7cafa6557ebf1338baf Reviewed-on: https://go-review.googlesource.com/118176 Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
924 lines
37 KiB
HTML
924 lines
37 KiB
HTML
<!--{
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"Title": "Go 1.6 Release Notes",
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"Path": "/doc/go1.6",
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"Template": true
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}-->
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<!--
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Edit .,s;^PKG:([a-z][A-Za-z0-9_/]+);<a href="/pkg/\1/"><code>\1</code></a>;g
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Edit .,s;^([a-z][A-Za-z0-9_/]+)\.([A-Z][A-Za-z0-9_]+\.)?([A-Z][A-Za-z0-9_]+)([ .',]|$);<a href="/pkg/\1/#\2\3"><code>\3</code></a>\4;g
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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 1.6</h2>
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<p>
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The latest Go release, version 1.6, arrives six months after 1.5.
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Most of its changes are in the implementation of the language, runtime, and libraries.
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There are no changes to the language specification.
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As always, the release maintains the Go 1 <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 before.
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</p>
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<p>
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The release adds new ports to <a href="#ports">Linux on 64-bit MIPS and Android on 32-bit x86</a>;
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defined and enforced <a href="#cgo">rules for sharing Go pointers with C</a>;
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transparent, automatic <a href="#http2">support for HTTP/2</a>;
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and a new mechanism for <a href="#template">template reuse</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 no language changes in this release.
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</p>
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<h2 id="ports">Ports</h2>
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<p>
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Go 1.6 adds experimental ports to
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Linux on 64-bit MIPS (<code>linux/mips64</code> and <code>linux/mips64le</code>).
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These ports support <code>cgo</code> but only with internal linking.
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</p>
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<p>
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Go 1.6 also adds an experimental port to Android on 32-bit x86 (<code>android/386</code>).
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</p>
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<p>
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On FreeBSD, Go 1.6 defaults to using <code>clang</code>, not <code>gcc</code>, as the external C compiler.
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</p>
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<p>
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On Linux on little-endian 64-bit PowerPC (<code>linux/ppc64le</code>),
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Go 1.6 now supports <code>cgo</code> with external linking and
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is roughly feature complete.
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</p>
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<p>
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On NaCl, Go 1.5 required SDK version pepper-41.
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Go 1.6 adds support for later SDK versions.
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</p>
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<p>
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On 32-bit x86 systems using the <code>-dynlink</code> or <code>-shared</code> compilation modes,
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the register CX is now overwritten by certain memory references and should
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be avoided in hand-written assembly.
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See the <a href="/doc/asm#x86">assembly documentation</a> for details.
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</p>
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<h2 id="tools">Tools</h2>
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<h3 id="cgo">Cgo</h3>
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<p>
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There is one major change to <a href="/cmd/cgo/"><code>cgo</code></a>, along with one minor change.
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</p>
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<p>
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The major change is the definition of rules for sharing Go pointers with C code,
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to ensure that such C code can coexist with Go's garbage collector.
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Briefly, Go and C may share memory allocated by Go
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when a pointer to that memory is passed to C as part of a <code>cgo</code> call,
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provided that the memory itself contains no pointers to Go-allocated memory,
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and provided that C does not retain the pointer after the call returns.
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These rules are checked by the runtime during program execution:
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if the runtime detects a violation, it prints a diagnosis and crashes the program.
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The checks can be disabled by setting the environment variable
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<code>GODEBUG=cgocheck=0</code>, but note that the vast majority of
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code identified by the checks is subtly incompatible with garbage collection
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in one way or another.
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Disabling the checks will typically only lead to more mysterious failure modes.
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Fixing the code in question should be strongly preferred
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over turning off the checks.
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See the <a href="/cmd/cgo/#hdr-Passing_pointers"><code>cgo</code> documentation</a> for more details.
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</p>
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<p>
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The minor change is
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the addition of explicit <code>C.complexfloat</code> and <code>C.complexdouble</code> types,
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separate from Go's <code>complex64</code> and <code>complex128</code>.
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Matching the other numeric types, C's complex types and Go's complex type are
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no longer interchangeable.
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</p>
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<h3 id="compiler">Compiler Toolchain</h3>
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<p>
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The compiler toolchain is mostly unchanged.
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Internally, the most significant change is that the parser is now hand-written
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instead of generated from <a href="/cmd/yacc/">yacc</a>.
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</p>
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<p>
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The compiler, linker, and <code>go</code> command have a new flag <code>-msan</code>,
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analogous to <code>-race</code> and only available on linux/amd64,
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that enables interoperation with the <a href="https://clang.llvm.org/docs/MemorySanitizer.html">Clang MemorySanitizer</a>.
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Such interoperation is useful mainly for testing a program containing suspect C or C++ code.
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</p>
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<p>
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The linker has a new option <code>-libgcc</code> to set the expected location
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of the C compiler support library when linking <a href="/cmd/cgo/"><code>cgo</code></a> code.
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The option is only consulted when using <code>-linkmode=internal</code>,
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and it may be set to <code>none</code> to disable the use of a support library.
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</p>
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<p>
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The implementation of <a href="/doc/go1.5#link">build modes started in Go 1.5</a> has been expanded to more systems.
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This release adds support for the <code>c-shared</code> mode on <code>android/386</code>, <code>android/amd64</code>,
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<code>android/arm64</code>, <code>linux/386</code>, and <code>linux/arm64</code>;
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for the <code>shared</code> mode on <code>linux/386</code>, <code>linux/arm</code>, <code>linux/amd64</code>, and <code>linux/ppc64le</code>;
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and for the new <code>pie</code> mode (generating position-independent executables) on
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<code>android/386</code>, <code>android/amd64</code>, <code>android/arm</code>, <code>android/arm64</code>, <code>linux/386</code>,
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<code>linux/amd64</code>, <code>linux/arm</code>, <code>linux/arm64</code>, and <code>linux/ppc64le</code>.
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See the <a href="https://golang.org/s/execmodes">design document</a> for details.
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</p>
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<p>
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As a reminder, the linker's <code>-X</code> flag changed in Go 1.5.
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In Go 1.4 and earlier, it took two arguments, as in
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</p>
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<pre>
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-X importpath.name value
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</pre>
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<p>
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Go 1.5 added an alternative syntax using a single argument
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that is itself a <code>name=value</code> pair:
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</p>
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<pre>
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-X importpath.name=value
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</pre>
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<p>
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In Go 1.5 the old syntax was still accepted, after printing a warning
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suggesting use of the new syntax instead.
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Go 1.6 continues to accept the old syntax and print the warning.
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Go 1.7 will remove support for the old syntax.
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</p>
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<h3 id="gccgo">Gccgo</h3>
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<p>
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The release schedules for the GCC and Go projects do not coincide.
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GCC release 5 contains the Go 1.4 version of gccgo.
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The next release, GCC 6, will have the Go 1.6.1 version of gccgo.
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</p>
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<h3 id="go_command">Go command</h3>
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<p>
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The <a href="/cmd/go"><code>go</code></a> command's basic operation
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is unchanged, but there are a number of changes worth noting.
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</p>
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<p>
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Go 1.5 introduced experimental support for vendoring,
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enabled by setting the <code>GO15VENDOREXPERIMENT</code> environment variable to <code>1</code>.
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Go 1.6 keeps the vendoring support, no longer considered experimental,
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and enables it by default.
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It can be disabled explicitly by setting
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the <code>GO15VENDOREXPERIMENT</code> environment variable to <code>0</code>.
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Go 1.7 will remove support for the environment variable.
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</p>
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<p>
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The most likely problem caused by enabling vendoring by default happens
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in source trees containing an existing directory named <code>vendor</code> that
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does not expect to be interpreted according to new vendoring semantics.
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In this case, the simplest fix is to rename the directory to anything other
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than <code>vendor</code> and update any affected import paths.
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</p>
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<p>
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For details about vendoring,
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see the documentation for the <a href="/cmd/go/#hdr-Vendor_Directories"><code>go</code> command</a>
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and the <a href="https://golang.org/s/go15vendor">design document</a>.
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</p>
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<p>
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There is a new build flag, <code>-msan</code>,
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that compiles Go with support for the LLVM memory sanitizer.
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This is intended mainly for use when linking against C or C++ code
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that is being checked with the memory sanitizer.
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</p>
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<h3 id="doc_command">Go doc command</h3>
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<p>
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Go 1.5 introduced the
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<a href="/cmd/go/#hdr-Show_documentation_for_package_or_symbol"><code>go doc</code></a> command,
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which allows references to packages using only the package name, as in
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<code>go</code> <code>doc</code> <code>http</code>.
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In the event of ambiguity, the Go 1.5 behavior was to use the package
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with the lexicographically earliest import path.
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In Go 1.6, ambiguity is resolved by preferring import paths with
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fewer elements, breaking ties using lexicographic comparison.
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An important effect of this change is that original copies of packages
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are now preferred over vendored copies.
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Successful searches also tend to run faster.
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</p>
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<h3 id="vet_command">Go vet command</h3>
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<p>
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The <a href="/cmd/vet"><code>go vet</code></a> command now diagnoses
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passing function or method values as arguments to <code>Printf</code>,
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such as when passing <code>f</code> where <code>f()</code> was intended.
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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 statements
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about performance are difficult to make.
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Some programs may run faster, some slower.
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On average the programs in the Go 1 benchmark suite run a few percent faster in Go 1.6
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than they did in Go 1.5.
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The garbage collector's pauses are even lower than in Go 1.5,
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especially for programs using
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a large amount of memory.
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</p>
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<p>
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There have been significant optimizations bringing more than 10% improvements
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to implementations of the
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<a href="/pkg/compress/bzip2/"><code>compress/bzip2</code></a>,
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<a href="/pkg/compress/gzip/"><code>compress/gzip</code></a>,
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<a href="/pkg/crypto/aes/"><code>crypto/aes</code></a>,
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<a href="/pkg/crypto/elliptic/"><code>crypto/elliptic</code></a>,
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<a href="/pkg/crypto/ecdsa/"><code>crypto/ecdsa</code></a>, and
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<a href="/pkg/sort/"><code>sort</code></a> packages.
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</p>
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<h2 id="library">Core library</h2>
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<h3 id="http2">HTTP/2</h3>
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<p>
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Go 1.6 adds transparent support in the
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<a href="/pkg/net/http/"><code>net/http</code></a> package
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for the new <a href="https://http2.github.io/">HTTP/2 protocol</a>.
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Go clients and servers will automatically use HTTP/2 as appropriate when using HTTPS.
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There is no exported API specific to details of the HTTP/2 protocol handling,
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just as there is no exported API specific to HTTP/1.1.
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</p>
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<p>
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Programs that must disable HTTP/2 can do so by setting
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<a href="/pkg/net/http/#Transport"><code>Transport.TLSNextProto</code></a> (for clients)
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or
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<a href="/pkg/net/http/#Server"><code>Server.TLSNextProto</code></a> (for servers)
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to a non-nil, empty map.
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</p>
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<p>
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Programs that must adjust HTTP/2 protocol-specific details can import and use
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<a href="https://golang.org/x/net/http2"><code>golang.org/x/net/http2</code></a>,
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in particular its
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<a href="https://godoc.org/golang.org/x/net/http2/#ConfigureServer">ConfigureServer</a>
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and
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<a href="https://godoc.org/golang.org/x/net/http2/#ConfigureTransport">ConfigureTransport</a>
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functions.
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</p>
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<h3 id="runtime">Runtime</h3>
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<p>
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The runtime has added lightweight, best-effort detection of concurrent misuse of maps.
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As always, if one goroutine is writing to a map, no other goroutine should be
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reading or writing the map concurrently.
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If the runtime detects this condition, it prints a diagnosis and crashes the program.
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The best way to find out more about the problem is to run the program
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under the
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<a href="https://blog.golang.org/race-detector">race detector</a>,
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which will more reliably identify the race
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and give more detail.
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</p>
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<p>
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For program-ending panics, the runtime now by default
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prints only the stack of the running goroutine,
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not all existing goroutines.
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Usually only the current goroutine is relevant to a panic,
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so omitting the others significantly reduces irrelevant output
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in a crash message.
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To see the stacks from all goroutines in crash messages, set the environment variable
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<code>GOTRACEBACK</code> to <code>all</code>
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or call
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<a href="/pkg/runtime/debug/#SetTraceback"><code>debug.SetTraceback</code></a>
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before the crash, and rerun the program.
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See the <a href="/pkg/runtime/#hdr-Environment_Variables">runtime documentation</a> for details.
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</p>
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<p>
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<em>Updating</em>:
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Uncaught panics intended to dump the state of the entire program,
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such as when a timeout is detected or when explicitly handling a received signal,
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should now call <code>debug.SetTraceback("all")</code> before panicking.
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Searching for uses of
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<a href="/pkg/os/signal/#Notify"><code>signal.Notify</code></a> may help identify such code.
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</p>
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<p>
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On Windows, Go programs in Go 1.5 and earlier forced
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the global Windows timer resolution to 1ms at startup
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by calling <code>timeBeginPeriod(1)</code>.
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Go no longer needs this for good scheduler performance,
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and changing the global timer resolution caused problems on some systems,
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so the call has been removed.
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</p>
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<p>
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When using <code>-buildmode=c-archive</code> or
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<code>-buildmode=c-shared</code> to build an archive or a shared
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library, the handling of signals has changed.
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In Go 1.5 the archive or shared library would install a signal handler
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for most signals.
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In Go 1.6 it will only install a signal handler for the
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synchronous signals needed to handle run-time panics in Go code:
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SIGBUS, SIGFPE, SIGSEGV.
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See the <a href="/pkg/os/signal">os/signal</a> package for more
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details.
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</p>
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<h3 id="reflect">Reflect</h3>
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<p>
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The
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<a href="/pkg/reflect/"><code>reflect</code></a> package has
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<a href="https://golang.org/issue/12367">resolved a long-standing incompatibility</a>
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between the gc and gccgo toolchains
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regarding embedded unexported struct types containing exported fields.
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Code that walks data structures using reflection, especially to implement
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serialization in the spirit
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of the
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<a href="/pkg/encoding/json/"><code>encoding/json</code></a> and
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<a href="/pkg/encoding/xml/"><code>encoding/xml</code></a> packages,
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may need to be updated.
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</p>
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<p>
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The problem arises when using reflection to walk through
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an embedded unexported struct-typed field
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into an exported field of that struct.
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In this case, <code>reflect</code> had incorrectly reported
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the embedded field as exported, by returning an empty <code>Field.PkgPath</code>.
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Now it correctly reports the field as unexported
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but ignores that fact when evaluating access to exported fields
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contained within the struct.
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</p>
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<p>
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<em>Updating</em>:
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Typically, code that previously walked over structs and used
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</p>
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<pre>
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f.PkgPath != ""
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</pre>
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|
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<p>
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to exclude inaccessible fields
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should now use
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</p>
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<pre>
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f.PkgPath != "" && !f.Anonymous
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</pre>
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<p>
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For example, see the changes to the implementations of
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<a href="https://go-review.googlesource.com/#/c/14011/2/src/encoding/json/encode.go"><code>encoding/json</code></a> and
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<a href="https://go-review.googlesource.com/#/c/14012/2/src/encoding/xml/typeinfo.go"><code>encoding/xml</code></a>.
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</p>
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<h3 id="sort">Sorting</h3>
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<p>
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In the
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<a href="/pkg/sort/"><code>sort</code></a>
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package,
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the implementation of
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<a href="/pkg/sort/#Sort"><code>Sort</code></a>
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has been rewritten to make about 10% fewer calls to the
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|
<a href="/pkg/sort/#Interface"><code>Interface</code></a>'s
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|
<code>Less</code> and <code>Swap</code>
|
|
methods, with a corresponding overall time savings.
|
|
The new algorithm does choose a different ordering than before
|
|
for values that compare equal (those pairs for which <code>Less(i,</code> <code>j)</code> and <code>Less(j,</code> <code>i)</code> are false).
|
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</p>
|
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<p>
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<em>Updating</em>:
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The definition of <code>Sort</code> makes no guarantee about the final order of equal values,
|
|
but the new behavior may still break programs that expect a specific order.
|
|
Such programs should either refine their <code>Less</code> implementations
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to report the desired order
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or should switch to
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<a href="/pkg/sort/#Stable"><code>Stable</code></a>,
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which preserves the original input order
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of equal values.
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</p>
|
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|
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<h3 id="template">Templates</h3>
|
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|
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<p>
|
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In the
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<a href="/pkg/text/template/">text/template</a> package,
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there are two significant new features to make writing templates easier.
|
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</p>
|
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<p>
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First, it is now possible to <a href="/pkg/text/template/#hdr-Text_and_spaces">trim spaces around template actions</a>,
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which can make template definitions more readable.
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A minus sign at the beginning of an action says to trim space before the action,
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and a minus sign at the end of an action says to trim space after the action.
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For example, the template
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</p>
|
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|
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<pre>
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{{"{{"}}23 -}}
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<
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{{"{{"}}- 45}}
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</pre>
|
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|
|
<p>
|
|
formats as <code>23<45</code>.
|
|
</p>
|
|
|
|
<p>
|
|
Second, the new <a href="/pkg/text/template/#hdr-Actions"><code>{{"{{"}}block}}</code> action</a>,
|
|
combined with allowing redefinition of named templates,
|
|
provides a simple way to define pieces of a template that
|
|
can be replaced in different instantiations.
|
|
There is <a href="/pkg/text/template/#example_Template_block">an example</a>
|
|
in the <code>text/template</code> package that demonstrates this new feature.
|
|
</p>
|
|
|
|
<h3 id="minor_library_changes">Minor changes to the library</h3>
|
|
|
|
<ul>
|
|
|
|
<li>
|
|
The <a href="/pkg/archive/tar/"><code>archive/tar</code></a> package's
|
|
implementation corrects many bugs in rare corner cases of the file format.
|
|
One visible change is that the
|
|
<a href="/pkg/archive/tar/#Reader"><code>Reader</code></a> type's
|
|
<a href="/pkg/archive/tar/#Reader.Read"><code>Read</code></a> method
|
|
now presents the content of special file types as being empty,
|
|
returning <code>io.EOF</code> immediately.
|
|
</li>
|
|
|
|
<li>
|
|
In the <a href="/pkg/archive/zip/"><code>archive/zip</code></a> package, the
|
|
<a href="/pkg/archive/zip/#Reader"><code>Reader</code></a> type now has a
|
|
<a href="/pkg/archive/zip/#Reader.RegisterDecompressor"><code>RegisterDecompressor</code></a> method,
|
|
and the
|
|
<a href="/pkg/archive/zip/#Writer"><code>Writer</code></a> type now has a
|
|
<a href="/pkg/archive/zip/#Writer.RegisterCompressor"><code>RegisterCompressor</code></a> method,
|
|
enabling control over compression options for individual zip files.
|
|
These take precedence over the pre-existing global
|
|
<a href="/pkg/archive/zip/#RegisterDecompressor"><code>RegisterDecompressor</code></a> and
|
|
<a href="/pkg/archive/zip/#RegisterCompressor"><code>RegisterCompressor</code></a> functions.
|
|
</li>
|
|
|
|
<li>
|
|
The <a href="/pkg/bufio/"><code>bufio</code></a> package's
|
|
<a href="/pkg/bufio/#Scanner"><code>Scanner</code></a> type now has a
|
|
<a href="/pkg/bufio/#Scanner.Buffer"><code>Buffer</code></a> method,
|
|
to specify an initial buffer and maximum buffer size to use during scanning.
|
|
This makes it possible, when needed, to scan tokens larger than
|
|
<code>MaxScanTokenSize</code>.
|
|
Also for the <code>Scanner</code>, the package now defines the
|
|
<a href="/pkg/bufio/#ErrFinalToken"><code>ErrFinalToken</code></a> error value, for use by
|
|
<a href="/pkg/bufio/#SplitFunc">split functions</a> to abort processing or to return a final empty token.
|
|
</li>
|
|
|
|
<li>
|
|
The <a href="/pkg/compress/flate/"><code>compress/flate</code></a> package
|
|
has deprecated its
|
|
<a href="/pkg/compress/flate/#ReadError"><code>ReadError</code></a> and
|
|
<a href="/pkg/compress/flate/#WriteError"><code>WriteError</code></a> error implementations.
|
|
In Go 1.5 they were only rarely returned when an error was encountered;
|
|
now they are never returned, although they remain defined for compatibility.
|
|
</li>
|
|
|
|
<li>
|
|
The <a href="/pkg/compress/flate/"><code>compress/flate</code></a>,
|
|
<a href="/pkg/compress/gzip/"><code>compress/gzip</code></a>, and
|
|
<a href="/pkg/compress/zlib/"><code>compress/zlib</code></a> packages
|
|
now report
|
|
<a href="/pkg/io/#ErrUnexpectedEOF"><code>io.ErrUnexpectedEOF</code></a> for truncated input streams, instead of
|
|
<a href="/pkg/io/#EOF"><code>io.EOF</code></a>.
|
|
</li>
|
|
|
|
<li>
|
|
The <a href="/pkg/crypto/cipher/"><code>crypto/cipher</code></a> package now
|
|
overwrites the destination buffer in the event of a GCM decryption failure.
|
|
This is to allow the AESNI code to avoid using a temporary buffer.
|
|
</li>
|
|
|
|
<li>
|
|
The <a href="/pkg/crypto/tls/"><code>crypto/tls</code></a> package
|
|
has a variety of minor changes.
|
|
It now allows
|
|
<a href="/pkg/crypto/tls/#Listen"><code>Listen</code></a>
|
|
to succeed when the
|
|
<a href="/pkg/crypto/tls/#Config"><code>Config</code></a>
|
|
has a nil <code>Certificates</code>, as long as the <code>GetCertificate</code> callback is set,
|
|
it adds support for RSA with AES-GCM cipher suites,
|
|
and
|
|
it adds a
|
|
<a href="/pkg/crypto/tls/#RecordHeaderError"><code>RecordHeaderError</code></a>
|
|
to allow clients (in particular, the <a href="/pkg/net/http/"><code>net/http</code></a> package)
|
|
to report a better error when attempting a TLS connection to a non-TLS server.
|
|
</li>
|
|
|
|
<li>
|
|
The <a href="/pkg/crypto/x509/"><code>crypto/x509</code></a> package
|
|
now permits certificates to contain negative serial numbers
|
|
(technically an error, but unfortunately common in practice),
|
|
and it defines a new
|
|
<a href="/pkg/crypto/x509/#InsecureAlgorithmError"><code>InsecureAlgorithmError</code></a>
|
|
to give a better error message when rejecting a certificate
|
|
signed with an insecure algorithm like MD5.
|
|
</li>
|
|
|
|
<li>
|
|
The <a href="/pkg/debug/dwarf"><code>debug/dwarf</code></a> and
|
|
<a href="/pkg/debug/elf/"><code>debug/elf</code></a> packages
|
|
together add support for compressed DWARF sections.
|
|
User code needs no updating: the sections are decompressed automatically when read.
|
|
</li>
|
|
|
|
<li>
|
|
The <a href="/pkg/debug/elf/"><code>debug/elf</code></a> package
|
|
adds support for general compressed ELF sections.
|
|
User code needs no updating: the sections are decompressed automatically when read.
|
|
However, compressed
|
|
<a href="/pkg/debug/elf/#Section"><code>Sections</code></a> do not support random access:
|
|
they have a nil <code>ReaderAt</code> field.
|
|
</li>
|
|
|
|
<li>
|
|
The <a href="/pkg/encoding/asn1/"><code>encoding/asn1</code></a> package
|
|
now exports
|
|
<a href="/pkg/encoding/asn1/#pkg-constants">tag and class constants</a>
|
|
useful for advanced parsing of ASN.1 structures.
|
|
</li>
|
|
|
|
<li>
|
|
Also in the <a href="/pkg/encoding/asn1/"><code>encoding/asn1</code></a> package,
|
|
<a href="/pkg/encoding/asn1/#Unmarshal"><code>Unmarshal</code></a> now rejects various non-standard integer and length encodings.
|
|
</li>
|
|
|
|
<li>
|
|
The <a href="/pkg/encoding/base64"><code>encoding/base64</code></a> package's
|
|
<a href="/pkg/encoding/base64/#Decoder"><code>Decoder</code></a> has been fixed
|
|
to process the final bytes of its input. Previously it processed as many four-byte tokens as
|
|
possible but ignored the remainder, up to three bytes.
|
|
The <code>Decoder</code> therefore now handles inputs in unpadded encodings (like
|
|
<a href="/pkg/encoding/base64/#RawURLEncoding">RawURLEncoding</a>) correctly,
|
|
but it also rejects inputs in padded encodings that are truncated or end with invalid bytes,
|
|
such as trailing spaces.
|
|
</li>
|
|
|
|
<li>
|
|
The <a href="/pkg/encoding/json/"><code>encoding/json</code></a> package
|
|
now checks the syntax of a
|
|
<a href="/pkg/encoding/json/#Number"><code>Number</code></a>
|
|
before marshaling it, requiring that it conforms to the JSON specification for numeric values.
|
|
As in previous releases, the zero <code>Number</code> (an empty string) is marshaled as a literal 0 (zero).
|
|
</li>
|
|
|
|
<li>
|
|
The <a href="/pkg/encoding/xml/"><code>encoding/xml</code></a> package's
|
|
<a href="/pkg/encoding/xml/#Marshal"><code>Marshal</code></a>
|
|
function now supports a <code>cdata</code> attribute, such as <code>chardata</code>
|
|
but encoding its argument in one or more <code><![CDATA[ ... ]]></code> tags.
|
|
</li>
|
|
|
|
<li>
|
|
Also in the <a href="/pkg/encoding/xml/"><code>encoding/xml</code></a> package,
|
|
<a href="/pkg/encoding/xml/#Decoder"><code>Decoder</code></a>'s
|
|
<a href="/pkg/encoding/xml/#Decoder.Token"><code>Token</code></a> method
|
|
now reports an error when encountering EOF before seeing all open tags closed,
|
|
consistent with its general requirement that tags in the input be properly matched.
|
|
To avoid that requirement, use
|
|
<a href="/pkg/encoding/xml/#Decoder.RawToken"><code>RawToken</code></a>.
|
|
</li>
|
|
|
|
<li>
|
|
The <a href="/pkg/fmt/"><code>fmt</code></a> package now allows
|
|
any integer type as an argument to
|
|
<a href="/pkg/fmt/#Printf"><code>Printf</code></a>'s <code>*</code> width and precision specification.
|
|
In previous releases, the argument to <code>*</code> was required to have type <code>int</code>.
|
|
</li>
|
|
|
|
<li>
|
|
Also in the <a href="/pkg/fmt/"><code>fmt</code></a> package,
|
|
<a href="/pkg/fmt/#Scanf"><code>Scanf</code></a> can now scan hexadecimal strings using %X, as an alias for %x.
|
|
Both formats accept any mix of upper- and lower-case hexadecimal.
|
|
</li>
|
|
|
|
<li>
|
|
The <a href="/pkg/image/"><code>image</code></a>
|
|
and
|
|
<a href="/pkg/image/color/"><code>image/color</code></a> packages
|
|
add
|
|
<a href="/pkg/image/#NYCbCrA"><code>NYCbCrA</code></a>
|
|
and
|
|
<a href="/pkg/image/color/#NYCbCrA"><code>NYCbCrA</code></a>
|
|
types, to support Y'CbCr images with non-premultiplied alpha.
|
|
</li>
|
|
|
|
<li>
|
|
The <a href="/pkg/io/"><code>io</code></a> package's
|
|
<a href="/pkg/io/#MultiWriter"><code>MultiWriter</code></a>
|
|
implementation now implements a <code>WriteString</code> method,
|
|
for use by
|
|
<a href="/pkg/io/#WriteString"><code>WriteString</code></a>.
|
|
</li>
|
|
|
|
<li>
|
|
In the <a href="/pkg/math/big/"><code>math/big</code></a> package,
|
|
<a href="/pkg/math/big/#Int"><code>Int</code></a> adds
|
|
<a href="/pkg/math/big/#Int.Append"><code>Append</code></a>
|
|
and
|
|
<a href="/pkg/math/big/#Int.Text"><code>Text</code></a>
|
|
methods to give more control over printing.
|
|
</li>
|
|
|
|
<li>
|
|
Also in the <a href="/pkg/math/big/"><code>math/big</code></a> package,
|
|
<a href="/pkg/math/big/#Float"><code>Float</code></a> now implements
|
|
<a href="/pkg/encoding/#TextMarshaler"><code>encoding.TextMarshaler</code></a> and
|
|
<a href="/pkg/encoding/#TextUnmarshaler"><code>encoding.TextUnmarshaler</code></a>,
|
|
allowing it to be serialized in a natural form by the
|
|
<a href="/pkg/encoding/json/"><code>encoding/json</code></a> and
|
|
<a href="/pkg/encoding/xml/"><code>encoding/xml</code></a> packages.
|
|
</li>
|
|
|
|
<li>
|
|
Also in the <a href="/pkg/math/big/"><code>math/big</code></a> package,
|
|
<a href="/pkg/math/big/#Float"><code>Float</code></a>'s
|
|
<a href="/pkg/math/big/#Float.Append"><code>Append</code></a> method now supports the special precision argument -1.
|
|
As in
|
|
<a href="/pkg/strconv/#ParseFloat"><code>strconv.ParseFloat</code></a>,
|
|
precision -1 means to use the smallest number of digits necessary such that
|
|
<a href="/pkg/math/big/#Float.Parse"><code>Parse</code></a>
|
|
reading the result into a <code>Float</code> of the same precision
|
|
will yield the original value.
|
|
</li>
|
|
|
|
<li>
|
|
The <a href="/pkg/math/rand/"><code>math/rand</code></a> package
|
|
adds a
|
|
<a href="/pkg/math/rand/#Read"><code>Read</code></a>
|
|
function, and likewise
|
|
<a href="/pkg/math/rand/#Rand"><code>Rand</code></a> adds a
|
|
<a href="/pkg/math/rand/#Rand.Read"><code>Read</code></a> method.
|
|
These make it easier to generate pseudorandom test data.
|
|
Note that, like the rest of the package,
|
|
these should not be used in cryptographic settings;
|
|
for such purposes, use the <a href="/pkg/crypto/rand/"><code>crypto/rand</code></a> package instead.
|
|
</li>
|
|
|
|
<li>
|
|
The <a href="/pkg/net/"><code>net</code></a> package's
|
|
<a href="/pkg/net/#ParseMAC"><code>ParseMAC</code></a> function now accepts 20-byte IP-over-InfiniBand (IPoIB) link-layer addresses.
|
|
</li>
|
|
|
|
|
|
<li>
|
|
Also in the <a href="/pkg/net/"><code>net</code></a> package,
|
|
there have been a few changes to DNS lookups.
|
|
First, the
|
|
<a href="/pkg/net/#DNSError"><code>DNSError</code></a> error implementation now implements
|
|
<a href="/pkg/net/#Error"><code>Error</code></a>,
|
|
and in particular its new
|
|
<a href="/pkg/net/#DNSError.IsTemporary"><code>IsTemporary</code></a>
|
|
method returns true for DNS server errors.
|
|
Second, DNS lookup functions such as
|
|
<a href="/pkg/net/#LookupAddr"><code>LookupAddr</code></a>
|
|
now return rooted domain names (with a trailing dot)
|
|
on Plan 9 and Windows, to match the behavior of Go on Unix systems.
|
|
</li>
|
|
|
|
<li>
|
|
The <a href="/pkg/net/http/"><code>net/http</code></a> package has
|
|
a number of minor additions beyond the HTTP/2 support already discussed.
|
|
First, the
|
|
<a href="/pkg/net/http/#FileServer"><code>FileServer</code></a> now sorts its generated directory listings by file name.
|
|
Second, the
|
|
<a href="/pkg/net/http/#ServeFile"><code>ServeFile</code></a> function now refuses to serve a result
|
|
if the request's URL path contains “..” (dot-dot) as a path element.
|
|
Programs should typically use <code>FileServer</code> and
|
|
<a href="/pkg/net/http/#Dir"><code>Dir</code></a>
|
|
instead of calling <code>ServeFile</code> directly.
|
|
Programs that need to serve file content in response to requests for URLs containing dot-dot can
|
|
still call <a href="/pkg/net/http/#ServeContent"><code>ServeContent</code></a>.
|
|
Third, the
|
|
<a href="/pkg/net/http/#Client"><code>Client</code></a> now allows user code to set the
|
|
<code>Expect:</code> <code>100-continue</code> header (see
|
|
<a href="/pkg/net/http/#Transport"><code>Transport.ExpectContinueTimeout</code></a>).
|
|
Fourth, there are
|
|
<a href="/pkg/net/http/#pkg-constants">five new error codes</a>:
|
|
<code>StatusPreconditionRequired</code> (428),
|
|
<code>StatusTooManyRequests</code> (429),
|
|
<code>StatusRequestHeaderFieldsTooLarge</code> (431), and
|
|
<code>StatusNetworkAuthenticationRequired</code> (511) from RFC 6585,
|
|
as well as the recently-approved
|
|
<code>StatusUnavailableForLegalReasons</code> (451).
|
|
Fifth, the implementation and documentation of
|
|
<a href="/pkg/net/http/#CloseNotifier"><code>CloseNotifier</code></a>
|
|
has been substantially changed.
|
|
The <a href="/pkg/net/http/#Hijacker"><code>Hijacker</code></a>
|
|
interface now works correctly on connections that have previously
|
|
been used with <code>CloseNotifier</code>.
|
|
The documentation now describes when <code>CloseNotifier</code>
|
|
is expected to work.
|
|
</li>
|
|
|
|
<li>
|
|
Also in the <a href="/pkg/net/http/"><code>net/http</code></a> package,
|
|
there are a few changes related to the handling of a
|
|
<a href="/pkg/net/http/#Request"><code>Request</code></a> data structure with its <code>Method</code> field set to the empty string.
|
|
An empty <code>Method</code> field has always been documented as an alias for <code>"GET"</code>
|
|
and it remains so.
|
|
However, Go 1.6 fixes a few routines that did not treat an empty
|
|
<code>Method</code> the same as an explicit <code>"GET"</code>.
|
|
Most notably, in previous releases
|
|
<a href="/pkg/net/http/#Client"><code>Client</code></a> followed redirects only with
|
|
<code>Method</code> set explicitly to <code>"GET"</code>;
|
|
in Go 1.6 <code>Client</code> also follows redirects for the empty <code>Method</code>.
|
|
Finally,
|
|
<a href="/pkg/net/http/#NewRequest"><code>NewRequest</code></a> accepts a <code>method</code> argument that has not been
|
|
documented as allowed to be empty.
|
|
In past releases, passing an empty <code>method</code> argument resulted
|
|
in a <code>Request</code> with an empty <code>Method</code> field.
|
|
In Go 1.6, the resulting <code>Request</code> always has an initialized
|
|
<code>Method</code> field: if its argument is an empty string, <code>NewRequest</code>
|
|
sets the <code>Method</code> field in the returned <code>Request</code> to <code>"GET"</code>.
|
|
</li>
|
|
|
|
<li>
|
|
The <a href="/pkg/net/http/httptest/"><code>net/http/httptest</code></a> package's
|
|
<a href="/pkg/net/http/httptest/#ResponseRecorder"><code>ResponseRecorder</code></a> now initializes a default Content-Type header
|
|
using the same content-sniffing algorithm as in
|
|
<a href="/pkg/net/http/#Server"><code>http.Server</code></a>.
|
|
</li>
|
|
|
|
<li>
|
|
The <a href="/pkg/net/url/"><code>net/url</code></a> package's
|
|
<a href="/pkg/net/url/#Parse"><code>Parse</code></a> is now stricter and more spec-compliant regarding the parsing
|
|
of host names.
|
|
For example, spaces in the host name are no longer accepted.
|
|
</li>
|
|
|
|
<li>
|
|
Also in the <a href="/pkg/net/url/"><code>net/url</code></a> package,
|
|
the <a href="/pkg/net/url/#Error"><code>Error</code></a> type now implements
|
|
<a href="/pkg/net/#Error"><code>net.Error</code></a>.
|
|
</li>
|
|
|
|
<li>
|
|
The <a href="/pkg/os/"><code>os</code></a> package's
|
|
<a href="/pkg/os/#IsExist"><code>IsExist</code></a>,
|
|
<a href="/pkg/os/#IsNotExist"><code>IsNotExist</code></a>,
|
|
and
|
|
<a href="/pkg/os/#IsPermission"><code>IsPermission</code></a>
|
|
now return correct results when inquiring about an
|
|
<a href="/pkg/os/#SyscallError"><code>SyscallError</code></a>.
|
|
</li>
|
|
|
|
<li>
|
|
On Unix-like systems, when a write
|
|
to <a href="/pkg/os/#pkg-variables"><code>os.Stdout</code>
|
|
or <code>os.Stderr</code></a> (more precisely, an <code>os.File</code>
|
|
opened for file descriptor 1 or 2) fails due to a broken pipe error,
|
|
the program will raise a <code>SIGPIPE</code> signal.
|
|
By default this will cause the program to exit; this may be changed by
|
|
calling the
|
|
<a href="/pkg/os/signal"><code>os/signal</code></a>
|
|
<a href="/pkg/os/signal/#Notify"><code>Notify</code></a> function
|
|
for <code>syscall.SIGPIPE</code>.
|
|
A write to a broken pipe on a file descriptor other 1 or 2 will simply
|
|
return <code>syscall.EPIPE</code> (possibly wrapped in
|
|
<a href="/pkg/os#PathError"><code>os.PathError</code></a>
|
|
and/or <a href="/pkg/os#SyscallError"><code>os.SyscallError</code></a>)
|
|
to the caller.
|
|
The old behavior of raising an uncatchable <code>SIGPIPE</code> signal
|
|
after 10 consecutive writes to a broken pipe no longer occurs.
|
|
</li>
|
|
|
|
<li>
|
|
In the <a href="/pkg/os/exec/"><code>os/exec</code></a> package,
|
|
<a href="/pkg/os/exec/#Cmd"><code>Cmd</code></a>'s
|
|
<a href="/pkg/os/exec/#Cmd.Output"><code>Output</code></a> method continues to return an
|
|
<a href="/pkg/os/exec/#ExitError"><code>ExitError</code></a> when a command exits with an unsuccessful status.
|
|
If standard error would otherwise have been discarded,
|
|
the returned <code>ExitError</code> now holds a prefix and suffix
|
|
(currently 32 kB) of the failed command's standard error output,
|
|
for debugging or for inclusion in error messages.
|
|
The <code>ExitError</code>'s
|
|
<a href="/pkg/os/exec/#ExitError.String"><code>String</code></a>
|
|
method does not show the captured standard error;
|
|
programs must retrieve it from the data structure
|
|
separately.
|
|
</li>
|
|
|
|
<li>
|
|
On Windows, the <a href="/pkg/path/filepath/"><code>path/filepath</code></a> package's
|
|
<a href="/pkg/path/filepath/#Join"><code>Join</code></a> function now correctly handles the case when the base is a relative drive path.
|
|
For example, <code>Join(`c:`,</code> <code>`a`)</code> now
|
|
returns <code>`c:a`</code> instead of <code>`c:\a`</code> as in past releases.
|
|
This may affect code that expects the incorrect result.
|
|
</li>
|
|
|
|
<li>
|
|
In the <a href="/pkg/regexp/"><code>regexp</code></a> package,
|
|
the
|
|
<a href="/pkg/regexp/#Regexp"><code>Regexp</code></a> type has always been safe for use by
|
|
concurrent goroutines.
|
|
It uses a <a href="/pkg/sync/#Mutex"><code>sync.Mutex</code></a> to protect
|
|
a cache of scratch spaces used during regular expression searches.
|
|
Some high-concurrency servers using the same <code>Regexp</code> from many goroutines
|
|
have seen degraded performance due to contention on that mutex.
|
|
To help such servers, <code>Regexp</code> now has a
|
|
<a href="/pkg/regexp/#Regexp.Copy"><code>Copy</code></a> method,
|
|
which makes a copy of a <code>Regexp</code> that shares most of the structure
|
|
of the original but has its own scratch space cache.
|
|
Two goroutines can use different copies of a <code>Regexp</code>
|
|
without mutex contention.
|
|
A copy does have additional space overhead, so <code>Copy</code>
|
|
should only be used when contention has been observed.
|
|
</li>
|
|
|
|
<li>
|
|
The <a href="/pkg/strconv/"><code>strconv</code></a> package adds
|
|
<a href="/pkg/strconv/#IsGraphic"><code>IsGraphic</code></a>,
|
|
similar to <a href="/pkg/strconv/#IsPrint"><code>IsPrint</code></a>.
|
|
It also adds
|
|
<a href="/pkg/strconv/#QuoteToGraphic"><code>QuoteToGraphic</code></a>,
|
|
<a href="/pkg/strconv/#QuoteRuneToGraphic"><code>QuoteRuneToGraphic</code></a>,
|
|
<a href="/pkg/strconv/#AppendQuoteToGraphic"><code>AppendQuoteToGraphic</code></a>,
|
|
and
|
|
<a href="/pkg/strconv/#AppendQuoteRuneToGraphic"><code>AppendQuoteRuneToGraphic</code></a>,
|
|
analogous to
|
|
<a href="/pkg/strconv/#QuoteToASCII"><code>QuoteToASCII</code></a>,
|
|
<a href="/pkg/strconv/#QuoteRuneToASCII"><code>QuoteRuneToASCII</code></a>,
|
|
and so on.
|
|
The <code>ASCII</code> family escapes all space characters except ASCII space (U+0020).
|
|
In contrast, the <code>Graphic</code> family does not escape any Unicode space characters (category Zs).
|
|
</li>
|
|
|
|
<li>
|
|
In the <a href="/pkg/testing/"><code>testing</code></a> package,
|
|
when a test calls
|
|
<a href="/pkg/testing/#T.Parallel">t.Parallel</a>,
|
|
that test is paused until all non-parallel tests complete, and then
|
|
that test continues execution with all other parallel tests.
|
|
Go 1.6 changes the time reported for such a test:
|
|
previously the time counted only the parallel execution,
|
|
but now it also counts the time from the start of testing
|
|
until the call to <code>t.Parallel</code>.
|
|
</li>
|
|
|
|
<li>
|
|
The <a href="/pkg/text/template/"><code>text/template</code></a> package
|
|
contains two minor changes, in addition to the <a href="#template">major changes</a>
|
|
described above.
|
|
First, it adds a new
|
|
<a href="/pkg/text/template/#ExecError"><code>ExecError</code></a> type
|
|
returned for any error during
|
|
<a href="/pkg/text/template/#Template.Execute"><code>Execute</code></a>
|
|
that does not originate in a <code>Write</code> to the underlying writer.
|
|
Callers can distinguish template usage errors from I/O errors by checking for
|
|
<code>ExecError</code>.
|
|
Second, the
|
|
<a href="/pkg/text/template/#Template.Funcs"><code>Funcs</code></a> method
|
|
now checks that the names used as keys in the
|
|
<a href="/pkg/text/template/#FuncMap"><code>FuncMap</code></a>
|
|
are identifiers that can appear in a template function invocation.
|
|
If not, <code>Funcs</code> panics.
|
|
</li>
|
|
|
|
<li>
|
|
The <a href="/pkg/time/"><code>time</code></a> package's
|
|
<a href="/pkg/time/#Parse"><code>Parse</code></a> function has always rejected any day of month larger than 31,
|
|
such as January 32.
|
|
In Go 1.6, <code>Parse</code> now also rejects February 29 in non-leap years,
|
|
February 30, February 31, April 31, June 31, September 31, and November 31.
|
|
</li>
|
|
|
|
</ul>
|
|
|