| <!--{ |
| "Title": "Go 1.17 Release Notes", |
| "Path": "/doc/go1.17" |
| }--> |
| |
| <!-- |
| NOTE: In this document and others in this directory, the convention is to |
| set fixed-width phrases with non-fixed-width spaces, as in |
| <code>hello</code> <code>world</code>. |
| Do not send CLs removing the interior tags from such phrases. |
| --> |
| |
| <style> |
| main ul li { margin: 0.5em 0; } |
| </style> |
| |
| <h2 id="introduction">DRAFT RELEASE NOTES — Introduction to Go 1.17</h2> |
| |
| <p> |
| <strong> |
| Go 1.17 is not yet released. These are work-in-progress |
| release notes. Go 1.17 is expected to be released in August 2021. |
| </strong> |
| </p> |
| |
| <h2 id="language">Changes to the language</h2> |
| |
| <p> |
| Go 1.17 includes three small enhancements to the language. |
| </p> |
| |
| <ul> |
| <li><!-- CL 216424; issue 395 --> |
| <a href="/ref/spec#Conversions_from_slice_to_array_pointer">Conversions |
| from slice to array pointer</a>: An expression <code>s</code> of |
| type <code>[]T</code> may now be converted to array pointer type |
| <code>*[N]T</code>. If <code>a</code> is the result of such a |
| conversion, then corresponding indices that are in range refer to |
| the same underlying elements: <code>&a[i] == &s[i]</code> |
| for <code>0 <= i < N</code>. The conversion panics if |
| <code>len(s)</code> is less than <code>N</code>. |
| </li> |
| |
| <li><!-- CL 312212; issue 40481 --> |
| <a href="/pkg/unsafe#Add"><code>unsafe.Add</code></a>: |
| <code>unsafe.Add(ptr, len)</code> adds <code>len</code> |
| to <code>ptr</code> and returns the updated pointer |
| <code>unsafe.Pointer(uintptr(ptr) + uintptr(len))</code>. |
| </li> |
| |
| <li><!-- CL 312212; issue 19367 --> |
| <a href="/pkg/unsafe#Slice"><code>unsafe.Slice</code></a>: |
| For expression <code>ptr</code> of type <code>*T</code>, |
| <code>unsafe.Slice(ptr, len)</code> returns a slice of |
| type <code>[]T</code> whose underlying array starts |
| at <code>ptr</code> and whose length and capacity |
| are <code>len</code>. |
| </li> |
| </ul> |
| |
| <p> |
| The package unsafe enhancements were added to simplify writing code that conforms |
| to <code>unsafe.Pointer</code>'s <a href="/pkg/unsafe/#Pointer">safety |
| rules</a>, but the rules remain unchanged. In particular, existing |
| programs that correctly use <code>unsafe.Pointer</code> remain |
| valid, and new programs must still follow the rules when |
| using <code>unsafe.Add</code> or <code>unsafe.Slice</code>. |
| </p> |
| |
| |
| <p> |
| Note that the new conversion from slice to array pointer is the |
| first case in which a type conversion can panic at run time. |
| Analysis tools that assume type conversions can never panic |
| should be updated to consider this possibility. |
| </p> |
| |
| <h2 id="ports">Ports</h2> |
| |
| <h3 id="darwin">Darwin</h3> |
| |
| <p><!-- golang.org/issue/23011 --> |
| As <a href="go1.16#darwin">announced</a> in the Go 1.16 release |
| notes, Go 1.17 requires macOS 10.13 High Sierra or later; support |
| for previous versions has been discontinued. |
| </p> |
| |
| <h3 id="windows">Windows</h3> |
| |
| <p><!-- golang.org/issue/36439 --> |
| Go 1.17 adds support of 64-bit ARM architecture on Windows (the |
| <code>windows/arm64</code> port). This port supports cgo. |
| </p> |
| |
| <h3 id="openbsd">OpenBSD</h3> |
| |
| <p><!-- golang.org/issue/43005 --> |
| The 64-bit MIPS architecture on OpenBSD (the <code>openbsd/mips64</code> |
| port) now supports cgo. |
| </p> |
| |
| <p><!-- golang.org/issue/36435 --> |
| In Go 1.16, on the 64-bit x86 and 64-bit ARM architectures on |
| OpenBSD (the <code>openbsd/amd64</code> and <code>openbsd/arm64</code> |
| ports) system calls are made through <code>libc</code>, instead |
| of directly using machine instructions. In Go 1.17, this is also |
| done on the 32-bit x86 and 32-bit ARM architectures on OpenBSD |
| (the <code>openbsd/386</code> and <code>openbsd/arm</code> ports). |
| This ensures compatibility with OpenBSD 6.9 onwards, which require |
| system calls to be made through <code>libc</code> for non-static |
| Go binaries. |
| </p> |
| |
| <h3 id="arm64">ARM64</h3> |
| |
| <p><!-- CL 288814 --> |
| Go programs now maintain stack frame pointers on the 64-bit ARM |
| architecture on all operating systems. Previously it maintained |
| stack frame pointers only on Linux, macOS, and iOS. |
| </p> |
| |
| <h2 id="tools">Tools</h2> |
| |
| <h3 id="go-command">Go command</h3> |
| |
| <h4 id="lazy-loading">Lazy module loading</h4> |
| |
| <p><!-- golang.org/issue/36460 --> |
| If a module specifies <code>go</code> <code>1.17</code> or higher in its |
| <code>go.mod</code> file, its transitive requirements are now loaded lazily, |
| avoiding the need to download or read <code>go.mod</code> files for |
| otherwise-irrelevant dependencies. To support lazy loading, in Go 1.17 modules |
| the <code>go</code> command maintains <em>explicit</em> requirements in |
| the <code>go.mod</code> file for every dependency that provides any package |
| transitively imported by any package or test within the module. |
| See <a href="https://golang.org/design/36460-lazy-module-loading">the design |
| document</a> for more detail. |
| <!-- TODO(bcmills): replace the design-doc link with proper documentation. --> |
| </p> |
| |
| <p><!-- golang.org/issue/45965 --> |
| Because the number of additional explicit requirements in the go.mod file may |
| be substantial, in a Go 1.17 module the newly-added requirements |
| on <em>indirect</em> dependencies are maintained in a |
| separate <code>require</code> block from the block containing direct |
| dependencies. |
| </p> |
| |
| <p><!-- golang.org/issue/45094 --> |
| To facilitate the upgrade to lazy loading, the |
| <code>go</code> <code>mod</code> <code>tidy</code> subcommand now supports |
| a <code>-go</code> flag to set or change the <code>go</code> version in |
| the <code>go.mod</code> file. To enable lazy loading for an existing module |
| without changing the selected versions of its dependencies, run: |
| </p> |
| |
| <pre> |
| go mod tidy -go=1.17 |
| </pre> |
| |
| <p><!-- golang.org/issue/46141 --> |
| By default, <code>go</code> <code>mod</code> <code>tidy</code> verifies that |
| the selected versions of dependencies relevant to the main module are the same |
| versions that would be used by the prior Go release (Go 1.16 for a module that |
| specifies <code>go</code> <code>1.17</code>), and preserves |
| the <code>go.sum</code> entries needed by that release even for dependencies |
| that are not normally needed by other commands. |
| </p> |
| |
| <p> |
| The <code>-compat</code> flag allows that version to be overridden to support |
| older (or only newer) versions, up to the version specified by |
| the <code>go</code> directive in the <code>go.mod</code> file. To tidy |
| a <code>go</code> <code>1.17</code> module for Go 1.17 only, without saving |
| checksums for (or checking for consistency with) Go 1.16: |
| </p> |
| |
| <pre> |
| go mod tidy -compat=1.17 |
| </pre> |
| |
| <p> |
| Note that even if the main module is tidied with <code>-compat=1.17</code>, |
| users who <code>require</code> the module from a |
| <code>go</code> <code>1.16</code> or earlier module will still be able to |
| use it, provided that the packages use only compatible language and library |
| features. |
| </p> |
| |
| <p><!-- golang.org/issue/46366 --> |
| The <code>go</code> <code>mod</code> <code>graph</code> subcommand also |
| supports the <code>-go</code> flag, which causes it to report the graph as |
| seen by the indicated Go version, showing dependencies that may otherwise be |
| pruned out by lazy loading. |
| </p> |
| |
| <h4 id="module-deprecation-comments">Module deprecation comments</h4> |
| |
| <p><!-- golang.org/issue/40357 --> |
| Module authors may deprecate a module by adding a |
| <a href="/ref/mod#go-mod-file-module-deprecation"><code>// Deprecated:</code> |
| comment</a> to <code>go.mod</code>, then tagging a new version. |
| <code>go</code> <code>get</code> now prints a warning if a module needed to |
| build packages named on the command line is deprecated. <code>go</code> |
| <code>list</code> <code>-m</code> <code>-u</code> prints deprecations for all |
| dependencies (use <code>-f</code> or <code>-json</code> to show the full |
| message). The <code>go</code> command considers different major versions to |
| be distinct modules, so this mechanism may be used, for example, to provide |
| users with migration instructions for a new major version. |
| </p> |
| |
| <h4 id="go-get"><code>go</code> <code>get</code></h4> |
| |
| <p><!-- golang.org/issue/37519 --> |
| The <code>go</code> <code>get</code> <code>-insecure</code> flag is |
| deprecated and has been removed. To permit the use of insecure schemes |
| when fetching dependencies, please use the <code>GOINSECURE</code> |
| environment variable. The <code>-insecure</code> flag also bypassed module |
| sum validation, use <code>GOPRIVATE</code> or <code>GONOSUMDB</code> if |
| you need that functionality. See <code>go</code> <code>help</code> |
| <code>environment</code> for details. |
| </p> |
| |
| <p><!-- golang.org/issue/43684 --> |
| <code>go</code> <code>get</code> prints a deprecation warning when installing |
| commands outside the main module (without the <code>-d</code> flag). |
| <code>go</code> <code>install</code> <code>cmd@version</code> should be used |
| instead to install a command at a specific version, using a suffix like |
| <code>@latest</code> or <code>@v1.2.3</code>. In Go 1.18, the <code>-d</code> |
| flag will always be enabled, and <code>go</code> <code>get</code> will only |
| be used to change dependencies in <code>go.mod</code>. |
| </p> |
| |
| <h4 id="missing-go-directive"><code>go.mod</code> files missing <code>go</code> directives</h4> |
| |
| <p><!-- golang.org/issue/44976 --> |
| If the main module's <code>go.mod</code> file does not contain |
| a <a href="/doc/modules/gomod-ref#go"><code>go</code> directive</a> and |
| the <code>go</code> command cannot update the <code>go.mod</code> file, the |
| <code>go</code> command now assumes <code>go 1.11</code> instead of the |
| current release. (<code>go</code> <code>mod</code> <code>init</code> has added |
| <code>go</code> directives automatically <a href="/doc/go1.12#modules">since |
| Go 1.12</a>.) |
| </p> |
| |
| <p><!-- golang.org/issue/44976 --> |
| If a module dependency lacks an explicit <code>go.mod</code> file, or |
| its <code>go.mod</code> file does not contain |
| a <a href="/doc/modules/gomod-ref#go"><code>go</code> directive</a>, |
| the <code>go</code> command now assumes <code>go 1.16</code> for that |
| dependency instead of the current release. (Dependencies developed in GOPATH |
| mode may lack a <code>go.mod</code> file, and |
| the <code>vendor/modules.txt</code> has to date never recorded |
| the <code>go</code> versions indicated by dependencies' <code>go.mod</code> |
| files.) |
| </p> |
| |
| <h4 id="vendor"><code>vendor</code> contents</h4> |
| |
| <p><!-- golang.org/issue/36876 --> |
| If the main module specifies <code>go</code> <code>1.17</code> or higher, |
| <code>go</code> <code>mod</code> <code>vendor</code> now annotates |
| <code>vendor/modules.txt</code> with the <code>go</code> version indicated by |
| each vendored module in its own <code>go.mod</code> file. The annotated |
| version is used when building the module's packages from vendored source code. |
| </p> |
| |
| <p><!-- golang.org/issue/42970 --> |
| If the main module specifies <code>go</code> <code>1.17</code> or higher, |
| <code>go</code> <code>mod</code> <code>vendor</code> now omits <code>go.mod</code> |
| and <code>go.sum</code> files for vendored dependencies, which can otherwise |
| interfere with the ability of the <code>go</code> command to identify the correct |
| module root when invoked within the <code>vendor</code> tree. |
| </p> |
| |
| <h4 id="password-prompts">Password prompts</h4> |
| |
| <p><!-- golang.org/issue/44904 --> |
| The <code>go</code> command by default now suppresses SSH password prompts and |
| Git Credential Manager prompts when fetching Git repositories using SSH, as it |
| already did previously for other Git password prompts. Users authenticating to |
| private Git repos with password-protected SSH may configure |
| an <code>ssh-agent</code> to enable the <code>go</code> command to use |
| password-protected SSH keys. |
| </p> |
| |
| <h4 id="go-mod-download"><code>go</code> <code>mod</code> <code>download</code></h4> |
| |
| <p><!-- golang.org/issue/45332 --> |
| When <code>go</code> <code>mod</code> <code>download</code> is invoked without |
| arguments, it will no longer save sums for downloaded module content to |
| <code>go.sum</code>. It may still make changes to <code>go.mod</code> and |
| <code>go.sum</code> needed to load the build list. This is the same as the |
| behavior in Go 1.15. To save sums for all modules, use <code>go</code> |
| <code>mod</code> <code>download</code> <code>all</code>. |
| </p> |
| |
| <h4 id="build-lines"><code>//go:build</code> lines</h4> |
| |
| <p> |
| The <code>go</code> command now understands <code>//go:build</code> lines |
| and prefers them over <code>// +build</code> lines. The new syntax uses |
| boolean expressions, just like Go, and should be less error-prone. |
| As of this release, the new syntax is fully supported, and all Go files |
| should be updated to have both forms with the same meaning. To aid in |
| migration, <a href="#gofmt"><code>gofmt</code></a> now automatically |
| synchronizes the two forms. For more details on the syntax and migration plan, |
| see |
| <a href="https://golang.org/design/draft-gobuild">https://golang.org/design/draft-gobuild</a>. |
| </p> |
| |
| <h4 id="go run"><code>go</code> <code>run</code></h4> |
| |
| <p><!-- golang.org/issue/42088 --> |
| <code>go</code> <code>run</code> now accepts arguments with version suffixes |
| (for example, <code>go</code> <code>run</code> |
| <code>example.com/cmd@v1.0.0</code>). This causes <code>go</code> |
| <code>run</code> to build and run packages in module-aware mode, ignoring the |
| <code>go.mod</code> file in the current directory or any parent directory, if |
| there is one. This is useful for running executables without installing them or |
| without changing dependencies of the current module. |
| </p> |
| |
| <h3 id="gofmt">Gofmt</h3> |
| |
| <p> |
| <code>gofmt</code> (and <code>go</code> <code>fmt</code>) now synchronizes |
| <code>//go:build</code> lines with <code>// +build</code> lines. If a file |
| only has <code>// +build</code> lines, they will be moved to the appropriate |
| location in the file, and matching <code>//go:build</code> lines will be |
| added. Otherwise, <code>// +build</code> lines will be overwritten based on |
| any existing <code>//go:build</code> lines. For more information, see |
| <a href="https://golang.org/design/draft-gobuild">https://golang.org/design/draft-gobuild</a>. |
| </p> |
| |
| <h3 id="vet">Vet</h3> |
| |
| <h4 id="vet-buildtags">New warning for mismatched <code>//go:build</code> and <code>// +build</code> lines</h4> |
| |
| <p><!-- CL 240609 --> |
| The <code>vet</code> tool now verifies that <code>//go:build</code> and |
| <code>// +build</code> lines are in the correct part of the file and |
| synchronized with each other. If they aren't, |
| <a href="#gofmt"><code>gofmt</code></a> can be used to fix them. For more |
| information, see |
| <a href="https://golang.org/design/draft-gobuild">https://golang.org/design/draft-gobuild</a>. |
| </p> |
| |
| <h4 id="vet-sigchanyzer">New warning for calling <code>signal.Notify</code> on unbuffered channels</h4> |
| |
| <p><!-- CL 299532 --> |
| The vet tool now warns about calls to <a href="/pkg/os/signal/#Notify">signal.Notify</a> |
| with incoming signals being sent to an unbuffered channel. Using an unbuffered channel |
| risks missing signals sent on them as <code>signal.Notify</code> does not block when |
| sending to a channel. For example: |
| </p> |
| |
| <pre> |
| c := make(chan os.Signal) |
| // signals are sent on c before the channel is read from. |
| // This signal may be dropped as c is unbuffered. |
| signal.Notify(c, os.Interrupt) |
| </pre> |
| |
| <p> |
| Users of <code>signal.Notify</code> should use channels with sufficient buffer space to keep up with the |
| expected signal rate. |
| </p> |
| |
| <h4 id="vet-error-stdmethods">New warnings for Is, As and Unwrap methods</h4> |
| |
| <p><!-- CL 321389 --> |
| The vet tool now warns about methods named <code>As</code>, <code>Is</code> or <code>Unwrap</code> |
| on types implementing the <code>error</code> interface that have a different signature than the |
| one expected by the <code>errors</code> package. The <code>errors.{As,Is,Unwrap}</code> functions |
| expect such methods to implement either <code>Is(error)</code> <code>bool</code>, |
| <code>As(interface{})</code> <code>bool</code>, or <code>Unwrap()</code> <code>error</code> |
| respectively. The functions <code>errors.{As,Is,Unwrap}</code> will ignore methods with the same |
| names but a different signature. For example: |
| </p> |
| |
| <pre> |
| type MyError struct { hint string } |
| func (m MyError) Error() string { ... } // MyError implements error. |
| func (MyError) Is(target interface{}) bool { ... } // target is interface{} instead of error. |
| func Foo() bool { |
| x, y := MyError{"A"}, MyError{"B"} |
| return errors.Is(x, y) // returns false as x != y and MyError does not have an `Is(error) bool` function. |
| } |
| </pre> |
| |
| <h3 id="cover">Cover</h3> |
| |
| <p><!-- CL 249759 --> |
| The <code>cover</code> tool now uses an optimized parser |
| from <code>golang.org/x/tools/cover</code>, which may be noticeably faster |
| when parsing large coverage profiles. |
| </p> |
| |
| <h2 id="compiler">Compiler</h2> |
| |
| <p><!-- golang.org/issue/40724 --> |
| Go 1.17 implements a new way of passing function arguments and results using |
| registers instead of the stack. This work is enabled for Linux, MacOS, and |
| Windows on the 64-bit x86 architecture (the <code>linux/amd64</code>, |
| <code>darwin/amd64</code>, <code>windows/amd64</code> ports). For a |
| representative set of Go packages and programs, benchmarking has shown |
| performance improvements of about 5%, and a typical reduction in binary size |
| of about 2%. |
| </p> |
| |
| <p> |
| This change does not affect the functionality of any safe Go code. It can affect |
| code outside the <a href="/doc/go1compat">compatibility guidelines</a> with |
| minimal impact. To maintain compatibility with existing assembly functions, |
| adapter functions converting between the new register-based calling convention |
| and the previous stack-based calling convention (also known as ABI wrappers) |
| are sometimes used. This is mostly invisible to users, except for assembly |
| functions that have their addresses taken in Go. Using <code>reflect.ValueOf(fn).Pointer()</code> |
| (or similar approaches such as via <code>unsafe.Pointer</code>) to get the address |
| of an assembly function will now return the address of the ABI wrapper. This is |
| mostly harmless, except for special-purpose assembly code (such as accessing |
| thread-local storage or requiring a special stack alignment). Assembly functions |
| called indirectly from Go via <code>func</code> values will now be made through |
| ABI wrappers, which may cause a very small performance overhead. Also, calling |
| Go functions from assembly may now go through ABI wrappers, with a very small |
| performance overhead. |
| </p> |
| |
| <p><!-- CL 304470 --> |
| The format of stack traces from the runtime (printed when an uncaught panic |
| occurs, or when <code>runtime.Stack</code> is called) is improved. Previously, |
| the function arguments were printed as hexadecimal words based on the memory |
| layout. Now each argument in the source code is printed separately, separated |
| by commas. Aggregate-typed (struct, array, string, slice, interface, and complex) |
| arguments are delimited by curly braces. A caveat is that the value of an |
| argument that only lives in a register and is not stored to memory may be |
| inaccurate. Function return values (which were usually inaccurate) are no longer |
| printed. |
| </p> |
| |
| <p><!-- CL 283112, golang.org/issue/28727 --> |
| Functions containing closures can now be inlined. One effect of this change is |
| that a function with a closure may actually produce a distinct closure function |
| for each place that the function is inlined. Hence, this change could reveal |
| bugs where Go functions are compared (incorrectly) by pointer value. Go |
| functions are by definition not comparable. |
| </p> |
| |
| <h2 id="library">Core library</h2> |
| |
| <h3 id="runtime/cgo"><a href="/pkg/runtime/cgo">Cgo</a></h3> |
| |
| <p> |
| The <a href="/pkg/runtime/cgo">runtime/cgo</a> package now provides a |
| new facility that allows to turn any Go values to a safe representation |
| that can be used to pass values between C and Go safely. See |
| <a href="/pkg/runtime/cgo#Handle">runtime/cgo.Handle</a> for more information. |
| </p> |
| |
| <h3 id="semicolons">URL query parsing</h3> |
| <!-- CL 325697, CL 326309 --> |
| |
| <p> |
| The <code>net/url</code> and <code>net/http</code> packages used to accept |
| <code>";"</code> (semicolon) as a setting separator in URL queries, in |
| addition to <code>"&"</code> (ampersand). Now, settings with non-percent-encoded |
| semicolons are rejected and <code>net/http</code> servers will log a warning to |
| <a href="/pkg/net/http#Server.ErrorLog"><code>Server.ErrorLog</code></a> |
| when encountering one in a request URL. |
| </p> |
| |
| <p> |
| For example, before Go 1.17 the <a href="/pkg/net/url#URL.Query"><code>Query</code></a> |
| method of the URL <code>example?a=1;b=2&c=3</code> would have returned |
| <code>map[a:[1] b:[2] c:[3]]</code>, while now it returns <code>map[c:[3]]</code>. |
| </p> |
| |
| <p> |
| When encountering such a query string, |
| <a href="/pkg/net/url#URL.Query"><code>URL.Query</code></a> |
| and |
| <a href="/pkg/net/http#Request.FormValue"><code>Request.FormValue</code></a> |
| ignore any settings that contain a semicolon, |
| <a href="/pkg/net/url#ParseQuery"><code>ParseQuery</code></a> |
| returns the remaining settings and an error, and |
| <a href="/pkg/net/http#Request.ParseForm"><code>Request.ParseForm</code></a> |
| and |
| <a href="/pkg/net/http#Request.ParseMultipartForm"><code>Request.ParseMultipartForm</code></a> |
| return an error but still set <code>Request</code> fields based on the |
| remaining settings. |
| </p> |
| |
| <p> |
| <code>net/http</code> users can restore the original behavior by using the new |
| <a href="/pkg/net/http#AllowQuerySemicolons"><code>AllowQuerySemicolons</code></a> |
| handler wrapper. This will also suppress the <code>ErrorLog</code> warning. |
| Note that accepting semicolons as query separators can lead to security issues |
| if different systems interpret cache keys differently. |
| See <a href="https://golang.org/issue/25192">issue 25192</a> for more information. |
| </p> |
| |
| <h3 id="ALPN">TLS strict ALPN</h3> |
| <!-- CL 289209, CL 325432 --> |
| |
| <p> |
| When <a href="/pkg/crypto/tls#Config.NextProtos"><code>Config.NextProtos</code></a> |
| is set, servers now enforce that there is an overlap between the configured |
| protocols and the ALPN protocols advertised by the client, if any. If there is |
| no mutually supported protocol, the connection is closed with the |
| <code>no_application_protocol</code> alert, as required by RFC 7301. This |
| helps mitigate <a href="https://alpaca-attack.com/">the ALPACA cross-protocol attack</a>. |
| </p> |
| |
| <p> |
| As an exception, when the value <code>"h2"</code> is included in the server's |
| <code>Config.NextProtos</code>, HTTP/1.1 clients will be allowed to connect as |
| if they didn't support ALPN. |
| See <a href="https://golang.org/issue/46310">issue 46310</a> for more information. |
| </p> |
| |
| <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 312310 --> |
| The new methods <a href="/pkg/archive/zip#File.OpenRaw"><code>File.OpenRaw</code></a>, <a href="/pkg/archive/zip#Writer.CreateRaw"><code>Writer.CreateRaw</code></a>, <a href="/pkg/archive/zip#Writer.Copy"><code>Writer.Copy</code></a> provide support for cases where performance is a primary concern. |
| </p> |
| </dd> |
| </dl><!-- archive/zip --> |
| |
| <dl id="bufio"><dt><a href="/pkg/bufio/">bufio</a></dt> |
| <dd> |
| <p><!-- CL 280492 --> |
| The <a href="/pkg/bufio/#Writer.WriteRune"><code>Writer.WriteRune</code></a> method |
| now writes the replacement character U+FFFD for negative rune values, |
| as it does for other invalid runes. |
| </p> |
| </dd> |
| </dl><!-- bufio --> |
| |
| <dl id="bytes"><dt><a href="/pkg/bytes/">bytes</a></dt> |
| <dd> |
| <p><!-- CL 280492 --> |
| The <a href="/pkg/bytes/#Buffer.WriteRune"><code>Buffer.WriteRune</code></a> method |
| now writes the replacement character U+FFFD for negative rune values, |
| as it does for other invalid runes. |
| </p> |
| </dd> |
| </dl><!-- bytes --> |
| |
| <dl id="compress/lzw"><dt><a href="/pkg/compress/lzw/">compress/lzw</a></dt> |
| <dd> |
| <p><!-- CL 273667 --> |
| The <a href="/pkg/compress/lzw/#NewReader"><code>NewReader</code></a> |
| function is guaranteed to return a value of the new |
| type <a href="/pkg/compress/lzw/#Reader"><code>Reader</code></a>, |
| and similarly <a href="/pkg/compress/lzw/#NewWriter"><code>NewWriter</code></a> |
| is guaranteed to return a value of the new |
| type <a href="/pkg/compress/lzw/#Writer"><code>Writer</code></a>. |
| These new types both implement a <code>Reset</code> method |
| (<a href="/pkg/compress/lzw/#Reader.Reset"><code>Reader.Reset</code></a>, |
| <a href="/pkg/compress/lzw/#Writer.Reset"><code>Writer.Reset</code></a>) |
| that allows reuse of the <code>Reader</code> or <code>Writer</code>. |
| </p> |
| </dd> |
| </dl><!-- compress/lzw --> |
| |
| <dl id="crypto/ed25519"><dt><a href="/pkg/crypto/ed25519/">crypto/ed25519</a></dt> |
| <dd> |
| <p><!-- CL 276272 --> |
| The <code>crypto/ed25519</code> package has been rewritten, and all |
| operations are now approximately twice as fast on amd64 and arm64. |
| The observable behavior has not otherwise changed. |
| </p> |
| </dd> |
| </dl><!-- crypto/ed25519 --> |
| |
| <dl id="crypto/elliptic"><dt><a href="/pkg/crypto/elliptic/">crypto/elliptic</a></dt> |
| <dd> |
| <p><!-- CL 233939 --> |
| <a href="/pkg/crypto/elliptic#CurveParams"><code>CurveParams</code></a> |
| methods now automatically invoke faster and safer dedicated |
| implementations for known curves (P-224, P-256, and P-521) when |
| available. Note that this is a best-effort approach and applications |
| should avoid using the generic, not constant-time <code>CurveParams</code> |
| methods and instead use dedicated |
| <a href="/pkg/crypto/elliptic#Curve"><code>Curve</code></a> implementations |
| such as <a href="/pkg/crypto/elliptic#P256"><code>P256</code></a>. |
| </p> |
| |
| <p><!-- CL 315271, CL 315274 --> |
| The <a href="/pkg/crypto/elliptic#P521"><code>P521</code></a> curve |
| implementation has been rewritten using code generated by the |
| <a href="https://github.com/mit-plv/fiat-crypto">fiat-crypto project</a>, |
| which is based on a formally-verified model of the arithmetic |
| operations. It is now constant-time and three times faster on amd64 and |
| arm64. The observable behavior has not otherwise changed. |
| </p> |
| </dd> |
| </dl><!-- crypto/elliptic --> |
| |
| <dl id="crypto/rand"><dt><a href="/pkg/crypto/rand/">crypto/rand</a></dt> |
| <dd> |
| <p><!-- CL 302489, CL 299134, CL 269999 --> |
| The <code>crypto/rand</code> package now uses the <code>getentropy</code> |
| syscall on macOS and the <code>getrandom</code> syscall on Solaris, |
| Illumos, and DragonFlyBSD. |
| </p> |
| </dd> |
| </dl><!-- crypto/rand --> |
| |
| <dl id="crypto/tls"><dt><a href="/pkg/crypto/tls/">crypto/tls</a></dt> |
| <dd> |
| <p><!-- CL 295370 --> |
| The new <a href="/pkg/crypto/tls#Conn.HandshakeContext"><code>Conn.HandshakeContext</code></a> |
| method allows the user to control cancellation of an in-progress TLS |
| handshake. The provided context is accessible from various callbacks through the new |
| <a href="/pkg/crypto/tls#ClientHelloInfo.Context"><code>ClientHelloInfo.Context</code></a> and |
| <a href="/pkg/crypto/tls#CertificateRequestInfo.Context"><code>CertificateRequestInfo.Context</code></a> |
| methods. Canceling the context after the handshake has finished has no effect. |
| </p> |
| |
| <p><!-- CL 314609 --> |
| Cipher suite ordering is now handled entirely by the |
| <code>crypto/tls</code> package. Currently, cipher suites are sorted based |
| on their security, performance, and hardware support taking into account |
| both the local and peer's hardware. The order of the |
| <a href="/pkg/crypto/tls#Config.CipherSuites"><code>Config.CipherSuites</code></a> |
| field is now ignored, as well as the |
| <a href="/pkg/crypto/tls#Config.PreferServerCipherSuites"><code>Config.PreferServerCipherSuites</code></a> |
| field. Note that <code>Config.CipherSuites</code> still allows |
| applications to choose what TLS 1.0–1.2 cipher suites to enable. |
| </p> |
| |
| <p> |
| The 3DES cipher suites have been moved to |
| <a href="/pkg/crypto/tls#InsecureCipherSuites"><code>InsecureCipherSuites</code></a> |
| due to <a href="https://sweet32.info/">fundamental block size-related |
| weakness</a>. They are still enabled by default but only as a last resort, |
| thanks to the cipher suite ordering change above. |
| </p> |
| |
| <p><!-- golang.org/issue/45428 --> |
| Beginning in the next release, Go 1.18, the |
| <a href="/pkg/crypto/tls/#Config.MinVersion"><code>Config.MinVersion</code></a> |
| for <code>crypto/tls</code> clients will default to TLS 1.2, disabling TLS 1.0 |
| and TLS 1.1 by default. Applications will be able to override the change by |
| explicitly setting <code>Config.MinVersion</code>. |
| This will not affect <code>crypto/tls</code> servers. |
| </p> |
| </dd> |
| </dl><!-- crypto/tls --> |
| |
| <dl id="crypto/x509"><dt><a href="/pkg/crypto/x509/">crypto/x509</a></dt> |
| <dd> |
| <p><!-- CL 224157 --> |
| <a href="/pkg/crypto/x509/#CreateCertificate"><code>CreateCertificate</code></a> |
| now returns an error if the provided private key doesn't match the |
| parent's public key, if any. The resulting certificate would have failed |
| to verify. |
| </p> |
| |
| <p><!-- CL 315209 --> |
| The temporary <code>GODEBUG=x509ignoreCN=0</code> flag has been removed. |
| </p> |
| |
| <p><!-- CL 274234 --> |
| <a href="/pkg/crypto/x509/#ParseCertificate"><code>ParseCertificate</code></a> |
| has been rewritten, and now consumes ~70% fewer resources. The observable |
| behavior has not otherwise changed, except for error messages. |
| </p> |
| |
| <p><!-- CL 321190 --> |
| On BSD systems, <code>/etc/ssl/certs</code> is now searched for trusted |
| roots. This adds support for the new system trusted certificate store in |
| FreeBSD 12.2+. |
| </p> |
| |
| <p><!-- golang.org/issue/41682 --> |
| Beginning in the next release, Go 1.18, <code>crypto/x509</code> will |
| reject certificates signed with the SHA-1 hash function. This doesn't |
| apply to self-signed root certificates. Practical attacks against SHA-1 |
| <a href="https://shattered.io/">have been demonstrated in 2017</a> and publicly |
| trusted Certificate Authorities have not issued SHA-1 certificates since 2015. |
| </p> |
| </dd> |
| </dl><!-- crypto/x509 --> |
| |
| <dl id="database/sql"><dt><a href="/pkg/database/sql/">database/sql</a></dt> |
| <dd> |
| <p><!-- CL 258360 --> |
| The <a href="/pkg/database/sql/#DB.Close"><code>DB.Close</code></a> method now closes |
| the <code>connector</code> field if the type in this field implements the |
| <a href="/pkg/io/#Closer"><code>io.Closer</code></a> interface. |
| </p> |
| |
| <p><!-- CL 311572 --> |
| The new |
| <a href="/pkg/database/sql/#NullInt16"><code>NullInt16</code></a> |
| and |
| <a href="/pkg/database/sql/#NullByte"><code>NullByte</code></a> |
| structs represent the int16 and byte values that may be null. These can be used as |
| destinations of the <a href="/pkg/database/sql/#Scan"><code>Scan</code></a> method, |
| similar to NullString. |
| </p> |
| </dd> |
| </dl><!-- database/sql --> |
| |
| <dl id="debug/elf"><dt><a href="/pkg/debug/elf/">debug/elf</a></dt> |
| <dd> |
| <p><!-- CL 239217 --> |
| The <a href="/pkg/debug/elf/#SHT_MIPS_ABIFLAGS"><code>SHT_MIPS_ABIFLAGS</code></a> |
| constant has been added. |
| </p> |
| </dd> |
| </dl><!-- debug/elf --> |
| |
| <dl id="encoding/binary"><dt><a href="/pkg/encoding/binary/">encoding/binary</a></dt> |
| <dd> |
| <p><!-- CL 299531 --> |
| <code>binary.Uvarint</code> will stop reading after <code>10 bytes</code> to avoid |
| wasted computations. If more than <code>10 bytes</code> are needed, the byte count returned is <code>-11</code>. |
| <br /> |
| Previous Go versions could return larger negative counts when reading incorrectly encoded varints. |
| </p> |
| </dd> |
| </dl><!-- encoding/binary --> |
| |
| <dl id="encoding/csv"><dt><a href="/pkg/encoding/csv/">encoding/csv</a></dt> |
| <dd> |
| <p><!-- CL 291290 --> |
| The new |
| <a href="/pkg/encoding/csv/#Reader.FieldPos"><code>Reader.FieldPos</code></a> |
| method returns the line and column corresponding to the start of |
| a given field in the record most recently returned by |
| <a href="/pkg/encoding/csv/#Reader.Read"><code>Read</code></a>. |
| </p> |
| </dd> |
| </dl><!-- encoding/csv --> |
| |
| <dl id="encoding/xml"><dt><a href="/pkg/encoding/xml/">encoding/xml</a></dt> |
| <dd> |
| <p><!-- CL 277893 --> |
| When a comment appears within a |
| <a href="/pkg/encoding/xml/#Directive"><code>Directive</code></a>, it is now replaced |
| with a single space instead of being completely elided. |
| </p> |
| |
| <p> |
| Invalid element or attribute names with leading, trailing, or multiple |
| colons are now stored unmodified into the |
| <a href="/pkg/encoding/xml/#Name"><code>Name.Local</code></a> field. |
| </p> |
| </dd> |
| </dl><!-- encoding/xml --> |
| |
| <dl id="flag"><dt><a href="/pkg/flag/">flag</a></dt> |
| <dd> |
| <p><!-- CL 271788 --> |
| Flag declarations now panic if an invalid name is specified. |
| </p> |
| </dd> |
| </dl><!-- flag --> |
| |
| <dl id="go/build"><dt><a href="/pkg/go/build/">go/build</a></dt> |
| <dd> |
| <p><!-- CL 310732 --> |
| The new |
| <a href="/pkg/go/build/#Context.ToolTags"><code>Context.ToolTags</code></a> |
| field holds the build tags appropriate to the current Go |
| toolchain configuration. |
| </p> |
| </dd> |
| </dl><!-- go/build --> |
| |
| <dl id="go/format"><dt><a href="/pkg/go/format/">go/format</a></dt> |
| <dd> |
| <p> |
| The <a href="/pkg/go/format/#Source"><code>Source</code></a> and |
| <a href="/pkg/go/format/#Node"><code>Node</code></a> functions now |
| synchronize <code>//go:build</code> lines with <code>// +build</code> |
| lines. If a file only has <code>// +build</code> lines, they will be |
| moved to the appropriate location in the file, and matching |
| <code>//go:build</code> lines will be added. Otherwise, |
| <code>// +build</code> lines will be overwritten based on any existing |
| <code>//go:build</code> lines. For more information, see |
| <a href="https://golang.org/design/draft-gobuild">https://golang.org/design/draft-gobuild</a>. |
| </p> |
| </dd> |
| </dl><!-- go/format --> |
| |
| <dl id="go/parser"><dt><a href="/pkg/go/parser/">go/parser</a></dt> |
| <dd> |
| <p><!-- CL 306149 --> |
| The new <a href="/pkg/go/parser/#SkipObjectResolution"><code>SkipObjectResolution</code></a> |
| <code>Mode</code> value instructs the parser not to resolve identifiers to |
| their declaration. This may improve parsing speed. |
| </p> |
| </dd> |
| </dl><!-- go/parser --> |
| |
| <dl id="image"><dt><a href="/pkg/image/">image</a></dt> |
| <dd> |
| <p><!-- CL 311129 --> |
| The concrete image types (<code>RGBA</code>, <code>Gray16</code> and so on) |
| now implement a new <a href="/pkg/image/#RGBA64Image"><code>RGBA64Image</code></a> |
| interface. Those concrete types, other than the chroma-subsampling |
| related <code>YCbCr</code> and <code>NYCbCrA</code>, also now implement |
| <a href="/pkg/image/draw/#RGBA64Image"><code>draw.RGBA64Image</code></a>, a |
| new interface in the <code>image/draw</code> package. |
| </p> |
| </dd> |
| </dl><!-- image --> |
| |
| <dl id="io/fs"><dt><a href="/pkg/io/fs/">io/fs</a></dt> |
| <dd> |
| <p><!-- CL 293649 --> |
| The new <a href="/pkg/io/fs/#FileInfoToDirEntry"><code>FileInfoToDirEntry</code></a> function converts a <code>FileInfo</code> to a <code>DirEntry</code>. |
| </p> |
| </dd> |
| </dl><!-- io/fs --> |
| |
| <dl id="math"><dt><a href="/pkg/math/">math</a></dt> |
| <dd> |
| <p><!-- CL 247058 --> |
| The math package now defines three more constants: <code>MaxUint</code>, <code>MaxInt</code> and <code>MinInt</code>. |
| For 32-bit systems their values are <code>2^32 - 1</code>, <code>2^31 - 1</code> and <code>-2^31</code>, respectively. |
| For 64-bit systems their values are <code>2^64 - 1</code>, <code>2^63 - 1</code> and <code>-2^63</code>, respectively. |
| </p> |
| </dd> |
| </dl><!-- math --> |
| |
| <dl id="mime"><dt><a href="/pkg/mime/">mime</a></dt> |
| <dd> |
| <p><!-- CL 305230 --> |
| On Unix systems, the table of MIME types is now read from the local system's |
| <a href="https://specifications.freedesktop.org/shared-mime-info-spec/shared-mime-info-spec-0.21.html">Shared MIME-info Database</a> |
| when available. |
| </p> |
| </dd> |
| </dl><!-- mime --> |
| |
| <dl id="mime/multipart"><dt><a href="/pkg/mime/multipart/">mime/multipart</a></dt> |
| <dd> |
| <p><!-- CL 313809 --> |
| <a href="/pkg/mime/multipart/#Part.FileName"><code>Part.FileName</code></a> |
| now applies |
| <a href="/pkg/path/filepath/#Base"><code>filepath.Base</code></a> to the |
| return value. This mitigates potential path traversal vulnerabilities in |
| applications that accept multipart messages, such as <code>net/http</code> |
| servers that call |
| <a href="/pkg/net/http/#Request.FormFile"><code>Request.FormFile</code></a>. |
| </p> |
| </dd> |
| </dl><!-- mime/multipart --> |
| |
| <dl id="net"><dt><a href="/pkg/net/">net</a></dt> |
| <dd> |
| <p><!-- CL 272668 --> |
| The new method <a href="/pkg/net/#IP.IsPrivate"><code>IP.IsPrivate</code></a> reports whether an address is |
| a private IPv4 address according to <a href="http://tools.ietf.org/html/rfc1918">RFC 1918</a> |
| or a local IPv6 address according <a href="http://tools.ietf.org/html/rfc4193">RFC 4193</a>. |
| </p> |
| |
| <p><!-- CL 301709 --> |
| The Go DNS resolver now only sends one DNS query when resolving an address for an IPv4-only or IPv6-only network, |
| rather than querying for both address families. |
| </p> |
| |
| <p><!-- CL 307030 --> |
| The <a href="/pkg/net/#ErrClosed"><code>ErrClosed</code></a> sentinel error and |
| <a href="/pkg/net/#ParseError"><code>ParseError</code></a> error type now implement |
| the <a href="/pkg/net/#Error"><code>net.Error</code></a> interface. |
| </p> |
| |
| <p><!-- CL 325829 --> |
| The <a href="/pkg/net/#ParseIP"><code>ParseIP</code></a> and <a href="/pkg/net/#ParseCIDR"><code>ParseCIDR</code></a> |
| functions now reject IPv4 addresses which contain decimal components with leading zeros. |
| |
| These components were always interpreted as decimal, but some operating systems treat them as octal. |
| This mismatch could hypothetically lead to security issues if a Go application was used to validate IP addresses |
| which were then used in their original form with non-Go applications which interpreted components as octal. Generally, |
| it is advisable to always re-encode values after validation, which avoids this class of parser misalignment issues. |
| </p> |
| </dd> |
| </dl><!-- net --> |
| |
| <dl id="net/http"><dt><a href="/pkg/net/http/">net/http</a></dt> |
| <dd> |
| <p><!-- CL 295370 --> |
| The <a href="/pkg/net/http/"><code>net/http</code></a> package now uses the new |
| <a href="/pkg/crypto/tls#Conn.HandshakeContext"><code>(*tls.Conn).HandshakeContext</code></a> |
| with the <a href="/pkg/net/http/#Request"><code>Request</code></a> context |
| when performing TLS handshakes in the client or server. |
| </p> |
| |
| <p><!-- CL 235437 --> |
| Setting the <a href="/pkg/net/http/#Server"><code>Server</code></a> |
| <code>ReadTimeout</code> or <code>WriteTimeout</code> fields to a negative value now indicates no timeout |
| rather than an immediate timeout. |
| </p> |
| |
| <p><!-- CL 308952 --> |
| The <a href="/pkg/net/http/#ReadRequest"><code>ReadRequest</code></a> function |
| now returns an error when the request has multiple Host headers. |
| </p> |
| |
| <p><!-- CL 313950 --> |
| When producing a redirect to the cleaned version of a URL, |
| <a href="/pkg/net/http/#ServeMux"><code>ServeMux</code></a> now always |
| uses relative URLs in the <code>Location</code> header. Previously it |
| would echo the full URL of the request, which could lead to unintended |
| redirects if the client could be made to send an absolute request URL. |
| </p> |
| |
| <p><!-- CL 308009, CL 313489 --> |
| When interpreting certain HTTP headers handled by <code>net/http</code>, |
| non-ASCII characters are now ignored or rejected. |
| </p> |
| |
| <p><!-- CL 325697 --> |
| If |
| <a href="/pkg/net/http/#Request.ParseForm"><code>Request.ParseForm</code></a> |
| returns an error when called by |
| <a href="/pkg/net/http/#Request.ParseMultipartForm"><code>Request.ParseMultipartForm</code></a>, |
| the latter now continues populating |
| <a href="/pkg/net/http/#Request.MultipartForm"><code>Request.MultipartForm</code></a> |
| before returning it. |
| </p> |
| </dd> |
| </dl><!-- net/http --> |
| |
| <dl id="net/http/httptest"><dt><a href="/pkg/net/http/httptest/">net/http/httptest</a></dt> |
| <dd> |
| <p><!-- CL 308950 --> |
| <a href="/pkg/net/http/httptest/#ResponseRecorder.WriteHeader"><code>ResponseRecorder.WriteHeader</code></a> |
| now panics when the provided code is not a valid three-digit HTTP status code. |
| This matches the behavior of <a href="/pkg/net/http/#ResponseWriter"><code>ResponseWriter</code></a> |
| implementations in the <a href="/pkg/net/http/"><code>net/http</code></a> package. |
| </p> |
| </dd> |
| </dl><!-- net/http/httptest --> |
| |
| <dl id="net/url"><dt><a href="/pkg/net/url/">net/url</a></dt> |
| <dd> |
| <p><!-- CL 314850 --> |
| The new method <a href="/pkg/net/url/#Values.Has"><code>Values.Has</code></a> |
| reports whether a query parameter is set. |
| </p> |
| </dd> |
| </dl><!-- net/url --> |
| |
| <dl id="os"><dt><a href="/pkg/os/">os</a></dt> |
| <dd> |
| <p><!-- CL 268020 --> |
| The <a href="/pkg/os/#File.WriteString"><code>File.WriteString</code></a> method |
| has been optimized to not make a copy of the input string. |
| </p> |
| </dd> |
| </dl><!-- os --> |
| |
| <dl id="reflect"><dt><a href="/pkg/reflect/">reflect</a></dt> |
| <dd> |
| <p><!-- CL 266197 --> |
| The new |
| <a href="/pkg/reflect/#StructField.IsExported"><code>StructField.IsExported</code></a> |
| and |
| <a href="/pkg/reflect/#Method.IsExported"><code>Method.IsExported</code></a> |
| methods report whether a struct field or type method is exported. |
| They provide a more readable alternative to checking whether <code>PkgPath</code> |
| is empty. |
| </p> |
| |
| <p><!-- CL 281233 --> |
| The new <a href="/pkg/reflect/#VisibleFields"><code>VisibleFields</code></a> function |
| returns all the visible fields in a struct type, including fields inside anonymous struct members. |
| </p> |
| |
| <p><!-- CL 284136 --> |
| The <a href="/pkg/reflect/#ArrayOf"><code>ArrayOf</code></a> function now panics when |
| called with a negative length. |
| </p> |
| |
| <p><!-- CL 301652 --> |
| Checking the <a href="/pkg/reflect/#Type"><code>Type.ConvertibleTo</code></a> method |
| is no longer sufficient to guarantee that a call to |
| <a href="/pkg/reflect/#Value.Convert"><code>Value.Convert</code></a> will not panic. |
| It may panic when converting `[]T` to `*[N]T` if the slice's length is less than N. |
| See the language changes section above. |
| </p> |
| </dd> |
| </dl><!-- reflect --> |
| |
| <dl id="runtime/metrics"><dt><a href="/pkg/runtime/metrics">runtime/metrics</a></dt> |
| <dd> |
| <p><!-- CL 308933, CL 312431, CL 312909 --> |
| New metrics were added that track total bytes and objects allocated and freed. |
| A new metric tracking the distribution of goroutine scheduling latencies was |
| also added. |
| </p> |
| </dd> |
| </dl><!-- runtime/metrics --> |
| |
| <dl id="runtime/pprof"><dt><a href="/pkg/runtime/pprof">runtime/pprof</a></dt> |
| <dd> |
| <p><!-- CL 299991 --> |
| Block profiles are no longer biased to favor infrequent long events over |
| frequent short events. |
| </p> |
| </dd> |
| </dl><!-- runtime/pprof --> |
| |
| <dl id="strconv"><dt><a href="/pkg/strconv/">strconv</a></dt> |
| <dd> |
| <p><!-- CL 170079, CL 170080 --> |
| The <code>strconv</code> package now uses Ulf Adams's Ryū algorithm for formatting floating-point numbers. |
| This algorithm improves performance on most inputs and is more than 99% faster on worst-case inputs. |
| </p> |
| |
| <p><!-- CL 314775 --> |
| The new <a href="/pkg/strconv/#QuotedPrefix"><code>QuotedPrefix</code></a> function |
| returns the quoted string (as understood by |
| <a href="/pkg/strconv/#Unquote"><code>Unquote</code></a>) |
| at the start of input. |
| </p> |
| </dd> |
| </dl><!-- strconv --> |
| |
| <dl id="strings"><dt><a href="/pkg/strings/">strings</a></dt> |
| <dd> |
| <p><!-- CL 280492 --> |
| The <a href="/pkg/strings/#Builder.WriteRune"><code>Builder.WriteRune</code></a> method |
| now writes the replacement character U+FFFD for negative rune values, |
| as it does for other invalid runes. |
| </p> |
| </dd> |
| </dl><!-- strings --> |
| |
| <dl id="sync/atomic"><dt><a href="/pkg/sync/atomic/">sync/atomic</a></dt> |
| <dd> |
| <p><!-- CL 241678 --> |
| <code>atomic.Value</code> now has <a href="/pkg/sync/atomic/#Value.Swap"><code>Swap</code></a> and |
| <a href="/pkg/sync/atomic/#Value.CompareAndSwap"><code>CompareAndSwap</code></a> methods that provide |
| additional atomic operations. |
| </p> |
| </dd> |
| </dl><!-- sync/atomic --> |
| |
| <dl id="syscall"><dt><a href="/pkg/syscall/">syscall</a></dt> |
| <dd> |
| <p><!-- CL 295371 --> |
| <p> |
| The <a href="/pkg/syscall/#GetQueuedCompletionStatus"><code>GetQueuedCompletionStatus</code></a> and |
| <a href="/pkg/syscall/#PostQueuedCompletionStatus"><code>PostQueuedCompletionStatus</code></a> |
| functions are now deprecated. These functions have incorrect signatures and are superseded by |
| equivalents in the <a href="https://godoc.org/golang.org/x/sys/windows"><code>golang.org/x/sys/windows</code></a> package. |
| </p> |
| |
| <p><!-- CL 313653 --> |
| On Unix-like systems, the process group of a child process is now set with signals blocked. |
| This avoids sending a <code>SIGTTOU</code> to the child when the parent is in a background process group. |
| </p> |
| |
| <p><!-- CL 288298, CL 288300 --> |
| The Windows version of |
| <a href="/pkg/syscall/#SysProcAttr"><code>SysProcAttr</code></a> |
| has two new fields. <code>AdditionalInheritedHandles</code> is |
| a list of additional handles to be inherited by the new child |
| process. <code>ParentProcess</code> permits specifying the |
| parent process of the new process. |
| |
| <p><!-- CL 311570 --> |
| The constant <code>MSG_CMSG_CLOEXEC</code> is now defined on |
| DragonFly and all OpenBSD systems (it was already defined on |
| some OpenBSD systems and all FreeBSD, NetBSD, and Linux systems). |
| </p> |
| |
| <p><!-- CL 315281 --> |
| The constants <code>SYS_WAIT6</code> and <code>WEXITED</code> |
| are now defined on NetBSD systems (<code>SYS_WAIT6</code> was |
| already defined on DragonFly and FreeBSD systems; |
| <code>WEXITED</code> was already defined on Darwin, DragonFly, |
| FreeBSD, Linux, and Solaris systems). |
| </p> |
| </dd> |
| </dl><!-- syscall --> |
| |
| <dl id="testing"><dt><a href="/pkg/testing/">testing</a></dt> |
| <dd> |
| <p><!-- CL 310033 --> |
| Added a new <a href="/cmd/go/#hdr-Testing_flags">testing flag</a> <code>-shuffle</code> which controls the execution order of tests and benchmarks. |
| </p> |
| <p><!-- CL 260577 --> |
| The new |
| <a href="/pkg/testing/#T.Setenv"><code>T.Setenv</code></a> |
| and <a href="/pkg/testing/#B.Setenv"><code>B.Setenv</code></a> |
| methods support setting an environment variable for the duration |
| of the test or benchmark. |
| </p> |
| </dd> |
| </dl><!-- testing --> |
| |
| <dl id="text/template/parse"><dt><a href="/pkg/text/template/parse/">text/template/parse</a></dt> |
| <dd> |
| <p><!-- CL 301493 --> |
| The new <a href="/pkg/text/template/parse/#Mode"><code>SkipFuncCheck</code></a> <a href=><code>Mode</code></a> |
| value changes the template parser to not verify that functions are defined. |
| </p> |
| </dd> |
| </dl><!-- text/template/parse --> |
| |
| <dl id="time"><dt><a href="/pkg/time/">time</a></dt> |
| <dd> |
| <p><!-- CL 260858 --> |
| The <a href="/pkg/time/#Time"><code>Time</code></a> type now has a |
| <a href="/pkg/time/#Time.GoString"><code>GoString</code></a> method that |
| will return a more useful value for times when printed with the |
| <code>%#v</code> format specifier in the <code>fmt</code> package. |
| </p> |
| |
| <p><!-- CL 264077 --> |
| The new <a href="/pkg/time/#Time.IsDST"><code>Time.IsDST</code></a> method can be used to check whether the time |
| is in Daylight Savings Time in its configured location. |
| </p> |
| |
| <p><!-- CL 293349 --> |
| The new <a href="/pkg/time/#Time.UnixMilli"><code>Time.UnixMilli</code></a> and |
| <a href="/pkg/time/#Time.UnixMicro"><code>Time.UnixMicro</code></a> methods return the number of milliseconds and |
| microseconds elapsed since January 1, 1970 UTC respectively.<br> |
| The new <code>UnixMilli</code> and <code>UnixMicro</code> functions return local Time corresponding to given |
| Unix time. |
| </p> |
| |
| <p><!-- CL 300996 --> |
| The package now accepts comma "," as a separator for fractional seconds when parsing and formatting time. |
| The following time formats are now accepted: |
| <ul> |
| <li>2006-01-02 14:06:03,999999999 -0700 MST</li> |
| <li>Mon Jan _2 14:06:03,120007 2006</li> |
| <li>Mon Jan 2 14:06:03,120007 2006</li> |
| </ul> |
| </p> |
| |
| <p><!-- CL 320252 --> |
| The new constant <a href="/pkg/time/#Layout"><code>Layout</code></a> |
| defines the reference time. |
| </p> |
| </dd> |
| </dl><!-- time --> |
| |
| <dl id="unicode"><dt><a href="/pkg/unicode/">unicode</a></dt> |
| <dd> |
| <p><!-- CL 280493 --> |
| The <a href="/pkg/unicode/#Is"><code>Is</code></a>, |
| <a href="/pkg/unicode/#IsGraphic"><code>IsGraphic</code></a>, |
| <a href="/pkg/unicode/#IsLetter"><code>IsLetter</code></a>, |
| <a href="/pkg/unicode/#IsLower"><code>IsLower</code></a>, |
| <a href="/pkg/unicode/#IsMark"><code>IsMark</code></a>, |
| <a href="/pkg/unicode/#IsNumber"><code>IsNumber</code></a>, |
| <a href="/pkg/unicode/#IsPrint"><code>IsPrint</code></a>, |
| <a href="/pkg/unicode/#IsPunct"><code>IsPunct</code></a>, |
| <a href="/pkg/unicode/#IsSpace"><code>IsSpace</code></a>, |
| <a href="/pkg/unicode/#IsSymbol"><code>IsSymbol</code></a>, and |
| <a href="/pkg/unicode/#IsUpper"><code>IsUpper</code></a> functions |
| now return <code>false</code> on negative rune values, as they do for other invalid runes. |
| </p> |
| </dd> |
| </dl><!-- unicode --> |