+++ /dev/null
-<!--{
- "Title": "Go 1.16 Release Notes",
- "Path": "/doc/go1.16"
-}-->
-
-<!--
-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">Introduction to Go 1.16</h2>
-
-<p>
- The latest Go release, version 1.16, arrives six months after <a href="/doc/go1.15">Go 1.15</a>.
- Most of its changes are in the implementation of the toolchain, runtime, and libraries.
- As always, the release maintains the Go 1 <a href="/doc/go1compat.html">promise of compatibility</a>.
- We expect almost all Go programs to continue to compile and run as before.
-</p>
-
-<h2 id="language">Changes to the language</h2>
-
-<p>
- There are no changes to the language.
-</p>
-
-<h2 id="ports">Ports</h2>
-
-<h3 id="darwin">Darwin and iOS</h3>
-
-<p><!-- golang.org/issue/38485, golang.org/issue/41385, CL 266373, more CLs -->
- Go 1.16 adds support of 64-bit ARM architecture on macOS (also known as
- Apple Silicon) with <code>GOOS=darwin</code>, <code>GOARCH=arm64</code>.
- Like the <code>darwin/amd64</code> port, the <code>darwin/arm64</code>
- port supports cgo, internal and external linking, <code>c-archive</code>,
- <code>c-shared</code>, and <code>pie</code> build modes, and the race
- detector.
-</p>
-
-<p><!-- CL 254740 -->
- The iOS port, which was previously <code>darwin/arm64</code>, has
- been renamed to <code>ios/arm64</code>. <code>GOOS=ios</code>
- implies the
- <code>darwin</code> build tag, just as <code>GOOS=android</code>
- implies the <code>linux</code> build tag. This change should be
- transparent to anyone using gomobile to build iOS apps.
-</p>
-
-<p><!-- golang.org/issue/42100, CL 263798 -->
- Go 1.16 adds an <code>ios/amd64</code> port, which targets the iOS
- simulator running on AMD64-based macOS. Previously this was
- unofficially supported through <code>darwin/amd64</code> with
- the <code>ios</code> build tag set. See also
- <a href="/misc/ios/README"><code>misc/ios/README</code></a> for
- details about how to build programs for iOS and iOS simulator.
-</p>
-
-<p><!-- golang.org/issue/23011 -->
- Go 1.16 is the last release that will run on macOS 10.12 Sierra.
- Go 1.17 will require macOS 10.13 High Sierra or later.
-</p>
-
-<h3 id="netbsd">NetBSD</h3>
-
-<p><!-- golang.org/issue/30824 -->
- Go now supports the 64-bit ARM architecture on NetBSD (the
- <code>netbsd/arm64</code> port).
-</p>
-
-<h3 id="openbsd">OpenBSD</h3>
-
-<p><!-- golang.org/issue/40995 -->
- Go now supports the MIPS64 architecture on OpenBSD
- (the <code>openbsd/mips64</code> port). This port does not yet
- support cgo.
-</p>
-
-<p><!-- golang.org/issue/36435, many CLs -->
- 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 now made through <code>libc</code>, instead of directly using
- the <code>SYSCALL</code>/<code>SVC</code> instruction. This ensures
- forward-compatibility with future versions of OpenBSD. In particular,
- OpenBSD 6.9 onwards will require system calls to be made through
- <code>libc</code> for non-static Go binaries.
-</p>
-
-<h3 id="386">386</h3>
-
-<p><!-- golang.org/issue/40255, golang.org/issue/41848, CL 258957, and CL 260017 -->
- As <a href="go1.15#386">announced</a> in the Go 1.15 release notes,
- Go 1.16 drops support for x87 mode compilation (<code>GO386=387</code>).
- Support for non-SSE2 processors is now available using soft float
- mode (<code>GO386=softfloat</code>).
- Users running on non-SSE2 processors should replace <code>GO386=387</code>
- with <code>GO386=softfloat</code>.
-</p>
-
-<h3 id="riscv">RISC-V</h3>
-
-<p><!-- golang.org/issue/36641, CL 267317 -->
- The <code>linux/riscv64</code> port now supports cgo and
- <code>-buildmode=pie</code>. This release also includes performance
- optimizations and code generation improvements for RISC-V.
-</p>
-
-<h2 id="tools">Tools</h2>
-
-<h3 id="go-command">Go command</h3>
-
-<h4 id="modules">Modules</h4>
-
-<p><!-- golang.org/issue/41330 -->
- Module-aware mode is enabled by default, regardless of whether a
- <code>go.mod</code> file is present in the current working directory or a
- parent directory. More precisely, the <code>GO111MODULE</code> environment
- variable now defaults to <code>on</code>. To switch to the previous behavior,
- set <code>GO111MODULE</code> to <code>auto</code>.
-</p>
-
-<p><!-- golang.org/issue/40728 -->
- Build commands like <code>go</code> <code>build</code> and <code>go</code>
- <code>test</code> no longer modify <code>go.mod</code> and <code>go.sum</code>
- by default. Instead, they report an error if a module requirement or checksum
- needs to be added or updated (as if the <code>-mod=readonly</code> flag were
- used). Module requirements and sums may be adjusted with <code>go</code>
- <code>mod</code> <code>tidy</code> or <code>go</code> <code>get</code>.
-</p>
-
-<p><!-- golang.org/issue/40276 -->
- <code>go</code> <code>install</code> now accepts arguments with
- version suffixes (for example, <code>go</code> <code>install</code>
- <code>example.com/cmd@v1.0.0</code>). This causes <code>go</code>
- <code>install</code> to build and install 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 installing executables without
- affecting the dependencies of the main module.
-</p>
-
-<p><!-- golang.org/issue/40276 -->
- <code>go</code> <code>install</code>, with or without a version suffix (as
- described above), is now the recommended way to build and install packages in
- module mode. <code>go</code> <code>get</code> should be used with the
- <code>-d</code> flag to adjust the current module's dependencies without
- building packages, and use of <code>go</code> <code>get</code> to build and
- install packages is deprecated. In a future release, the <code>-d</code> flag
- will always be enabled.
-</p>
-
-<p><!-- golang.org/issue/24031 -->
- <code>retract</code> directives may now be used in a <code>go.mod</code> file
- to indicate that certain published versions of the module should not be used
- by other modules. A module author may retract a version after a severe problem
- is discovered or if the version was published unintentionally.
-</p>
-
-<p><!-- golang.org/issue/26603 -->
- The <code>go</code> <code>mod</code> <code>vendor</code>
- and <code>go</code> <code>mod</code> <code>tidy</code> subcommands now accept
- the <code>-e</code> flag, which instructs them to proceed despite errors in
- resolving missing packages.
-</p>
-
-<p><!-- golang.org/issue/36465 -->
- The <code>go</code> command now ignores requirements on module versions
- excluded by <code>exclude</code> directives in the main module. Previously,
- the <code>go</code> command used the next version higher than an excluded
- version, but that version could change over time, resulting in
- non-reproducible builds.
-</p>
-
-<p><!-- golang.org/issue/43052, golang.org/issue/43985 -->
- In module mode, the <code>go</code> command now disallows import paths that
- include non-ASCII characters or path elements with a leading dot character
- (<code>.</code>). Module paths with these characters were already disallowed
- (see <a href="/ref/mod#go-mod-file-ident">Module paths and versions</a>),
- so this change affects only paths within module subdirectories.
-</p>
-
-<h4 id="embed">Embedding Files</h4>
-
-<p>
- The <code>go</code> command now supports including
- static files and file trees as part of the final executable,
- using the new <code>//go:embed</code> directive.
- See the documentation for the new
- <a href="/pkg/embed/"><code>embed</code></a>
- package for details.
-</p>
-
-<h4 id="go-test"><code>go</code> <code>test</code></h4>
-
-<p><!-- golang.org/issue/29062 -->
- When using <code>go</code> <code>test</code>, a test that
- calls <code>os.Exit(0)</code> during execution of a test function
- will now be considered to fail.
- This will help catch cases in which a test calls code that calls
- <code>os.Exit(0)</code> and thereby stops running all future tests.
- If a <code>TestMain</code> function calls <code>os.Exit(0)</code>
- that is still considered to be a passing test.
-</p>
-
-<p><!-- golang.org/issue/39484 -->
- <code>go</code> <code>test</code> reports an error when the <code>-c</code>
- or <code>-i</code> flags are used together with unknown flags. Normally,
- unknown flags are passed to tests, but when <code>-c</code> or <code>-i</code>
- are used, tests are not run.
-</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 will be removed in a future version. This flag permits
- fetching from repositories and resolving custom domains using insecure
- schemes such as HTTP, and also bypasses module sum validation using the
- checksum database. To permit the use of insecure schemes, use the
- <code>GOINSECURE</code> environment variable instead. To bypass module
- sum validation, use <code>GOPRIVATE</code> or <code>GONOSUMDB</code>.
- See <code>go</code> <code>help</code> <code>environment</code> for details.
-</p>
-
-<p><!-- golang.org/cl/263267 -->
- <code>go</code> <code>get</code> <code>example.com/mod@patch</code> now
- requires that some version of <code>example.com/mod</code> already be
- required by the main module.
- (However, <code>go</code> <code>get</code> <code>-u=patch</code> continues
- to patch even newly-added dependencies.)
-</p>
-
-<h4 id="govcs"><code>GOVCS</code> environment variable</h4>
-
-<p><!-- golang.org/issue/266420 -->
- <code>GOVCS</code> is a new environment variable that limits which version
- control tools the <code>go</code> command may use to download source code.
- This mitigates security issues with tools that are typically used in trusted,
- authenticated environments. By default, <code>git</code> and <code>hg</code>
- may be used to download code from any repository. <code>svn</code>,
- <code>bzr</code>, and <code>fossil</code> may only be used to download code
- from repositories with module paths or package paths matching patterns in
- the <code>GOPRIVATE</code> environment variable. See
- <a href="/cmd/go/#hdr-Controlling_version_control_with_GOVCS"><code>go</code>
- <code>help</code> <code>vcs</code></a> for details.
-</p>
-
-<h4 id="all-pattern">The <code>all</code> pattern</h4>
-
-<p><!-- golang.org/cl/240623 -->
- When the main module's <code>go.mod</code> file
- declares <code>go</code> <code>1.16</code> or higher, the <code>all</code>
- package pattern now matches only those packages that are transitively imported
- by a package or test found in the main module. (Packages imported by <em>tests
- of</em> packages imported by the main module are no longer included.) This is
- the same set of packages retained
- by <code>go</code> <code>mod</code> <code>vendor</code> since Go 1.11.
-</p>
-
-<h4 id="toolexec">The <code>-toolexec</code> build flag</h4>
-
-<p><!-- golang.org/cl/263357 -->
- When the <code>-toolexec</code> build flag is specified to use a program when
- invoking toolchain programs like compile or asm, the environment variable
- <code>TOOLEXEC_IMPORTPATH</code> is now set to the import path of the package
- being built.
-</p>
-
-<h4 id="i-flag">The <code>-i</code> build flag</h4>
-
-<p><!-- golang.org/issue/41696 -->
- The <code>-i</code> flag accepted by <code>go</code> <code>build</code>,
- <code>go</code> <code>install</code>, and <code>go</code> <code>test</code> is
- now deprecated. The <code>-i</code> flag instructs the <code>go</code> command
- to install packages imported by packages named on the command line. Since
- the build cache was introduced in Go 1.10, the <code>-i</code> flag no longer
- has a significant effect on build times, and it causes errors when the install
- directory is not writable.
-</p>
-
-<h4 id="list-buildid">The <code>list</code> command</h4>
-
-<p><!-- golang.org/cl/263542 -->
- When the <code>-export</code> flag is specified, the <code>BuildID</code>
- field is now set to the build ID of the compiled package. This is equivalent
- to running <code>go</code> <code>tool</code> <code>buildid</code> on
- <code>go</code> <code>list</code> <code>-exported</code> <code>-f</code> <code>{{.Export}}</code>,
- but without the extra step.
-</p>
-
-<h4 id="overlay-flag">The <code>-overlay</code> flag</h4>
-
-<p><!-- golang.org/issue/39958 -->
- The <code>-overlay</code> flag specifies a JSON configuration file containing
- a set of file path replacements. The <code>-overlay</code> flag may be used
- with all build commands and <code>go</code> <code>mod</code> subcommands.
- It is primarily intended to be used by editor tooling such as gopls to
- understand the effects of unsaved changes to source files. The config file
- maps actual file paths to replacement file paths and the <code>go</code>
- command and its builds will run as if the actual file paths exist with the
- contents given by the replacement file paths, or don't exist if the replacement
- file paths are empty.
-</p>
-
-<h3 id="cgo">Cgo</h3>
-
-<p><!-- CL 252378 -->
- The <a href="/cmd/cgo">cgo</a> tool will no longer try to translate
- C struct bitfields into Go struct fields, even if their size can be
- represented in Go. The order in which C bitfields appear in memory
- is implementation dependent, so in some cases the cgo tool produced
- results that were silently incorrect.
-</p>
-
-<h3 id="vet">Vet</h3>
-
-<h4 id="vet-testing-T">New warning for invalid testing.T use in
-goroutines</h4>
-
-<p><!-- CL 235677 -->
- The vet tool now warns about invalid calls to the <code>testing.T</code>
- method <code>Fatal</code> from within a goroutine created during the test.
- This also warns on calls to <code>Fatalf</code>, <code>FailNow</code>, and
- <code>Skip{,f,Now}</code> methods on <code>testing.T</code> tests or
- <code>testing.B</code> benchmarks.
-</p>
-
-<p>
- Calls to these methods stop the execution of the created goroutine and not
- the <code>Test*</code> or <code>Benchmark*</code> function. So these are
- <a href="/pkg/testing/#T.FailNow">required</a> to be called by the goroutine
- running the test or benchmark function. For example:
-</p>
-
-<pre>
-func TestFoo(t *testing.T) {
- go func() {
- if condition() {
- t.Fatal("oops") // This exits the inner func instead of TestFoo.
- }
- ...
- }()
-}
-</pre>
-
-<p>
- Code calling <code>t.Fatal</code> (or a similar method) from a created
- goroutine should be rewritten to signal the test failure using
- <code>t.Error</code> and exit the goroutine early using an alternative
- method, such as using a <code>return</code> statement. The previous example
- could be rewritten as:
-</p>
-
-<pre>
-func TestFoo(t *testing.T) {
- go func() {
- if condition() {
- t.Error("oops")
- return
- }
- ...
- }()
-}
-</pre>
-
-<h4 id="vet-frame-pointer">New warning for frame pointer</h4>
-
-<p><!-- CL 248686, CL 276372 -->
- The vet tool now warns about amd64 assembly that clobbers the BP
- register (the frame pointer) without saving and restoring it,
- contrary to the calling convention. Code that doesn't preserve the
- BP register must be modified to either not use BP at all or preserve
- BP by saving and restoring it. An easy way to preserve BP is to set
- the frame size to a nonzero value, which causes the generated
- prologue and epilogue to preserve the BP register for you.
- See <a href="https://golang.org/cl/248260">CL 248260</a> for example
- fixes.
-</p>
-
-<h4 id="vet-asn1-unmarshal">New warning for asn1.Unmarshal</h4>
-
-<p><!-- CL 243397 -->
- The vet tool now warns about incorrectly passing a non-pointer or nil argument to
- <a href="/pkg/encoding/asn1/#Unmarshal"><code>asn1.Unmarshal</code></a>.
- This is like the existing checks for
- <a href="/pkg/encoding/json/#Unmarshal"><code>encoding/json.Unmarshal</code></a>
- and <a href="/pkg/encoding/xml/#Unmarshal"><code>encoding/xml.Unmarshal</code></a>.
-</p>
-
-<h2 id="runtime">Runtime</h2>
-
-<p>
- The new <a href="/pkg/runtime/metrics/"><code>runtime/metrics</code></a> package
- introduces a stable interface for reading
- implementation-defined metrics from the Go runtime.
- It supersedes existing functions like
- <a href="/pkg/runtime/#ReadMemStats"><code>runtime.ReadMemStats</code></a>
- and
- <a href="/pkg/runtime/debug/#GCStats"><code>debug.GCStats</code></a>
- and is significantly more general and efficient.
- See the package documentation for more details.
-</p>
-
-<p><!-- CL 254659 -->
- Setting the <code>GODEBUG</code> environment variable
- to <code>inittrace=1</code> now causes the runtime to emit a single
- line to standard error for each package <code>init</code>,
- summarizing its execution time and memory allocation. This trace can
- be used to find bottlenecks or regressions in Go startup
- performance.
- The <a href="/pkg/runtime/#hdr-Environment_Variables"><code>GODEBUG</code>
- documentation</a> describes the format.
-</p>
-
-<p><!-- CL 267100 -->
- On Linux, the runtime now defaults to releasing memory to the
- operating system promptly (using <code>MADV_DONTNEED</code>), rather
- than lazily when the operating system is under memory pressure
- (using <code>MADV_FREE</code>). This means process-level memory
- statistics like RSS will more accurately reflect the amount of
- physical memory being used by Go processes. Systems that are
- currently using <code>GODEBUG=madvdontneed=1</code> to improve
- memory monitoring behavior no longer need to set this environment
- variable.
-</p>
-
-<p><!-- CL 220419, CL 271987 -->
- Go 1.16 fixes a discrepancy between the race detector and
- the <a href="/ref/mem">Go memory model</a>. The race detector now
- more precisely follows the channel synchronization rules of the
- memory model. As a result, the detector may now report races it
- previously missed.
-</p>
-
-<h2 id="compiler">Compiler</h2>
-
-<p><!-- CL 256459, CL 264837, CL 266203, CL 256460 -->
- The compiler can now inline functions with
- non-labeled <code>for</code> loops, method values, and type
- switches. The inliner can also detect more indirect calls where
- inlining is possible.
-</p>
-
-<h2 id="linker">Linker</h2>
-
-<p><!-- CL 248197 -->
- This release includes additional improvements to the Go linker,
- reducing linker resource usage (both time and memory) and improving
- code robustness/maintainability. These changes form the second half
- of a two-release project to
- <a href="https://golang.org/s/better-linker">modernize the Go
- linker</a>.
-</p>
-
-<p>
- The linker changes in 1.16 extend the 1.15 improvements to all
- supported architecture/OS combinations (the 1.15 performance improvements
- were primarily focused on <code>ELF</code>-based OSes and
- <code>amd64</code> architectures). For a representative set of
- large Go programs, linking is 20-25% faster than 1.15 and requires
- 5-15% less memory on average for <code>linux/amd64</code>, with larger
- improvements for other architectures and OSes. Most binaries are
- also smaller as a result of more aggressive symbol pruning.
-</p>
-
-<p><!-- CL 255259 -->
- On Windows, <code>go build -buildmode=c-shared</code> now generates Windows
- ASLR DLLs by default. ASLR can be disabled with <code>--ldflags=-aslr=false</code>.
-</p>
-
-<h2 id="library">Core library</h2>
-
-<h3 id="library-embed">Embedded Files</h3>
-
-<p>
- The new <a href="/pkg/embed/"><code>embed</code></a> package
- provides access to files embedded in the program during compilation
- using the new <a href="#embed"><code>//go:embed</code> directive</a>.
-</p>
-
-<h3 id="fs">File Systems</h3>
-
-<p>
- The new <a href="/pkg/io/fs/"><code>io/fs</code></a> package
- defines the <a href="/pkg/io/fs/#FS"><code>fs.FS</code></a> interface,
- an abstraction for read-only trees of files.
- The standard library packages have been adapted to make use
- of the interface as appropriate.
-</p>
-
-<p>
- On the producer side of the interface,
- the new <a href="/pkg/embed/#FS"><code>embed.FS</code></a> type
- implements <code>fs.FS</code>, as does
- <a href="/pkg/archive/zip/#Reader"><code>zip.Reader</code></a>.
- The new <a href="/pkg/os/#DirFS"><code>os.DirFS</code></a> function
- provides an implementation of <code>fs.FS</code> backed by a tree
- of operating system files.
-</p>
-
-<p>
- On the consumer side,
- the new <a href="/pkg/net/http/#FS"><code>http.FS</code></a>
- function converts an <code>fs.FS</code> to an
- <a href="/pkg/net/http/#FileSystem"><code>http.FileSystem</code></a>.
- Also, the <a href="/pkg/html/template/"><code>html/template</code></a>
- and <a href="/pkg/text/template/"><code>text/template</code></a>
- packages’ <a href="/pkg/html/template/#ParseFS"><code>ParseFS</code></a>
- functions and methods read templates from an <code>fs.FS</code>.
-</p>
-
-<p>
- For testing code that implements <code>fs.FS</code>,
- the new <a href="/pkg/testing/fstest/"><code>testing/fstest</code></a>
- package provides a <a href="/pkg/testing/fstest/#TestFS"><code>TestFS</code></a>
- function that checks for and reports common mistakes.
- It also provides a simple in-memory file system implementation,
- <a href="/pkg/testing/fstest/#MapFS"><code>MapFS</code></a>,
- which can be useful for testing code that accepts <code>fs.FS</code>
- implementations.
-</p>
-
-<h3 id="ioutil">Deprecation of io/ioutil</h3>
-
-<p>
- The <a href="/pkg/io/ioutil/"><code>io/ioutil</code></a> package has
- turned out to be a poorly defined and hard to understand collection
- of things. All functionality provided by the package has been moved
- to other packages. The <code>io/ioutil</code> package remains and
- will continue to work as before, but we encourage new code to use
- the new definitions in the <a href="/pkg/io/"><code>io</code></a> and
- <a href="/pkg/os/"><code>os</code></a> packages.
-
- Here is a list of the new locations of the names exported
- by <code>io/ioutil</code>:
- <ul>
- <li><a href="/pkg/io/ioutil/#Discard"><code>Discard</code></a>
- => <a href="/pkg/io/#Discard"><code>io.Discard</code></a></li>
- <li><a href="/pkg/io/ioutil/#NopCloser"><code>NopCloser</code></a>
- => <a href="/pkg/io/#NopCloser"><code>io.NopCloser</code></a></li>
- <li><a href="/pkg/io/ioutil/#ReadAll"><code>ReadAll</code></a>
- => <a href="/pkg/io/#ReadAll"><code>io.ReadAll</code></a></li>
- <li><a href="/pkg/io/ioutil/#ReadDir"><code>ReadDir</code></a>
- => <a href="/pkg/os/#ReadDir"><code>os.ReadDir</code></a>
- (note: returns a slice of
- <a href="/pkg/os/#DirEntry"><code>os.DirEntry</code></a>
- rather than a slice of
- <a href="/pkg/io/fs/#FileInfo"><code>fs.FileInfo</code></a>)
- </li>
- <li><a href="/pkg/io/ioutil/#ReadFile"><code>ReadFile</code></a>
- => <a href="/pkg/os/#ReadFile"><code>os.ReadFile</code></a></li>
- <li><a href="/pkg/io/ioutil/#TempDir"><code>TempDir</code></a>
- => <a href="/pkg/os/#MkdirTemp"><code>os.MkdirTemp</code></a></li>
- <li><a href="/pkg/io/ioutil/#TempFile"><code>TempFile</code></a>
- => <a href="/pkg/os/#CreateTemp"><code>os.CreateTemp</code></a></li>
- <li><a href="/pkg/io/ioutil/#WriteFile"><code>WriteFile</code></a>
- => <a href="/pkg/os/#WriteFile"><code>os.WriteFile</code></a></li>
- </ul>
-</p>
-
-<!-- okay-after-beta1
- TODO: decide if any additional changes are worth factoring out from
- "Minor changes to the library" and highlighting in "Core library"
--->
-
-<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 243937 -->
- The new <a href="/pkg/archive/zip/#Reader.Open"><code>Reader.Open</code></a>
- method implements the <a href="/pkg/io/fs/#FS"><code>fs.FS</code></a>
- interface.
- </p>
- </dd>
-</dl>
-
-<dl id="crypto/dsa"><dt><a href="/pkg/crypto/dsa/">crypto/dsa</a></dt>
- <dd>
- <p><!-- CL 257939 -->
- The <a href="/pkg/crypto/dsa/"><code>crypto/dsa</code></a> package is now deprecated.
- See <a href="https://golang.org/issue/40337">issue #40337</a>.
- </p>
- </dd>
-</dl><!-- crypto/dsa -->
-
-<dl id="crypto/hmac"><dt><a href="/pkg/crypto/hmac/">crypto/hmac</a></dt>
- <dd>
- <p><!-- CL 261960 -->
- <a href="/pkg/crypto/hmac/#New"><code>New</code></a> will now panic if
- separate calls to the hash generation function fail to return new values.
- Previously, the behavior was undefined and invalid outputs were sometimes
- generated.
- </p>
- </dd>
-</dl><!-- crypto/hmac -->
-
-<dl id="crypto/tls"><dt><a href="/pkg/crypto/tls/">crypto/tls</a></dt>
- <dd>
- <p><!-- CL 256897 -->
- I/O operations on closing or closed TLS connections can now be detected
- using the new <a href="/pkg/net/#ErrClosed"><code>net.ErrClosed</code></a>
- error. A typical use would be <code>errors.Is(err, net.ErrClosed)</code>.
- </p>
-
- <p><!-- CL 266037 -->
- A default write deadline is now set in
- <a href="/pkg/crypto/tls/#Conn.Close"><code>Conn.Close</code></a>
- before sending the "close notify" alert, in order to prevent blocking
- indefinitely.
- </p>
-
- <p><!-- CL 239748 -->
- Clients now return a handshake error if the server selects
- <a href="/pkg/crypto/tls/#ConnectionState.NegotiatedProtocol">
- an ALPN protocol</a> that was not in
- <a href="/pkg/crypto/tls/#Config.NextProtos">
- the list advertised by the client</a>.
- </p>
-
- <p><!-- CL 262857 -->
- Servers will now prefer other available AEAD cipher suites (such as ChaCha20Poly1305)
- over AES-GCM cipher suites if either the client or server doesn't have AES hardware
- support, unless both <a href="/pkg/crypto/tls/#Config.PreferServerCipherSuites">
- <code>Config.PreferServerCipherSuites</code></a>
- and <a href="/pkg/crypto/tls/#Config.CipherSuites"><code>Config.CipherSuites</code></a>
- are set. The client is assumed not to have AES hardware support if it does
- not signal a preference for AES-GCM cipher suites.
- </p>
-
- <p><!-- CL 246637 -->
- <a href="/pkg/crypto/tls/#Config.Clone"><code>Config.Clone</code></a> now
- returns nil if the receiver is nil, rather than panicking.
- </p>
- </dd>
-</dl><!-- crypto/tls -->
-
-<dl id="crypto/x509"><dt><a href="/pkg/crypto/x509/">crypto/x509</a></dt>
- <dd>
- <p>
- The <code>GODEBUG=x509ignoreCN=0</code> flag will be removed in Go 1.17.
- It enables the legacy behavior of treating the <code>CommonName</code>
- field on X.509 certificates as a host name when no Subject Alternative
- Names are present.
- </p>
-
- <p><!-- CL 235078 -->
- <a href="/pkg/crypto/x509/#ParseCertificate"><code>ParseCertificate</code></a> and
- <a href="/pkg/crypto/x509/#CreateCertificate"><code>CreateCertificate</code></a>
- now enforce string encoding restrictions for the <code>DNSNames</code>,
- <code>EmailAddresses</code>, and <code>URIs</code> fields. These fields
- can only contain strings with characters within the ASCII range.
- </p>
-
- <p><!-- CL 259697 -->
- <a href="/pkg/crypto/x509/#CreateCertificate"><code>CreateCertificate</code></a>
- now verifies the generated certificate's signature using the signer's
- public key. If the signature is invalid, an error is returned, instead of
- a malformed certificate.
- </p>
-
- <p><!-- CL 257939 -->
- DSA signature verification is no longer supported. Note that DSA signature
- generation was never supported.
- See <a href="https://golang.org/issue/40337">issue #40337</a>.
- </p>
-
- <p><!-- CL 257257 -->
- On Windows, <a href="/pkg/crypto/x509/#Certificate.Verify"><code>Certificate.Verify</code></a>
- will now return all certificate chains that are built by the platform
- certificate verifier, instead of just the highest ranked chain.
- </p>
-
- <p><!-- CL 262343 -->
- The new <a href="/pkg/crypto/x509/#SystemRootsError.Unwrap"><code>SystemRootsError.Unwrap</code></a>
- method allows accessing the <a href="/pkg/crypto/x509/#SystemRootsError.Err"><code>Err</code></a>
- field through the <a href="/pkg/errors"><code>errors</code></a> package functions.
- </p>
-
- <p><!-- CL 230025 -->
- On Unix systems, the <code>crypto/x509</code> package is now more
- efficient in how it stores its copy of the system cert pool.
- Programs that use only a small number of roots will use around a
- half megabyte less memory.
- </p>
-
- </dd>
-</dl><!-- crypto/x509 -->
-
-<dl id="debug/elf"><dt><a href="/pkg/debug/elf/">debug/elf</a></dt>
- <dd>
- <p><!-- CL 255138 -->
- More <a href="/pkg/debug/elf/#DT_NULL"><code>DT</code></a>
- and <a href="/pkg/debug/elf/#PT_NULL"><code>PT</code></a>
- constants have been added.
- </p>
- </dd>
-</dl><!-- debug/elf -->
-
-<dl id="encoding/asn1"><dt><a href="/pkg/encoding/asn1">encoding/asn1</a></dt>
- <dd>
- <p><!-- CL 255881 -->
- <a href="/pkg/encoding/asn1/#Unmarshal"><code>Unmarshal</code></a> and
- <a href="/pkg/encoding/asn1/#UnmarshalWithParams"><code>UnmarshalWithParams</code></a>
- now return an error instead of panicking when the argument is not
- a pointer or is nil. This change matches the behavior of other
- encoding packages such as <a href="/pkg/encoding/json"><code>encoding/json</code></a>.
- </p>
- </dd>
-</dl>
-
-<dl id="encoding/json"><dt><a href="/pkg/encoding/json/">encoding/json</a></dt>
- <dd>
- <p><!-- CL 234818 -->
- The <code>json</code> struct field tags understood by
- <a href="/pkg/encoding/json/#Marshal"><code>Marshal</code></a>,
- <a href="/pkg/encoding/json/#Unmarshal"><code>Unmarshal</code></a>,
- and related functionality now permit semicolon characters within
- a JSON object name for a Go struct field.
- </p>
- </dd>
-</dl><!-- encoding/json -->
-
-<dl id="encoding/xml"><dt><a href="/pkg/encoding/xml/">encoding/xml</a></dt>
- <dd>
- <p><!-- CL 264024 -->
- The encoder has always taken care to avoid using namespace prefixes
- beginning with <code>xml</code>, which are reserved by the XML
- specification.
- Now, following the specification more closely, that check is
- case-insensitive, so that prefixes beginning
- with <code>XML</code>, <code>XmL</code>, and so on are also
- avoided.
- </p>
- </dd>
-</dl><!-- encoding/xml -->
-
-<dl id="flag"><dt><a href="/pkg/flag/">flag</a></dt>
- <dd>
- <p><!-- CL 240014 -->
- The new <a href="/pkg/flag/#Func"><code>Func</code></a> function
- allows registering a flag implemented by calling a function,
- as a lighter-weight alternative to implementing the
- <a href="/pkg/flag/#Value"><code>Value</code></a> interface.
- </p>
- </dd>
-</dl><!-- flag -->
-
-<dl id="go/build"><dt><a href="/pkg/go/build/">go/build</a></dt>
- <dd>
- <p><!-- CL 243941, CL 283636 -->
- The <a href="/pkg/go/build/#Package"><code>Package</code></a>
- struct has new fields that report information
- about <code>//go:embed</code> directives in the package:
- <a href="/pkg/go/build/#Package.EmbedPatterns"><code>EmbedPatterns</code></a>,
- <a href="/pkg/go/build/#Package.EmbedPatternPos"><code>EmbedPatternPos</code></a>,
- <a href="/pkg/go/build/#Package.TestEmbedPatterns"><code>TestEmbedPatterns</code></a>,
- <a href="/pkg/go/build/#Package.TestEmbedPatternPos"><code>TestEmbedPatternPos</code></a>,
- <a href="/pkg/go/build/#Package.XTestEmbedPatterns"><code>XTestEmbedPatterns</code></a>,
- <a href="/pkg/go/build/#Package.XTestEmbedPatternPos"><code>XTestEmbedPatternPos</code></a>.
- </p>
-
- <p><!-- CL 240551 -->
- The <a href="/pkg/go/build/#Package"><code>Package</code></a> field
- <a href="/pkg/go/build/#Package.IgnoredGoFiles"><code>IgnoredGoFiles</code></a>
- will no longer include files that start with "_" or ".",
- as those files are always ignored.
- <code>IgnoredGoFiles</code> is for files ignored because of
- build constraints.
- </p>
-
- <p><!-- CL 240551 -->
- The new <a href="/pkg/go/build/#Package"><code>Package</code></a>
- field <a href="/pkg/go/build/#Package.IgnoredOtherFiles"><code>IgnoredOtherFiles</code></a>
- has a list of non-Go files ignored because of build constraints.
- </p>
- </dd>
-</dl><!-- go/build -->
-
-<dl id="go/build/constraint"><dt><a href="/pkg/go/build/constraint/">go/build/constraint</a></dt>
- <dd>
- <p><!-- CL 240604 -->
- The new
- <a href="/pkg/go/build/constraint/"><code>go/build/constraint</code></a>
- package parses build constraint lines, both the original
- <code>// +build</code> syntax and the <code>//go:build</code>
- syntax that will be introduced in Go 1.17.
- This package exists so that tools built with Go 1.16 will be able
- to process Go 1.17 source code.
- See <a href="https://golang.org/design/draft-gobuild">https://golang.org/design/draft-gobuild</a>
- for details about the build constraint syntaxes and the planned
- transition to the <code>//go:build</code> syntax.
- Note that <code>//go:build</code> lines are <b>not</b> supported
- in Go 1.16 and should not be introduced into Go programs yet.
- </p>
- </dd>
-</dl><!-- go/build/constraint -->
-
-<dl id="html/template"><dt><a href="/pkg/html/template/">html/template</a></dt>
- <dd>
- <p><!-- CL 243938 -->
- The new <a href="/pkg/html/template/#ParseFS"><code>template.ParseFS</code></a>
- function and <a href="/pkg/html/template/#Template.ParseFS"><code>template.Template.ParseFS</code></a>
- method are like <a href="/pkg/html/template/#ParseGlob"><code>template.ParseGlob</code></a>
- and <a href="/pkg/html/template/#Template.ParseGlob"><code>template.Template.ParseGlob</code></a>,
- but read the templates from an <a href="/pkg/io/fs/#FS"><code>fs.FS</code></a>.
- </p>
- </dd>
-</dl><!-- html/template -->
-
-<dl id="io"><dt><a href="/pkg/io/">io</a></dt>
- <dd>
- <p><!-- CL 261577 -->
- The package now defines a
- <a href="/pkg/io/#ReadSeekCloser"><code>ReadSeekCloser</code></a> interface.
- </p>
-
- <p><!-- CL 263141 -->
- The package now defines
- <a href="/pkg/io/#Discard"><code>Discard</code></a>,
- <a href="/pkg/io/#NopCloser"><code>NopCloser</code></a>, and
- <a href="/pkg/io/#ReadAll"><code>ReadAll</code></a>,
- to be used instead of the same names in the
- <a href="/pkg/io/ioutil/"><code>io/ioutil</code></a> package.
- </p>
- </dd>
-</dl><!-- io -->
-
-<dl id="log"><dt><a href="/pkg/log/">log</a></dt>
- <dd>
- <p><!-- CL 264460 -->
- The new <a href="/pkg/log/#Default"><code>Default</code></a> function
- provides access to the default <a href="/pkg/log/#Logger"><code>Logger</code></a>.
- </p>
- </dd>
-</dl><!-- log -->
-
-<dl id="log/syslog"><dt><a href="/pkg/log/syslog/">log/syslog</a></dt>
- <dd>
- <p><!-- CL 264297 -->
- The <a href="/pkg/log/syslog/#Writer"><code>Writer</code></a>
- now uses the local message format
- (omitting the host name and using a shorter time stamp)
- when logging to custom Unix domain sockets,
- matching the format already used for the default log socket.
- </p>
- </dd>
-</dl><!-- log/syslog -->
-
-<dl id="mime/multipart"><dt><a href="/pkg/mime/multipart/">mime/multipart</a></dt>
- <dd>
- <p><!-- CL 247477 -->
- The <a href="/pkg/mime/multipart/#Reader"><code>Reader</code></a>'s
- <a href="/pkg/mime/multipart/#Reader.ReadForm"><code>ReadForm</code></a>
- method no longer rejects form data
- when passed the maximum int64 value as a limit.
- </p>
- </dd>
-</dl><!-- mime/multipart -->
-
-<dl id="net"><dt><a href="/pkg/net/">net</a></dt>
- <dd>
- <p><!-- CL 250357 -->
- The case of I/O on a closed network connection, or I/O on a network
- connection that is closed before any of the I/O completes, can now
- be detected using the new <a href="/pkg/net/#ErrClosed"><code>ErrClosed</code></a>
- error. A typical use would be <code>errors.Is(err, net.ErrClosed)</code>.
- In earlier releases the only way to reliably detect this case was to
- match the string returned by the <code>Error</code> method
- with <code>"use of closed network connection"</code>.
- </p>
-
- <p><!-- CL 255898 -->
- In previous Go releases the default TCP listener backlog size on Linux systems,
- set by <code>/proc/sys/net/core/somaxconn</code>, was limited to a maximum of <code>65535</code>.
- On Linux kernel version 4.1 and above, the maximum is now <code>4294967295</code>.
- </p>
-
- <p><!-- CL 238629 -->
- On Linux, host name lookups no longer use DNS before checking
- <code>/etc/hosts</code> when <code>/etc/nsswitch.conf</code>
- is missing; this is common on musl-based systems and makes
- Go programs match the behavior of C programs on those systems.
- </p>
- </dd>
-</dl><!-- net -->
-
-<dl id="net/http"><dt><a href="/pkg/net/http/">net/http</a></dt>
- <dd>
- <p><!-- CL 233637 -->
- In the <a href="/pkg/net/http/"><code>net/http</code></a> package, the
- behavior of <a href="/pkg/net/http/#StripPrefix"><code>StripPrefix</code></a>
- has been changed to strip the prefix from the request URL's
- <code>RawPath</code> field in addition to its <code>Path</code> field.
- In past releases, only the <code>Path</code> field was trimmed, and so if the
- request URL contained any escaped characters the URL would be modified to
- have mismatched <code>Path</code> and <code>RawPath</code> fields.
- In Go 1.16, <code>StripPrefix</code> trims both fields.
- If there are escaped characters in the prefix part of the request URL the
- handler serves a 404 instead of its previous behavior of invoking the
- underlying handler with a mismatched <code>Path</code>/<code>RawPath</code> pair.
- </p>
-
- <p><!-- CL 252497 -->
- The <a href="/pkg/net/http/"><code>net/http</code></a> package now rejects HTTP range requests
- of the form <code>"Range": "bytes=--N"</code> where <code>"-N"</code> is a negative suffix length, for
- example <code>"Range": "bytes=--2"</code>. It now replies with a <code>416 "Range Not Satisfiable"</code> response.
- </p>
-
- <p><!-- CL 256498, golang.org/issue/36990 -->
- Cookies set with <a href="/pkg/net/http/#SameSiteDefaultMode"><code>SameSiteDefaultMode</code></a>
- now behave according to the current spec (no attribute is set) instead of
- generating a SameSite key without a value.
- </p>
-
- <p><!-- CL 250039 -->
- The <a href="/pkg/net/http/#Client"><code>Client</code></a> now sends
- an explicit <code>Content-Length:</code> <code>0</code>
- header in <code>PATCH</code> requests with empty bodies,
- matching the existing behavior of <code>POST</code> and <code>PUT</code>.
- </p>
-
- <p><!-- CL 249440 -->
- The <a href="/pkg/net/http/#ProxyFromEnvironment"><code>ProxyFromEnvironment</code></a>
- function no longer returns the setting of the <code>HTTP_PROXY</code>
- environment variable for <code>https://</code> URLs when
- <code>HTTPS_PROXY</code> is unset.
- </p>
-
- <p><!-- 259917 -->
- The <a href="/pkg/net/http/#Transport"><code>Transport</code></a>
- type has a new field
- <a href="/pkg/net/http/#Transport.GetProxyConnectHeader"><code>GetProxyConnectHeader</code></a>
- which may be set to a function that returns headers to send to a
- proxy during a <code>CONNECT</code> request.
- In effect <code>GetProxyConnectHeader</code> is a dynamic
- version of the existing field
- <a href="/pkg/net/http/#Transport.ProxyConnectHeader"><code>ProxyConnectHeader</code></a>;
- if <code>GetProxyConnectHeader</code> is not <code>nil</code>,
- then <code>ProxyConnectHeader</code> is ignored.
- </p>
-
- <p><!-- CL 243939 -->
- The new <a href="/pkg/net/http/#FS"><code>http.FS</code></a>
- function converts an <a href="/pkg/io/fs/#FS"><code>fs.FS</code></a>
- to an <a href="/pkg/net/http/#FileSystem"><code>http.FileSystem</code></a>.
- </p>
- </dd>
-</dl><!-- net/http -->
-
-<dl id="net/http/httputil"><dt><a href="/pkg/net/http/httputil/">net/http/httputil</a></dt>
- <dd>
- <p><!-- CL 260637 -->
- <a href="/pkg/net/http/httputil/#ReverseProxy"><code>ReverseProxy</code></a>
- now flushes buffered data more aggressively when proxying
- streamed responses with unknown body lengths.
- </p>
- </dd>
-</dl><!-- net/http/httputil -->
-
-<dl id="net/smtp"><dt><a href="/pkg/net/smtp/">net/smtp</a></dt>
- <dd>
- <p><!-- CL 247257 -->
- The <a href="/pkg/net/smtp/#Client"><code>Client</code></a>'s
- <a href="/pkg/net/smtp/#Client.Mail"><code>Mail</code></a>
- method now sends the <code>SMTPUTF8</code> directive to
- servers that support it, signaling that addresses are encoded in UTF-8.
- </p>
- </dd>
-</dl><!-- net/smtp -->
-
-<dl id="os"><dt><a href="/pkg/os/">os</a></dt>
- <dd>
- <p><!-- CL 242998 -->
- <a href="/pkg/os/#Process.Signal"><code>Process.Signal</code></a> now
- returns <a href="/pkg/os/#ErrProcessDone"><code>ErrProcessDone</code></a>
- instead of the unexported <code>errFinished</code> when the process has
- already finished.
- </p>
-
- <p><!-- CL 261540 -->
- The package defines a new type
- <a href="/pkg/os/#DirEntry"><code>DirEntry</code></a>
- as an alias for <a href="/pkg/io/fs/#DirEntry"><code>fs.DirEntry</code></a>.
- The new <a href="/pkg/os/#ReadDir"><code>ReadDir</code></a>
- function and the new
- <a href="/pkg/os/#File.ReadDir"><code>File.ReadDir</code></a>
- method can be used to read the contents of a directory into a
- slice of <a href="/pkg/os/#DirEntry"><code>DirEntry</code></a>.
- The <a href="/pkg/os/#File.Readdir"><code>File.Readdir</code></a>
- method (note the lower case <code>d</code> in <code>dir</code>)
- still exists, returning a slice of
- <a href="/pkg/os/#FileInfo"><code>FileInfo</code></a>, but for
- most programs it will be more efficient to switch to
- <a href="/pkg/os/#File.ReadDir"><code>File.ReadDir</code></a>.
- </p>
-
- <p><!-- CL 263141 -->
- The package now defines
- <a href="/pkg/os/#CreateTemp"><code>CreateTemp</code></a>,
- <a href="/pkg/os/#MkdirTemp"><code>MkdirTemp</code></a>,
- <a href="/pkg/os/#ReadFile"><code>ReadFile</code></a>, and
- <a href="/pkg/os/#WriteFile"><code>WriteFile</code></a>,
- to be used instead of functions defined in the
- <a href="/pkg/io/ioutil/"><code>io/ioutil</code></a> package.
- </p>
-
- <p><!-- CL 243906 -->
- The types <a href="/pkg/os/#FileInfo"><code>FileInfo</code></a>,
- <a href="/pkg/os/#FileMode"><code>FileMode</code></a>, and
- <a href="/pkg/os/#PathError"><code>PathError</code></a>
- are now aliases for types of the same name in the
- <a href="/pkg/io/fs/"><code>io/fs</code></a> package.
- Function signatures in the <a href="/pkg/os/"><code>os</code></a>
- package have been updated to refer to the names in the
- <a href="/pkg/io/fs/"><code>io/fs</code></a> package.
- This should not affect any existing code.
- </p>
-
- <p><!-- CL 243911 -->
- The new <a href="/pkg/os/#DirFS"><code>DirFS</code></a> function
- provides an implementation of
- <a href="/pkg/io/fs/#FS"><code>fs.FS</code></a> backed by a tree
- of operating system files.
- </p>
- </dd>
-</dl><!-- os -->
-
-<dl id="os/signal"><dt><a href="/pkg/os/signal/">os/signal</a></dt>
- <dd>
- <p><!-- CL 219640 -->
- The new
- <a href="/pkg/os/signal/#NotifyContext"><code>NotifyContext</code></a>
- function allows creating contexts that are canceled upon arrival of
- specific signals.
- </p>
- </dd>
-</dl><!-- os/signal -->
-
-<dl id="path"><dt><a href="/pkg/path/">path</a></dt>
- <dd>
- <p><!-- CL 264397, golang.org/issues/28614 -->
- The <a href="/pkg/path/#Match"><code>Match</code></a> function now
- returns an error if the unmatched part of the pattern has a
- syntax error. Previously, the function returned early on a failed
- match, and thus did not report any later syntax error in the
- pattern.
- </p>
- </dd>
-</dl><!-- path -->
-
-<dl id="path/filepath"><dt><a href="/pkg/path/filepath/">path/filepath</a></dt>
- <dd>
- <p><!-- CL 267887 -->
- The new function
- <a href="/pkg/path/filepath/#WalkDir"><code>WalkDir</code></a>
- is similar to
- <a href="/pkg/path/filepath/#Walk"><code>Walk</code></a>,
- but is typically more efficient.
- The function passed to <code>WalkDir</code> receives a
- <a href="/pkg/io/fs/#DirEntry"><code>fs.DirEntry</code></a>
- instead of a
- <a href="/pkg/io/fs/#FileInfo"><code>fs.FileInfo</code></a>.
- (To clarify for those who recall the <code>Walk</code> function
- as taking an <a href="/pkg/os/#FileInfo"><code>os.FileInfo</code></a>,
- <code>os.FileInfo</code> is now an alias for <code>fs.FileInfo</code>.)
- </p>
-
- <p><!-- CL 264397, golang.org/issues/28614 -->
- The <a href="/pkg/path/filepath#Match"><code>Match</code></a> and
- <a href="/pkg/path/filepath#Glob"><code>Glob</code></a> functions now
- return an error if the unmatched part of the pattern has a
- syntax error. Previously, the functions returned early on a failed
- match, and thus did not report any later syntax error in the
- pattern.
- </p>
- </dd>
-</dl><!-- path/filepath -->
-
-<dl id="runtime/debug"><dt><a href="/pkg/runtime/debug/">runtime/debug</a></dt>
- <dd>
- <p><!-- CL 249677 -->
- The <a href="/pkg/runtime#Error"><code>runtime.Error</code></a> values
- used when <code>SetPanicOnFault</code> is enabled may now have an
- <code>Addr</code> method. If that method exists, it returns the memory
- address that triggered the fault.
- </p>
- </dd>
-</dl><!-- runtime/debug -->
-
-<dl id="strconv"><dt><a href="/pkg/strconv/">strconv</a></dt>
- <dd>
- <p><!-- CL 260858 -->
- <a href="/pkg/strconv/#ParseFloat"><code>ParseFloat</code></a> now uses
- the <a
- href="https://nigeltao.github.io/blog/2020/eisel-lemire.html">Eisel-Lemire
- algorithm</a>, improving performance by up to a factor of 2. This can
- also speed up decoding textual formats like <a
- href="/pkg/encoding/json/"><code>encoding/json</code></a>.
- </p>
- </dd>
-</dl><!-- strconv -->
-
-<dl id="syscall"><dt><a href="/pkg/syscall/">syscall</a></dt>
- <dd>
- <p><!-- CL 263271 -->
- <a href="/pkg/syscall/?GOOS=windows#NewCallback"><code>NewCallback</code></a>
- and
- <a href="/pkg/syscall/?GOOS=windows#NewCallbackCDecl"><code>NewCallbackCDecl</code></a>
- now correctly support callback functions with multiple
- sub-<code>uintptr</code>-sized arguments in a row. This may
- require changing uses of these functions to eliminate manual
- padding between small arguments.
- </p>
-
- <p><!-- CL 261917 -->
- <a href="/pkg/syscall/?GOOS=windows#SysProcAttr"><code>SysProcAttr</code></a> on Windows has a new <code>NoInheritHandles</code> field that disables inheriting handles when creating a new process.
- </p>
-
- <p><!-- CL 269761, golang.org/issue/42584 -->
- <a href="/pkg/syscall/?GOOS=windows#DLLError"><code>DLLError</code></a> on Windows now has an <code>Unwrap</code> method for unwrapping its underlying error.
- </p>
-
- <p><!-- CL 210639 -->
- On Linux,
- <a href="/pkg/syscall/#Setgid"><code>Setgid</code></a>,
- <a href="/pkg/syscall/#Setuid"><code>Setuid</code></a>,
- and related calls are now implemented.
- Previously, they returned an <code>syscall.EOPNOTSUPP</code> error.
- </p>
-
- <p><!-- CL 210639 -->
- On Linux, the new functions
- <a href="/pkg/syscall/#AllThreadsSyscall"><code>AllThreadsSyscall</code></a>
- and <a href="/pkg/syscall/#AllThreadsSyscall6"><code>AllThreadsSyscall6</code></a>
- may be used to make a system call on all Go threads in the process.
- These functions may only be used by programs that do not use cgo;
- if a program uses cgo, they will always return
- <a href="/pkg/syscall/#ENOTSUP"><code>syscall.ENOTSUP</code></a>.
- </p>
- </dd>
-</dl><!-- syscall -->
-
-<dl id="testing/iotest"><dt><a href="/pkg/testing/iotest/">testing/iotest</a></dt>
- <dd>
- <p><!-- CL 199501 -->
- The new
- <a href="/pkg/testing/iotest/#ErrReader"><code>ErrReader</code></a>
- function returns an
- <a href="/pkg/io/#Reader"><code>io.Reader</code></a> that always
- returns an error.
- </p>
-
- <p><!-- CL 243909 -->
- The new
- <a href="/pkg/testing/iotest/#TestReader"><code>TestReader</code></a>
- function tests that an <a href="/pkg/io/#Reader"><code>io.Reader</code></a>
- behaves correctly.
- </p>
- </dd>
-</dl><!-- testing/iotest -->
-
-<dl id="text/template"><dt><a href="/pkg/text/template/">text/template</a></dt>
- <dd>
- <p><!-- CL 254257, golang.org/issue/29770 -->
- Newlines characters are now allowed inside action delimiters,
- permitting actions to span multiple lines.
- </p>
-
- <p><!-- CL 243938 -->
- The new <a href="/pkg/text/template/#ParseFS"><code>template.ParseFS</code></a>
- function and <a href="/pkg/text/template/#Template.ParseFS"><code>template.Template.ParseFS</code></a>
- method are like <a href="/pkg/text/template/#ParseGlob"><code>template.ParseGlob</code></a>
- and <a href="/pkg/text/template/#Template.ParseGlob"><code>template.Template.ParseGlob</code></a>,
- but read the templates from an <a href="/pkg/io/fs/#FS"><code>fs.FS</code></a>.
- </p>
- </dd>
-</dl><!-- text/template -->
-
-<dl id="text/template/parse"><dt><a href="/pkg/text/template/parse/">text/template/parse</a></dt>
- <dd>
- <p><!-- CL 229398, golang.org/issue/34652 -->
- A new <a href="/pkg/text/template/parse/#CommentNode"><code>CommentNode</code></a>
- was added to the parse tree. The <a href="/pkg/text/template/parse/#Mode"><code>Mode</code></a>
- field in the <code>parse.Tree</code> enables access to it.
- </p>
- </dd>
-</dl><!-- text/template/parse -->
-
-<dl id="time/tzdata"><dt><a href="/pkg/time/tzdata/">time/tzdata</a></dt>
- <dd>
- <p><!-- CL 261877 -->
- The slim timezone data format is now used for the timezone database in
- <code>$GOROOT/lib/time/zoneinfo.zip</code> and the embedded copy in this
- package. This reduces the size of the timezone database by about 350 KB.
- </p>
- </dd>
-</dl><!-- time/tzdata -->
-
-<dl id="unicode"><dt><a href="/pkg/unicode/">unicode</a></dt>
- <dd>
- <p><!-- CL 248765 -->
- The <a href="/pkg/unicode/"><code>unicode</code></a> package and associated
- support throughout the system has been upgraded from Unicode 12.0.0 to
- <a href="https://www.unicode.org/versions/Unicode13.0.0/">Unicode 13.0.0</a>,
- which adds 5,930 new characters, including four new scripts, and 55 new emoji.
- Unicode 13.0.0 also designates plane 3 (U+30000-U+3FFFF) as the tertiary
- ideographic plane.
- </p>
- </dd>
-</dl><!-- unicode -->