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diff --git a/doc/go1.16.html b/doc/go1.16.html new file mode 100644 index 0000000..0beb62d --- /dev/null +++ b/doc/go1.16.html @@ -0,0 +1,1220 @@ +<!--{ + "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/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 --> |