+++ /dev/null
-<!--{
- "Title": "Go 1.19 Release Notes",
- "Path": "/doc/go1.19"
-}-->
-<!--
-NOTE: In this document and others in this directory, the convention is to
-set fixed-width phrases with non-fixed-width spaces, as in
-<code>hello</code> <code>world</code>.
-Do not send CLs removing the interior tags from such phrases.
--->
-<style>
- main ul li { margin: 0.5em 0; }
-</style>
-<h2 id="introduction">DRAFT RELEASE NOTES — Introduction to Go 1.19</h2>
-<p>
- <strong>
- Go 1.19 is not yet released. These are work-in-progress
- release notes. Go 1.19 is expected to be released in August 2022.
- </strong>
-</p>
-
-<h2 id="language">Changes to the language</h2>
-
-<p><!-- https://go.dev/issue/52038 -->
- There is only one small change to the language,
- a <a href="https://github.com/golang/go/issues/52038">very small correction</a>
- to the <a href="/ref/spec#Declarations_and_scope">scope of type parameters in method declarations</a>.
- Existing programs are unaffected.
-</p>
-
-<h2 id="mem">Memory Model</h2>
-
-<p><!-- https://go.dev/issue/50859 -->
- The <a href="/ref/mem">Go memory model</a> has been
- <a href="https://research.swtch.com/gomm">revised</a> to align Go with
- the memory model used by C, C++, Java, JavaScript, Rust, and Swift.
- Go only provides sequentially consistent atomics, not any of the more relaxed forms found in other languages.
- Along with the memory model update,
- Go 1.19 introduces <a href="#atomic_types">new types in the <code>sync/atomic</code> package</a>
- that make it easier to use atomic values, such as
- <a href="/pkg/sync/atomic/#Int64">atomic.Int64</a>
- and
- <a href="/pkg/sync/atomic/#Pointer">atomic.Pointer[T]</a>.
-</p>
-
-<h2 id="ports">Ports</h2>
-
-<h3 id="loong64">LoongArch 64-bit</h3>
-<p><!-- https://go.dev/issue/46229 -->
- Go 1.19 adds support for the Loongson 64-bit architecture
- <a href="https://loongson.github.io/LoongArch-Documentation">LoongArch</a>
- on Linux (<code>GOOS=linux</code>, <code>GOARCH=loong64</code>).
- The implemented ABI is LP64D. Minimum kernel version supported is 5.19.
-</p>
-<p>
- Note that most existing commercial Linux distributions for LoongArch come
- with older kernels, with a historical incompatible system call ABI.
- Compiled binaries will not work on these systems, even if statically linked.
- Users on such unsupported systems are limited to the distribution-provided
- Go package.
-</p>
-
-<h3 id="riscv64">RISC-V</h3>
-<p><!-- CL 402374 -->
- The <code>riscv64</code> port now supports passing function arguments
- and result using registers. Benchmarking shows typical performance
- improvements of 10% or more on <code>riscv64</code>.
-</p>
-
-<h2 id="tools">Tools</h2>
-
-<h3 id="go-doc">Doc Comments</h3>
-
-<p><!-- https://go.dev/issue/51082 --><!-- CL 384265, CL 397276, CL 397278, CL 397279, CL 397281, CL 397284 -->
-Go 1.19 adds support for links, lists, and clearer headings in doc comments.
-As part of this change, <a href="/cmd/gofmt"><code>gofmt</code></a>
-now reformats doc comments to make their rendered meaning clearer.
-See “<a href="/doc/comment">Go Doc Comments</a>”
-for syntax details and descriptions of common mistakes now highlighted by <code>gofmt</code>.
-As another part of this change, the new package <a href="/pkg/go/doc/comment/">go/doc/comment</a>
-provides parsing and reformatting of doc comments
-as well as support for rendering them to HTML, Markdown, and text.
-</p>
-
-<h3 id="go-unix">New <code>unix</code> build constraint</h3>
-
-<p><!-- CL 389934 --><!-- https://go.dev/issue/20322 --><!-- https://go.dev/issue/51572 -->
- The build constraint <code>unix</code> is now recognized
- in <code>//go:build</code> lines. The constraint is satisfied
- if the target operating system, also known as <code>GOOS</code>, is
- a Unix or Unix-like system. For the 1.19 release it is satisfied
- if <code>GOOS</code> is one of
- <code>aix</code>, <code>android</code>, <code>darwin</code>,
- <code>dragonfly</code>, <code>freebsd</code>, <code>hurd</code>,
- <code>illumos</code>, <code>ios</code>, <code>linux</code>,
- <code>netbsd</code>, <code>openbsd</code>, or <code>solaris</code>.
- In future releases the <code>unix</code> constraint may match
- additional newly supported operating systems.
-</p>
-
-<h3 id="go-command">Go command</h3>
-
-<!-- https://go.dev/issue/51461 -->
-<p>
- The <code>-trimpath</code> flag, if set, is now included in the build settings
- stamped into Go binaries by <code>go</code> <code>build</code>, and can be
- examined using
- <a href="https://pkg.go.dev/cmd/go#hdr-Print_Go_version"><code>go</code> <code>version</code> <code>-m</code></a>
- or <a href="https://pkg.go.dev/runtime/debug#ReadBuildInfo"><code>debug.ReadBuildInfo</code></a>.
-</p>
-<p>
- <code>go</code> <code>generate</code> now sets the <code>GOROOT</code>
- environment variable explicitly in the generator's environment, so that
- generators can locate the correct <code>GOROOT</code> even if built
- with <code>-trimpath</code>.
-</p>
-
-<p><!-- CL 404134 -->
- <code>go</code> <code>test</code> and <code>go</code> <code>generate</code> now place
- <code>GOROOT/bin</code> at the beginning of the <code>PATH</code> used for the
- subprocess, so tests and generators that execute the <code>go</code> command
- will resolve it to same <code>GOROOT</code>.
-</p>
-
-<p><!-- CL 398058 -->
- <code>go</code> <code>env</code> now quotes entries that contain spaces in
- the <code>CGO_CFLAGS</code>, <code>CGO_CPPFLAGS</code>, <code>CGO_CXXFLAGS</code>, <code>CGO_FFLAGS</code>, <code>CGO_LDFLAGS</code>,
- and <code>GOGCCFLAGS</code> variables it reports.
-</p>
-
-<p><!-- https://go.dev/issue/29666 -->
- <code>go</code> <code>list</code> <code>-json</code> now accepts a
- comma-separated list of JSON fields to populate. If a list is specified,
- the JSON output will include only those fields, and
- <code>go</code> <code>list</code> may avoid work to compute fields that are
- not included. In some cases, this may suppress errors that would otherwise
- be reported.
-</p>
-
-<p><!-- CL 410821 -->
- The <code>go</code> command now caches information necessary to load some modules,
- which should result in a speed-up of some <code>go</code> <code>list</code> invocations.
-</p>
-
-<h3 id="vet">Vet</h3>
-
-<p><!-- https://go.dev/issue/47528 -->
- The <code>vet</code> checker “errorsas” now reports when
- <a href="/pkg/errors/#As"><code>errors.As</code></a> is called
- with a second argument of type <code>*error</code>,
- a common mistake.
-</p>
-
-<h2 id="runtime">Runtime</h2>
-
-<p><!-- https://go.dev/issue/48409 --><!-- CL 397018 -->
- The runtime now includes support for a soft memory limit. This memory limit
- includes the Go heap and all other memory managed by the runtime, and
- excludes external memory sources such as mappings of the binary itself,
- memory managed in other languages, and memory held by the operating system on
- behalf of the Go program. This limit may be managed via
- <a href="/pkg/runtime/debug/#SetMemoryLimit"><code>runtime/debug.SetMemoryLimit</code></a>
- or the equivalent
- <a href="/pkg/runtime/#hdr-Environment_Variables"><code>GOMEMLIMIT</code></a>
- environment variable. The limit works in conjunction with
- <a href="/pkg/runtime/debug/#SetGCPercent"><code>runtime/debug.SetGCPercent</code></a>
- / <a href="/pkg/runtime/#hdr-Environment_Variables"><code>GOGC</code></a>,
- and will be respected even if <code>GOGC=off</code>, allowing Go programs to
- always make maximal use of their memory limit, improving resource efficiency
- in some cases. See <a href="/doc/gc-guide">the GC guide</a> for
- a detailed guide explaining the soft memory limit in more detail, as well as
- a variety of common use-cases and scenarios. Please note that small memory
- limits, on the order of tens of megabytes or less, are less likely to be
- respected due to external latency factors, such as OS scheduling. See
- <a href="https://go.dev/issue/52433">issue 52433</a> for more details. Larger
- memory limits, on the order of hundreds of megabytes or more, are stable and
- production-ready.
-</p>
-
-<p><!-- CL 353989 -->
- In order to limit the effects of GC thrashing when the program's live heap
- size approaches the soft memory limit, the Go runtime also attempts to limit
- total GC CPU utilization to 50%, excluding idle time, choosing to use more
- memory over preventing application progress. In practice, we expect this limit
- to only play a role in exceptional cases, and the new
- <a href="/pkg/runtime/metrics/#hdr-Supported_metrics">runtime metric</a>
- <code>/gc/limiter/last-enabled:gc-cycle</code> reports when this last
- occurred.
-</p>
-
-<p><!-- https://go.dev/issue/44163 -->
- The runtime now schedules many fewer GC worker goroutines on idle operating
- system threads when the application is idle enough to force a periodic GC
- cycle.
-</p>
-
-<p><!-- https://go.dev/issue/18138 --><!-- CL 345889 -->
- The runtime will now allocate initial goroutine stacks based on the historic
- average stack usage of goroutines. This avoids some of the early stack growth
- and copying needed in the average case in exchange for at most 2x wasted
- space on below-average goroutines.
-</p>
-
-<p><!-- https://go.dev/issue/46279 --><!-- CL 393354 --><!-- CL 392415 -->
- On Unix operating systems, Go programs that import package
- <a href="/pkg/os/">os</a> now automatically increase the open file limit
- (<code>RLIMIT_NOFILE</code>) to the maximum allowed value;
- that is, they change the soft limit to match the hard limit.
- This corrects artificially low limits set on some systems for compatibility with very old C programs using the
- <a href="https://en.wikipedia.org/wiki/Select_(Unix)"><i>select</i></a> system call.
- Go programs are not helped by that limit, and instead even simple programs like <code>gofmt</code>
- often ran out of file descriptors on such systems when processing many files in parallel.
- One impact of this change is that Go programs that in turn execute very old C programs in child processes
- may run those programs with too high a limit.
- This can be corrected by setting the hard limit before invoking the Go program.
-</p>
-
-<p><!-- https://go.dev/issue/51485 --><!-- CL 390421 -->
- Unrecoverable fatal errors (such as concurrent map writes, or unlock of
- unlocked mutexes) now print a simpler traceback excluding runtime metadata
- (equivalent to a fatal panic) unless <code>GOTRACEBACK=system</code> or
- <code>crash</code>. Runtime-internal fatal error tracebacks always include
- full metadata regardless of the value of <code>GOTRACEBACK</code>
-</p>
-
-<p><!-- https://go.dev/issue/50614 --><!-- CL 395754 -->
- Support for debugger-injected function calls has been added on ARM64,
- enabling users to call functions from their binary in an interactive
- debugging session when using a debugger that is updated to make use of this
- functionality.
-</p>
-
-<p><!-- https://go.dev/issue/44853 -->
- The <a href="/doc/go1.18#go-build-asan">address sanitizer support added in Go 1.18</a>
- now handles function arguments and global variables more precisely.
-</p>
-
-<h2 id="compiler">Compiler</h2>
-
-<p><!-- https://go.dev/issue/5496 --><!-- CL 357330, 395714, 403979 -->
- The compiler now uses
- a <a href="https://en.wikipedia.org/wiki/Branch_table">jump
- table</a> to implement large integer and string switch statements.
- Performance improvements for the switch statement vary but can be
- on the order of 20% faster.
- (<code>GOARCH=amd64</code> and <code>GOARCH=arm64</code> only)
-</p>
-<p><!-- CL 391014 -->
- The Go compiler now requires the <code>-p=importpath</code> flag to
- build a linkable object file. This is already supplied by
- the <code>go</code> command and by Bazel. Any other build systems
- that invoke the Go compiler directly will need to make sure they
- pass this flag as well.
-</p>
-<p><!-- CL 415235 --><!-- CL 415236 -->
- The Go compiler no longer accepts the <code>-importmap</code>
- or <code>-installsuffix</code> flags. Build systems that invoke the
- Go compiler directly must use the <code>-importcfg</code> flag
- instead. (The <code>go</code> command's <code>-installsuffix</code>
- build flag is still supported and unaffected by this change.)
-</p>
-
-<h2 id="assembler">Assembler</h2>
-<p><!-- CL 404298 -->
- Like the compiler, the assembler now requires the
- <code>-p=importpath</code> flag to build a linkable object file.
- This is already supplied by the <code>go</code> command. Any other
- build systems that invoke the Go assembler directly will need to
- make sure they pass this flag as well.
-</p>
-
-<h2 id="linker">Linker</h2>
-<p><!-- https://go.dev/issue/50796, CL 380755 -->
- On ELF platforms, the linker now emits compressed DWARF sections in
- the standard gABI format (<code>SHF_COMPRESSED</code>), instead of
- the legacy <code>.zdebug</code> format.
-</p>
-
-<h2 id="library">Core library</h2>
-
-<h3 id="atomic_types">New atomic types</h3>
-
-<p><!-- https://go.dev/issue/50860 --><!-- CL 381317 -->
- The <a href="/pkg/sync/atomic/"><code>sync/atomic</code></a> package defines new atomic types
- <a href="/pkg/sync/atomic/#Bool"><code>Bool</code></a>,
- <a href="/pkg/sync/atomic/#Int32"><code>Int32</code></a>,
- <a href="/pkg/sync/atomic/#Int64"><code>Int64</code></a>,
- <a href="/pkg/sync/atomic/#Uint32"><code>Uint32</code></a>,
- <a href="/pkg/sync/atomic/#Uint64"><code>Uint64</code></a>,
- <a href="/pkg/sync/atomic/#Uintptr"><code>Uintptr</code></a>, and
- <a href="/pkg/sync/atomic/#Pointer"><code>Pointer</code></a>.
- These types hide the underlying values so that all accesses are forced to use
- the atomic APIs.
- <a href="/pkg/sync/atomic/#Pointer"><code>Pointer</code></a> also avoids
- the need to convert to
- <a href="/pkg/unsafe/#Pointer"><code>unsafe.Pointer</code></a> at call sites.
- <a href="/pkg/sync/atomic/#Int64"><code>Int64</code></a> and
- <a href="/pkg/sync/atomic/#Uint64"><code>Uint64</code></a> are
- automatically aligned to 64-bit boundaries in structs and allocated data,
- even on 32-bit systems.
-</p>
-
-<h3 id="os-exec-path">PATH lookups</h3>
-
-<p><!-- https://go.dev/issue/43724 -->
- <!-- CL 381374 --><!-- CL 403274 -->
- <a href="/pkg/os/exec/#Command"><code>Command</code></a> and
- <a href="/pkg/os/exec/#LookPath"><code>LookPath</code></a> no longer
- allow results from a PATH search to be found relative to the current directory.
- This removes a <a href="/blog/path-security">common source of security problems</a>
- but may also break existing programs that depend on using, say, <code>exec.Command("prog")</code>
- to run a binary named <code>prog</code> (or, on Windows, <code>prog.exe</code>) in the current directory.
- See the <a href="/pkg/os/exec/"><code>os/exec</code></a> package documentation for
- information about how best to update such programs.
-</p>
-
-<p><!-- https://go.dev/issue/43947 -->
- On Windows, <code>Command</code> and <code>LookPath</code> now respect the
- <a href="https://docs.microsoft.com/en-us/windows/win32/api/processenv/nf-processenv-needcurrentdirectoryforexepatha"><code>NoDefaultCurrentDirectoryInExePath</code></a>
- environment variable, making it possible to disable
- the default implicit search of “<code>.</code>” in PATH lookups on Windows systems.
-</p>
-
-<h3 id="minor_library_changes">Minor changes to the library</h3>
-<p>
- As always, there are various minor changes and updates to the library,
- made with the Go 1 <a href="/doc/go1compat">promise of compatibility</a>
- in mind.
- There are also various performance improvements, not enumerated here.
-</p>
-
-<dl id="archive/zip"><dt><a href="/pkg/archive/zip/">archive/zip</a></dt>
- <dd>
- <p><!-- CL 387976 -->
- <a href="/pkg/archive/zip/#Reader"><code>Reader</code></a>
- now ignores non-ZIP data at the start of a ZIP file, matching most other implementations.
- This is necessary to read some Java JAR files, among other uses.
- </p>
- </dd>
-</dl><!-- archive/zip -->
-
-<dl id="crypto/elliptic"><dt><a href="/pkg/crypto/elliptic/">crypto/elliptic</a></dt>
- <dd>
- <p><!-- CL 382995 -->
- Operating on invalid curve points (those for which the
- <code>IsOnCurve</code> method returns false, and which are never returned
- by <code>Unmarshal</code> or by a <code>Curve</code> method operating on a
- valid point) has always been undefined behavior and can lead to key
- recovery attacks. If an invalid point is supplied to
- <a href="/pkg/crypto/elliptic/#Marshal"><code>Marshal</code></a>,
- <a href="/pkg/crypto/elliptic/#MarshalCompressed"><code>MarshalCompressed</code></a>,
- <a href="/pkg/crypto/elliptic/#Curve.Add"><code>Add</code></a>,
- <a href="/pkg/crypto/elliptic/#Curve.Double"><code>Double</code></a>, or
- <a href="/pkg/crypto/elliptic/#Curve.ScalarMult"><code>ScalarMult</code></a>,
- they will now panic.
- </p>
-
- <p><!-- golang.org/issue/52182 -->
- <code>ScalarBaseMult</code> operations on the <code>P224</code>,
- <code>P384</code>, and <code>P521</code> curves are now up to three
- times faster, leading to similar speedups in some ECDSA operations. The
- generic (not platform optimized) <code>P256</code> implementation was
- replaced with one derived from a formally verified model; this might
- lead to significant slowdowns on 32-bit platforms.
- </p>
- </dd>
-</dl><!-- crypto/elliptic -->
-
-<dl id="crypto/rand"><dt><a href="/pkg/crypto/rand/">crypto/rand</a></dt>
- <dd>
- <p><!-- CL 370894 --><!-- CL 390038 -->
- <a href="/pkg/crypto/rand/#Read"><code>Read</code></a> no longer buffers
- random data obtained from the operating system between calls. Applications
- that perform many small reads at high frequency might choose to wrap
- <a href="/pkg/crypto/rand/#Reader"><code>Reader</code></a> in a
- <a href="/pkg/bufio/#Reader"><code>bufio.Reader</code></a> for performance
- reasons, taking care to use
- <a href="/pkg/io/#ReadFull"><code>io.ReadFull</code></a>
- to ensure no partial reads occur.
- </p>
-
- <p><!-- CL 375215 -->
- On Plan 9, <code>Read</code> has been reimplemented, replacing the ANSI
- X9.31 algorithm with a fast key erasure generator.
- </p>
-
- <p><!-- CL 391554 --><!-- CL 387554 -->
- The <a href="/pkg/crypto/rand/#Prime"><code>Prime</code></a>
- implementation was changed to use only rejection sampling,
- which removes a bias when generating small primes in non-cryptographic contexts,
- removes one possible minor timing leak,
- and better aligns the behavior with BoringSSL,
- all while simplifying the implementation.
- The change does produce different outputs for a given random source
- stream compared to the previous implementation,
- which can break tests written expecting specific results from
- specific deterministic random sources.
- To help prevent such problems in the future,
- the implementation is now intentionally non-deterministic with respect to the input stream.
- </p>
- </dd>
-</dl><!-- crypto/rand -->
-
-<dl id="crypto/tls"><dt><a href="/pkg/crypto/tls/">crypto/tls</a></dt>
- <dd>
- <p><!-- CL 400974 --><!-- https://go.dev/issue/45428 -->
- The <code>GODEBUG</code> option <code>tls10default=1</code> has been
- removed. It is still possible to enable TLS 1.0 client-side by setting
- <a href="/pkg/crypto/tls/#Config.MinVersion"><code>Config.MinVersion</code></a>.
- </p>
-
- <p><!-- CL 384894 -->
- The TLS server and client now reject duplicate extensions in TLS
- handshakes, as required by RFC 5246, Section 7.4.1.4 and RFC 8446, Section
- 4.2.
- </p>
- </dd>
-</dl><!-- crypto/tls -->
-
-<dl id="crypto/x509"><dt><a href="/pkg/crypto/x509/">crypto/x509</a></dt>
- <dd>
- <p><!-- CL 285872 -->
- <a href="/pkg/crypto/x509/#CreateCertificate"><code>CreateCertificate</code></a>
- no longer supports creating certificates with <code>SignatureAlgorithm</code>
- set to <code>MD5WithRSA</code>.
- </p>
-
- <p><!-- CL 400494 -->
- <code>CreateCertificate</code> no longer accepts negative serial numbers.
- </p>
-
- <p><!-- CL 399827 -->
- <code>CreateCertificate</code> will not emit an empty SEQUENCE anymore
- when the produced certificate has no extensions.
- </p>
-
- <p><!-- CL 396774 -->
- Removal of the <code>GODEBUG</code> option<code>x509sha1=1</code>,
- originally planned for Go 1.19, has been rescheduled to a future release.
- Applications using it should work on migrating. Practical attacks against
- SHA-1 have been demonstrated since 2017 and publicly trusted Certificate
- Authorities have not issued SHA-1 certificates since 2015.
- </p>
-
- <p><!-- CL 383215 -->
- <a href="/pkg/crypto/x509/#ParseCertificate"><code>ParseCertificate</code></a>
- and <a href="/pkg/crypto/x509/#ParseCertificateRequest"><code>ParseCertificateRequest</code></a>
- now reject certificates and CSRs which contain duplicate extensions.
- </p>
-
- <p><!-- https://go.dev/issue/46057 --><!-- https://go.dev/issue/35044 --><!-- CL 398237 --><!-- CL 400175 --><!-- CL 388915 -->
- The new <a href="/pkg/crypto/x509/#CertPool.Clone"><code>CertPool.Clone</code></a>
- and <a href="/pkg/crypto/x509/#CertPool.Equal"><code>CertPool.Equal</code></a>
- methods allow cloning a <code>CertPool</code> and checking the equivalence of two
- <code>CertPool</code>s respectively.
- </p>
-
- <p><!-- https://go.dev/issue/50674 --><!-- CL 390834 -->
- The new function <a href="/pkg/crypto/x509/#ParseRevocationList"><code>ParseRevocationList</code></a>
- provides a faster, safer to use CRL parser which returns a
- <a href="/pkg/crypto/x509/#RevocationList"><code>RevocationList</code></a>.
- Parsing a CRL also populates the new <code>RevocationList</code> fields
- <code>RawIssuer</code>, <code>Signature</code>,
- <code>AuthorityKeyId</code>, and <code>Extensions</code>, which are ignored by
- <a href="/pkg/crypto/x509/#CreateRevocationList"><code>CreateRevocationList</code></a>.
- </p><p>
- The new method <a href="/pkg/crypto/x509/#RevocationList.CheckSignatureFrom"><code>RevocationList.CheckSignatureFrom</code></a>
- checks that the signature on a CRL is a valid signature from a
- <a href="/pkg/crypto/x509/#Certificate"><code>Certificate</code></a>.
- </p><p>
- The <a href="/pkg/crypto/x509/#ParseCRL"><code>ParseCRL</code></a> and
- <a href="/pkg/crypto/x509/#ParseDERCRL"><code>ParseDERCRL</code></a> functions
- are now deprecated in favor of <code>ParseRevocationList</code>.
- The <a href="/pkg/crypto/x509/#Certificate.CheckCRLSignature"><code>Certificate.CheckCRLSignature</code></a>
- method is deprecated in favor of <code>RevocationList.CheckSignatureFrom</code>.
- </p>
-
- <p><!-- CL 389555, CL 401115, CL 403554 -->
- The path builder of <a href="/pkg/crypto/x509/#Certificate.Verify"><code>Certificate.Verify</code></a>
- was overhauled and should now produce better chains and/or be more efficient in complicated scenarios.
- Name constraints are now also enforced on non-leaf certificates.
- </p>
- </dd>
-</dl><!-- crypto/x509 -->
-
-<dl id="crypto/x509/pkix"><dt><a href="/pkg/crypto/x509/pkix/">crypto/x509/pkix</a></dt>
- <dd>
- <p><!-- CL 390834 -->
- The types <a href="/pkg/crypto/x509/pkix/#CertificateList"><code>CertificateList</code></a> and
- <a href="/pkg/crypto/x509/pkix/#TBSCertificateList"><code>TBSCertificateList</code></a>
- have been deprecated. The new <a href="#crypto/x509"><code>crypto/x509</code> CRL functionality</a>
- should be used instead.
- </p>
- </dd>
-</dl><!-- crypto/x509/pkix -->
-
-<dl id="debug/elf"><dt><a href="/pkg/debug/elf/">debug/elf</a></dt>
- <dd>
- <p><!-- CL 396735 -->
- The new <code>EM_LOONGARCH</code> and <code>R_LARCH_*</code> constants
- support the loong64 port.
- </p>
- </dd>
-</dl><!-- debug/elf -->
-
-<dl id="debug/pe"><dt><a href="/pkg/debug/pe/">debug/pe</a></dt>
- <dd>
- <p><!-- https://go.dev/issue/51868 --><!-- CL 394534 -->
- The new <a href="/pkg/debug/pe/#File.COFFSymbolReadSectionDefAux"><code>File.COFFSymbolReadSectionDefAux</code></a>
- method, which returns a <a href="/pkg/debug/pe/#COFFSymbolAuxFormat5"><code>COFFSymbolAuxFormat5</code></a>,
- provides access to COMDAT information in PE file sections.
- These are supported by new <code>IMAGE_COMDAT_*</code> and <code>IMAGE_SCN_*</code> constants.
- </p>
- </dd>
-</dl><!-- debug/pe -->
-
-<dl id="encoding/binary"><dt><a href="/pkg/encoding/binary/">encoding/binary</a></dt>
- <dd>
- <p><!-- https://go.dev/issue/50601 --><!-- CL 386017 --><!-- CL 389636 -->
- The new interface
- <a href="/pkg/encoding/binary/#AppendByteOrder"><code>AppendByteOrder</code></a>
- provides efficient methods for appending a <code>uint16</code>, <code>uint32</code>, or <code>uint64</code>
- to a byte slice.
- <a href="/pkg/encoding/binary/#BigEndian"><code>BigEndian</code></a> and
- <a href="/pkg/encoding/binary/#LittleEndian"><code>LittleEndian</code></a> now implement this interface.
- </p>
- <p><!-- https://go.dev/issue/51644 --><!-- CL 400176 -->
- Similarly, the new functions
- <a href="/pkg/encoding/binary/#AppendUvarint"><code>AppendUvarint</code></a> and
- <a href="/pkg/encoding/binary/#AppendVarint"><code>AppendVarint</code></a>
- are efficient appending versions of
- <a href="/pkg/encoding/binary/#PutUvarint"><code>PutUvarint</code></a> and
- <a href="/pkg/encoding/binary/#PutVarint"><code>PutVarint</code></a>.
- </p>
- </dd>
-</dl><!-- encoding/binary -->
-
-<dl id="encoding/csv"><dt><a href="/pkg/encoding/csv/">encoding/csv</a></dt>
- <dd>
- <p><!-- https://go.dev/issue/43401 --><!-- CL 405675 -->
- The new method
- <a href="/pkg/encoding/csv/#Reader.InputOffset"><code>Reader.InputOffset</code></a>
- reports the reader's current input position as a byte offset,
- analogous to <code>encoding/json</code>'s
- <a href="/pkg/encoding/json/#Decoder.InputOffset"><code>Decoder.InputOffset</code></a>.
- </p>
- </dd>
-</dl><!-- encoding/csv -->
-
-<dl id="encoding/xml"><dt><a href="/pkg/encoding/xml/">encoding/xml</a></dt>
- <dd>
- <p><!-- https://go.dev/issue/45628 --><!-- CL 311270 -->
- The new method
- <a href="/pkg/encoding/xml/#Decoder.InputPos"><code>Decoder.InputPos</code></a>
- reports the reader's current input position as a line and column,
- analogous to <code>encoding/csv</code>'s
- <a href="/pkg/encoding/csv/#Decoder.FieldPos"><code>Decoder.FieldPos</code></a>.
- </p>
- </dd>
-</dl><!-- encoding/xml -->
-
-<dl id="flag"><dt><a href="/pkg/flag/">flag</a></dt>
- <dd>
- <p><!-- https://go.dev/issue/45754 --><!-- CL 313329 -->
- The new function
- <a href="/pkg/flag/#TextVar"><code>TextVar</code></a>
- defines a flag with a value implementing
- <a href="/pkg/encoding/#TextUnmarshaler"><code>encoding.TextUnmarshaler</code></a>,
- allowing command-line flag variables to have types such as
- <a href="/pkg/math/big/#Int"><code>big.Int</code></a>,
- <a href="/pkg/net/netip/#Addr"><code>netip.Addr</code></a>, and
- <a href="/pkg/time/#Time"><code>time.Time</code></a>.
- </p>
- </dd>
-</dl><!-- flag -->
-
-<dl id="fmt"><dt><a href="/pkg/fmt/">fmt</a></dt>
- <dd>
- <p><!-- https://go.dev/issue/47579 --><!-- CL 406177 -->
- The new functions
- <a href="/pkg/fmt/#Append"><code>Append</code></a>,
- <a href="/pkg/fmt/#Appendf"><code>Appendf</code></a>, and
- <a href="/pkg/fmt/#Appendln"><code>Appendln</code></a>
- append formatted data to byte slices.
- </p>
- </dd>
-</dl><!-- fmt -->
-
-<dl id="go/parser"><dt><a href="/pkg/go/parser/">go/parser</a></dt>
- <dd>
- <p><!-- CL 403696 -->
- The parser now recognizes <code>~x</code> as a unary expression with operator
- <a href="/pkg/go/token/#TILDE">token.TILDE</a>,
- allowing better error recovery when a type constraint such as <code>~int</code> is used in an incorrect context.
- </p>
- </dd>
-</dl><!-- go/parser -->
-
-<dl id="go/types"><dt><a href="/pkg/go/types/">go/types</a></dt>
- <dd>
- <p><!-- https://go.dev/issue/51682 --><!-- CL 395535 -->
- The new methods <a href="/pkg/go/types/#Func.Origin"><code>Func.Origin</code></a>
- and <a href="/pkg/go/types/#Var.Origin"><code>Var.Origin</code></a> return the
- corresponding <a href="/pkg/go/types/#Object"><code>Object</code></a> of the
- generic type for synthetic <a href="/pkg/go/types/#Func"><code>Func</code></a>
- and <a href="/pkg/go/types/#Var"><code>Var</code></a> objects created during type
- instantiation.
- </p>
- <p><!-- https://go.dev/issue/52728 --><!-- CL 404885 -->
- It is no longer possible to produce an infinite number of distinct-but-identical
- <a href="/pkg/go/types/#Named"><code>Named</code></a> type instantiations via
- recursive calls to
- <a href="/pkg/go/types/#Named.Underlying"><code>Named.Underlying</code></a> or
- <a href="/pkg/go/types/#Named.Method"><code>Named.Method</code></a>.
- </p>
- </dd>
-</dl><!-- go/types -->
-
-
-<dl id="hash/maphash"><dt><a href="/pkg/hash/maphash/">hash/maphash</a></dt>
- <dd>
- <p><!-- https://go.dev/issue/42710 --><!-- CL 392494 -->
- The new functions
- <a href="/pkg/hash/maphash/#Bytes"><code>Bytes</code></a>
- and
- <a href="/pkg/hash/maphash/#String"><code>String</code></a>
- provide an efficient way hash a single byte slice or string.
- They are equivalent to using the more general
- <a href="/pkg/hash/maphash/#Hash"><code>Hash</code></a>
- with a single write, but they avoid setup overhead for small inputs.
- </p>
- </dd>
-</dl><!-- hash/maphash -->
-
-<dl id="html/template"><dt><a href="/pkg/html/template/">html/template</a></dt>
- <dd>
- <p><!-- https://go.dev/issue/46121 --><!-- CL 389156 -->
- The type <a href="/pkg/html/template/#FuncMap"><code>FuncMap</code></a>
- is now an alias for
- <code>text/template</code>'s <a href="/pkg/text/template/#FuncMap"><code>FuncMap</code></a>
- instead of its own named type.
- This allows writing code that operates on a <code>FuncMap</code> from either setting.
- </p>
- </dd>
-</dl><!-- html/template -->
-
-<dl id="image/draw"><dt><a href="/pkg/image/draw/">image/draw</a></dt>
- <dd>
- <p><!-- CL 396795 -->
- <a href="/pkg/image/draw/#Draw"><code>Draw</code></a> with the
- <a href="/pkg/image/draw/#Src"><code>Src</code></a> operator preserves
- non-premultiplied-alpha colors when destination and source images are
- both <a href="/pkg/image/#NRGBA"><code>image.NRGBA</code></a>
- or both <a href="/pkg/image/#NRGBA64"><code>image.NRGBA64</code></a>.
- This reverts a behavior change accidentally introduced by a Go 1.18
- library optimization; the code now matches the behavior in Go 1.17 and earlier.
- </p>
- </dd>
-</dl><!-- image/draw -->
-
-<dl id="io"><dt><a href="/pkg/io/">io</a></dt>
- <dd>
- <p><!-- https://go.dev/issue/51566 --><!-- CL 400236 -->
- <a href="/pkg/io/#NopCloser"><code>NopCloser</code></a>'s result now implements
- <a href="/pkg/io/#WriterTo"><code>WriterTo</code></a>
- whenever its input does.
- </p>
-
- <p><!-- https://go.dev/issue/50842 -->
- <a href="/pkg/io/#MultiReader"><code>MultiReader</code></a>'s result now implements
- <a href="/pkg/io/#WriterTo"><code>WriterTo</code></a> unconditionally.
- If any underlying reader does not implement <code>WriterTo</code>,
- it is simulated appropriately.
- </p>
- </dd>
-</dl><!-- io -->
-
-<dl id="mime"><dt><a href="/pkg/mime/">mime</a></dt>
- <dd>
- <p><!-- CL 406894 -->
- On Windows only, the mime package now ignores a registry entry
- recording that the extension <code>.js</code> should have MIME
- type <code>text/plain</code>. This is a common unintentional
- misconfiguration on Windows systems. The effect is
- that <code>.js</code> will have the default MIME
- type <code>text/javascript; charset=utf-8</code>.
- Applications that expect <code>text/plain</code> on Windows must
- now explicitly call
- <a href="/pkg/mime/#AddExtensionType"><code>AddExtensionType</code></a>.
- </p>
- </dd>
-</dl>
-
-<dl id="net"><dt><a href="/pkg/net/">net</a></dt>
- <dd>
- <p><!-- CL 386016 -->
- The pure Go resolver will now use EDNS(0) to include a suggested
- maximum reply packet length, permitting reply packets to contain
- up to 1232 bytes (the previous maximum was 512).
- In the unlikely event that this causes problems with a local DNS
- resolver, setting the environment variable
- <code>GODEBUG=netdns=cgo</code> to use the cgo-based resolver
- should work.
- Please report any such problems on <a href="/issue/new">the
- issue tracker</a>.
- </p>
-
- <p><!-- https://go.dev/issue/51428 --><!-- CL 396877 -->
- When a net package function or method returns an "I/O timeout"
- error, the error will now satisfy <code>errors.Is(err,
- context.DeadlineExceeded)</code>. When a net package function
- returns an "operation was canceled" error, the error will now
- satisfy <code>errors.Is(err, context.Canceled)</code>.
- These changes are intended to make it easier for code to test
- for cases in which a context cancellation or timeout causes a net
- package function or method to return an error, while preserving
- backward compatibility for error messages.
- </p>
-
- <p><!-- https://go.dev/issue/33097 --><!-- CL 400654 -->
- <a href="/pkg/net/#Resolver.PreferGo"><code>Resolver.PreferGo</code></a>
- is now implemented on Windows and Plan 9. It previously only worked on Unix
- platforms. Combined with
- <a href="/pkg/net/#Dialer.Resolver"><code>Dialer.Resolver</code></a> and
- <a href="/pkg/net/#Resolver.Dial"><code>Resolver.Dial</code></a>, it's now
- possible to write portable programs and be in control of all DNS name lookups
- when dialing.
- </p>
-
- <p>
- The <code>net</code> package now has initial support for the <code>netgo</code>
- build tag on Windows. When used, the package uses the Go DNS client (as used
- by <code>Resolver.PreferGo</code>) instead of asking Windows for
- DNS results. The upstream DNS server it discovers from Windows
- may not yet be correct with complex system network configurations, however.
- </p>
- </dd>
-</dl><!-- net -->
-
-<dl id="net/http"><dt><a href="/pkg/net/http/">net/http</a></dt>
- <dd>
- <p><!-- CL 269997 -->
- <a href="/pkg/net/http/#ResponseWriter"><code>ResponseWriter.WriteHeader</code></a>
- now supports sending user-defined 1xx informational headers.
- </p>
-
- <p><!-- CL 361397 -->
- The <code>io.ReadCloser</code> returned by
- <a href="/pkg/net/http/#MaxBytesReader"><code>MaxBytesReader</code></a>
- will now return the defined error type
- <a href="/pkg/net/http/#MaxBytesError"><code>MaxBytesError</code></a>
- when its read limit is exceeded.
- </p>
-
- <p><!-- CL 375354 -->
- The HTTP client will handle a 3xx response without a
- <code>Location</code> header by returning it to the caller,
- rather than treating it as an error.
- </p>
- </dd>
-</dl><!-- net/http -->
-
-<dl id="net/url"><dt><a href="/pkg/net/url/">net/url</a></dt>
- <dd>
- <p><!-- CL 374654 -->
- The new
- <a href="/pkg/net/url/#JoinPath"><code>JoinPath</code></a>
- function and
- <a href="/pkg/net/url/#URL.JoinPath"><code>URL.JoinPath</code></a>
- method create a new <code>URL</code> by joining a list of path
- elements.
- </p>
- <p><!-- https://go.dev/issue/46059 -->
- The <code>URL</code> type now distinguishes between URLs with no
- authority and URLs with an empty authority. For example,
- <code>http:///path</code> has an empty authority (host),
- while <code>http:/path</code> has none.
- </p>
- <p>
- The new <a href="/pkg/net/url/#URL"><code>URL</code></a> field
- <code>OmitHost</code> is set to <code>true</code> when a
- <code>URL</code> has an empty authority.
- </p>
-
- </dd>
-</dl><!-- net/url -->
-
-<dl id="os/exec"><dt><a href="/pkg/os/exec/">os/exec</a></dt>
- <dd>
- <p><!-- https://go.dev/issue/50599 --><!-- CL 401340 -->
- A <a href="/pkg/os/exec/#Cmd"><code>Cmd</code></a> with a non-empty <code>Dir</code> field
- and nil <code>Env</code> now implicitly sets the <code>PWD</code> environment
- variable for the subprocess to match <code>Dir</code>.
- </p>
- <p>
- The new method <a href="/pkg/os/exec/#Cmd.Environ"><code>Cmd.Environ</code></a> reports the
- environment that would be used to run the command, including the
- implicitly set <code>PWD</code> variable.
- </p>
- </dd>
-</dl> <!-- os/exec -->
-
-<dl id="reflect"><dt><a href="/pkg/reflect/">reflect</a></dt>
- <dd>
- <p><!-- https://go.dev/issue/47066 --><!-- CL 357331 -->
- The method <a href="/pkg/reflect/#Value.Bytes"><code>Value.Bytes</code></a>
- now accepts addressable arrays in addition to slices.
- </p>
- <p><!-- CL 400954 -->
- The methods <a href="/pkg/reflect/#Value.Len"><code>Value.Len</code></a>
- and <a href="/pkg/reflect/#Value.Cap"><code>Value.Cap</code></a>
- now successfully operate on a pointer to an array and return the length of that array,
- to match what the <a href="/ref/spec#Length_and_capacity">builtin
- <code>len</code> and <code>cap</code> functions do</a>.
- </p>
- </dd>
-</dl><!-- reflect -->
-
-<dl id="regexp/syntax"><dt><a href="/pkg/regexp/syntax/">regexp/syntax</a></dt>
- <dd>
- <p><!-- https://go.dev/issue/51684 --><!-- CL 401076 -->
- Go 1.18 release candidate 1, Go 1.17.8, and Go 1.16.15 included a security fix
- to the regular expression parser, making it reject very deeply nested expressions.
- Because Go patch releases do not introduce new API,
- the parser returned <a href="/pkg/regexp/syntax/#ErrInternalError"><code>syntax.ErrInternalError</code></a> in this case.
- Go 1.19 adds a more specific error, <a href="/pkg/regexp/syntax/#ErrNestingDepth"><code>syntax.ErrNestingDepth</code></a>,
- which the parser now returns instead.
- </p>
- </dd>
-</dl><!-- regexp -->
-
-<dl id="pkg-runtime"><dt><a href="/pkg/runtime/">runtime</a></dt>
- <dd>
- <p><!-- https://go.dev/issue/51461 -->
- The <a href="/pkg/runtime/#GOROOT"><code>GOROOT</code></a> function now returns the empty string
- (instead of <code>"go"</code>) when the binary was built with
- the <code>-trimpath</code> flag set and the <code>GOROOT</code>
- variable is not set in the process environment.
- </p>
- </dd>
-</dl><!-- runtime -->
-
-<dl id="runtime/metrics"><dt><a href="/pkg/runtime/metrics/">runtime/metrics</a></dt>
- <dd>
- <p><!-- https://go.dev/issue/47216 --><!-- CL 404305 -->
- The new <code>/sched/gomaxprocs:threads</code>
- <a href="/pkg/runtime/metrics/#hdr-Supported_metrics">metric</a> reports
- the current
- <a href="/pkg/runtime/#GOMAXPROCS"><code>runtime.GOMAXPROCS</code></a>
- value.
- </p>
-
- <p><!-- https://go.dev/issue/47216 --><!-- CL 404306 -->
- The new <code>/cgo/go-to-c-calls:calls</code>
- <a href="/pkg/runtime/metrics/#hdr-Supported_metrics">metric</a>
- reports the total number of calls made from Go to C. This metric is
- identical to the
- <a href="/pkg/runtime/#NumCgoCall"><code>runtime.NumCgoCall</code></a>
- function.
- </p>
-
- <p><!-- https://go.dev/issue/48409 --><!-- CL 403614 -->
- The new <code>/gc/limiter/last-enabled:gc-cycle</code>
- <a href="/pkg/runtime/metrics/#hdr-Supported_metrics">metric</a>
- reports the last GC cycle when the GC CPU limiter was enabled. See the
- <a href="#runtime">runtime notes</a> for details about the GC CPU limiter.
- </p>
- </dd>
-</dl><!-- runtime/metrics -->
-
-<dl id="runtime/pprof"><dt><a href="/pkg/runtime/pprof/">runtime/pprof</a></dt>
- <dd>
- <p><!-- https://go.dev/issue/33250 --><!-- CL 387415 -->
- Stop-the-world pause times have been significantly reduced when
- collecting goroutine profiles, reducing the overall latency impact to the
- application.
- </p>
-
- <p><!-- CL 391434 -->
- <code>MaxRSS</code> is now reported in heap profiles for all Unix
- operating systems (it was previously only reported for
- <code>GOOS=android</code>, <code>darwin</code>, <code>ios</code>, and
- <code>linux</code>).
- </p>
- </dd>
-</dl><!-- runtime/pprof -->
-
-<dl id="runtime/race"><dt><a href="/pkg/runtime/race/">runtime/race</a></dt>
- <dd>
- <p><!-- https://go.dev/issue/49761 --><!-- CL 333529 -->
- The race detector has been upgraded to use thread sanitizer
- version v3 on all supported platforms
- except <code>windows/amd64</code>
- and <code>openbsd/amd64</code>, which remain on v2.
- Compared to v2, it is now typically 1.5x to 2x faster, uses half
- as much memory, and it supports an unlimited number of
- goroutines.
- On Linux, the race detector now requires at least glibc version
- 2.17 and GNU binutils 2.26.
- </p>
-
- <p><!-- CL 336549 -->
- The race detector is now supported on <code>GOARCH=s390x</code>.
- </p>
-
- <p><!-- https://go.dev/issue/52090 -->
- Race detector support for <code>openbsd/amd64</code> has been
- removed from thread sanitizer upstream, so it is unlikely to
- ever be updated from v2.
- </p>
- </dd>
-</dl><!-- runtime/race -->
-
-<dl id="runtime/trace"><dt><a href="/pkg/runtime/trace/">runtime/trace</a></dt>
- <dd>
- <p><!-- CL 400795 -->
- When tracing and the
- <a href="/pkg/runtime/pprof/#StartCPUProfile">CPU profiler</a> are
- enabled simultaneously, the execution trace includes CPU profile
- samples as instantaneous events.
- </p>
- </dd>
-</dl><!-- runtime/trace -->
-
-<dl id="sort"><dt><a href="/pkg/sort/">sort</a></dt>
- <dd>
- <p><!-- CL 371574 -->
- The sorting algorithm has been rewritten to use
- <a href="https://arxiv.org/pdf/2106.05123.pdf">pattern-defeating quicksort</a>, which
- is faster for several common scenarios.
- </p>
- <p><!-- https://go.dev/issue/50340 --><!-- CL 396514 -->
- The new function
- <a href="/pkg/sort/#Find"><code>Find</code></a>
- is like
- <a href="/pkg/sort/#Search"><code>Search</code></a>
- but often easier to use: it returns an additional boolean reporting whether an equal value was found.
- </p>
- </dd>
-</dl><!-- sort -->
-
-<dl id="strconv"><dt><a href="/pkg/strconv/">strconv</a></dt>
- <dd>
- <p><!-- CL 397255 -->
- <a href="/pkg/strconv/#Quote"><code>Quote</code></a>
- and related functions now quote the rune U+007F as <code>\x7f</code>,
- not <code>\u007f</code>,
- for consistency with other ASCII values.
- </p>
- </dd>
-</dl><!-- strconv -->
-
-<dl id="syscall"><dt><a href="/pkg/syscall/">syscall</a></dt>
- <dd>
- <p><!-- https://go.dev/issue/51192 --><!-- CL 385796 -->
- On PowerPC (<code>GOARCH=ppc64</code>, <code>ppc64le</code>),
- <a href="/pkg/syscall/#Syscall"><code>Syscall</code></a>,
- <a href="/pkg/syscall/#Syscall6"><code>Syscall6</code></a>,
- <a href="/pkg/syscall/#RawSyscall"><code>RawSyscall</code></a>, and
- <a href="/pkg/syscall/#RawSyscall6"><code>RawSyscall6</code></a>
- now always return 0 for return value <code>r2</code> instead of an
- undefined value.
- </p>
-
- <p><!-- CL 391434 -->
- On AIX and Solaris, <a href="/pkg/syscall/#Getrusage"><code>Getrusage</code></a> is now defined.
- </p>
- </dd>
-</dl><!-- syscall -->
-
-<dl id="time"><dt><a href="/pkg/time/">time</a></dt>
- <dd>
- <p><!-- https://go.dev/issue/51414 --><!-- CL 393515 -->
- The new method
- <a href="/pkg/time/#Duration.Abs"><code>Duration.Abs</code></a>
- provides a convenient and safe way to take the absolute value of a duration,
- converting −2⁶³ to 2⁶³−1.
- (This boundary case can happen as the result of subtracting a recent time from the zero time.)
- </p>
- <p><!-- https://go.dev/issue/50062 --><!-- CL 405374 -->
- The new method
- <a href="/pkg/time/#Time.ZoneBounds"><code>Time.ZoneBounds</code></a>
- returns the start and end times of the time zone in effect at a given time.
- It can be used in a loop to enumerate all the known time zone transitions at a given location.
- </p>
- </dd>
-</dl><!-- time -->
-
-<!-- Silence these false positives from x/build/cmd/relnote: -->
-<!-- CL 382460 -->
-<!-- CL 384154 -->
-<!-- CL 384554 -->
-<!-- CL 392134 -->
-<!-- CL 392414 -->
-<!-- CL 396215 -->
-<!-- CL 403058 -->
-<!-- CL 410133 -->
-<!-- https://go.dev/issue/27837 -->
-<!-- https://go.dev/issue/38340 -->
-<!-- https://go.dev/issue/42516 -->
-<!-- https://go.dev/issue/45713 -->
-<!-- https://go.dev/issue/46654 -->
-<!-- https://go.dev/issue/48257 -->
-<!-- https://go.dev/issue/50447 -->
-<!-- https://go.dev/issue/50720 -->
-<!-- https://go.dev/issue/50792 -->
-<!-- https://go.dev/issue/51115 -->
-<!-- https://go.dev/issue/51447 -->