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It's not needed per CL 499515. Change-Id: I2a5ce46be93dad1442c0aad736fd8d230ee35f39 Reviewed-on: https://go-review.googlesource.com/c/go/+/501996 Auto-Submit: Ian Lance Taylor <iant@google.com> Reviewed-by: Quim Muntal <quimmuntal@gmail.com> Reviewed-by: Eli Bendersky <eliben@google.com> Reviewed-by: Ian Lance Taylor <iant@google.com> TryBot-Bypass: Ian Lance Taylor <iant@google.com>
1235 lines
52 KiB
HTML
1235 lines
52 KiB
HTML
<!--{
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"Title": "Go 1.21 Release Notes",
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"Path": "/doc/go1.21"
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}-->
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<!--
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NOTE: In this document and others in this directory, the convention is to
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set fixed-width phrases with non-fixed-width spaces, as in
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<code>hello</code> <code>world</code>.
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Do not send CLs removing the interior tags from such phrases.
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-->
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<style>
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main ul li { margin: 0.5em 0; }
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</style>
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<h2 id="introduction">DRAFT RELEASE NOTES — Introduction to Go 1.21</h2>
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<p>
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<strong>
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Go 1.21 is not yet released. These are work-in-progress
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release notes. Go 1.21 is expected to be released in August 2023.
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</strong>
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</p>
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<p>
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The latest Go release, version 1.21, arrives six months after <a href="/doc/go1.20">Go 1.20</a>.
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Most of its changes are in the implementation of the toolchain, runtime, and libraries.
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As always, the release maintains the Go 1 <a href="/doc/go1compat">promise of compatibility</a>;
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in fact, Go 1.21 <a href="#godebug">improves upon that promise</a>.
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We expect almost all Go programs to continue to compile and run as before.
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</p>
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<p><!-- https://go.dev/issue/57631 -->
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Go 1.21 introduces a small change to the numbering of releases.
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In the past, we used Go 1.<i>N</i> to refer to both the overall Go language version and release family
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as well as the first release in that family.
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Starting in Go 1.21, the first release is now Go 1.<i>N</i>.0.
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Today we are releasing both the Go 1.21 language and its initial implementation, the Go 1.21.0 release.
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These notes refer to “Go 1.21”; tools like <code>go</code> <code>version</code> will report “<code>go1.21.0</code>”
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(until you upgrade to Go 1.21.1).
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See “<a href="/doc/toolchain#versions">Go versions</a>” in the “Go Toolchains” documentation for details
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about the new version numbering.
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</p>
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<h2 id="language">Changes to the language</h2>
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<p>
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Go 1.21 adds three new built-ins to the language.
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<ul>
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<li><!-- https://go.dev/issue/59488 -->
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The new functions <code>min</code> and <code>max</code> compute the
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smallest (or largest, for <code>max</code>) value of a fixed number
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of given arguments.
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See the language spec for
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<a href="https://tip.golang.org/ref/spec#Min_and_max">details</a>.
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</li>
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<li><!-- https://go.dev/issue/56351 -->
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The new function <code>clear</code> deletes all elements from a
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map or zeroes all elements of a slice.
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See the language spec for
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<a href="https://tip.golang.org/ref/spec#Clear">details</a>.
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</li>
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</ul>
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</p>
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<p><!-- https://go.dev/issue/57411 -->
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Package initialization order is now specified more precisely. The
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new algorithm is:
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<ul>
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<li>
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Sort all packages by import path.
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</li>
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<li>Repeat until the list of packages is empty:
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<ul>
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<li>
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Find the first package in the list for which all imports are
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already initialized.
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</li>
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<li>
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Initialize that package and remove it from the list.
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</li>
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</ul>
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</li>
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</ul>
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This may change the behavior of some programs that rely on a
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specific initialization ordering that was not expressed by explicit
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imports. The behavior of such programs was not well defined by the
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spec in past releases. The new rule provides an unambiguous definition.
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</p>
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<p>
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Multiple improvements that increase the power and precision of type inference have been made.
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</p>
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<ul>
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<li><!-- https://go.dev/issue/59338 -->
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A (possibly partially instantiated generic) function may now be called with arguments that are
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themselves (possibly partially instantiated) generic functions.
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The compiler will attempt to infer the missing type arguments of the callee (as before) and,
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for each argument that is a generic function that is not fully instantiated,
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its missing type arguments (new).
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Typical use cases are calls to generic functions operating on containers
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(such as <a href="/pkg/slices#IndexFunc">slices.IndexFunc</a>) where a function argument
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may also be generic, and where the type argument of the called function and its arguments
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are inferred from the container type.
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More generally, a generic function may now be used without explicit instantiation when
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it is assigned to a variable or returned as a result value if the type arguments can
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be inferred from the assignment.
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</li>
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<li><!-- https://go.dev/issue/60353, https://go.dev/issue/57192, https://go.dev/issue/52397, https://go.dev/issue/41176 -->
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Type inference now also considers methods when a value is assigned to an interface:
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type arguments for type parameters used in method signatures may be inferred from
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the corresponding parameter types of matching methods.
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</li>
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<li><!-- https://go.dev/issue/51593 https://go.dev/issue/39661 -->
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Similarly, since a type argument must implement all the methods of its corresponding constraint,
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the methods of the type argument and constraint are matched which may lead to the inference of
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additional type arguments.
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</li>
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<li><!-- https://go.dev/issue/58671 -->
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If multiple untyped constant arguments of different kinds (such as an untyped int and
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an untyped floating-point constant) are passed to parameters with the same (not otherwise
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specified) type parameter type, instead of an error, now type inference determines the
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type using the same approach as an operator with untyped constant operands.
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This change brings the types inferred from untyped constant arguments in line with the
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types of constant expressions.
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</li>
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<li><!-- https://go.dev/issue/59750 -->
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Type inference is now precise when matching corresponding types in assignments:
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component types (such as the the elements of slices, or the parameter types in function signatures)
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must be identical (given suitable type arguments) to match, otherwise inference fails.
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This change produces more accurate error messages:
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where in the past type inference may have succeeded incorrectly and lead to an invalid assignment,
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the compiler now reports an inference error if two types can't possibly match.
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</li>
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</ul>
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<p><!-- https://go.dev/issue/58650 -->
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More generally, the description of
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<a href="https://tip.golang.org/ref/spec#Type_inference">type inference</a>
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in the language spec has been clarified.
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Together, all these changes make type inference more powerful and inference failures less surprising.
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</p>
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<!-- https://go.dev/issue/57969 -->
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<p>
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Go 1.21 includes a preview of a language change we are considering for a future version of Go:
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making for loop variables per-iteration instead of per-loop, to avoid accidental sharing bugs.
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For details about how to try that language change, see <a href="https://go.dev/wiki/LoopvarExperiment">the LoopvarExperiment wiki page</a>.
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</p>
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<p>
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TODO: complete this section
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</p>
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<h2 id="tools">Tools</h2>
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<p>
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Go 1.21 adds improved support for backwards compatibility and forwards compatibility
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in the Go toolchain.
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</p>
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<p><!-- https://go.dev/issue/56986 -->
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To improve backwards compatibility, Go 1.21 formalizes
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Go's use of the GODEBUG environment variable to control
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the default behavior for changes that are non-breaking according to the
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<a href="/doc/go1compat">compatibility policy</a>
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but nonetheless may cause existing programs to break.
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(For example, programs that depend on buggy behavior may break
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when a bug is fixed, but bug fixes are not considered breaking changes.)
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When Go must make this kind of behavior change,
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it now chooses between the old and new behavior based on the
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<code>go</code> line in the workspace's <code>go.work</code> file
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or else the main module's <code>go.mod</code> file.
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Upgrading to a new Go toolchain but leaving the <code>go</code> line
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set to its original (older) Go version preserves the behavior of the older
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toolchain.
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With this compatibility support, the latest Go toolchain should always
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be the best, most secure, implementation of an older version of Go.
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See “<a href="/doc/godebug">Go, Backwards Compatibility, and GODEBUG</a>” for details.
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</p>
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<p><!-- https://go.dev/issue/57001 -->
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To improve forwards compatibility, Go 1.21 now reads the <code>go</code> line
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in a <code>go.work</code> or <code>go.mod</code> file as a strict
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minimum requirement: <code>go</code> <code>1.21.0</code> means
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that the workspace or module cannot be used with Go 1.20 or with Go 1.21rc1.
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This allows projects that depend on fixes made in later versions of Go
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to ensure that they are not used with earlier versions.
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It also gives better error reporting for projects that make use of new Go features:
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when the problem is that a newer Go version is needed,
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that problem is reported clearly, instead of attempting to build the code
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and instead printing errors about unresolved imports or syntax errors.
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</p>
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<p>
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To make these new stricter version requirements easier to manage,
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the <code>go</code> command can now invoke not just the toolchain
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bundled in its own release but also other Go toolchain versions found in the PATH
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or downloaded on demand.
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If a <code>go.mod</code> or <code>go.work</code> <code>go</code> line
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declares a minimum requirement on a newer version of Go, the <code>go</code>
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command will find and run that version automatically.
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The new <code>toolchain</code> directive sets a suggested minimum toolchain to use,
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which may be newer than the strict <code>go</code> minimum.
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See “<a href="/doc/toolchain">Go Toolchains</a>” for details.
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</p>
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<h3 id="go-command">Go command</h3>
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<p><!-- https://go.dev/issue/58099, CL 474236 -->
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The <code>-pgo</code> build flag now defaults to <code>-pgo=auto</code>,
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and the restriction of specifying a single main package on the command
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line is now removed. If a file named <code>default.pgo</code> is present
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in the main package's directory, the <code>go</code> command will use
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it to enable profile-guided optimization for building the corresponding
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program.
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</p>
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<p>
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The <code>-C</code> <code>dir</code> flag must now be the first
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flag on the command-line when used.
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</p>
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<p><!-- https://go.dev/issue/37708, CL 463837 -->
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The new <code>go</code> <code>test</code> option
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<code>-fullpath</code> prints full path names in test log messages,
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rather than just base names.
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</p>
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<p><!-- https://go.dev/issue/15513, CL 466397 -->
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The <code>go</code> <code>test</code> <code>-c</code> flag now
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supports writing test binaries for multiple packages, each to
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<code>pkg.test</code> where <code>pkg</code> is the package name.
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It is an error if more than one test package being compiled has a given package name.]
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</p>
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<p><!-- https://go.dev/issue/15513, CL 466397 -->
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The <code>go</code> <code>test</code> <code>-o</code> flag now
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accepts a directory argument, in which case test binaries are written to that
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directory instead of the current directory.
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</p>
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<h3 id="cgo">Cgo</h3>
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<p><!-- CL 490819 -->
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In files that <code>import "C"</code>, the Go toolchain now
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correctly reports errors for attempts to declare Go methods on C types.
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</p>
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<h2 id="runtime-changes">Runtime</h2>
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<p>
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TODO: complete this section, or delete if not needed
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</p>
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<p><!-- https://go.dev/issue/7181 -->
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When printing very deep stacks, the runtime now prints the first 50
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(innermost) frames followed by the bottom 50 (outermost) frames,
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rather than just printing the first 100 frames. This makes it easier
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to see how deeply recursive stacks started, and is especially
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valuable for debugging stack overflows.
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</p>
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<p><!-- https://go.dev/issue/59960 -->
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On Linux platforms that support transparent huge pages, the Go runtime
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now manages which parts of the heap may be backed by huge pages more
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explicitly. This leads to better utilization of memory: small heaps
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should see less memory used (up to 50% in pathological cases) while
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large heaps should see fewer broken huge pages for dense parts of the
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heap, improving CPU usage and latency by up to 1%.
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</p>
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<p><!-- https://go.dev/issue/57069, https://go.dev/issue/56966 -->
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As a result of runtime-internal garbage collection tuning,
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applications may see up to a 40% reduction in application tail latency
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and a small decrease in memory use. Some applications may also observe
|
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a small loss in throughput.
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The memory use decrease should be proportional to the loss in
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throughput, such that the previous release's throughput/memory
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tradeoff may be recovered (with little change to latency) by
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increasing <code>GOGC</code> and/or <code>GOMEMLIMIT</code> slightly.
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</p>
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<p><!-- https://go.dev/issue/51676 -->
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Calls from C to Go on threads created in C require some setup to prepare for
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Go execution. On Unix platforms, this setup is now preserved across multiple
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calls from the same thread. This significantly reduces the overhead of
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subsequent C to Go calls from ~1-3 microseconds per call to ~100-200
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nanoseconds per call.
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</p>
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<h2 id="compiler">Compiler</h2>
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<p>
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Profile-guide optimization (PGO), added as a preview in Go 1.20, is now ready
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for general use. PGO enables additional optimizations on code identified as
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hot by profiles of production workloads. As mentioned in the
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<a href="#go-command">Go command section</a>, PGO is enabled by default for
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binaries that contain a <code>default.pgo</code> profile in the main
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package directory. Performance improvements vary depending on application
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behavior, with most programs from a representative set of Go programs seeing
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between 2 and 7% improvement from enabling PGO. See the
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<a href="/doc/pgo">PGO user guide</a> for detailed documentation.
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</p>
|
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<!-- https://go.dev/issue/59959 -->
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<p>
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PGO builds can now devirtualize some interface method calls, adding a
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concrete call to the most common callee. This enables further optimization,
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such as inlining the callee.
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</p>
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<p>
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TODO: complete this section, or delete if not needed
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</p>
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<h2 id="assembler">Assembler</h2>
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<!-- https://go.dev/issue/58378 -->
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<p>
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On amd64, frameless nosplit assembly functions are no longer automatically marked as <code>NOFRAME</code>.
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Instead, the <code>NOFRAME</code> attribute must be explicitly specified if desired,
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which is already the behavior on other architectures supporting frame pointers.
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With this, the runtime now maintains the frame pointers for stack transitions.
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</p>
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<!-- CL 476295 -->
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<p>
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The verifier that checks for incorrect uses of <code>R15</code> when dynamic linking on amd64 has been improved.
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</p>
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<h2 id="linker">Linker</h2>
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<p><!-- https://go.dev/issue/57302, CL 461749 -->
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On Windows AMD64, the linker (with help from the compiler) now emits
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SEH unwinding data by default, which improves the integration
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of Go applications with Windows debuggers and other tools.
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</p>
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<!-- CL 457455 -->
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<p>
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<!-- cmd/link: generate .xdata PE section -->
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</p>
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<!-- CL 463395, CL 461315 -->
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<p>
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In Go 1.21 the linker (with help from the compiler) is now capable of
|
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deleting dead (unreferenced) global map variables, if the number of
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entries in the variable initializer is sufficiently large, and if the
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initializer expressions are side-effect free.
|
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</p>
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<p>
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TODO: complete this section, or delete if not needed
|
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</p>
|
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<h2 id="library">Core library</h2>
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<h3 id="slog">New log/slog package</h3>
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<p><!-- https://go.dev/issue/59060, https://go.dev/issue/59141, https://go.dev/issue/59204, https://go.dev/issue/59280,
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https://go.dev/issue/59282, https://go.dev/issue/59339, https://go.dev/issue/59345,
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|
CL 477295, CL 484096, CL 486376, CL 486415, CL 487855 -->
|
|
The new <a href="/pkg/log/slog">log/slog</a> package provides structured logging with levels.
|
|
Structured logging emits key-value pairs
|
|
to enable fast, accurate processing of large amounts of log data.
|
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The package supports integration with popular log analysis tools and services.
|
|
</p>
|
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|
|
<h3 id="slogtest">New testing/slogtest package</h3>
|
|
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<p><!-- CL 487895 -->
|
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The new <a href="/pkg/testing/slogtest">testing/slogtest</a> package can help
|
|
to validate <a href="/pkg/log/slog#Handler">slog.Handler</a> implementations.
|
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</p>
|
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|
|
<h3 id="slices">New slices package</h3>
|
|
|
|
<p>
|
|
<!-- https://go.dev/issue/45955, https://go.dev/issue/54768 -->
|
|
<!-- https://go.dev/issue/57348, https://go.dev/issue/57433 -->
|
|
<!-- https://go.dev/issue/58565, https://go.dev/issue/60091 -->
|
|
<!-- CL 467417, CL 468855, CL 483175, CL 496078, CL 498175 -->
|
|
The new <a href="/pkg/slices">slices</a> package provides many common
|
|
operations on slices, using generic functions that work with slices
|
|
of any element type.
|
|
</p>
|
|
|
|
<h3 id="maps">New maps package</h3>
|
|
|
|
<p><!-- https://go.dev/issue/57436, CL 464343 -->
|
|
The new <a href="/pkg/maps/">maps</a> package provides several
|
|
common operations on maps, using generic functions that work with
|
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maps of any key or element type.
|
|
</p>
|
|
|
|
<p><!-- https://go.dev/issue/59488, CL 469356 -->
|
|
The new <a href="/pkg/cmp/">cmp</a> package defines the type
|
|
constraint <a href="/pkg/cmp/#Ordered"><code>Ordered</code></a> and
|
|
two new generic functions
|
|
<a href="/pkg/cmp/#Less"><code>Less</code></a>
|
|
and <a href="/pkg/cmp/#Compare"><code>Compare</code></a> that are
|
|
useful with <a href="/ref/spec/#Comparison_operators">ordered
|
|
types</a>.
|
|
</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>
|
|
|
|
<p>
|
|
TODO: complete this section
|
|
</p>
|
|
|
|
<dl id="archive/tar"><dt><a href="/pkg/archive/tar/">archive/tar</a></dt>
|
|
<dd>
|
|
<p><!-- https://go.dev/issue/54451, CL 491175 -->
|
|
The implementation of the
|
|
<a href="/pkg/io/fs/#FileInfo"><code>io/fs.FileInfo</code></a>
|
|
interface returned by
|
|
<a href="/pkg/archive/tar/#Header.FileInfo"><code>Header.FileInfo</code></a>
|
|
now implements a <code>String</code> method that calls
|
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<a href="/pkg/io/fs/#FormatFileInfo"><code>io/fs.FormatFileInfo</code></a>.
|
|
</p>
|
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</dd>
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</dl><!-- archive/tar -->
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|
|
<dl id="archive/zip"><dt><a href="/pkg/archive/zip/">archive/zip</a></dt>
|
|
<dd>
|
|
<p><!-- https://go.dev/issue/54451, CL 491175 -->
|
|
The implementation of the
|
|
<a href="/pkg/io/fs/#FileInfo"><code>io/fs.FileInfo</code></a>
|
|
interface returned by
|
|
<a href="/pkg/archive/zip/#FileHeader.FileInfo"><code>FileHeader.FileInfo</code></a>
|
|
now implements a <code>String</code> method that calls
|
|
<a href="/pkg/io/fs/#FormatFileInfo"><code>io/fs.FormatFileInfo</code></a>.
|
|
</p>
|
|
|
|
<p><!-- https://go.dev/issue/54451, CL 491175 -->
|
|
The implementation of the
|
|
<a href="/pkg/io/fs/#DirEntry"><code>io/fs.DirEntry</code></a>
|
|
interface returned by the
|
|
<a href="/pkg/io/fs/#ReadDirFile.ReadDir"><code>io/fs.ReadDirFile.ReadDir</code></a>
|
|
method of the
|
|
<a href="/pkg/io/fs/#File"><code>io/fs.File</code></a>
|
|
returned by
|
|
<a href="/pkg/archive/zip/#Reader.Open"><code>Reader.Open</code></a>
|
|
now implements a <code>String</code> method that calls
|
|
<a href="/pkg/io/fs/#FormatDirEntry"><code>io/fs.FormatDirEntry</code></a>.
|
|
</p>
|
|
</dd>
|
|
</dl><!-- archive/zip -->
|
|
|
|
<dl id="bytes"><dt><a href="/pkg/bytes/">bytes</a></dt>
|
|
<dd>
|
|
<p><!-- https://go.dev/issue/53685, CL 474635 -->
|
|
The <a href="/pkg/bytes/#Buffer"><code>Buffer</code></a> type
|
|
has two new methods:
|
|
<a href="/pkg/bytes/#Buffer.Available"><code>Available</code></a>
|
|
and <a href="/pkg/bytes/#AvailableBuffer"><code>AvailableBuffer</code></a>.
|
|
These may be used along with the
|
|
<a href="/pkg/bytes/#Buffer.Write"><code>Write</code></a>
|
|
method to append directly to the <code>Buffer</code>.
|
|
</p>
|
|
</dd>
|
|
</dl><!-- bytes -->
|
|
|
|
<dl id="context"><dt><a href="/pkg/context/">context</a></dt>
|
|
<dd>
|
|
<p><!-- https://go.dev/issue/40221, CL 479918 -->
|
|
The new <a href="/pkg/context/#WithoutCancel"><code>WithoutCancel</code></a>
|
|
function returns a copy of a context that is not canceled when the original
|
|
context is canceled.
|
|
</p>
|
|
<p><!-- https://go.dev/issue/56661, CL 449318 -->
|
|
The new <a href="/pkg/context/#WithDeadlineCause"><code>WithDeadlineCause</code></a>
|
|
and <a href="/pkg/context/#WithTimeoutCause"><code>WithTimeoutCause</code></a>
|
|
functions provide a way to set a context cancellation cause when a deadline or
|
|
timer expires. The cause may be retrieved with the
|
|
<a href="/pkg/context/#Cause"><code>Cause</code></a> function.
|
|
</p>
|
|
<p><!-- https://go.dev/issue/57928, CL 482695 -->
|
|
The new <a href="/pkg/context/#AfterFunc"><code>AfterFunc</code></a>
|
|
function registers a function to run after a context has been cancelled.
|
|
</p>
|
|
</dd>
|
|
</dl>
|
|
|
|
<dl id="crypto/elliptic"><dt><a href="/pkg/crypto/elliptic/">crypto/elliptic</a></dt>
|
|
<dd>
|
|
<p><!-- CL 459977 -->
|
|
All of the <a href="/pkg/crypto/elliptic/#Curve"><code>Curve</code></a> methods have been deprecated, along with <a href="/pkg/crypto/elliptic/#GenerateKey"><code>GenerateKey</code></a>, <a href="/pkg/crypto/elliptic/#Marshal"><code>Marshal</code></a>, and <a href="/pkg/crypto/elliptic/#Unmarshal"><code>Unmarshal</code></a>. For ECDH operations, the new <a href="/pkg/crypto/ecdh/"><code>crypto/ecdh</code></a> package should be used instead. For lower-level operations, use third-party modules such as <a href="https://pkg.go.dev/filippo.io/nistec">filippo.io/nistec</a>.
|
|
</p>
|
|
</dd>
|
|
</dl><!-- crypto/elliptic -->
|
|
|
|
<dl id="crypto/rand"><dt><a href="/pkg/crypto/rand/">crypto/rand</a></dt>
|
|
<dd>
|
|
<p><!-- CL 463123 -->
|
|
The <a href="/pkg/crypto/rand/"><code>crypto/rand</code></a> package now uses the <code>getrandom</code> system call on NetBSD 10.0 and later.
|
|
</p>
|
|
</dd>
|
|
</dl><!-- crypto/rand -->
|
|
|
|
<dl id="crypto/rsa"><dt><a href="/pkg/crypto/rsa/">crypto/rsa</a></dt>
|
|
<dd>
|
|
<p><!-- CL 471259, CL 492935 -->
|
|
The performance of private RSA operations (decryption and signing) is now better than Go 1.19 for <code>GOOS=amd64</code> and <code>GOOS=arm64</code>. It had regressed in Go 1.20.
|
|
</p>
|
|
<p>
|
|
Due to the addition of private fields to <a href="/pkg/crypto/rsa/#PrecomputedValues"><code>PrecomputedValues</code></a>, <a href="/pkg/crypto/rsa/#PrivateKey.Precompute"><code>PrivateKey.Precompute</code></a> must be called for optimal performance even if deserializing (for example from JSON) a previously-precomputed private key.
|
|
</p>
|
|
<p><!-- https://go.dev/issue/56921, CL 459976 -->
|
|
The <a href="/pkg/crypto/rsa/#GenerateMultiPrimeKey"><code>GenerateMultiPrimeKey</code></a> function and the <a href="/pkg/crypto/rsa/#PrecomputedValues.CRTValues"><code>PrecomputedValues.CRTValues</code></a> field have been deprecated. <a href="/pkg/crypto/rsa/#PrecomputedValues.CRTValues"><code>PrecomputedValues.CRTValues</code></a> will still be populated when <a href="/pkg/crypto/rsa/#PrivateKey.Precompute"><code>PrivateKey.Precompute</code></a> is called, but the values will not be used during decryption operations.
|
|
</p>
|
|
</dd>
|
|
</dl><!-- crypto/rsa -->
|
|
|
|
<!-- CL 483815 reverted -->
|
|
|
|
<dl id="crypto/sha256"><dt><a href="/pkg/crypto/sha256/">crypto/sha256</a></dt>
|
|
<dd>
|
|
<p><!-- https://go.dev/issue/50543, CL 408795 -->
|
|
SHA-224 and SHA-256 operations now use native instructions when available when <code>GOOS=amd64</code>, providing a performance improvement on the order of 3-4x.
|
|
</p>
|
|
</dd>
|
|
</dl><!-- crypto/sha256 -->
|
|
|
|
<!-- CL 481478 reverted -->
|
|
<!-- CL 483816 reverted -->
|
|
|
|
<dl id="crypto/tls"><dt><a href="/pkg/crypto/tls/">crypto/tls</a></dt>
|
|
<dd>
|
|
<p><!-- https://go.dev/issue/60105 -->
|
|
Applications can now control the content of session tickets.
|
|
<ul>
|
|
<li>
|
|
The new <a href="/pkg/crypto/tls/#SessionState"><code>SessionState</code></a> type
|
|
describes a resumable session.
|
|
</li>
|
|
<li>
|
|
The <a href="/pkg/crypto/tls/#SessionState.Bytes"><code>SessionState.Bytes</code></a>
|
|
method and <a href="/pkg/crypto/tls/#ParseSessionState"><code>ParseSessionState</code></a>
|
|
function serialize and deserialize a <code>SessionState</code>.
|
|
</li>
|
|
<li>
|
|
The <a href="/pkg/crypto/tls/#Config.WrapSession"><code>Config.WrapSession</code></a> and
|
|
<a href="/pkg/crypto/tls/#Config.UnwrapSession"><code>Config.UnwrapSession</code></a>
|
|
hooks convert a <code>SessionState</code> to and from a ticket.
|
|
</li>
|
|
<li>
|
|
The <a href="/pkg/crypto/tls/#Config.EncryptTicket"><code>Config.EncryptTicket</code></a>
|
|
and <a href="/pkg/crypto/tls/#Config.DecryptTicket"><code>Config.DecryptTicket</code></a>
|
|
methods provide a default implementation of <code>WrapSession</code> and
|
|
<code>UnwrapSession</code>.
|
|
</li>
|
|
<li>
|
|
The <a href="/pkg/crypto/tls/#ClientSessionState.ResumptionState"><code>ClientSessionState.ResumptionState</code></a> method and
|
|
<a href="/pkg/crypto/tls/#NewResumptionState"><code>NewResumptionState</code></a> function
|
|
may be used by a <code>ClientSessionCache</code> implementation to store and
|
|
resume sessions.
|
|
</li>
|
|
</ul>
|
|
</p>
|
|
|
|
<p><!-- CL 497376 -->
|
|
The package now supports the extended master secret extension (RFC 7627),
|
|
and enables it by default. Additionally, the deprecation of
|
|
<a href="/pkg/crypto/tls/#ConnectionState.TLSUnique"><code>ConnectionState.TLSUnique</code></a>
|
|
has been reverted, and it is populated when a connection which uses
|
|
extended master secret is resumed. Session tickets produced by
|
|
Go pre-1.21 are not interoperable with Go 1.21, meaning connections
|
|
resumed across versions will fall back to full handshakes.
|
|
</p>
|
|
|
|
<p><!-- https://go.dev/issue/44886, https://go.dev/issue/60107 -->
|
|
The new <a href="/pkg/crypto/tls/#QUICConn"><code>QUICConn</code></a> type
|
|
provides support for QUIC implementations. Note that this is not itself
|
|
a QUIC implementation.
|
|
</p>
|
|
|
|
<p><!-- https://go.dev/issue/46308 -->
|
|
The new <a href="/pkg/crypto/tls/#VersionName"></code>VersionName</code></a> function
|
|
returns the name for a TLS version number.
|
|
</p>
|
|
</dd>
|
|
</dl><!-- crypto/tls -->
|
|
|
|
<dl id="crypto/x509"><dt><a href="/pkg/crypto/x509/">crypto/x509</a></dt>
|
|
<dd>
|
|
<p><!-- https://go.dev/issue/53573, CL 468875 -->
|
|
<a href="/pkg/crypto/x509/#RevocationList.RevokedCertificates"><code>RevocationList.RevokedCertificates</code></a> has been deprecated and replaced with the new <a href="/pkg/crypto/x509/#RevocationList.Entries"><code>RevocationList.Entries</code></a> field, which is a slice of <a href="/pkg/crypto/x509/#RevocationListEntry"><code>RevocationListEntry</code></a>. <a href="/pkg/crypto/x509/#RevocationListEntry"><code>RevocationListEntry</code></a> contains all of the fields in <a href="/pkg/crypto/x509/#pkix.RevokedCertificate"><code>pkix.RevokedCertificate</code></a>, as well as the revocation reason code.
|
|
</p>
|
|
</dd>
|
|
</dl><!-- crypto/x509 -->
|
|
|
|
<dl id="debug/elf"><dt><a href="/pkg/debug/elf/">debug/elf</a></dt>
|
|
<dd>
|
|
<p><!-- https://go.dev/issue/56892, CL 452617 -->
|
|
The new
|
|
<a href="/pkg/debug/elf/#File.DynValue"><code>File.DynValue</code></a>
|
|
method may be used to retrieve the numeric values listed with a
|
|
given dynamic tag.
|
|
</p>
|
|
|
|
<p><!-- https://go.dev/issue/56887, CL 452496 -->
|
|
The constant flags permitted in a <code>DT_FLAGS_1</code>
|
|
dynamic tag are now defined with type
|
|
<a href="/pkg/debug/elf/#DynFlag1"><code>DynFlag1</code></a>. These
|
|
tags have names starting with <code>DF_1</code>.
|
|
</p>
|
|
|
|
<p><!-- CL 473256 -->
|
|
The package now defines the constant
|
|
<a href="/pkg/debug/elf/#COMPRESS_ZSTD"><code>COMPRESS_ZSTD</code></a>.
|
|
</p>
|
|
|
|
<p><!-- https://go.dev/issue/60348, CL 496918 -->
|
|
The package now defines the constant
|
|
<a href="/pkg/debug/elf/#R_PPC64_REL24_P9NOTOC"><code>R_PPC64_REL24_P9NOTOC</code></a>.
|
|
</p>
|
|
</dd>
|
|
</dl><!-- debug/elf -->
|
|
|
|
<dl id="debug/pe"><dt><a href="/pkg/debug/pe/">debug/pe</a></dt>
|
|
<dd>
|
|
<p><!-- CL 488475 -->
|
|
Attempts to read from a section containing uninitialized data
|
|
using
|
|
<a href="/pkg/debug/pe/#Section.Data"><code>Section.Data</code></a>
|
|
or the reader returned by <a href="/pkg/debug/pe/#Section.Open"><code>Section.Open</code></a>
|
|
now return an error.
|
|
</p>
|
|
</dd>
|
|
</dl><!-- debug/pe -->
|
|
|
|
<dl id="embed"><dt><a href="/pkg/embed/">embed</a></dt>
|
|
<dd>
|
|
<p><!-- https://go.dev/issue/57803, CL 483235 -->
|
|
The <a href="/pkg/io/fs/#File"><code>io/fs.File</code></a>
|
|
returned by
|
|
<a href="/pkg/embed/#FS.Open"><code>FS.Open</code></a> now
|
|
has a <code>ReadAt</code> method that
|
|
implements <a href="/pkg/io/#ReaderAt"><code>io.ReaderAt</code></a>.
|
|
</p>
|
|
|
|
<p><!-- https://go.dev/issue/54451, CL 491175 -->
|
|
Calling <code><a href="/pkg/embed/FS.Open">FS.Open</a>.<a href="/pkg/io/fs/#File.Stat">Stat</a></code>
|
|
will return a type that now implements a <code>String</code>
|
|
method that calls
|
|
<a href="/pkg/io/fs/#FormatFileInfo"><code>io/fs.FormatFileInfo</code></a>.
|
|
</p>
|
|
</dd>
|
|
</dl><!-- embed -->
|
|
|
|
<dl id="errors"><dt><a href="/pkg/errors/">errors</a></dt>
|
|
<dd>
|
|
<p><!-- https://go.dev/issue/41198, CL 473935 -->
|
|
The new
|
|
<a href="/pkg/errors/#ErrUnsupported"><code>ErrUnsupported</code></a>
|
|
error provides a standardized way to indicate that a requested
|
|
operation may not be performed because it is unsupported.
|
|
For example, a call to
|
|
<a href="/pkg/os/#Link"><code>os.Link</code></a> when using a
|
|
file system that does not support hard links.
|
|
</p>
|
|
</dd>
|
|
</dl><!-- errors -->
|
|
|
|
<dl id="flag"><dt><a href="/pkg/flag/">flag</a></dt>
|
|
<dd>
|
|
<p><!-- https://go.dev/issue/53747, CL 476015 -->
|
|
The new <a href="/pkg/flag/#BoolFunc"><code>BoolFunc</code></a>
|
|
function and
|
|
<a href="/pkg/flag/#FlagSet.BoolFunc"><code>FlagSet.BoolFunc</code></a>
|
|
method define a flag that does not require an argument and calls
|
|
a function when the flag is used. This is similar to
|
|
<a href="/pkg/flag/#Func"><code>Func</code></a> but for a
|
|
boolean flag.
|
|
</p>
|
|
|
|
<p><!-- CL 480215 -->
|
|
A flag definition
|
|
(via <a href="/pkg/flag/#Bool"><code>Bool</code></a>,
|
|
<a href="/pkg/flag/#BoolVar"><code>BoolVar</code></a>,
|
|
<a href="/pkg/flag/#Int"><code>Int</code></a>,
|
|
<a href="/pkg/flag/#IntVar"><code>IntVar</code></a>, etc.)
|
|
will panic if <a href="/pkg/flag/#Set"><code>Set</code></a> has
|
|
already been called on a flag with the same name. This change is
|
|
intended to detect cases where <a href="#language">changes in
|
|
initialization order</a> cause flag operations to occur in a
|
|
different order than expected. In many cases the fix to this
|
|
problem is to introduce a explicit package dependence to
|
|
correctly order the definition before any
|
|
<a href="/pkg/flag/#Set"><code>Set</code></a> operations.
|
|
</p>
|
|
</dd>
|
|
</dl><!-- flag -->
|
|
|
|
<dl id="go/ast"><dt><a href="/pkg/go/ast/">go/ast</a></dt>
|
|
<dd>
|
|
<p><!-- https://go.dev/issue/28089, CL 487935 -->
|
|
The new <a href="/pkg/go/ast/#IsGenerated"><code>IsGenerated</code></a> predicate
|
|
reports whether a file syntax tree contains the
|
|
<a href="https://go.dev/s/generatedcode">special comment</a>
|
|
that conventionally indicates that the file was generated by a tool.
|
|
</p>
|
|
</dd>
|
|
|
|
<dd>
|
|
<p><!-- https://go.dev/issue/59033, CL 476276 -->
|
|
The new
|
|
<a href="/pkg/go/ast/#File.GoVersion"><code>File.GoVersion</code></a>
|
|
field records the minimum Go version required by
|
|
any <code>//go:build</code> or <code>// +build</code>
|
|
directives.
|
|
</p>
|
|
</dd>
|
|
</dl><!-- go/ast -->
|
|
|
|
<dl id="go/build"><dt><a href="/pkg/go/build/">go/build</a></dt>
|
|
<dd>
|
|
<p><!-- https://go.dev/issue/56986, CL 453603 -->
|
|
The package now parses build directives (comments that start
|
|
with <code>//go:</code>) in file headers (before
|
|
the <code>package</code> declaration). These directives are
|
|
available in the new
|
|
<a href="/pkg/go/build#Package"><code>Package</code></a> fields
|
|
<a href="/pkg/go/build#Package.Directives"><code>Directives</code></a>,
|
|
<a href="/pkg/go/build#Package.TestDirectives"><code>TestDirectives</code></a>,
|
|
and
|
|
<a href="/pkg/go/build#Package.XTestDirectives"><code>XTestDirectives</code></a>.
|
|
</p>
|
|
</dd>
|
|
</dl><!-- go/build -->
|
|
|
|
<dl id="go/build/constraint"><dt><a href="/pkg/go/build/constraint/">go/build/constraint</a></dt>
|
|
<dd>
|
|
<p><!-- https://go.dev/issue/59033, CL 476275 -->
|
|
The new
|
|
<a href="/pkg/go/build/constraint/#GoVersion"><code>GoVersion</code></a>
|
|
function returns the minimum Go version implied by a build
|
|
expression.
|
|
</p>
|
|
</dd>
|
|
</dl><!-- go/build/constraint -->
|
|
|
|
<dl id="go/token"><dt><a href="/pkg/go/token/">go/token</a></dt>
|
|
<dd>
|
|
<p><!-- https://go.dev/issue/57708, CL 464515 -->
|
|
The new <a href="/pkg/go/token/#File.Lines"><code>File.Lines</code></a> method
|
|
returns the file's line-number table in the same form as accepted by
|
|
<code>File.SetLines</code>.
|
|
</p>
|
|
</dd>
|
|
</dl><!-- go/token -->
|
|
|
|
<dl id="hash/maphash"><dt><a href="/pkg/hash/maphash/">hash/maphash</a></dt>
|
|
<dd>
|
|
<p><!-- https://go.dev/issue/47342, CL 468795 -->
|
|
The <code>hash/maphash</code> package now has a pure Go implementation, selectable with the <code>purego</code> build tag.
|
|
</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/59584, CL 496395 -->
|
|
The new error
|
|
<a href="/pkg/html/template/#ErrJSTemplate"><code>ErrJSTemplate</code></a>
|
|
is returned when an action appears in a JavaScript template
|
|
literal. Previously an unexported error was returned.
|
|
</p>
|
|
</dd>
|
|
</dl><!-- html/template -->
|
|
|
|
<dl id="io/fs"><dt><a href="/pkg/io/fs/">io/fs</a></dt>
|
|
<dd>
|
|
<p><!-- https://go.dev/issue/54451, CL 489555 -->
|
|
The new
|
|
<a href="/pkg/io/fs/#FormatFileInfo"><code>FormatFileInfo</code></a>
|
|
function returns a formatted version of a
|
|
<a href="/pkg/io/fs/#FileInfo"><code>FileInfo</code></a>.
|
|
The new
|
|
<a href="/pkg/io/fs/#FormatDirEntry"><code>FormatDirEntry</code></a>
|
|
function returns a formatted version of a
|
|
<a href="/pkg/io/fs/#FileInfo"><code>DirEntry</code></a>.
|
|
The implementation of
|
|
<a href="/pkg/io/fs/#DirEntry"><code>DirEntry</code></a>
|
|
returned by
|
|
<a href="/pkg/io/fs/#ReadDir"><code>ReadDir</code></a> now
|
|
implements a <code>String</code> method that calls
|
|
<a href="/pkg/io/fs/#FormatDirEntry"><code>FormatDirEntry</code></a>,
|
|
and the same is true for
|
|
the <a href="/pkg/io/fs/#DirEntry"><code>DirEntry</code></a>
|
|
value passed to
|
|
<a href="/pkg/io/fs/#WalkDirFunc"><code>WalkDirFunc</code></a>.
|
|
</p>
|
|
</dd>
|
|
</dl><!-- io/fs -->
|
|
|
|
<!-- https://go.dev/issue/56491 rolled back by https://go.dev/issue/60519 -->
|
|
<!-- CL 459435 reverted by CL 467255 -->
|
|
<!-- CL 467515 reverted by CL 499416 -->
|
|
|
|
<dl id="math/big"><dt><a href="/pkg/math/big/">math/big</a></dt>
|
|
<dd>
|
|
<p><!-- https://go.dev/issue/56984, CL 453115, CL 500116 -->
|
|
The new <a href="/pkg/math/big/#Int.Float64"><code>Int.Float64</code></a>
|
|
method returns the nearest floating-point value to a
|
|
multi-precision integer, along with an indication of any
|
|
rounding that occurred.
|
|
</p>
|
|
</dd>
|
|
</dl><!-- math/big -->
|
|
|
|
<dl id="net"><dt><a href="/pkg/net/">net</a></dt>
|
|
<dd>
|
|
<p>
|
|
<!-- https://go.dev/issue/59166, https://go.dev/issue/56539 -->
|
|
<!-- CL 471136, CL 471137, CL 471140 -->
|
|
On Linux, the <a href="/pkg/net/">net</a> package can now use
|
|
Multipath TCP when the kernel supports it. It is not used by
|
|
default. To use Multipath TCP when available on a client, call
|
|
the
|
|
<a href="/pkg/net/#Dialer.SetMultipathTCP"><code>Dialer.SetMultipathTCP</code></a>
|
|
method before calling the
|
|
<a href="/pkg/net/#Dialer.Dial"><code>Dialer.Dial</code></a> or
|
|
<a href="/pkg/net/#Dialer.DialContext"><code>Dialer.DialContext</code></a>
|
|
methods. To use Multipath TCP when available on a server, call
|
|
the
|
|
<a href="/pkg/net/#ListenConfig.SetMultipathTCP"><code>ListenConfig.SetMultipathTCP</code></a>
|
|
method before calling the
|
|
<a href="/pkg/net/#ListenConfig.Listen"><code>ListenConfig.Listen</code></a>
|
|
method. Specify the network as <code>"tcp"</code> or
|
|
<code>"tcp4"</code> or <code>"tcp6"</code> as usual. If
|
|
Multipath TCP is not supported by the kernel or the remote host,
|
|
the connection will silently fall back to TCP. To test whether a
|
|
particular connection is using Multipath TCP, use the
|
|
<a href="/pkg/net/#TCPConn.MultipathTCP"><code>TCPConn.MultipathTCP</code></a>
|
|
method.
|
|
</p>
|
|
<p>
|
|
In a future Go release we may enable Multipath TCP by default on
|
|
systems that support it.
|
|
</p>
|
|
</dd>
|
|
</dl><!-- net -->
|
|
|
|
<dl id="net/http"><dt><a href="/pkg/net/http/">net/http</a></dt>
|
|
<dd>
|
|
<p><!-- CL 472636 -->
|
|
The new <a href="/pkg/net/http#ResponseController.EnableFullDuplex"><code>ResponseController.EnableFullDuplex</code></a>
|
|
method allows server handlers to concurrently read from an HTTP/1
|
|
request body while writing the response. Normally, the HTTP/1 server
|
|
automatically consumes any remaining request body before starting to
|
|
write the response, to avoid deadlocking clients which attempt to
|
|
write a complete request before reading the response. The
|
|
<code>EnableFullDuplex</code> method disables this behavior.
|
|
</p>
|
|
|
|
<p><!-- https://go.dev/issue/44855, CL 382117 -->
|
|
The new <a href="/pkg/net/http/#ErrSchemeMismatch"><code>ErrSchemeMismatch</code></a> error is returned by <a href="/pkg/net/http/#Client"><code>Client</code></a> and <a href="/pkg/net/http/#Transport"><code>Transport</code></a> when the server responds to an HTTPS request with an HTTP response.
|
|
</p>
|
|
|
|
<p><!-- CL 494122 -->
|
|
The <a href="/pkg/net/http/">net/http</a> package now supports
|
|
<a href="/pkg/errors/#ErrUnsupported"><code>errors.ErrUnsupported</code></a>,
|
|
in that the expression
|
|
<code>errors.Is(http.ErrNotSupported, errors.ErrUnsupported)</code>
|
|
will return true.
|
|
</p>
|
|
</dd>
|
|
</dl><!-- net/http -->
|
|
|
|
<dl id="os"><dt><a href="/pkg/os/">os</a></dt>
|
|
<dd>
|
|
<p><!-- https://go.dev/issue/32558, CL 219638 -->
|
|
Programs may now pass an empty <code>time.Time</code> value to
|
|
the <a href="/pkg/os/#Chtimes"><code>Chtimes</code></a> function
|
|
to leave either the access time or the modification time unchanged.
|
|
</p>
|
|
|
|
<p><!-- CL 480135 -->
|
|
On Windows the
|
|
<a href="/pkg/os#File.Chdir"><code>File.Chdir</code></a> method
|
|
now changes the current directory to the file, rather than
|
|
always returning an error.
|
|
</p>
|
|
|
|
<p><!-- CL 495079 -->
|
|
On Unix systems, if a non-blocking descriptor is passed
|
|
to <a href="/pkg/os/#NewFile"><code>NewFile</code></a>, calling
|
|
the <a href="/pkg/os/#File.Fd"><code>File.Fd</code></a> method
|
|
will now return a non-blocking descriptor. Previously the
|
|
descriptor was converted to blocking mode.
|
|
</p>
|
|
|
|
<p><!-- CL 477215 -->
|
|
On Windows calling
|
|
<a href="/pkg/os/#Truncate"><code>Truncate</code></a> on a
|
|
non-existent file used to create an empty file. It now returns
|
|
an error indicating that the file does not exist.
|
|
</p>
|
|
|
|
<p><!-- https://go.dev/issue/56899, CL 463219 -->
|
|
On Windows calling
|
|
<a href="/pkg/os/#TempDir"><code>TempDir</code></a> now uses
|
|
GetTempPath2W when available, instead of GetTempPathW. The
|
|
new behavior is a security hardening measure that prevents
|
|
temporary files created by processes running as SYSTEM to
|
|
be accessed by non-SYSTEM processes.
|
|
</p>
|
|
|
|
<p><!-- CL 493036 -->
|
|
On Windows the os package now supports working with files whose
|
|
names, stored as UTF-16, can't be represented as valid UTF-8.
|
|
</p>
|
|
|
|
<p><!-- https://go.dev/issue/54451, CL 491175 -->
|
|
The implementation of the
|
|
<a href="/pkg/io/fs/#DirEntry"><code>io/fs.DirEntry</code></a>
|
|
interface returned by the
|
|
<a href="/pkg/os/#ReadDir"><code>ReadDir</code></a> function and
|
|
the <a href="/pkg/os/#File.ReadDir"><code>File.ReadDir</code></a>
|
|
method now implements a <code>String</code> method that calls
|
|
<a href="/pkg/io/fs/#FormatDirEntry"><code>io/fs.FormatDirEntry</code></a>.
|
|
</p>
|
|
|
|
<p><!-- https://go.dev/issue/53761, CL 416775, CL 498015-->
|
|
The implementation of the
|
|
<a href="/pkg/io/fs/#FS"><code>io/fs.FS</code></a> interface returned by
|
|
the <a href="/pkg/os/#DirFS"><code>DirFS</code></a> function now implements
|
|
the <a href="/pkg/io/fs/#ReadFileFS"><code>io/fs.ReadFileFS</code></a> and
|
|
the <a href="/pkg/io/fs/#ReadDirFS"><code>io/fs.ReadDirFS</code></a>
|
|
interfaces.
|
|
</p>
|
|
</dd>
|
|
</dl><!-- os -->
|
|
|
|
<dl id="path/filepath"><dt><a href="/pkg/path/filepath/">path/filepath</a></dt>
|
|
<dd>
|
|
<p>
|
|
The implementation of the
|
|
<a href="/pkg/io/fs/#DirEntry"><code>io/fs.DirEntry</code></a>
|
|
interface passed to the function argument of
|
|
<a href="/pkg/path/filepath/#WalkDir"><code>WalkDir</code></a>
|
|
now implements a <code>String</code> method that calls
|
|
<a href="/pkg/io/fs/#FormatDirEntry"><code>io/fs.FormatDirEntry</code></a>.
|
|
</p>
|
|
</dd>
|
|
</dl><!-- path/filepath -->
|
|
|
|
<!-- CL 459455 reverted -->
|
|
|
|
<dl id="reflect"><dt><a href="/pkg/reflect/">reflect</a></dt>
|
|
<dd>
|
|
<p><!-- CL 408826, CL 413474 -->
|
|
In Go 1.21, <a href="/pkg/reflect/#ValueOf"><code>ValueOf</code></a>
|
|
no longer forces its argument to be allocated on the heap, allowing
|
|
a <code>Value</code>'s content to be allocated on the stack. Most
|
|
operations on a <code>Value</code> also allow the underlying value
|
|
to be stack allocated.
|
|
</p>
|
|
|
|
<p><!-- https://go.dev/issue/55002 -->
|
|
The new <a href="/pkg/reflect/#Value"><code>Value</code></a>
|
|
method <a href="/pkg/reflect/#Value.Clear"><code>Value.Clear</code></a>
|
|
clears the contents of a map or zeros the contents of a slice.
|
|
This corresponds to the new <code>clear</code> built-in
|
|
<a href="#language">added to the language</a>.
|
|
</p>
|
|
|
|
<p><!-- https://go.dev/issue/56906, CL 452762 -->
|
|
The <a href="/pkg/reflect/#SliceHeader"><code>SliceHeader</code></a>
|
|
and <a href="/pkg/reflect/#StringHeader"><code>StringHeader</code></a>
|
|
types are now deprecated. In new code
|
|
prefer <a href="/pkg/unsafe/#Slice"><code>unsafe.Slice</code></a>,
|
|
<a href="/pkg/unsafe/#SliceData"><code>unsafe.SliceData</code></a>,
|
|
<a href="/pkg/unsafe/#String"><code>unsafe.String</code></a>,
|
|
or <a href="/pkg/unsafe/#StringData"><code>unsafe.StringData</code></a>.
|
|
</p>
|
|
</dd>
|
|
</dl><!-- reflect -->
|
|
|
|
<dl id="regexp"><dt><a href="/pkg/regexp/">regexp</a></dt>
|
|
<dd>
|
|
<p><!-- https://go.dev/issue/46159, CL 479401 -->
|
|
<a href="/pkg/regexp#Regexp"><code>Regexp</code></a> now defines
|
|
<a href="/pkg/regexp#Regexp.MarshalText"><code>MarshalText</code></a>
|
|
and <a href="/pkg/regexp#Regexp.UnmarshalText"><code>UnmarshalText</code></a>
|
|
methods. These implement
|
|
<a href="/pkg/encoding#TextMarshaler"><code>encoding.TextMarshaler</code></a>
|
|
and
|
|
<a href="/pkg/encoding#TextUnmarshaler"><code>encoding.TextUnmarshaler</code></a>
|
|
and will be used by packages such as
|
|
<a href="/pkg/encoding/json">encoding/json</a>.
|
|
</p>
|
|
</dd>
|
|
</dl><!-- regexp -->
|
|
|
|
<dl id="runtime"><dt><a href="/pkg/runtime/">runtime</a></dt>
|
|
<dd>
|
|
<p><!-- https://go.dev/issue/38651, CL 435337 -->
|
|
Textual stack traces produced by Go programs, such as those
|
|
produced when crashing, calling <code>runtime.Stack</code>, or
|
|
collecting a goroutine profile with <code>debug=2</code>, now
|
|
include the IDs of the goroutines that created each goroutine in
|
|
the stack trace.
|
|
</p>
|
|
|
|
<p><!-- https://go.dev/issue/57441, CL 474915 -->
|
|
Crashing Go applications can now opt-in to Windows Error Reporting (WER) by setting the environment variable
|
|
<code>GOTRACEBACK=wer</code> or calling <a href="/pkg/runtime/debug/#SetTraceback"><code>debug.SetTraceback("wer")</code></a>
|
|
before the crash. Other than enabling WER, the runtime will behave as with <code>GOTRACEBACK=crash</code>.
|
|
On non-Windows systems, <code>GOTRACEBACK=wer</code> is ignored.
|
|
</p>
|
|
|
|
<p><!-- CL 447778 -->
|
|
<code>GODEBUG=cgocheck=2</code>, a thorough checker of cgo pointer passing rules,
|
|
is no longer available as a <a href="/pkg/runtime#hdr-Environment_Variables">debug option</a>.
|
|
Instead, it is available as an experiment using <code>GOEXPERIMENT=cgocheck2</code>.
|
|
In particular this means that this mode has to be selected at build time instead of startup time.
|
|
<p>
|
|
<code>GODEBUG=cgocheck=1</code> is still available (and is still the default).
|
|
</p>
|
|
|
|
<p><!-- https://go.dev/issue/46787, CL 367296 -->
|
|
A new type <code>Pinner</code> has been added to the runtime
|
|
package. <code>Pinner</code>s may be used to "pin" Go memory
|
|
such that it may be used more freely by non-Go code. For instance,
|
|
passing Go values that reference pinned Go memory to C code is
|
|
now allowed. Previously, passing any such nested reference was
|
|
disallowed by the
|
|
<a href="https://pkg.go.dev/cmd/cgo#hdr-Passing_pointers">cgo pointer passing rules.</a>
|
|
|
|
See <a href="/pkg/runtime#Pinner">the docs</a> for more details.
|
|
</p>
|
|
|
|
<!-- CL 472195 no release note needed -->
|
|
</dd>
|
|
</dl><!-- runtime -->
|
|
|
|
<dl id="runtime/metrics"><dt><a href="/pkg/runtime/metrics/">runtime/metrics</a></dt>
|
|
<dd>
|
|
<p><!-- https://go.dev/issue/56857, CL 497315 -->
|
|
A few previously-internal GC metrics, such as live heap size, are
|
|
now available.
|
|
|
|
<code>GOGC</code> and <code>GOMEMLIMIT</code> are also now
|
|
available as metrics.
|
|
</p>
|
|
</dd>
|
|
</dl><!-- runtime/metrics -->
|
|
|
|
<dl id="runtime/trace"><dt><a href="/pkg/runtime/trace/">runtime/trace</a></dt>
|
|
<dd>
|
|
<p><!-- https://go.dev/issue/16638 -->
|
|
Collecting traces on amd64 and arm64 now incurs a substantially
|
|
smaller CPU cost: up to a 10x improvement over the previous release.
|
|
</p>
|
|
|
|
<p><!-- CL 494495 -->
|
|
Traces now contain explicit stop-the-world events for every reason
|
|
the Go runtime might stop-the-world, not just garbage collection.
|
|
</p>
|
|
</dd>
|
|
</dl><!-- runtime/trace -->
|
|
|
|
<dl id="sync"><dt><a href="/pkg/sync/">sync</a></dt>
|
|
<dd>
|
|
<p><!-- https://go.dev/issue/56102, CL 451356 -->
|
|
The new <a href="/pkg/sync/#OnceFunc"><code>OnceFunc</code></a>,
|
|
<a href="/pkg/sync/#OnceValue"><code>OnceValue</code></a>, and
|
|
<a href="/pkg/sync/#OnceValues"><code>OnceValues</code></a>
|
|
functions capture a common use of <a href="/pkg/sync/#Once">Once</a> to
|
|
lazily initialize a value on first use.
|
|
</p>
|
|
</dd>
|
|
</dl>
|
|
|
|
<dl id="syscall"><dt><a href="/pkg/syscall/">syscall</a></dt>
|
|
<dd>
|
|
<p><!-- CL 480135 -->
|
|
On Windows the
|
|
<a href="/pkg/syscall#Fchdir"><code>Fchdir</code></a> function
|
|
now changes the current directory to its argument, rather than
|
|
always returning an error.
|
|
</p>
|
|
|
|
<p><!-- https://go.dev/issue/46259, CL 458335 -->
|
|
On FreeBSD
|
|
<a href="/pkg/syscall#SysProcAttr"><code>SysProcAttr</code></a>
|
|
has a new field <code>Jail</code> that may be used to put the
|
|
newly created process in a jailed environment.
|
|
</p>
|
|
|
|
<p><!-- CL 493036 -->
|
|
On Windows the syscall package now supports working with files whose
|
|
names, stored as UTF-16, can't be represented as valid UTF-8.
|
|
The <a href="/pkg/syscall#UTF16ToString"><code>UTF16ToString</code></a>
|
|
and <a href="/pkg/syscall#UTF16FromString"><code>UTF16FromString</code></a>
|
|
functions now convert between UTF-16 data and
|
|
<a href="https://simonsapin.github.io/wtf-8/">WTF-8</a> strings.
|
|
This is backward compatible as WTF-8 is a superset of the UTF-8
|
|
format that was used in earlier releases.
|
|
</p>
|
|
|
|
<p><!-- CL 476578, CL 476875, CL 476916 -->
|
|
Several error values match the new
|
|
<a href="/pkg/errors/#ErrUnsupported"><code>errors.ErrUnsupported</code></a>,
|
|
such that <code>errors.Is(err, errors.ErrUnsupported)</code>
|
|
returns true.
|
|
<ul>
|
|
<li><code>ENOSYS</code></li>
|
|
<li><code>ENOTSUP</code></li>
|
|
<li><code>EOPNOTSUPP</code></li>
|
|
<li><code>EPLAN9</code> (Plan 9 only)</li>
|
|
<li><code>ERROR_CALL_NOT_IMPLEMENTED</code> (Windows only)</li>
|
|
<li><code>ERROR_NOT_SUPPORTED</code> (Windows only)</li>
|
|
<li><code>EWINDOWS</code> (Windows only)</li>
|
|
</ul>
|
|
</p>
|
|
</dd>
|
|
</dl><!-- syscall -->
|
|
|
|
<dl id="testing"><dt><a href="/pkg/testing/">testing</a></dt>
|
|
<dd>
|
|
<p><!-- https://go.dev/issue/37708, CL 463837 -->
|
|
The new <code>-test.fullpath</code> option will print full path
|
|
names in test log messages, rather than just base names.
|
|
</p>
|
|
|
|
<p><!-- https://go.dev/issue/52600, CL 475496 -->
|
|
The new <a href="/pkg/testing/#Testing"><code>Testing</code></a> function reports whether the program is a test created by <code>go</code> <code>test</code>.
|
|
</p>
|
|
</dd>
|
|
</dl><!-- testing -->
|
|
|
|
<dl id="testing/fstest"><dt><a href="/pkg/testing/fstest/">testing/fstest</a></dt>
|
|
<dd>
|
|
<p><!-- https://go.dev/issue/54451, CL 491175 -->
|
|
Calling <code><a href="/pkg/testing/fstest/MapFS.Open">Open</a>.<a href="/pkg/io/fs/#File.Stat">Stat</a></code>
|
|
will return a type that now implements a <code>String</code>
|
|
method that calls
|
|
<a href="/pkg/io/fs/#FormatFileInfo"><code>io/fs.FormatFileInfo</code></a>.
|
|
</p>
|
|
</dd>
|
|
</dl><!-- testing/fstest -->
|
|
|
|
<dl id="unicode"><dt><a href="/pkg/unicode/">unicode</a></dt>
|
|
<dd>
|
|
<p><!-- CL 456837 -->
|
|
The <a href="/pkg/unicode/"><code>unicode</code></a> package and
|
|
associated support throughout the system has been upgraded to
|
|
<a href="https://www.unicode.org/versions/Unicode15.0.0/">Unicode 15.0.0</a>.
|
|
</p>
|
|
</dl><!-- unicode -->
|
|
|
|
<h2 id="ports">Ports</h2>
|
|
|
|
<h3 id="darwin">Darwin</h3>
|
|
|
|
<p><!-- https://go.dev/issue/57125 -->
|
|
As <a href="go1.20#darwin">announced</a> in the Go 1.20 release notes,
|
|
Go 1.21 requires macOS 10.15 Catalina or later;
|
|
support for previous versions has been discontinued.
|
|
</p>
|
|
|
|
<h3 id="windows">Windows</h3>
|
|
|
|
<p><!-- https://go.dev/issue/57003, https://go.dev/issue/57004 -->
|
|
As <a href="go1.20#windows">announced</a> in the Go 1.20 release notes,
|
|
Go 1.21 requires at least Windows 10 or Windows Server 2016;
|
|
support for previous versions has been discontinued.
|
|
</p>
|
|
|
|
<!-- CL 470695 -->
|
|
<p>
|
|
<!-- cmd/dist: default to GOARM=7 on all non-arm systems -->
|
|
</p>
|
|
|
|
<h3 id="wasm">WebAssembly</h3>
|
|
|
|
<p><!-- https://go.dev/issue/38248, https://go.dev/issue/59149, CL 489255 -->
|
|
The new <code>go:wasmimport</code> directive can now be used in Go programs
|
|
to import functions from the WebAssembly host.
|
|
</p>
|
|
|
|
<!-- https://go.dev/issue/56100 -->
|
|
<p>
|
|
The Go scheduler now interacts much more efficiently with the
|
|
JavaScript event loop, especially in applications that block
|
|
frequently on asynchronous events.
|
|
</p>
|
|
|
|
|
|
<h3 id="wasip1">WebAssembly System Interface</h3>
|
|
|
|
<p><!-- https://go.dev/issue/58141 -->
|
|
Go 1.21 adds an experimental port to the <a href="https://wasi.dev/">
|
|
WebAssembly System Interface (WASI)</a>, Preview 1
|
|
(<code>GOOS=wasip1</code>, <code>GOARCH=wasm</code>).
|
|
</p>
|
|
|
|
<p>
|
|
As a result of the addition of the new <code>GOOS</code> value
|
|
"<code>wasip1</code>", Go files named <code>*_wasip1.go</code>
|
|
will now be <a href="/pkg/go/build/#hdr-Build_Constraints">ignored
|
|
by Go tools</a> except when that <code>GOOS</code> value is being
|
|
used.
|
|
If you have existing filenames matching that pattern, you will
|
|
need to rename them.
|
|
</p>
|
|
|
|
|
|
<!-- proposals for x repos that don't need to be mentioned here but
|
|
are picked up by the relnote tool. -->
|
|
<!-- https://go.dev/issue/54232 -->
|
|
<!-- https://go.dev/issue/57906 -->
|
|
<!-- https://go.dev/issue/58668 -->
|
|
<!-- https://go.dev/issue/59676 -->
|
|
|
|
<!-- changes to cmd/api that don't need release notes. -->
|
|
<!-- CL 469115, CL 469135, CL 499981 -->
|
|
|
|
<!-- proposals that don't need release enotes. -->
|
|
<!-- https://go.dev/issue/10275 -->
|
|
<!-- https://go.dev/issue/59719 -->
|