go1.23/go1.23.changes

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Tue Aug 13 16:16:34 UTC 2024 - Jeff Kowalczyk <jkowalczyk@suse.com>

- go1.23 (released 2024-08-13) is a major release of Go.
  go1.23.x minor releases will be provided through August 2025.
  https://github.com/golang/go/wiki/Go-Release-Cycle
  go1.23 arrives six months after go1.22. Most of its changes are
  in the implementation of the toolchain, runtime, and libraries.
  As always, the release maintains the Go 1 promise of
  compatibility. We expect almost all Go programs to continue to
  compile and run as before.
  Refs boo#1229122 go1.23 release tracking
  * Language change: Go 1.23 makes the (Go 1.22) "range-over-func"
    experiment a part of the language. The "range" clause in a
    "for-range" loop now accepts iterator functions of the
    following types:
    func(func() bool)
    func(func(K) bool)
    func(func(K, V) bool)
    as range expressions. Calls of the iterator argument function
    produce the iteration values for the "for-range" loop. For
    details see the iter package documentation and the language
    spec. For motivation see the 2022 "range-over-func" discussion.
  * Language change: Go 1.23 includes preview support for generic
    type aliases. Building the toolchain with
    GOEXPERIMENT=aliastypeparams enables this feature within a
    package. (Using generic alias types across package boundaries
    is not yet supported.)
  * Opt-in Telemetry: Starting in Go 1.23, the Go toolchain can
    collect usage and breakage statistics that help the Go team
    understand how the Go toolchain is used and how well it is
    working. We refer to these statistics as Go telemetry.
    Go telemetry is an opt-in system, controlled by the go
    telemetry command. By default, the toolchain programs collect
    statistics in counter files that can be inspected locally but
    are otherwise unused (go telemetry local).
    To help us keep Go working well and understand Go usage, please
    consider opting in to Go telemetry by running go telemetry
    on. In that mode, anonymous counter reports are uploaded to
    telemetry.go.dev weekly, where they are aggregated into graphs
    and also made available for download by any Go contributors or
    users wanting to analyze the data. See "Go Telemetry" for more
    details about the Go Telemetry system.
  * go command: Setting the GOROOT_FINAL environment variable no
    longer has an effect (#62047). Distributions that install the
    go command to a location other than $GOROOT/bin/go should
    install a symlink instead of relocating or copying the go
    binary.
  * go command: The new go env -changed flag causes the command to
    print only those settings whose effective value differs from
    the default value that would be obtained in an empty
    environment with no prior uses of the -w flag.
  * go command: The new go mod tidy -diff flag causes the command
    not to modify the files but instead print the necessary changes
    as a unified diff. It exits with a non-zero code if updates are
    needed.
  * go command: The go list -m -json command now includes new Sum
    and GoModSum fields. This is similar to the existing behavior
    of the go mod download -json command.
  * go command: The new godebug directive in go.mod and go.work
    declares a GODEBUG setting to apply for the work module or
    workspace in use.
  * go vet: The go vet subcommand now includes the stdversion
    analyzer, which flags references to symbols that are too new
    for the version of Go in effect in the referring file. (The
    effective version is determined by the go directive in the
    file's enclosing go.mod file, and by any //go:build constraints
    in the file.)
    For example, it will report a diagnostic for a reference to the
    reflect.TypeFor function (introduced in go1.22) from a file in
    a module whose go.mod file specifies go 1.21.
  * cgo: cmd/cgo supports the new -ldflags flag for passing flags
    to the C linker. The go command uses it automatically, avoiding
    "argument list too long" errors with a very large CGO_LDFLAGS.
  * go trace: The trace tool now better tolerates partially broken
    traces by attempting to recover what trace data it can. This
    functionality is particularly helpful when viewing a trace that
    was collected during a program crash, since the trace data
    leading up to the crash will now be recoverable under most
    circumstances.
  * Runtime: The traceback printed by the runtime after an
    unhandled panic or other fatal error now indents the second and
    subsequent lines of the error message (for example, the
    argument to panic) by a single tab, so that it can be
    unambiguously distinguished from the stack trace of the first
    goroutine. See go#64590 for discussion.
  * Compiler: The build time overhead to building with Profile
    Guided Optimization has been reduced significantly. Previously,
    large builds could see 100%+ build time increase from enabling
    PGO. In Go 1.23, overhead should be in the single digit
    percentages.
  * Compiler: The compiler in Go 1.23 can now overlap the stack
    frame slots of local variables accessed in disjoint regions of
    a function, which reduces stack usage for Go applications.
  * Compiler: For 386 and amd64, the compiler will use information
    from PGO to align certain hot blocks in loops. This improves
    performance an additional 1-1.5% at a cost of an additional
    0.1% text and binary size. This is currently only implemented
    on 386 and amd64 because it has not shown an improvement on
    other platforms. Hot block alignment can be disabled with
    -gcflags=[<packages>=]-d=alignhot=0.
  * Linker: The linker now disallows using a //go:linkname
    directive to refer to internal symbols in the standard library
    (including the runtime) that are not marked with //go:linkname
    on their definitions. Similarly, the linker disallows
    references to such symbols from assembly code. For backward
    compatibility, existing usages of //go:linkname found in a
    large open-source code corpus remain supported. Any new
    references to standard library internal symbols will be
    disallowed.
  * Linker: A linker command line flag -checklinkname=0 can be used
    to disable this check, for debugging and experimenting
    purposes.
  * Linker: When building a dynamically linked ELF binary
    (including PIE binary), the new -bindnow flag enables immediate
    function binding.
  * Standard library changes:
  * timer: 1.23 makes two significant changes to the implementation
    of time.Timer and time.Ticker.
    First, Timers and Tickers that are no longer referred to by the
    program become eligible for garbage collection immediately,
    even if their Stop methods have not been called. Earlier
    versions of Go did not collect unstopped Timers until after
    they had fired and never collected unstopped Tickers.
    Second, the timer channel associated with a Timer or Ticker is
    now unbuffered, with capacity 0. The main effect of this change
    is that Go now guarantees that for any call to a Reset or Stop
    method, no stale values prepared before that call will be sent
    or received after the call. Earlier versions of Go used
    channels with a one-element buffer, making it difficult to use
    Reset and Stop correctly. A visible effect of this change is
    that len and cap of timer channels now returns 0 instead of 1,
    which may affect programs that poll the length to decide
    whether a receive on the timer channel will succeed. Such code
    should use a non-blocking receive instead.
    These new behaviors are only enabled when the main Go program
    is in a module with a go.mod go line using Go 1.23.0 or
    later. When Go 1.23 builds older programs, the old behaviors
    remain in effect. The new GODEBUG setting asynctimerchan=1 can
    be used to revert back to asynchronous channel behaviors even
    when a program names Go 1.23.0 or later in its go.mod file.
  * unique: The new unique package provides facilities for
    canonicalizing values (like "interning" or "hash-consing").
    Any value of comparable type may be canonicalized with the new
    Make[T] function, which produces a reference to a canonical
    copy of the value in the form of a Handle[T]. Two Handle[T] are
    equal if and only if the values used to produce the handles are
    equal, allowing programs to deduplicate values and reduce their
    memory footprint. Comparing two Handle[T] values is efficient,
    reducing down to a simple pointer comparison.
  * iter: The new iter package provides the basic definitions for
    working with user-defined iterators.
  * slices: The slices package adds several functions that work
    with iterators:
    - All returns an iterator over slice indexes and values.
    - Values returns an iterator over slice elements.
    - Backward returns an iterator that loops over a slice backward.
    - Collect collects values from an iterator into a new slice.
    - AppendSeq appends values from an iterator to an existing slice.
    - Sorted collects values from an iterator into a new slice, and then sorts the slice.
    - SortedFunc is like Sorted but with a comparison function.
    - SortedStableFunc is like SortFunc but uses a stable sort algorithm.
    - Chunk returns an iterator over consecutive sub-slices of up to n elements of a slice.
  * maps: The maps package adds several functions that work with
    iterators:
    - All returns an iterator over key-value pairs from a map.
    - Keys returns an iterator over keys in a map.
    - Values returns an iterator over values in a map.
    - Insert adds the key-value pairs from an iterator to an existing map.
    - Collect collects key-value pairs from an iterator into a new map and returns it.
  * structs: The new structs package provides types for struct
    fields that modify properties of the containing struct type
    such as memory layout.
    In this release, the only such type is HostLayout which
    indicates that a structure with a field of that type has a
    layout that conforms to host platform expectations.
  * Minor changes to the standard library: As always, there are
    various minor changes and updates to the library, made with the
    Go 1 promise of compatibility in mind.
  * archive/tar: If the argument to FileInfoHeader implements the
    new FileInfoNames interface, then the interface methods will be
    used to set the Uname/Gname of the file header. This allows
    applications to override the system-dependent Uname/Gname
    lookup.
  * crypto/tls: The TLS client now supports the Encrypted Client
    Hello draft specification. This feature can be enabled by
    setting the Config.EncryptedClientHelloConfigList field to an
    encoded ECHConfigList for the host that is being connected to.
  * crypto/tls: The QUICConn type used by QUIC implementations
    includes new events reporting on the state of session
    resumption, and provides a way for the QUIC layer to add data
    to session tickets and session cache entries.
  * crypto/tls: 3DES cipher suites were removed from the default
    list used when Config.CipherSuites is nil. The default can be
    reverted by adding tls3des=1 to the GODEBUG environment
    variable.
  * crypto/tls: The experimental post-quantum key exchange
    mechanism X25519Kyber768Draft00 is now enabled by default when
    Config.CurvePreferences is nil. The default can be reverted by
    adding tlskyber=0 to the GODEBUG environment variable.
  * crypto/tls: Go 1.23 changed the behavior of X509KeyPair and
    LoadX509KeyPair to populate the Certificate.Leaf field of the
    returned Certificate. The new x509keypairleaf GODEBUG setting
    is added for this behavior.
  * crypto/x509: CreateCertificateRequest now correctly supports
    RSA-PSS signature algorithms.
  * crypto/x509: CreateCertificateRequest and CreateRevocationList
    now verify the generated signature using the signer's public
    key. If the signature is invalid, an error is returned. This
    has been the behavior of CreateCertificate since Go 1.16.
  * crypto/x509: The x509sha1 GODEBUG setting will be removed in
    the next Go major release (Go 1.24). This will mean that
    crypto/x509 will no longer support verifying signatures on
    certificates that use SHA-1 based signature algorithms.
  * crypto/x509: The new ParseOID function parses a dot-encoded
    ASN.1 Object Identifier string. The OID type now implements the
    encoding.BinaryMarshaler, encoding.BinaryUnmarshaler,
    encoding.TextMarshaler, encoding.TextUnmarshaler interfaces.
    database/sql
  * crypto/x509: Errors returned by driver.Valuer implementations
    are now wrapped for improved error handling during operations
    like DB.Query, DB.Exec, and DB.QueryRow.
  * debug/elf: The debug/elf package now defines
    PT_OPENBSD_NOBTCFI. This ProgType is used to disable Branch
    Tracking Control Flow Integrity (BTCFI) enforcement on OpenBSD
    binaries.
  * debug/elf: Now defines the symbol type constants STT_RELC,
    STT_SRELC, and STT_GNU_IFUNC.
  * encoding/binary The new Encode and Decode functions are byte
    slice equivalents to Read and Write. Append allows marshaling
    multiple data into the same byte slice.
  * go/ast: The new Preorder function returns a convenient iterator
    over all the nodes of a syntax tree.
  * go/types: The Func type, which represents a function or method
    symbol, now has a Func.Signature method that returns the
    function's type, which is always a Signature.
  * go/types: The Alias type now has an Rhs method that returns the
    type on the right-hand side of its declaration: given type A =
    B, the Rhs of A is B. (go#66559)
  * go/types: The methods Alias.Origin, Alias.SetTypeParams,
    Alias.TypeParams, and Alias.TypeArgs have been added. They are
    needed for generic alias types.
  * go/types: By default, go/types now produces Alias type nodes
    for type aliases. This behavior can be controlled by the
    GODEBUG gotypesalias flag. Its default has changed from 0 in Go
    1.22 to 1 in Go 1.23.
  * math/rand/v2: The Uint function and Rand.Uint method have been
    added. They were inadvertently left out of Go 1.22.
  * math/rand/v2: The new ChaCha8.Read method implements the
    io.Reader interface.
  * net: The new type KeepAliveConfig permits fine-tuning the
    keep-alive options for TCP connections, via a new
    TCPConn.SetKeepAliveConfig method and new KeepAliveConfig
    fields for Dialer and ListenConfig.
  * net: The DNSError type now wraps errors caused by timeouts or
    cancellation. For example, errors.Is(someDNSErr,
    context.DeadlineExceedeed) will now report whether a DNS error
    was caused by a timeout.
  * net: The new GODEBUG setting netedns0=0 disables sending EDNS0
    additional headers on DNS requests, as they reportedly break
    the DNS server on some modems.
  * net/http: Cookie now preserves double quotes surrounding a
    cookie value. The new Cookie.Quoted field indicates whether the
    Cookie.Value was originally quoted.
  * net/http: The new Request.CookiesNamed method retrieves all
    cookies that match the given name.
  * net/http: The new Cookie.Partitioned field identifies cookies
    with the Partitioned attribute.
  * net/http: The patterns used by ServeMux now allow one or more
    spaces or tabs after the method name. Previously, only a single
    space was permitted.
  * net/http: The new ParseCookie function parses a Cookie header
    value and returns all the cookies which were set in it. Since
    the same cookie name can appear multiple times the returned
    Values can contain more than one value for a given key.
  * net/http: The new ParseSetCookie function parses a Set-Cookie
    header value and returns a cookie. It returns an error on
    syntax error.
  * net/http: ServeContent, ServeFile, and ServeFileFS now remove
    the Cache-Control, Content-Encoding, Etag, and Last-Modified
    headers when serving an error. These headers usually apply to
    the non-error content, but not to the text of errors.
  * net/http: Middleware which wraps a ResponseWriter and applies
    on-the-fly encoding, such as Content-Encoding: gzip, will not
    function after this change. The previous behavior of
    ServeContent, ServeFile, and ServeFileFS may be restored by
    setting GODEBUG=httpservecontentkeepheaders=1.
    Note that middleware which changes the size of the served
    content (such as by compressing it) already does not function
    properly when ServeContent handles a Range request. On-the-fly
    compression should use the Transfer-Encoding header instead of
    Content-Encoding.
  * net/http: For inbound requests, the new Request.Pattern field
    contains the ServeMux pattern (if any) that matched the
    request. This field is not set when GODEBUG=httpmuxgo121=1 is
    set.
  * net/http/httptest: The new NewRequestWithContext method creates
    an incoming request with a context.Context.
  * net/netip: In Go 1.22 and earlier, using reflect.DeepEqual to
    compare an Addr holding an IPv4 address to one holding the
    IPv4-mapped IPv6 form of that address incorrectly returned
    true, even though the Addr values were different when comparing
    with == or Addr.Compare. This bug is now fixed and all three
    approaches now report the same result.
  * os: The Stat function now sets the ModeSocket bit for files
    that are Unix sockets on Windows. These files are identified by
    having a reparse tag set to IO_REPARSE_TAG_AF_UNIX.
  * os: On Windows, the mode bits reported by Lstat and Stat for
    reparse points changed. Mount points no longer have ModeSymlink
    set, and reparse points that are not symlinks, Unix sockets, or
    dedup files now always have ModeIrregular set. This behavior is
    controlled by the winsymlink setting. For Go 1.23, it defaults
    to winsymlink=1. Previous versions default to winsymlink=0.
  * os: The CopyFS function copies an io/fs.FS into the local
    filesystem.
  * os: On Windows, Readlink no longer tries to normalize volumes
    to drive letters, which was not always even possible. This
    behavior is controlled by the winreadlinkvolume setting. For Go
    1.23, it defaults to winreadlinkvolume=1. Previous versions
    default to winreadlinkvolume=0.
  * os: On Linux with pidfd support (generally Linux v5.4+),
    Process-related functions and methods use pidfd (rather than
    PID) internally, eliminating potential mistargeting when a PID
    is reused by the OS. Pidfd support is fully transparent to a
    user, except for additional process file descriptors that a
    process may have.
  * path/filepath: The new Localize function safely converts a
    slash-separated path into an operating system path.
  * path/filepath: On Windows, EvalSymlinks no longer evaluates
    mount points, which was a source of many inconsistencies and
    bugs. This behavior is controlled by the winsymlink
    setting. For Go 1.23, it defaults to winsymlink=1. Previous
    versions default to winsymlink=0.
  * path/filepath: On Windows, EvalSymlinks no longer tries to
    normalize volumes to drive letters, which was not always even
    possible. This behavior is controlled by the winreadlinkvolume
    setting. For Go 1.23, it defaults to
    winreadlinkvolume=1. Previous versions default to
    winreadlinkvolume=0.
  * reflect: The new methods synonymous with the methods of the
    same name in Value are added to Type:
    - Type.OverflowComplex
    - Type.OverflowFloat
    - Type.OverflowInt
    - Type.OverflowUint
  * reflect: The new SliceAt function is analogous to NewAt, but
    for slices.
  * reflect: The Value.Pointer and Value.UnsafePointer methods now
    support values of kind String.
  * reflect: The new methods Value.Seq and Value.Seq2 return
    sequences that iterate over the value as though it were used in
    a for/range loop. The new methods Type.CanSeq and Type.CanSeq2
    report whether calling Value.Seq and Value.Seq2, respectively,
    will succeed without panicking.
  * runtime/debug: The SetCrashOutput function allows the user to
    specify an alternate file to which the runtime should write its
    fatal crash report. It may be used to construct an automated
    reporting mechanism for all unexpected crashes, not just those
    in goroutines that explicitly use recover.
  * runtime/pprof: The maximum stack depth for alloc, mutex, block,
    threadcreate and goroutine profiles has been raised from 32 to
    128 frames.
  * runtime/trace: The runtime now explicitly flushes trace data
    when a program crashes due to an uncaught panic. This means
    that more complete trace data will be available in a trace if
    the program crashes while tracing is active.
  * slices: The Repeat function returns a new slice that repeats
    the provided slice the given number of times.
  * sync: The Map.Clear method deletes all the entries, resulting
    in an empty Map. It is analogous to clear.
  * sync/atomic: The new And and Or operators apply a bitwise AND
    or OR to the given input, returning the old value.
  * syscall: The syscall package now defines WSAENOPROTOOPT on
    Windows.
  * syscall: The GetsockoptInt function is now supported on
    Windows.
  * testing/fstest: TestFS now returns a structured error that can
    be unwrapped (via method Unwrap() []error). This allows
    inspecting errors using errors.Is or errors.As.
  * text/template: Templates now support the new "else with"
    action, which reduces template complexity in some use cases.
  * time: Parse and ParseInLocation now return an error if the time
    zone offset is out of range.
  * unicode/utf16: The RuneLen function returns the number of
    16-bit words in the UTF-16 encoding of the rune. It returns -1
    if the rune is not a valid value to encode in UTF-16.
  * Port: Darwin: As announced in the Go 1.22 release notes, Go
    1.23 requires macOS 11 Big Sur or later; support for previous
    versions has been discontinued.
  * Port: Linux: Go 1.23 is the last release that requires Linux
    kernel version 2.6.32 or later. Go 1.24 will require Linux
    kernel version 3.17 or later, with an exception that systems
    running 3.10 or later will continue to be supported if the
    kernel has been patched to support the getrandom system call.
  * Port: OpenBSD: Go 1.23 adds experimental support for OpenBSD on
    64-bit RISC-V (GOOS=openbsd, GOARCH=riscv64).
  * Port: ARM64: Go 1.23 introduces a new GOARM64 environment
    variable, which specifies the minimum target version of the
    ARM64 architecture at compile time. Allowed values are v8.{0-9}
    and v9.{0-5}. This may be followed by an option specifying
    extensions implemented by target hardware. Valid options are
    ,lse and ,crypto.
    The GOARM64 environment variable defaults to v8.0.
  * Port: RISC-V: Go 1.23 introduces a new GORISCV64 environment
    variable, which selects the RISC-V user-mode application
    profile for which to compile. Allowed values are rva20u64 and
    rva22u64.
    The GORISCV64 environment variable defaults to rva20u64.
  * Port: Wasm: The go_wasip1_wasm_exec script in GOROOT/misc/wasm
    has dropped support for versions of wasmtime < 14.0.0.

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Tue Jul 16 15:33:13 UTC 2024 - Jeff Kowalczyk <jkowalczyk@suse.com>

- go1.23rc2 (released 2024-07-16) is a release candidate version of
  go1.23 cut from the master branch at the revision tagged
  go1.23rc2.

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Fri Jun 21 16:32:19 UTC 2024 - Jeff Kowalczyk <jkowalczyk@suse.com>

- go1.23rc1 (released 2024-06-21) is a release candidate version of
  go1.23 cut from the master branch at the revision tagged
  go1.23rc1.
  * go1.23 now requires the final point release of go1.20 or later
    for bootstrap. Go upstream expects that go1.24 will require the
    final point release of Go 1.23 or later for bootstrap.