File go1.26.changes of Package go1.26.42657
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Tue Feb 10 19:27:55 UTC 2026 - Jeff Kowalczyk <jkowalczyk@suse.com>
- go1.26.0 (released 2026-02-10) is a major release of Go.
go1.26.x minor releases will be provided through February 2027.
https://github.com/golang/go/wiki/Go-Release-Cycle
go1.26 arrives six months after Go 1.25. 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#1255111 go1.26 release tracking
* Language change: The built-in new function, which creates a new
variable, now allows its operand to be an expression,
specifying the initial value of the variable.
* Language change: The restriction that a generic type may not
refer to itself in its type parameter list has been lifted. It
is now possible to specify type constraints that refer to the
generic type being constrained.
* go command: The venerable go fix command has been completely
revamped and is now the home of Go’s modernizers. It provides a
dependable, push-button way to update Go code bases to the
latest idioms and core library APIs. The initial suite of
modernizers includes dozens of fixers to make use of modern
features of the Go language and library, as well a source-level
inliner that allows users to automate their own API migrations
using //go:fix inline directives. These fixers should not
change the behavior of your program, so if you encounter any
issues with a fix performed by go fix, please report it.
* go command: The rewritten go fix command builds atop the exact
same Go analysis framework as go vet. This means the same
analyzers that provide diagnostics in go vet can be used to
suggest and apply fixes in go fix. The go fix command’s
historical fixers, all of which were obsolete, have been
removed.
* go command: Two upcoming Go blog posts will go into more detail
on modernizers, the inliner, and how to get the most out of go
fix.
* go command: go mod init now defaults to a lower go version in
new go.mod files. Running go mod init using a toolchain of
version 1.N.X will create a go.mod file specifying the Go
version go 1.(N-1).0. Pre-release versions of 1.N will create
go.mod files specifying go 1.(N-2).0. For example, the Go 1.26
release candidates will create go.mod files with go 1.24.0, and
Go 1.26 and its minor releases will create go.mod files with go
1.25.0. This is intended to encourage the creation of modules
that are compatible with currently supported versions of
Go. For additional control over the go version in new modules,
go mod init can be followed up with go get go@version.
* go command: cmd/doc, and go tool doc have been deleted. go doc
can be used as a replacement for go tool doc: it takes the same
flags and arguments and has the same behavior.
* pprof: The pprof tool web UI, enabled with the -http flag, now
defaults to the flame graph view. The previous graph view is
available in the “View -> Graph” menu, or via /ui/graph.
* Runtime: The new Green Tea garbage collector, previously
available as an experiment in Go 1.25, is now enabled by
default after incorporating feedback. This garbage collector’s
design improves the performance of marking and scanning small
objects through better locality and CPU scalability. Benchmark
results vary, but we expect somewhere between a 10–40%
reduction in garbage collection overhead in real-world programs
that heavily use the garbage collector. Further improvements,
on the order of 10% in garbage collection overhead, are
expected when running on newer amd64-based CPU platforms (Intel
Ice Lake or AMD Zen 4 and newer), as the garbage collector now
leverages vector instructions for scanning small objects when
possible. The new garbage collector may be disabled by setting
GOEXPERIMENT=nogreenteagc at build time. This opt-out setting
is expected to be removed in Go 1.27. If you disable the new
garbage collector for any reason related to its performance or
behavior, please file an issue.
* Runtime: cgo: The baseline runtime overhead of cgo calls has
been reduced by ~30%.
* Runtime: Heap base address randomization: On 64-bit platforms,
the runtime now randomizes the heap base address at
startup. This is a security enhancement that makes it harder
for attackers to predict memory addresses and exploit
vulnerabilities when using cgo. This feature may be disabled by
setting GOEXPERIMENT=norandomizedheapbase64 at build time. This
opt-out setting is expected to be removed in a future Go
release.
* Runtime: Experimental goroutine leak profile: A new profile
type that reports leaked goroutines is now available as an
experiment. The new profile type, named goroutineleak in the
runtime/pprof package, may be enabled by setting
GOEXPERIMENT=goroutineleakprofile at build time. Enabling the
experiment also makes the profile available as a net/http/pprof
endpoint, /debug/pprof/goroutineleak. A leaked goroutine is a
goroutine blocked on some concurrency primitive (channels,
sync.Mutex, sync.Cond, etc) that cannot possibly become
unblocked. The runtime detects leaked goroutines using the
garbage collector: if a goroutine G is blocked on concurrency
primitive P, and P is unreachable from any runnable goroutine
or any goroutine that those could unblock, then P cannot be
unblocked, so goroutine G can never wake up. While it is
impossible to detect permanently blocked goroutines in all
cases, this approach detects a large class of such
leaks. Because this technique builds on reachability, the
runtime may fail to identify leaks caused by blocking on
concurrency primitives reachable through global variables or
the local variables of runnable goroutines. Special thanks to
Vlad Saioc at Uber for contributing this work. The underlying
theory is presented in detail in a publication by Saioc et
al. The implementation is production-ready, and is only
considered an experiment for the purposes of collecting
feedback on the API, specifically the choice to make it a new
profile. The feature is also designed to not incur any
additional run-time overhead unless it is actively in-use. We
encourage users to try out the new feature in the Go
playground, in tests, in continuous integration, and in
production. We welcome additional feedback on the proposal
issue. We aim to enable goroutine leak profiles by default in
Go 1.27.
* Compiler: The compiler can now allocate the backing store for
slices on the stack in more situations, which improves
performance. If this change is causing trouble, the bisect tool
can be used to find the allocation causing trouble using the
-compile=variablemake flag. All such new stack allocations can
also be turned off using -gcflags=all=-d=variablemakehash=n. If
you encounter issues with this optimization, please file an
issue.
* Linker: On 64-bit ARM-based Windows (the windows/arm64 port),
the linker now supports internal linking mode of cgo programs,
which can be requested with the -ldflags=-linkmode=internal
flag.
* Linker: There are several minor changes to executable
files. These changes do not affect running Go programs. They
may affect programs that analyze Go executables, and they may
affect people who use external linking mode with custom linker
scripts.
* Linker: The moduledata structure is now in its own section,
named .go.module.
* Linker: The moduledata cutab field, which is a slice, now has
the correct length; previously the length was four times too
large.
* Linker: The pcHeader found at the start of the .gopclntab
section no longer records the start of the text section. That
field is now always zero.
* Linker: That pcHeader change was made so that the .gopclntab
section no longer contains any relocations. On platforms that
support relro, the section has moved from the relro segment to
the rodata segment.
* Linker: The funcdata symbols and the findfunctab have moved
from the .rodata section to the .gopclntab section.
* Linker: The .gosymtab section has been removed. It was
previously always present but empty.
* Linker: When using internal linking, ELF sections now appear in
the section header list sorted by address. The previous order
was somewhat unpredictable.
* Linker: The references to section names here use the ELF names
as seen on Linux and other systems. The Mach-O names as seen on
Darwin start with a double underscore and do not contain any
dots.
* Bootstrap: As mentioned in the Go 1.24 release notes, Go 1.26
now requires Go 1.24.6 or later for bootstrap. We expect that
Go 1.28 will require a minor release of Go 1.26 or later for
bootstrap.
* Standard Library: New crypto/hpke package: The new crypto/hpke
package implements Hybrid Public Key Encryption (HPKE) as
specified in RFC 9180, including support for post-quantum
hybrid KEMs.
* Standard Library: New experimental simd/archsimd package: Go
1.26 introduces a new experimental simd/archsimd package, which
can be enabled by setting the environment variable
GOEXPERIMENT=simd at build time. This package provides access
to architecture-specific SIMD operations. It is currently
available on the amd64 architecture and supports 128-bit,
256-bit, and 512-bit vector types, such as Int8x16 and
Float64x8, with operations such as Int8x16.Add. The API is not
yet considered stable. We intend to provide support for other
architectures in future versions, but the API intentionally
architecture-specific and thus non-portable. In addition, we
plan to develop a high-level portable SIMD package in the
future.
* Standard Library: New experimental runtime/secret package: The
new runtime/secret package is available as an experiment, which
can be enabled by setting the environment variable
GOEXPERIMENT=runtimesecret at build time. It provides a
facility for securely erasing temporaries used in code that
manipulates secret information—typically cryptographic in
nature—such as registers, stack, new heap allocations. This
package is intended to make it easier to ensure forward
secrecy. It currently supports the amd64 and arm64
architectures on Linux.
* bytes: The new Buffer.Peek method returns the next n bytes from
the buffer without advancing it.
* crypto: The new Encapsulator and Decapsulator interfaces allow
accepting abstract KEM encapsulation or decapsulation keys.
* crypto/dsa: The random parameter to GenerateKey is now
ignored. Instead, it now always uses a secure source of
cryptographically random bytes. For deterministic testing, use
the new testing/cryptotest.SetGlobalRandom function. The new
GODEBUG setting cryptocustomrand=1 temporarily restores the old
behavior.
* crypto/ecdh: The random parameter to Curve.GenerateKey is now
ignored. Instead, it now always uses a secure source of
cryptographically random bytes. For deterministic testing, use
the new testing/cryptotest.SetGlobalRandom function. The new
GODEBUG setting cryptocustomrand=1 temporarily restores the old
behavior. The new KeyExchanger interface, implemented by
PrivateKey, makes it possible to accept abstract ECDH private
keys, e.g. those implemented in hardware.
* crypto/ecdsa: The big.Int fields of PublicKey and PrivateKey
are now deprecated. The random parameter to GenerateKey,
SignASN1, Sign, and PrivateKey.Sign is now ignored. Instead,
they now always use a secure source of cryptographically random
bytes. For deterministic testing, use the new
testing/cryptotest.SetGlobalRandom function. The new GODEBUG
setting cryptocustomrand=1 temporarily restores the old
behavior.
* crypto/ed25519: If the random parameter to GenerateKey is nil,
GenerateKey now always uses a secure source of
cryptographically random bytes, instead of crypto/rand.Reader
(which could have been overridden). The new GODEBUG setting
cryptocustomrand=1 temporarily restores the old behavior.
* crypto/fips140: The new WithoutEnforcement and Enforced
functions now allow running in GODEBUG=fips140=only mode while
selectively disabling the strict FIPS 140-3 checks. Version
returns the resolved FIPS 140-3 Go Cryptographic Module version
when building against a frozen module with GOFIPS140.
* crypto/mlkem: The new DecapsulationKey768.Encapsulator and
DecapsulationKey1024.Encapsulator methods implement the new
crypto.Decapsulator interface.
* crypto/mlkem/mlkemtest: The new crypto/mlkem/mlkemtest package
exposes the Encapsulate768 and Encapsulate1024 functions which
implement derandomized ML-KEM encapsulation, for use with
known-answer tests.
* crypto/rand: The random parameter to Prime is now
ignored. Instead, it now always uses a secure source of
cryptographically random bytes. For deterministic testing, use
the new testing/cryptotest.SetGlobalRandom function. The new
GODEBUG setting cryptocustomrand=1 temporarily restores the old
behavior.
* crypto/rsa: The new EncryptOAEPWithOptions function allows
specifying different hash functions for OAEP padding and MGF1
mask generation.
* crypto/rsa: The random parameter to GenerateKey,
GenerateMultiPrimeKey, and EncryptPKCS1v15 is now
ignored. Instead, they now always use a secure source of
cryptographically random bytes. For deterministic testing, use
the new testing/cryptotest.SetGlobalRandom function. The new
GODEBUG setting cryptocustomrand=1 temporarily restores the old
behavior.
* crypto/rsa: If PrivateKey fields are modified after calling
PrivateKey.Precompute, PrivateKey.Validate now fails.
* crypto/rsa: PrivateKey.D is now checked for consistency with
precomputed values, even if it is not used.
* crypto/rsa: Unsafe PKCS #1 v1.5 encryption padding (implemented
by EncryptPKCS1v15, DecryptPKCS1v15, and
DecryptPKCS1v15SessionKey) is now deprecated.
* crypto/subtle: The WithDataIndependentTiming function no longer
locks the calling goroutine to the OS thread while executing
the passed function. Additionally, any goroutines which are
spawned during the execution of the passed function and their
descendants now inherit the properties of
WithDataIndependentTiming for their lifetime. This change also
affects cgo in the following ways:
* crypto/subtle: Any C code called via cgo from within the
function passed to WithDataIndependentTiming, or from a
goroutine spawned by the function passed to
WithDataIndependentTiming and its descendants, will also have
data independent timing enabled for the duration of the
call. If the C code disables data independent timing, it will
be re-enabled on return to Go.
* crypto/subtle: If C code called via cgo, from the function
passed to WithDataIndependentTiming or elsewhere, enables or
disables data independent timing then calling into Go will
preserve that state for the duration of the call.
* crypto/tls: The hybrid SecP256r1MLKEM768 and SecP384r1MLKEM1024
post-quantum key exchanges are now enabled by default. They can
be disabled by setting Config.CurvePreferences or with the
tlssecpmlkem=0 GODEBUG setting.
* crypto/tls: The new ClientHelloInfo.HelloRetryRequest field
indicates if the ClientHello was sent in response to a
HelloRetryRequest message. The new
ConnectionState.HelloRetryRequest field indicates if the server
sent a HelloRetryRequest, or if the client received a
HelloRetryRequest, depending on connection role.
* crypto/tls: The QUICConn type used by QUIC implementations
includes a new event for reporting TLS handshake errors.
* crypto/tls: If Certificate.PrivateKey implements
crypto.MessageSigner, its SignMessage method is used instead of
Sign in TLS 1.2 and later.
* crypto/tls: The following GODEBUG settings introduced in Go
1.22 and Go 1.23 will be removed in the next major Go
release. Starting in Go 1.27, the new behavior will apply
regardless of GODEBUG setting or go.mod language version.
* crypto/tls: GODEBUG tlsunsafeekm:
ConnectionState.ExportKeyingMaterial will require TLS 1.3 or
Extended Master Secret.
* crypto/tls: GODEBUG tlsrsakex: legacy RSA-only key exchanges
without ECDH won’t be enabled by default.
* crypto/tls: GODEBUG tls10server: the default minimum TLS
version for both clients and servers will be TLS 1.2.
* crypto/tls: GODEBUG tls3des: the default cipher suites will not
include 3DES.
* crypto/tls: GODEBUG x509keypairleaf: X509KeyPair and
LoadX509KeyPair will always populate the Certificate.Leaf
field.
* crypto/x509: The ExtKeyUsage and KeyUsage types now have String
methods that return the corresponding OID names as defined in
RFC 5280 and other registries.
* crypto/x509: The ExtKeyUsage type now has an OID method that
returns the corresponding OID for the EKU.
* crypto/x509: The new OIDFromASN1OID function allows converting
an encoding/asn1.ObjectIdentifier into an OID.
* debug/elf: Additional R_LARCH_* constants from LoongArch ELF
psABI v20250521 (global version v2.40) are defined for use with
LoongArch systems.
* errors: The new AsType function is a generic version of As. It
is type-safe, faster, and, in most cases, easier to use.
* fmt: For unformatted strings, fmt.Errorf("x") now allocates
less and generally matches the allocations for errors.New("x").
* go/ast: The new ParseDirective function parses directive
comments, which are comments such as //go:generate. Source code
tools can support their own directive comments and this new API
should help them implement the conventional syntax.
* go/ast: The new BasicLit.ValueEnd field records the precise end
position of a literal so that the BasicLit.End method can now
always return the correct answer. (Previously it was computed
using a heuristic that was incorrect for multi-line raw string
literals in Windows source files, due to removal of carriage
returns.)
* go/ast: Programs that update the ValuePos field of BasicLits
produced by the parser may need to also update or clear the
ValueEnd field to avoid minor differences in formatted output.
* go/token: The new File.End convenience method returns the
file’s end position.
* go/types: The gotypesalias GODEBUG setting introduced in Go
1.22 will be removed in the next major Go release. Starting in
Go 1.27, the go/types package will always produce an Alias type
for the representation of type aliases regardless of GODEBUG
setting or go.mod language version.
* image/jpeg: The JPEG encoder and decoder have been replaced
with new, faster, more accurate implementations. Code that
expects specific bit-for-bit outputs from the encoder or
decoder may need to be updated.
* io: ReadAll now allocates less intermediate memory and returns
a minimally sized final slice. It is often about two times
faster while typically allocating around half as much total
memory, with more benefit for larger inputs.
* log/slog: The NewMultiHandler function creates a MultiHandler
that invokes all the given Handlers. Its Enabled method reports
whether any of the handlers’ Enabled methods return true. Its
Handle, WithAttrs and WithGroup methods call the corresponding
method on each of the enabled handlers.
* net: The new Dialer methods DialIP, DialTCP, DialUDP, and
DialUnix permit dialing specific network types with context
values.
* net/http: The new HTTP2Config.StrictMaxConcurrentRequests field
controls whether a new connection should be opened if an
existing HTTP/2 connection has exceeded its stream limit.
* net/http: The new Transport.NewClientConn method returns a
client connection to an HTTP server. Most users should continue
to use Transport.RoundTrip to make requests, which manages a
pool of connections. NewClientConn is useful for users who need
to implement their own connection management.
* net/http: Client now uses and sets cookies scoped to URLs with
the host portion matching Request.Host when
available. Previously, the connection address host was always
used.
* net/http/httptest: The HTTP client returned by Server.Client
will now redirect requests for example.com and any subdomains
to the server being tested.
* net/http/httputil: The ReverseProxy.Director configuration
field is deprecated in favor of ReverseProxy.Rewrite.
* net/http/httputil: A malicious client can remove headers added
by a Director function by designating those headers as
hop-by-hop. Since there is no way to address this problem
within the scope of the Director API, we added a new Rewrite
hook in Go 1.20. Rewrite hooks are provided with both the
unmodified inbound request received by the proxy and the
outbound request which will be sent by the proxy. Since the
Director hook is fundamentally unsafe, we are now deprecating
it.
* net/netip: The new Prefix.Compare method compares two prefixes.
* net/url: Parse now rejects malformed URLs containing colons in
the host subcomponent, such as http://::1/ or
http://localhost:80:80/. URLs containing bracketed IPv6
addresses, such as http://[::1]/ are still accepted. The new
GODEBUG setting urlstrictcolons=0 restores the old behavior.
* os: The new Process.WithHandle method provides access to an
internal process handle on supported platforms (pidfd on Linux
5.4 or later, Handle on Windows).
* os: On Windows, the OpenFile flag parameter can now contain any
combination of Windows-specific file flags, such as
FILE_FLAG_OVERLAPPED and FILE_FLAG_SEQUENTIAL_SCAN, for control
of file or device caching behavior, access modes, and other
special-purpose flags.
* os/signal: NotifyContext now cancels the returned context with
context.CancelCauseFunc and an error indicating which signal
was received.
* reflect: The new methods Type.Fields, Type.Methods, Type.Ins
and Type.Outs return iterators for a type’s fields (for a
struct type), methods, inputs and outputs parameters (for a
function type), respectively. Similarly, the new methods
Value.Fields and Value.Methods return iterators over a value’s
fields or methods, respectively. Each iteration yields the type
information (StructField or Method) of a field or method, along
with the field or method Value.
* runtime/metrics: Several new scheduler metrics have been added,
including counts of goroutines in various states (waiting,
runnable, etc.) under the /sched/goroutines prefix, the number
of OS threads the runtime is aware of with
/sched/threads:threads, and the total number of goroutines
created by the program with
/sched/goroutines-created:goroutines.
* testing: The new methods T.ArtifactDir, B.ArtifactDir, and
F.ArtifactDir return a directory in which to write test output
files (artifacts).
* testing: When the -artifacts flag is provided to go test, this
directory will be located under the output directory (specified
with -outputdir, or the current directory by
default). Otherwise, artifacts are stored in a temporary
directory which is removed after the test completes.
* testing: The first call to ArtifactDir when -artifacts is
provided writes the location of the directory to the test log.
* testing: The B.Loop method no longer prevents inlining in the
loop body, which could lead to unanticipated allocation and
slower benchmarks. With this fix, we expect that all benchmarks
can be converted from the old B.N style to the new B.Loop style
with no ill effects. Within the body of a for b.Loop() { ... }
loop, function call parameters, results, and assigned variables
are still kept alive, preventing the compiler from optimizing
away entire parts of the benchmark.
* testing/cryptotest: The new SetGlobalRandom function configures
a global, deterministic cryptographic randomness source for the
duration of the test. It affects crypto/rand, and all implicit
sources of cryptographic randomness in the crypto/... packages.
* time: The asynctimerchan GODEBUG setting introduced in Go 1.23
will be removed in the next major Go release. Starting in Go
1.27, the time package will always use unbuffered (synchronous)
channels for timers regardless of GODEBUG setting or go.mod
language version.
* Ports: Darwin: Go 1.26 is the last release that will run on
macOS 12 Monterey. Go 1.27 will require macOS 13 Ventura or
later.
* Ports: FreeBSD: The freebsd/riscv64 port (GOOS=freebsd
GOARCH=riscv64) has been marked broken. See issue 76475 for
details.
* Ports: Windows: As announced in the Go 1.25 release notes, the
broken 32-bit windows/arm port (GOOS=windows GOARCH=arm) has
been removed.
* Ports: PowerPC: Go 1.26 is the last release that supports the
ELFv1 ABI on the big-endian 64-bit PowerPC port on Linux
(GOOS=linux GOARCH=ppc64). It will switch to the ELFv2 ABI in
Go 1.27. As the port does not currently support linking against
other ELF objects, we expect this change to be transparent to
users.
* Ports: RISC-V: The linux/riscv64 port now supports the race
detector.
* Ports: S390X: The s390x port now supports passing function
arguments and results using registers.
* Ports: WebAssembly: The compiler now unconditionally makes use
of the sign extension and non-trapping floating-point to
integer conversion instructions. These features have been
standardized since at least Wasm 2.0. The corresponding GOWASM
settings, signext and satconv, are now ignored.
* Ports: WebAssembly: For WebAssembly applications, the runtime
now manages chunks of heap memory in much smaller increments,
leading to significantly reduced memory usage for applications
with heaps less than around 16 MiB in size.
-------------------------------------------------------------------
Wed Feb 4 15:46:44 UTC 2026 - Jeff Kowalczyk <jkowalczyk@suse.com>
- go1.26rc3 (released 2026-02-04) is a release candidate version of
go1.26 cut from the master branch at the revision tagged
go1.26rc3.
Refs boo#1255111 go1.26 release tracking
-------------------------------------------------------------------
Thu Jan 15 18:32:04 UTC 2026 - Jeff Kowalczyk <jkowalczyk@suse.com>
- go1.26rc2 (released 2026-01-15) is a release candidate version of
go1.26 cut from the master branch at the revision tagged
go1.26rc2.
Refs boo#1255111 go1.26 release tracking
* go1.26 requires go1.24.6 or later for bootstrap.
-------------------------------------------------------------------
Tue Dec 16 20:00:53 UTC 2025 - Jeff Kowalczyk <jkowalczyk@suse.com>
- go1.26rc1 (released 2025-12-16) is a release candidate version of
go1.26 cut from the master branch at the revision tagged
go1.26rc1.
Refs boo#1255111 go1.26 release tracking
* go1.26 requires go1.24.6 or later for bootstrap.
