- - Go 1.19 is not yet released. These are work-in-progress - release notes. Go 1.19 is expected to be released in August 2022. - -
- -- There is only one small change to the language, - a very small correction - to the scope of type parameters in method declarations. - Existing programs are unaffected. -
- -
- The Go memory model has been
- revised to align Go with
- the memory model used by C, C++, Java, JavaScript, Rust, and Swift.
- Go only provides sequentially consistent atomics, not any of the more relaxed forms found in other languages.
- Along with the memory model update,
- Go 1.19 introduces new types in the sync/atomic package
- that make it easier to use atomic values, such as
- atomic.Int64
- and
- atomic.Pointer[T].
-
- Go 1.19 adds support for the Loongson 64-bit architecture
- LoongArch
- on Linux (GOOS=linux, GOARCH=loong64).
- The implemented ABI is LP64D. Minimum kernel version supported is 5.19.
-
- Note that most existing commercial Linux distributions for LoongArch come - with older kernels, with a historical incompatible system call ABI. - Compiled binaries will not work on these systems, even if statically linked. - Users on such unsupported systems are limited to the distribution-provided - Go package. -
- -
- The riscv64 port now supports passing function arguments
- and result using registers. Benchmarking shows typical performance
- improvements of 10% or more on riscv64.
-
-Go 1.19 adds support for links, lists, and clearer headings in doc comments.
-As part of this change, gofmt
-now reformats doc comments to make their rendered meaning clearer.
-See “Go Doc Comments”
-for syntax details and descriptions of common mistakes now highlighted by gofmt.
-As another part of this change, the new package go/doc/comment
-provides parsing and reformatting of doc comments
-as well as support for rendering them to HTML, Markdown, and text.
-
unix build constraint
- The build constraint unix is now recognized
- in //go:build lines. The constraint is satisfied
- if the target operating system, also known as GOOS, is
- a Unix or Unix-like system. For the 1.19 release it is satisfied
- if GOOS is one of
- aix, android, darwin,
- dragonfly, freebsd, hurd,
- illumos, ios, linux,
- netbsd, openbsd, or solaris.
- In future releases the unix constraint may match
- additional newly supported operating systems.
-
- The -trimpath flag, if set, is now included in the build settings
- stamped into Go binaries by go build, and can be
- examined using
- go version -m
- or debug.ReadBuildInfo.
-
- go generate now sets the GOROOT
- environment variable explicitly in the generator's environment, so that
- generators can locate the correct GOROOT even if built
- with -trimpath.
-
- go test and go generate now place
- GOROOT/bin at the beginning of the PATH used for the
- subprocess, so tests and generators that execute the go command
- will resolve it to same GOROOT.
-
- go env now quotes entries that contain spaces in
- the CGO_CFLAGS, CGO_CPPFLAGS, CGO_CXXFLAGS, CGO_FFLAGS, CGO_LDFLAGS,
- and GOGCCFLAGS variables it reports.
-
- go list -json now accepts a
- comma-separated list of JSON fields to populate. If a list is specified,
- the JSON output will include only those fields, and
- go list may avoid work to compute fields that are
- not included. In some cases, this may suppress errors that would otherwise
- be reported.
-
- The go command now caches information necessary to load some modules,
- which should result in a speed-up of some go list invocations.
-
- The vet checker “errorsas” now reports when
- errors.As is called
- with a second argument of type *error,
- a common mistake.
-
- The runtime now includes support for a soft memory limit. This memory limit
- includes the Go heap and all other memory managed by the runtime, and
- excludes external memory sources such as mappings of the binary itself,
- memory managed in other languages, and memory held by the operating system on
- behalf of the Go program. This limit may be managed via
- runtime/debug.SetMemoryLimit
- or the equivalent
- GOMEMLIMIT
- environment variable. The limit works in conjunction with
- runtime/debug.SetGCPercent
- / GOGC,
- and will be respected even if GOGC=off, allowing Go programs to
- always make maximal use of their memory limit, improving resource efficiency
- in some cases. See the GC guide for
- a detailed guide explaining the soft memory limit in more detail, as well as
- a variety of common use-cases and scenarios. Please note that small memory
- limits, on the order of tens of megabytes or less, are less likely to be
- respected due to external latency factors, such as OS scheduling. See
- issue 52433 for more details. Larger
- memory limits, on the order of hundreds of megabytes or more, are stable and
- production-ready.
-
- In order to limit the effects of GC thrashing when the program's live heap
- size approaches the soft memory limit, the Go runtime also attempts to limit
- total GC CPU utilization to 50%, excluding idle time, choosing to use more
- memory over preventing application progress. In practice, we expect this limit
- to only play a role in exceptional cases, and the new
- runtime metric
- /gc/limiter/last-enabled:gc-cycle reports when this last
- occurred.
-
- The runtime now schedules many fewer GC worker goroutines on idle operating - system threads when the application is idle enough to force a periodic GC - cycle. -
- -- The runtime will now allocate initial goroutine stacks based on the historic - average stack usage of goroutines. This avoids some of the early stack growth - and copying needed in the average case in exchange for at most 2x wasted - space on below-average goroutines. -
- -
- On Unix operating systems, Go programs that import package
- os now automatically increase the open file limit
- (RLIMIT_NOFILE) to the maximum allowed value;
- that is, they change the soft limit to match the hard limit.
- This corrects artificially low limits set on some systems for compatibility with very old C programs using the
- select system call.
- Go programs are not helped by that limit, and instead even simple programs like gofmt
- often ran out of file descriptors on such systems when processing many files in parallel.
- One impact of this change is that Go programs that in turn execute very old C programs in child processes
- may run those programs with too high a limit.
- This can be corrected by setting the hard limit before invoking the Go program.
-
- Unrecoverable fatal errors (such as concurrent map writes, or unlock of
- unlocked mutexes) now print a simpler traceback excluding runtime metadata
- (equivalent to a fatal panic) unless GOTRACEBACK=system or
- crash. Runtime-internal fatal error tracebacks always include
- full metadata regardless of the value of GOTRACEBACK
-
- Support for debugger-injected function calls has been added on ARM64, - enabling users to call functions from their binary in an interactive - debugging session when using a debugger that is updated to make use of this - functionality. -
- -- The address sanitizer support added in Go 1.18 - now handles function arguments and global variables more precisely. -
- -
- The compiler now uses
- a jump
- table to implement large integer and string switch statements.
- Performance improvements for the switch statement vary but can be
- on the order of 20% faster.
- (GOARCH=amd64 and GOARCH=arm64 only)
-
- The Go compiler now requires the -p=importpath flag to
- build a linkable object file. This is already supplied by
- the go command and by Bazel. Any other build systems
- that invoke the Go compiler directly will need to make sure they
- pass this flag as well.
-
- The Go compiler no longer accepts the -importmap
- or -installsuffix flags. Build systems that invoke the
- Go compiler directly must use the -importcfg flag
- instead. (The go command's -installsuffix
- build flag is still supported and unaffected by this change.)
-
- Like the compiler, the assembler now requires the
- -p=importpath flag to build a linkable object file.
- This is already supplied by the go command. Any other
- build systems that invoke the Go assembler directly will need to
- make sure they pass this flag as well.
-
- On ELF platforms, the linker now emits compressed DWARF sections in
- the standard gABI format (SHF_COMPRESSED), instead of
- the legacy .zdebug format.
-
- The sync/atomic package defines new atomic types
- Bool,
- Int32,
- Int64,
- Uint32,
- Uint64,
- Uintptr, and
- Pointer.
- These types hide the underlying values so that all accesses are forced to use
- the atomic APIs.
- Pointer also avoids
- the need to convert to
- unsafe.Pointer at call sites.
- Int64 and
- Uint64 are
- automatically aligned to 64-bit boundaries in structs and allocated data,
- even on 32-bit systems.
-
-
- Command and
- LookPath no longer
- allow results from a PATH search to be found relative to the current directory.
- This removes a common source of security problems
- but may also break existing programs that depend on using, say, exec.Command("prog")
- to run a binary named prog (or, on Windows, prog.exe) in the current directory.
- See the os/exec package documentation for
- information about how best to update such programs.
-
- On Windows, Command and LookPath now respect the
- NoDefaultCurrentDirectoryInExePath
- environment variable, making it possible to disable
- the default implicit search of “.” in PATH lookups on Windows systems.
-
- As always, there are various minor changes and updates to the library, - made with the Go 1 promise of compatibility - in mind. - There are also various performance improvements, not enumerated here. -
- -
- Reader
- now ignores non-ZIP data at the start of a ZIP file, matching most other implementations.
- This is necessary to read some Java JAR files, among other uses.
-
- Operating on invalid curve points (those for which the
- IsOnCurve method returns false, and which are never returned
- by Unmarshal or by a Curve method operating on a
- valid point) has always been undefined behavior and can lead to key
- recovery attacks. If an invalid point is supplied to
- Marshal,
- MarshalCompressed,
- Add,
- Double, or
- ScalarMult,
- they will now panic.
-
- ScalarBaseMult operations on the P224,
- P384, and P521 curves are now up to three
- times faster, leading to similar speedups in some ECDSA operations. The
- generic (not platform optimized) P256 implementation was
- replaced with one derived from a formally verified model; this might
- lead to significant slowdowns on 32-bit platforms.
-
- Read no longer buffers
- random data obtained from the operating system between calls. Applications
- that perform many small reads at high frequency might choose to wrap
- Reader in a
- bufio.Reader for performance
- reasons, taking care to use
- io.ReadFull
- to ensure no partial reads occur.
-
- On Plan 9, Read has been reimplemented, replacing the ANSI
- X9.31 algorithm with a fast key erasure generator.
-
- The Prime
- implementation was changed to use only rejection sampling,
- which removes a bias when generating small primes in non-cryptographic contexts,
- removes one possible minor timing leak,
- and better aligns the behavior with BoringSSL,
- all while simplifying the implementation.
- The change does produce different outputs for a given random source
- stream compared to the previous implementation,
- which can break tests written expecting specific results from
- specific deterministic random sources.
- To help prevent such problems in the future,
- the implementation is now intentionally non-deterministic with respect to the input stream.
-
- The GODEBUG option tls10default=1 has been
- removed. It is still possible to enable TLS 1.0 client-side by setting
- Config.MinVersion.
-
- The TLS server and client now reject duplicate extensions in TLS - handshakes, as required by RFC 5246, Section 7.4.1.4 and RFC 8446, Section - 4.2. -
-
- CreateCertificate
- no longer supports creating certificates with SignatureAlgorithm
- set to MD5WithRSA.
-
- CreateCertificate no longer accepts negative serial numbers.
-
- CreateCertificate will not emit an empty SEQUENCE anymore
- when the produced certificate has no extensions.
-
- Removal of the GODEBUG optionx509sha1=1,
- originally planned for Go 1.19, has been rescheduled to a future release.
- Applications using it should work on migrating. Practical attacks against
- SHA-1 have been demonstrated since 2017 and publicly trusted Certificate
- Authorities have not issued SHA-1 certificates since 2015.
-
- ParseCertificate
- and ParseCertificateRequest
- now reject certificates and CSRs which contain duplicate extensions.
-
- The new CertPool.Clone
- and CertPool.Equal
- methods allow cloning a CertPool and checking the equivalence of two
- CertPools respectively.
-
- The new function ParseRevocationList
- provides a faster, safer to use CRL parser which returns a
- RevocationList.
- Parsing a CRL also populates the new RevocationList fields
- RawIssuer, Signature,
- AuthorityKeyId, and Extensions, which are ignored by
- CreateRevocationList.
-
- The new method RevocationList.CheckSignatureFrom
- checks that the signature on a CRL is a valid signature from a
- Certificate.
-
- The ParseCRL and
- ParseDERCRL functions
- are now deprecated in favor of ParseRevocationList.
- The Certificate.CheckCRLSignature
- method is deprecated in favor of RevocationList.CheckSignatureFrom.
-
- The path builder of Certificate.Verify
- was overhauled and should now produce better chains and/or be more efficient in complicated scenarios.
- Name constraints are now also enforced on non-leaf certificates.
-
- The types CertificateList and
- TBSCertificateList
- have been deprecated. The new crypto/x509 CRL functionality
- should be used instead.
-
- The new EM_LOONGARCH and R_LARCH_* constants
- support the loong64 port.
-
- The new File.COFFSymbolReadSectionDefAux
- method, which returns a COFFSymbolAuxFormat5,
- provides access to COMDAT information in PE file sections.
- These are supported by new IMAGE_COMDAT_* and IMAGE_SCN_* constants.
-
- The new interface
- AppendByteOrder
- provides efficient methods for appending a uint16, uint32, or uint64
- to a byte slice.
- BigEndian and
- LittleEndian now implement this interface.
-
- Similarly, the new functions
- AppendUvarint and
- AppendVarint
- are efficient appending versions of
- PutUvarint and
- PutVarint.
-
- The new method
- Reader.InputOffset
- reports the reader's current input position as a byte offset,
- analogous to encoding/json's
- Decoder.InputOffset.
-
- The new method
- Decoder.InputPos
- reports the reader's current input position as a line and column,
- analogous to encoding/csv's
- Decoder.FieldPos.
-
- The new function
- TextVar
- defines a flag with a value implementing
- encoding.TextUnmarshaler,
- allowing command-line flag variables to have types such as
- big.Int,
- netip.Addr, and
- time.Time.
-
- The new functions
- Append,
- Appendf, and
- Appendln
- append formatted data to byte slices.
-
- The parser now recognizes ~x as a unary expression with operator
- token.TILDE,
- allowing better error recovery when a type constraint such as ~int is used in an incorrect context.
-
- The new methods Func.Origin
- and Var.Origin return the
- corresponding Object of the
- generic type for synthetic Func
- and Var objects created during type
- instantiation.
-
- It is no longer possible to produce an infinite number of distinct-but-identical
- Named type instantiations via
- recursive calls to
- Named.Underlying or
- Named.Method.
-
- The new functions
- Bytes
- and
- String
- provide an efficient way hash a single byte slice or string.
- They are equivalent to using the more general
- Hash
- with a single write, but they avoid setup overhead for small inputs.
-
- The type FuncMap
- is now an alias for
- text/template's FuncMap
- instead of its own named type.
- This allows writing code that operates on a FuncMap from either setting.
-
- Draw with the
- Src operator preserves
- non-premultiplied-alpha colors when destination and source images are
- both image.NRGBA
- or both image.NRGBA64.
- This reverts a behavior change accidentally introduced by a Go 1.18
- library optimization; the code now matches the behavior in Go 1.17 and earlier.
-
- NopCloser's result now implements
- WriterTo
- whenever its input does.
-
- MultiReader's result now implements
- WriterTo unconditionally.
- If any underlying reader does not implement WriterTo,
- it is simulated appropriately.
-
- On Windows only, the mime package now ignores a registry entry
- recording that the extension .js should have MIME
- type text/plain. This is a common unintentional
- misconfiguration on Windows systems. The effect is
- that .js will have the default MIME
- type text/javascript; charset=utf-8.
- Applications that expect text/plain on Windows must
- now explicitly call
- AddExtensionType.
-
- The pure Go resolver will now use EDNS(0) to include a suggested
- maximum reply packet length, permitting reply packets to contain
- up to 1232 bytes (the previous maximum was 512).
- In the unlikely event that this causes problems with a local DNS
- resolver, setting the environment variable
- GODEBUG=netdns=cgo to use the cgo-based resolver
- should work.
- Please report any such problems on the
- issue tracker.
-
- When a net package function or method returns an "I/O timeout"
- error, the error will now satisfy errors.Is(err,
- context.DeadlineExceeded). When a net package function
- returns an "operation was canceled" error, the error will now
- satisfy errors.Is(err, context.Canceled).
- These changes are intended to make it easier for code to test
- for cases in which a context cancellation or timeout causes a net
- package function or method to return an error, while preserving
- backward compatibility for error messages.
-
- Resolver.PreferGo
- is now implemented on Windows and Plan 9. It previously only worked on Unix
- platforms. Combined with
- Dialer.Resolver and
- Resolver.Dial, it's now
- possible to write portable programs and be in control of all DNS name lookups
- when dialing.
-
- The net package now has initial support for the netgo
- build tag on Windows. When used, the package uses the Go DNS client (as used
- by Resolver.PreferGo) instead of asking Windows for
- DNS results. The upstream DNS server it discovers from Windows
- may not yet be correct with complex system network configurations, however.
-
- ResponseWriter.WriteHeader
- now supports sending user-defined 1xx informational headers.
-
- The io.ReadCloser returned by
- MaxBytesReader
- will now return the defined error type
- MaxBytesError
- when its read limit is exceeded.
-
- The HTTP client will handle a 3xx response without a
- Location header by returning it to the caller,
- rather than treating it as an error.
-
- The new
- JoinPath
- function and
- URL.JoinPath
- method create a new URL by joining a list of path
- elements.
-
- The URL type now distinguishes between URLs with no
- authority and URLs with an empty authority. For example,
- http:///path has an empty authority (host),
- while http:/path has none.
-
- The new URL field
- OmitHost is set to true when a
- URL has an empty authority.
-
- A Cmd with a non-empty Dir field
- and nil Env now implicitly sets the PWD environment
- variable for the subprocess to match Dir.
-
- The new method Cmd.Environ reports the
- environment that would be used to run the command, including the
- implicitly set PWD variable.
-
- The method Value.Bytes
- now accepts addressable arrays in addition to slices.
-
- The methods Value.Len
- and Value.Cap
- now successfully operate on a pointer to an array and return the length of that array,
- to match what the builtin
- len and cap functions do.
-
- Go 1.18 release candidate 1, Go 1.17.8, and Go 1.16.15 included a security fix
- to the regular expression parser, making it reject very deeply nested expressions.
- Because Go patch releases do not introduce new API,
- the parser returned syntax.ErrInternalError in this case.
- Go 1.19 adds a more specific error, syntax.ErrNestingDepth,
- which the parser now returns instead.
-
- The GOROOT function now returns the empty string
- (instead of "go") when the binary was built with
- the -trimpath flag set and the GOROOT
- variable is not set in the process environment.
-
- The new /sched/gomaxprocs:threads
- metric reports
- the current
- runtime.GOMAXPROCS
- value.
-
- The new /cgo/go-to-c-calls:calls
- metric
- reports the total number of calls made from Go to C. This metric is
- identical to the
- runtime.NumCgoCall
- function.
-
- The new /gc/limiter/last-enabled:gc-cycle
- metric
- reports the last GC cycle when the GC CPU limiter was enabled. See the
- runtime notes for details about the GC CPU limiter.
-
- Stop-the-world pause times have been significantly reduced when - collecting goroutine profiles, reducing the overall latency impact to the - application. -
- -
- MaxRSS is now reported in heap profiles for all Unix
- operating systems (it was previously only reported for
- GOOS=android, darwin, ios, and
- linux).
-
- The race detector has been upgraded to use thread sanitizer
- version v3 on all supported platforms
- except windows/amd64
- and openbsd/amd64, which remain on v2.
- Compared to v2, it is now typically 1.5x to 2x faster, uses half
- as much memory, and it supports an unlimited number of
- goroutines.
- On Linux, the race detector now requires at least glibc version
- 2.17 and GNU binutils 2.26.
-
- The race detector is now supported on GOARCH=s390x.
-
- Race detector support for openbsd/amd64 has been
- removed from thread sanitizer upstream, so it is unlikely to
- ever be updated from v2.
-
- When tracing and the - CPU profiler are - enabled simultaneously, the execution trace includes CPU profile - samples as instantaneous events. -
-- The sorting algorithm has been rewritten to use - pattern-defeating quicksort, which - is faster for several common scenarios. -
-
- The new function
- Find
- is like
- Search
- but often easier to use: it returns an additional boolean reporting whether an equal value was found.
-
- Quote
- and related functions now quote the rune U+007F as \x7f,
- not \u007f,
- for consistency with other ASCII values.
-
- On PowerPC (GOARCH=ppc64, ppc64le),
- Syscall,
- Syscall6,
- RawSyscall, and
- RawSyscall6
- now always return 0 for return value r2 instead of an
- undefined value.
-
- On AIX and Solaris, Getrusage is now defined.
-
- The new method
- Duration.Abs
- provides a convenient and safe way to take the absolute value of a duration,
- converting −2⁶³ to 2⁶³−1.
- (This boundary case can happen as the result of subtracting a recent time from the zero time.)
-
- The new method
- Time.ZoneBounds
- returns the start and end times of the time zone in effect at a given time.
- It can be used in a loop to enumerate all the known time zone transitions at a given location.
-