From bcb89fc17a0ff8b588a8d413fa120cc89e053561 Mon Sep 17 00:00:00 2001 From: Carlos Amedee Date: Mon, 28 Feb 2022 18:04:20 -0500 Subject: [PATCH] doc: start draft of go1.19 release notes, move go1.18 to x/website This template is based on CL 342070 and previous ones like it. Continue to eagerly include often-used sections, and clarify that the TODO is about completing the section, or removing if it turns out not to be needed. Move the Go 1.18 release notes to x/website, since that's the new home for past Go release notes as of CL 291711. They're added to x/website in CL 388556. For #51400 Updates #47694 Change-Id: I7b5213e039ad6e14a7ff7ad486311efcecc06824 Reviewed-on: https://go-review.googlesource.com/c/go/+/388515 Trust: Carlos Amedee Run-TryBot: Carlos Amedee Reviewed-by: Dmitri Shuralyov Reviewed-by: Alex Rakoczy TryBot-Result: Gopher Robot --- doc/go1.18.html | 1364 ----------------------------------------------- doc/go1.19.html | 61 +++ 2 files changed, 61 insertions(+), 1364 deletions(-) delete mode 100644 doc/go1.18.html create mode 100644 doc/go1.19.html diff --git a/doc/go1.18.html b/doc/go1.18.html deleted file mode 100644 index 524fa0495b..0000000000 --- a/doc/go1.18.html +++ /dev/null @@ -1,1364 +0,0 @@ - - - - - - -

DRAFT RELEASE NOTES — Introduction to Go 1.18

- -

- - Go 1.18 is not yet released. These are work-in-progress - release notes. Go 1.18 is expected to be released in February 2022. - -

- -

Changes to the language

- -

Generics

- -

- Go 1.18 includes an implementation of generic features as described by the - Type - Parameters Proposal. - This includes major - but fully backward-compatible - changes to the language. -

- -

- These new language changes required a large amount of new code that - has not had significant testing in production settings. That will - only happen as more people write and use generic code. We believe - that this feature is well implemented and high quality. However, - unlike most aspects of Go, we can't back up that belief with real - world experience. Therefore, while we encourage the use of generics - where it makes sense, please use appropriate caution when deploying - generic code in production. -

- -

- While we believe that the new language features are well designed - and clearly specified, it is possible that we have made mistakes. - We want to stress that the Go 1 - compatibility guarantee says "If it becomes necessary to address - an inconsistency or incompleteness in the specification, resolving - the issue could affect the meaning or legality of existing - programs. We reserve the right to address such issues, including - updating the implementations." It also says "If a compiler or - library has a bug that violates the specification, a program that - depends on the buggy behavior may break if the bug is fixed. We - reserve the right to fix such bugs." In other words, it is possible - that there will be code using generics that will work with the 1.18 - release but break in later releases. We do not plan or expect to - make any such change. However, breaking 1.18 programs in future - releases may become necessary for reasons that we cannot today - foresee. We will minimize any such breakage as much as possible, but - we can't guarantee that the breakage will be zero. -

- -

- The following is a list of the most visible changes. For a more comprehensive overview, see the - proposal. - For details see the language spec. -

- -
    -
  • - The syntax for - function and - type declarations - now accepts - type parameters. -
    • -
  • - Parameterized functions and types can be instantiated by following them with a list of - type arguments in square brackets. -
    • -
  • - The new token ~ has been added to the set of - operators and punctuation. -
    • -
  • - The syntax for - Interface types - now permits the embedding of arbitrary types (not just type names of interfaces) - as well as union and ~T type elements. Such interfaces may only be used - as type constraints. - An interface now defines a set of types as well as a set of methods. -
    • -
  • - The new - predeclared identifier - any is an alias for the empty interface. It may be used instead of - interface{}. -
    • -
  • - The new - predeclared identifier - comparable is an interface that denotes the set of all types which can be - compared using == or !=. It may only be used as (or embedded in) - a type constraint. -
    • -
- -

- There are three experimental packages using generics that may be - useful. - These packages are in x/exp repository; their API is not covered by - the Go 1 guarantee and may change as we gain more experience with - generics. -

-
golang.org/x/exp/constraints
-
-

- Constraints that are useful for generic code, such as - constraints.Ordered. -

-
- -
golang.org/x/exp/slices
-
-

- A collection of generic functions that operate on slices of - any element type. -

-
- -
golang.org/x/exp/maps
-
-

- A collection of generic functions that operate on maps of - any key or element type. -

-
-
-

- -

- The current generics implementation has the following limitations: -

    -
  • - The Go compiler cannot currently handle type declarations inside generic functions - or methods. We hope to provide support for this feature in Go 1.19. -
    • -
  • - The Go compiler currently does not accept arguments of type parameter type with - the predeclared functions real, imag, and complex. - We hope to remove this restriction in Go 1.19. -
    • -
  • - The Go compiler currently only supports calling a method m on a value - x of type parameter type P if m is explicitly - declared by P's constraint interface. - Similarly, method values x.m and method expressions - P.m also are only supported if m is explicitly - declared by P, even though m might be in the method set - of P by virtue of the fact that all types in P implement - m. We hope to remove this restriction in Go 1.19. -
    • -
  • - Embedding a type parameter, or a pointer to a type parameter, as - an unnamed field in a struct type is not permitted. Similarly, - embedding a type parameter in an interface type is not permitted. - Whether these will ever be permitted is unclear at present. -
    • -
  • - A union element with more than one term may not contain an - interface type with a non-empty method set. Whether this will - ever be permitted is unclear at present. -
    • -
-

- -

Bug fixes

- -

- The Go 1.18 compiler now correctly reports declared but not used errors - for variables that are set inside a function literal but are never used. Before Go 1.18, - the compiler did not report an error in such cases. This fixes long-outstanding compiler - issue #8560. As a result of this change, - (possibly incorrect) programs may not compile anymore. The necessary fix is - straightforward: fix the program if it was in fact incorrect, or use the offending - variable, for instance by assigning it to the blank identifier _. - Since go vet always pointed out this error, the number of affected - programs is likely very small. -

- -

- The Go 1.18 compiler now reports an overflow when passing a rune constant expression - such as '1' << 32 as an argument to the predeclared functions - print and println, consistent with the behavior of - user-defined functions. Before Go 1.18, the compiler did not report an error - in such cases but silently accepted such constant arguments if they fit into an - int64. As a result of this change, (possibly incorrect) programs - may not compile anymore. The necessary fix is straightforward: fix the program if it - was in fact incorrect, or explicitly convert the offending argument to the correct type. - Since go vet always pointed out this error, the number of affected - programs is likely very small. -

- -

Ports

- -

AMD64

- -

- Go 1.18 introduces the new GOAMD64 environment variable, which selects at compile time - a minimum target version of the AMD64 architecture. Allowed values are v1, - v2, v3, or v4. Each higher level requires, - and takes advantage of, additional processor features. A detailed - description can be found - here. -

-

- The GOAMD64 environment variable defaults to v1. -

- -

RISC-V

- -

- The 64-bit RISC-V architecture on Linux (the linux/riscv64 port) - now supports the c-archive and c-shared build modes. -

- -

Linux

- -

- Go 1.18 requires Linux kernel version 2.6.32 or later. -

- -

Windows

- -

- The windows/arm and windows/arm64 ports now support - non-cooperative preemption, bringing that capability to all four Windows - ports, which should hopefully address subtle bugs encountered when calling - into Win32 functions that block for extended periods of time. -

- -

iOS

- -

- On iOS (the ios/arm64 port) - and iOS simulator running on AMD64-based macOS (the ios/amd64 port), - Go 1.18 now requires iOS 12 or later; support for previous versions has been discontinued. -

- -

FreeBSD

- -

- Go 1.18 is the last release that is supported on FreeBSD 11.x, which has - already reached end-of-life. Go 1.19 will require FreeBSD 12.2+ or FreeBSD - 13.0+. - FreeBSD 13.0+ will require a kernel with the COMPAT_FREEBSD12 option set (this is the default). -

- -

Tools

- -

Fuzzing

- -

- Go 1.18 includes an implementation of fuzzing as described by - the fuzzing proposal. -

- -

- See the fuzzing landing page to get - started. -

- -

- Please be aware that fuzzing can consume a lot of memory and may impact your - machine’s performance while it runs. Also be aware that the fuzzing engine - writes values that expand test coverage to a fuzz cache directory within - $GOCACHE/fuzz while it runs. There is currently no limit to the - number of files or total bytes that may be written to the fuzz cache, so it - may occupy a large amount of storage (possibly several GBs). -

- -

Go command

- -

go get

- -

- go get no longer builds or installs packages in - module-aware mode. go get is now dedicated to - adjusting dependencies in go.mod. Effectively, the - -d flag is always enabled. To install the latest version - of an executable outside the context of the current module, use - go - install example.com/cmd@latest. Any - version query - may be used instead of latest. This form of go - install was added in Go 1.16, so projects supporting older - versions may need to provide install instructions for both go - install and go get. go - get now reports an error when used outside a module, since there - is no go.mod file to update. In GOPATH mode (with - GO111MODULE=off), go get still builds - and installs packages, as before. -

- -

Automatic go.mod and go.sum updates

- -

- The go mod graph, - go mod vendor, - go mod verify, and - go mod why subcommands - no longer automatically update the go.mod and - go.sum files. - (Those files can be updated explicitly using go get, - go mod tidy, or - go mod download.) -

- -

go version

- -

- The go command now embeds version control information in - binaries. It includes the currently checked-out revision, commit time, and a - flag indicating whether edited or untracked files are present. Version - control information is embedded if the go command is invoked in - a directory within a Git, Mercurial, Fossil, or Bazaar repository, and the - main package and its containing main module are in the same - repository. This information may be omitted using the flag - -buildvcs=false. -

- -

- Additionally, the go command embeds information about the build, - including build and tool tags (set with -tags), compiler, - assembler, and linker flags (like -gcflags), whether cgo was - enabled, and if it was, the values of the cgo environment variables - (like CGO_CFLAGS). - Both VCS and build information may be read together with module - information using - go version -m file or - runtime/debug.ReadBuildInfo (for the currently running binary) - or the new debug/buildinfo - package. -

- -

- The underlying data format of the embedded build information can change with - new go releases, so an older version of go may not handle the - build information produced with a newer version of go. - To read the version information from a binary built with go 1.18, - use the go version command and the - debug/buildinfo package from go 1.18+. -

- -

go mod download

- -

- If the main module's go.mod file - specifies go 1.17 - or higher, go mod download without - arguments now downloads source code for only the modules - explicitly required in the main - module's go.mod file. (In a go 1.17 or - higher module, that set already includes all dependencies needed to build the - packages and tests in the main module.) - To also download source code for transitive dependencies, use - go mod download all. -

- -

go mod vendor

- -

- The go mod vendor subcommand now - supports a -o flag to set the output directory. - (Other go commands still read from the vendor - directory at the module root when loading packages - with -mod=vendor, so the main use for this flag is for - third-party tools that need to collect package source code.) -

- -

go mod tidy

- -

- The go mod tidy command now retains - additional checksums in the go.sum file for modules whose source - code is needed to verify that each imported package is provided by only one - module in the build list. Because this - condition is rare and failure to apply it results in a build error, this - change is not conditioned on the go version in the main - module's go.mod file. -

- -

go work

- -

- The go command now supports a "Workspace" mode. If a - go.work file is found in the working directory or a - parent directory, or one is specified using the GOWORK - environment variable, it will put the go command into workspace mode. - In workspace mode, the go.work file will be used to - determine the set of main modules used as the roots for module - resolution, instead of using the normally-found go.mod - file to specify the single main module. For more information see the - go work - documentation. -

- -

go build -asan

- -

- The go build command and related commands - now support an -asan flag that enables interoperation - with C (or C++) code compiled with the address sanitizer (C compiler - option -fsanitize=address). -

- -

go test

- -

- The go command now supports additional command line - options for the new fuzzing support described - above: -

    -
  • - go test supports - -fuzz, -fuzztime, and - -fuzzminimizetime options. - For documentation on these see - go help testflag. -
    • -
  • - go clean supports a -fuzzcache - option. - For documentation see - go help clean. -
    • -
-

- -

//go:build lines

- -

-Go 1.17 introduced //go:build lines as a more readable way to write build constraints, -instead of // +build lines. -As of Go 1.17, gofmt adds //go:build lines -to match existing +build lines and keeps them in sync, -while go vet diagnoses when they are out of sync. -

- -

Since the release of Go 1.18 marks the end of support for Go 1.16, -all supported versions of Go now understand //go:build lines. -In Go 1.18, go fix now removes the now-obsolete -// +build lines in modules declaring -go 1.17 or later in their go.mod files. -

- -

-For more information, see https://go.dev/design/draft-gobuild. -

- -

Gofmt

- -

- gofmt now reads and formats input files concurrently, with a - memory limit proportional to GOMAXPROCS. On a machine with - multiple CPUs, gofmt should now be significantly faster. -

- -

Vet

- -

Updates for Generics

- -

- The vet tool is updated to support generic code. In most cases, - it reports an error in generic code whenever it would report an error in the - equivalent non-generic code after substituting for type parameters with a - type from their - type set. - - For example, vet reports a format error in - 

func Print[T ~int|~string](t T) {
-	fmt.Printf("%d", t)
-}
- because it would report a format error in the non-generic equivalent of - Print[string]: - 
func PrintString(x string) {
-	fmt.Printf("%d", x)
-}
-

- -

Precision improvements for existing checkers

- -

- The cmd/vet checkers copylock, printf, - sortslice, testinggoroutine, and tests - have all had moderate precision improvements to handle additional code patterns. - This may lead to newly reported errors in existing packages. For example, the - printf checker now tracks formatting strings created by - concatenating string constants. So vet will report an error in: -

-  // fmt.Printf formatting directive %d is being passed to Println.
-  fmt.Println("%d"+` ≡ x (mod 2)`+"\n", x%2)
-
-

- -

Runtime

- -

- The garbage collector now includes non-heap sources of garbage collector work - (e.g., stack scanning) when determining how frequently to run. As a result, - garbage collector overhead is more predictable when these sources are - significant. For most applications these changes will be negligible; however, - some Go applications may now use less memory and spend more time on garbage - collection, or vice versa, than before. The intended workaround is to tweak - GOGC where necessary. -

- -

- The runtime now returns memory to the operating system more efficiently and has - been tuned to work more aggressively as a result. -

- -

- Go 1.17 generally improved the formatting of arguments in stack traces, - but could print inaccurate values for arguments passed in registers. - This is improved in Go 1.18 by printing a question mark (?) - after each value that may be inaccurate. -

- -

- The built-in function append now uses a slightly different formula - when deciding how much to grow a slice when it must allocate a new underlying array. - The new formula is less prone to sudden transitions in allocation behavior. -

- -

Compiler

- -

- Go 1.17 implemented a new way of passing - function arguments and results using registers instead of the stack - on 64-bit x86 architecture on selected operating systems. - Go 1.18 expands the supported platforms to include 64-bit ARM (GOARCH=arm64), - big- and little-endian 64-bit PowerPC (GOARCH=ppc64, ppc64le), - as well as 64-bit x86 architecture (GOARCH=amd64) - on all operating systems. - On 64-bit ARM and 64-bit PowerPC systems, benchmarking shows - typical performance improvements of 10% or more. -

- -

- As mentioned in the Go 1.17 release notes, - this change does not affect the functionality of any safe Go code and - is designed to have no impact on most assembly code. See the - Go 1.17 release notes for more details. -

- -

- The compiler now can inline functions that contain range loops or - labeled for loops. -

- -

- The new -asan compiler option supports the - new go command -asan option. -

- -

- Because the compiler's type checker was replaced in its entirety to - support generics, some error messages now may use different wording - than before. In some cases, pre-Go 1.18 error messages provided more - detail or were phrased in a more helpful way. - We intend to address these cases in Go 1.19. -

- -

- Because of changes in the compiler related to supporting generics, the - Go 1.18 compile speed can be roughly 15% slower than the Go 1.17 compile speed. - The execution time of the compiled code is not affected. We - intend to improve the speed of the compiler in Go 1.19. -

- -

Linker

- -

- The linker emits far fewer relocations. - As a result, most codebases will link faster, require less memory to link, - and generate smaller binaries. - Tools that process Go binaries should use Go 1.18's debug/gosym package - to transparently handle both old and new binaries. -

- -

- The new -asan linker option supports the - new go command -asan option. -

- -

Bootstrap

- -

-When building a Go release from source and GOROOT_BOOTSTRAP -is not set, previous versions of Go looked for a Go 1.4 or later bootstrap toolchain -in the directory $HOME/go1.4 (%HOMEDRIVE%%HOMEPATH%\go1.4 on Windows). -Go now looks first for $HOME/go1.17 or $HOME/sdk/go1.17 -before falling back to $HOME/go1.4. -We intend for Go 1.19 to require Go 1.17 or later for bootstrap, -and this change should make the transition smoother. -For more details, see go.dev/issue/44505. -

- -

Core library

- -

New debug/buildinfo package

- -

- The new debug/buildinfo package - provides access to module versions, version control information, and build - flags embedded in executable files built by the go command. - The same information is also available via - runtime/debug.ReadBuildInfo - for the currently running binary and via go - version -m on the command line. -

- -

New net/netip package

- -

- The new net/netip - package defines a new IP address type, Addr. - Compared to the existing - net.IP type, the netip.Addr type takes less - memory, is immutable, and is comparable so it supports == - and can be used as a map key. -

-

- In addition to Addr, the package defines - AddrPort, representing - an IP and port, and - Prefix, representing - a network CIDR prefix. -

-

- The package also defines several functions to create and examine - these new types: - AddrFrom4, - AddrFrom16, - AddrFromSlice, - AddrPortFrom, - IPv4Unspecified, - IPv6LinkLocalAllNodes, - IPv6Unspecified, - MustParseAddr, - MustParseAddrPort, - MustParsePrefix, - ParseAddr, - ParseAddrPort, - ParsePrefix, - PrefixFrom. -

-

- The net package includes new - methods that parallel existing methods, but - return netip.AddrPort instead of the - heavier-weight net.IP or - *net.UDPAddr types: - Resolver.LookupNetIP, - UDPConn.ReadFromUDPAddrPort, - UDPConn.ReadMsgUDPAddrPort, - UDPConn.WriteToUDPAddrPort, - UDPConn.WriteMsgUDPAddrPort. - The new UDPConn methods support allocation-free I/O. -

-

- The net package also now includes functions and methods - to convert between the existing - TCPAddr/UDPAddr - types and netip.AddrPort: - TCPAddrFromAddrPort, - UDPAddrFromAddrPort, - TCPAddr.AddrPort, - UDPAddr.AddrPort. -

- -

TLS 1.0 and 1.1 disabled by default client-side

- -

- If Config.MinVersion - is not set, it now defaults to TLS 1.2 for client connections. Any safely - up-to-date server is expected to support TLS 1.2, and browsers have required - it since 2020. TLS 1.0 and 1.1 are still supported by setting - Config.MinVersion to VersionTLS10. - The server-side default is unchanged at TLS 1.0. -

- -

- The default can be temporarily reverted to TLS 1.0 by setting the - GODEBUG=tls10default=1 environment variable. - This option will be removed in Go 1.19. -

- -

Rejecting SHA-1 certificates

- -

- crypto/x509 will now - reject certificates signed with the SHA-1 hash function. This doesn't - apply to self-signed root certificates. Practical attacks against SHA-1 - have been demonstrated since 2017 and publicly - trusted Certificate Authorities have not issued SHA-1 certificates since 2015. -

- -

- This can be temporarily reverted by setting the - GODEBUG=x509sha1=1 environment variable. - This option will be removed in Go 1.19. -

- -

Minor changes to the library

- -

- As always, there are various minor changes and updates to the library, - made with the Go 1 promise of compatibility - in mind. -

- -
bufio
-
-

- The new Writer.AvailableBuffer - method returns an empty buffer with a possibly non-empty capacity for use - with append-like APIs. After appending, the buffer can be provided to a - succeeding Write call and possibly avoid any copying. -

- -

- The Reader.Reset and - Writer.Reset methods - now use the default buffer size when called on objects with a - nil buffer. -

-
-
- -
bytes
-
-

- The new Cut function - slices a []byte around a separator. It can replace - and simplify many common uses of - Index, - IndexByte, - IndexRune, - and SplitN. -

- -

- Trim, TrimLeft, - and TrimRight are now allocation free and, especially for - small ASCII cutsets, up to 10 times faster. -

- -

- The Title function is now deprecated. It doesn't - handle Unicode punctuation and language-specific capitalization rules, and is superseded by the - golang.org/x/text/cases package. -

-
-
- -
crypto/elliptic
-
-

- The P224, - P384, and - P521 curve - implementations are now all backed by code generated by the - addchain and - fiat-crypto - projects, the latter of which is based on a formally-verified model - of the arithmetic operations. They now use safer complete formulas - and internal APIs. P-224 and P-384 are now approximately four times - faster. All specific curve implementations are now constant-time. -

- -

- Operating on invalid curve points (those for which the - IsOnCurve method returns false, and which are never returned - by Unmarshal or - a Curve method operating on a valid point) has always been - undefined behavior, can lead to key recovery attacks, and is now - unsupported by the new backend. If an invalid point is supplied to a - P224, P384, or P521 method, that - method will now return a random point. The behavior might change to an - explicit panic in a future release. -

-
-
- -
crypto/tls
-
-

- The new Conn.NetConn - method allows access to the underlying - net.Conn. -

-
-
- -
crypto/x509
-
-

- Certificate.Verify - now uses platform APIs to verify certificate validity on macOS and iOS when it - is called with a nil - VerifyOpts.Roots - or when using the root pool returned from - SystemCertPool. -

- -

- SystemCertPool - is now available on Windows. -

- -

- On Windows, macOS, and iOS, when a - CertPool returned by - SystemCertPool - has additional certificates added to it, - Certificate.Verify - will do two verifications: one using the platform verifier APIs and the - system roots, and one using the Go verifier and the additional roots. - Chains returned by the platform verifier APIs will be prioritized. -

- -

- CertPool.Subjects - is deprecated. On Windows, macOS, and iOS the - CertPool returned by - SystemCertPool - will return a pool which does not include system roots in the slice - returned by Subjects, as a static list can't appropriately - represent the platform policies and might not be available at all from the - platform APIs. -

-
-
- -
debug/dwarf
-
-

- The StructField - and BasicType - structs both now have a DataBitOffset field, which - holds the value of the DW_AT_data_bit_offset - attribute if present. -

-
- -
debug/elf
-
-

- The R_PPC64_RELATIVE - constant has been added. -

-
-
- -
debug/plan9obj
-
-

- The File.Symbols - method now returns the new exported error - value ErrNoSymbols - if the file has no symbol section. -

-
-
- -
go/ast
-
-

- Per the proposal - - Additions to go/ast and go/token to support parameterized functions and types - - the following additions are made to the go/ast package: -

    -
  • - the FuncType - and TypeSpec - nodes have a new field TypeParams to hold type parameters, if any. -
    • -
  • - The new expression node IndexListExpr - represents index expressions with multiple indices, used for function and type instantiations - with more than one explicit type argument. -
    • -
-

-
-
- -
go/constant
-
-

- The new Kind.String - method returns a human-readable name for the receiver kind. -

-
-
- -
go/token
-
-

- The new constant TILDE - represents the ~ token per the proposal - - Additions to go/ast and go/token to support parameterized functions and types - . -

-
-
- -
go/types
-
-

- The new Config.GoVersion - field sets the accepted Go language version. -

- -

- Per the proposal - - Additions to go/types to support type parameters - - the following additions are made to the go/types package: -

-
    -
  • - The new type - TypeParam, factory function - NewTypeParam, - and associated methods are added to represent a type parameter. -
    • -
  • - The new type - TypeParamList holds a list of - type parameters. -
    • -
  • - The new type - TypeList holds a list of types. -
    • -
  • - The new factory function - NewSignatureType allocates a - Signature with - (receiver or function) type parameters. - To access those type parameters, the Signature type has two new methods - Signature.RecvTypeParams and - Signature.TypeParams. -
    • -
  • - Named types have four new methods: - Named.Origin to get the original - parameterized types of instantiated types, - Named.TypeArgs and - Named.TypeParams to get the - type arguments or type parameters of an instantiated or parameterized type, and - Named.SetTypeParams to set the - type parameters (for instance, when importing a named type where allocation of the named - type and setting of type parameters cannot be done simultaneously due to possible cycles). -
    • -
  • - The Interface type has four new methods: - Interface.IsComparable and - Interface.IsMethodSet to - query properties of the type set defined by the interface, and - Interface.MarkImplicit and - Interface.IsImplicit to set - and test whether the interface is an implicit interface around a type constraint literal. -
    • -
  • - The new types - Union and - Term, factory functions - NewUnion and - NewTerm, and associated - methods are added to represent type sets in interfaces. -
    • -
  • - The new function - Instantiate - instantiates a parameterized type. -
    • -
  • - The new Info.Instances - map records function and type instantiations through the new - Instance type. -
    • -
  • - The new type ArgumentError - and associated methods are added to represent an error related to a type argument. -
    • -
  • - The new type Context and factory function - NewContext - are added to facilitate sharing of identical type instances - across type-checked packages, via the new - Config.Context - field. -
    • -
-

- The predicates - AssignableTo, - ConvertibleTo, - Implements, - Identical, - IdenticalIgnoreTags, and - AssertableTo - now also work with arguments that are or contain generalized interfaces, i.e. interfaces - that may only be used as type constraints in Go code. - Note that the behavior of AssertableTo is undefined if the first argument - is a generalized interface. -

-
-
- -
html/template
-
-

- Within a range pipeline the new - {{break}} command will end the loop early and the - new {{continue}} command will immediately start the - next loop iteration. -

- -

- The and function no longer always evaluates all arguments; it - stops evaluating arguments after the first argument that evaluates to - false. Similarly, the or function now stops evaluating - arguments after the first argument that evaluates to true. This makes a - difference if any of the arguments is a function call. -

-
-
- -
image/draw
-
-

- The Draw and DrawMask fallback implementations - (used when the arguments are not the most common image types) are now - faster when those arguments implement the optional - draw.RGBA64Image - and image.RGBA64Image - interfaces that were added in Go 1.17. -

-
-
- -
net
-
-

- net.Error.Temporary has been deprecated. -

-
-
- -
net/http
-
-

- On WebAssembly targets, the Dial, DialContext, - DialTLS and DialTLSContext method fields in - Transport - will now be correctly used, if specified, for making HTTP requests. -

- -

- The new - Cookie.Valid - method reports whether the cookie is valid. -

- -

- The new - MaxBytesHandler - function creates a Handler that wraps its - ResponseWriter and Request.Body with a - MaxBytesReader. -

-
-
- -
os/user
-
-

- User.GroupIds - now uses a Go native implementation when cgo is not available. -

-
-
- -
reflect
-
-

- The new - Value.SetIterKey - and Value.SetIterValue - methods set a Value using a map iterator as the source. They are equivalent to - Value.Set(iter.Key()) and Value.Set(iter.Value()), but - do fewer allocations. -

- -

- The new - Value.UnsafePointer - method returns the Value's value as an unsafe.Pointer. - This allows callers to migrate from Value.UnsafeAddr - and Value.Pointer - to eliminate the need to perform uintptr to unsafe.Pointer conversions at the callsite (as unsafe.Pointer rules require). -

- -

- The new - MapIter.Reset - method changes its receiver to iterate over a - different map. The use of - MapIter.Reset - allows allocation-free iteration - over many maps. -

- -

- A number of methods ( - Value.CanInt, - Value.CanUint, - Value.CanFloat, - Value.CanComplex - ) - have been added to - Value - to test if a conversion is safe. -

- -

- Value.FieldByIndexErr - has been added to avoid the panic that occurs in - Value.FieldByIndex - when stepping through a nil pointer to an embedded struct. -

- -

- reflect.Ptr and - reflect.PtrTo - have been renamed to - reflect.Pointer and - reflect.PointerTo, - respectively, for consistency with the rest of the reflect package. - The old names will continue to work, but will be deprecated in a - future Go release. -

-
-
- -
regexp
-
-

- regexp - now treats each invalid byte of a UTF-8 string as U+FFFD. -

-
-
- -
runtime/debug
-
-

- The BuildInfo - struct has two new fields, containing additional information - about how the binary was built: -

    -
  • GoVersion - holds the version of Go used to build the binary. -
    • -
  • - Settings - is a slice of - BuildSettings - structs holding key/value pairs describing the build. -
    • -
-

-
-
- -
runtime/pprof
-
-

- The CPU profiler now uses per-thread timers on Linux. This increases the - maximum CPU usage that a profile can observe, and reduces some forms of - bias. -

-
-
- -
strconv
-
-

- strconv.Unquote - now rejects Unicode surrogate halves. -

-
-
- -
strings
-
-

- The new Cut function - slices a string around a separator. It can replace - and simplify many common uses of - Index, - IndexByte, - IndexRune, - and SplitN. -

- -

- The new Clone function copies the input - string without the returned cloned string referencing - the input string's memory. -

- -

- Trim, TrimLeft, - and TrimRight are now allocation free and, especially for - small ASCII cutsets, up to 10 times faster. -

- -

- The Title function is now deprecated. It doesn't - handle Unicode punctuation and language-specific capitalization rules, and is superseded by the - golang.org/x/text/cases package. -

-
-
- -
sync
-
-

- The new methods - Mutex.TryLock, - RWMutex.TryLock, and - RWMutex.TryRLock, - will acquire the lock if it is not currently held. -

-
-
- -
syscall
-
-

- The new function SyscallN - has been introduced for Windows, allowing for calls with arbitrary number - of arguments. As a result, - Syscall, - Syscall6, - Syscall9, - Syscall12, - Syscall15, and - Syscall18 are - deprecated in favor of SyscallN. -

- -

- SysProcAttr.Pdeathsig - is now supported in FreeBSD. -

-
-
- -
syscall/js
-
-

- The Wrapper interface has been removed. -

-
-
- -
testing
-
-

- The precedence of / in the argument for -run and - -bench has been increased. A/B|C/D used to be - treated as A/(B|C)/D and is now treated as - (A/B)|(C/D). -

- -

- If the -run option does not select any tests, the - -count option is ignored. This could change the behavior of - existing tests in the unlikely case that a test changes the set of subtests - that are run each time the test function itself is run. -

- -

- The new testing.F type - is used by the new fuzzing support described - above. Tests also now support the command line - options -test.fuzz, -test.fuzztime, and - -test.fuzzminimizetime. -

-
-
- -
text/template
-
-

- Within a range pipeline the new - {{break}} command will end the loop early and the - new {{continue}} command will immediately start the - next loop iteration. -

- -

- The and function no longer always evaluates all arguments; it - stops evaluating arguments after the first argument that evaluates to - false. Similarly, the or function now stops evaluating - arguments after the first argument that evaluates to true. This makes a - difference if any of the arguments is a function call. -

-
-
- -
text/template/parse
-
-

- The package supports the new - text/template and - html/template - {{break}} command via the new constant - NodeBreak - and the new type - BreakNode, - and similarly supports the new {{continue}} command - via the new constant - NodeContinue - and the new type - ContinueNode. -

-
-
- -
unicode/utf8
-
-

- The new AppendRune function appends the UTF-8 - encoding of a rune to a []byte. -

-
-
diff --git a/doc/go1.19.html b/doc/go1.19.html new file mode 100644 index 0000000000..a68c27ecc8 --- /dev/null +++ b/doc/go1.19.html @@ -0,0 +1,61 @@ + + + +

DRAFT RELEASE NOTES — Introduction to Go 1.19

+

+ + 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. + +

+

Changes to the language

+

+ TODO: complete this section +

+

Ports

+

+ TODO: complete this section, or delete if not needed +

+

Tools

+

+ TODO: complete this section, or delete if not needed +

+

Go command

+

+ TODO: complete this section, or delete if not needed +

+

Runtime

+

+ TODO: complete this section, or delete if not needed +

+

Compiler

+

+ TODO: complete this section, or delete if not needed +

+

Linker

+

+ TODO: complete this section, or delete if not needed +

+

Core library

+

+ TODO: complete this section +

+

Minor changes to the library

+

+ As always, there are various minor changes and updates to the library, + made with the Go 1 promise of compatibility + in mind. +

+

+ TODO: complete this section +

-- 2.48.1