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

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Ports

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

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Go command

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.

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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.

Runtime

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Compiler

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Linker

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Core library

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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.

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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.

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.

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.