Go (golang) 1.17, the next release of the open-source, Google-developed programming language, is now in a beta release stage, with changes intended to simplify coding for safety.

The first beta was published on June 10, with the production release expected in August. Release notes cite three small enhancements to the language, intended to simplify writing code that conforms to unsafe. Pointer’s safety rules. These enhancements include:

• Expressions of type []T may now be converted to array pointer type *[N]T. If a is the result of such a conversion, then corresponding indices that are in range refer to the same underlying elements: &a[i] == &s[i] for 0 <= i < N. The conversion panics if len(s) is less than N.
• unsafe.Add: unsafe.Add(ptr, len) adds len to ptr and returns the updated pointer unsafe.Pointer(uintptr(ptr) + uintptr(len)).
• unsafe.Slice: For expression ptr of type *T, unsafe.Slice(ptr, len) returns a slice of type []T whose underlying array starts at ptr and whose length and capacity are len.

For the compiler, Go 1.17 implements a new way of passing function arguments and results using registers rather than the stack. This is enabled for Linux, macOS, and Windows on the 64-bit x86 architecture. Benchmarking has shown a resulting performance improvement of about 5% and a typical reduction in the binary size of about 2%. This change does not affect the functionality of the safe Go code but can affect code outside the compatibility guidelines with minimal impacts. Also with the compiler, functions containing closures can be inlined. One effect of this is that a function with a closure may produce a distinct closure function for each place that the function is inlined. This change could reveal bugs where Go functions are incorrectly compared by pointer value. Go functions by definition are not comparable.

In the area of module loading, if a module specifies go 1.17 or higher in its go. mod file, its transitive requirements now are loaded lazily, avoiding the need to download or read go. mod files for otherwise irrelevant dependencies. Also in Go 1.17, there are new warnings for As, Is, and Unwrap methods. The cover tool, meanwhile, now uses an optimized parser from golang.org.x.tools/cover, which can be noticeably faster when parsing large overage files. There are also minor changes to the library.

Binary and source distributions for the Go 1.17 beta can be downloaded from golang.org. Those who have Go already installed can access the beta by using the following go command:

$ go get golang.org/dl/go1.17beta1

$ go1.17beta1 download

Predecessor release Go 1.16 was made available in February, featuring library and runtime enhancements. The current stable releases include Go 1.16.5 and Go 1.15.13. A fuzzing capability for Go developers is planned for a future release of the language.