Go 1.24 arrives with generic type aliases, boosted WebAssembly support

Go 1.24, an update to Google‘s popular open source programming language, is now generally available as a production release, with full backing for generic type aliases, performance improvements, and improved WebAssembly support. The release was unveiled February 11, and can be downloaded from Go.dev. Previously, a release candidate was published in mid-December.

Release notes for Go 1.24 note that the release brings full support for generic type aliases, in which a type alias may be parameterized like a defined type. For now, generic type aliases can be disabled by setting GOEXPERIMENT=noaliastypeparams. This parameter setting will be removed in Go 1.25.

For WebAssembly, Go 1.24 offers a go:wasmexport directive for Go programs to export functions to the WebAssembly host. The release also supports building a Go program as a WASI reactor/library.

With the go command in Go 1.24, Go modules now can track executable dependencies using tool directives in go.mod files. This removes the need for a previous workaround of adding tools as blank imports to a file conventionally named tools.go. The go tool command now can run these tools in addition to tools shipped with the Go distribution. Also with the go command, a new GOAUTH environment variable offers a flexible way to authenticate private module fetches.

Cgo, for creating Go packages that call C code, now supports new annotations for C functions to improve runtime performance. With these improvements, #cgo noescape cFunctionName tells the compiler that memory passed to the C function cFunctionName does not escape. Also, #cgo nocallback cFunctionName tells the compiler that the C function cFunctionName does not call back to any Go functions.

Other new features and improvements in Go 1.24:

• Multiple performance improvements to the runtime in Go 1.24 have decreased CPU overheads by 2% to 3% on average across a suite of representative benchmarks. These include a new builtin map implementation based on Swiss Tables, more efficient memory allocation of small objects, and a new runtime-internal mutex implementation.
• A new tests analyzer reports common mistakes in declarations of tests, fuzzers, benchmarks, and examples in test packages, such as incorrect signatures, or examples that document non-existent identifiers. Some of these mistakes might cause tests not to run.
• The cmd/go internal binary and test caching mechanism now can be implemented by child processes implementing a JSON protocol between the cmd/go tool and the child process named by the GOCACHEPROG environment variable.
• An experimental testing/synctest package supports testing concurrent code.
• The debug/elf package offers support for handling symbol versions in dynamic ELF (Executable and Linkable Format) files.
• For Linux, Go 1.24 requires Linux kernel version 3.2 or later.

Go 1.24 follows Go 1.23, released in August 2024, featuring reduced build times for profile-guided optimization.