Go 1 24

Go 1.24

This overview applies when the project's target Go version is at least 1.24.

Language

• Available capability: parameterised type aliases when an existing generic type must be re-exported or renamed without creating a distinct defined type.
• Unsupported or discouraged: depend on GOEXPERIMENT=noaliastypeparams; it is a temporary opt-out and the corresponding experiment switch is removed in Go 1.25.

Tools and modules

• Tooling support: executable dependencies with tool directives in go.mod instead of blank imports in tools.go. Add one with go get -tool, run it with go tool, and use the tool meta-pattern to upgrade or install all tracked tools.
• Available capability: go build -json, go install -json, and go test -json when automation needs structured build diagnostics. Update consumers to distinguish build actions interleaved with test actions.
• Configuration support: GOAUTH for authenticated private-module fetches instead of embedding credentials in repository configuration.
• GODEBUG=toolchaintrace=1 is available when diagnosing automatic toolchain selection.
• go vet can catch malformed tests, non-constant fmt.Printf(s) calls without arguments, invalid point-release build tags, and copied locks in three-clause loop variables.
• Apply #cgo noescape and #cgo nocallback only when the C function's behaviour proves the annotation; incorrect declarations can invalidate compiler assumptions.

Runtime and resource lifetime

• runtime.AddCleanup is the modern alternative to runtime.SetFinalizer. Use it for one or more cleanups without delaying reclamation or creating the same cycle-related leaks as finalisers.
• Available capability: weak.Pointer only for low-level caches, weak maps, or canonicalisation structures that cannot use unique; do not use weak reachability as ordinary ownership.
• the Swiss-table map and new runtime mutex is defaults. Use GOEXPERIMENT=noswissmap or nospinbitmutex only to isolate an upgrade regression.

Filesystems and encoding

• Available capability: os.OpenRoot and os.Root operations when filesystem access must remain beneath a directory, including across symbolic links.
• Modern alternative: iterator-returning bytes and strings split, field, and line functions when streaming values avoids an intermediate slice.
• Interface support: encoding.TextAppender or encoding.BinaryAppender when a type can append its representation into caller-owned storage and avoid a fresh allocation.
• Available capability: the JSON omitzero tag when the semantic requirement is to omit a zero value, especially zero time.Time values. Keep omitempty for JSON-empty semantics.
• Available capability: iterator methods in go/types rather than Len and At index loops when traversing exposed sequences.

Cryptography

• Available capability: the standard-library crypto/mlkem, crypto/hkdf, crypto/pbkdf2, and crypto/sha3 packages instead of their golang.org/x/crypto predecessors when Go 1.24 is the minimum target.
• cipher.NewGCMWithRandomNonce is available when AES-GCM nonce generation and ciphertext prefixing should be handled by the AEAD. Do not separately supply a nonce to that AEAD.
• Replacement: deprecated OFB and CFB modes with authenticated AEAD modes. Use CTR only when an unauthenticated stream mode is explicitly required.
• Reject RSA keys smaller than 1024 bits. Use GODEBUG=rsa1024min=0 only in a test that must exercise a legacy key.
• crypto/rand.Text supports cryptographically secure random text.
• Available capability: crypto/subtle.WithDataIndependentTiming around code that requires supported architecture-specific data-independent timing.
• X25519MLKEM768 is enabled in TLS defaults, while the earlier experimental X25519Kyber768Draft00 mechanism is unavailable.
• Select a Go Cryptographic Module with GOFIPS140 and enable FIPS mode with GODEBUG=fips140=... only when the deployment's compliance policy requires it.

Testing

• Modern alternative: for b.Loop() { ... } in benchmarks so setup runs once and benchmarked calls remain live against compiler elimination.
• Available capability: T.Context or B.Context for work that must be cancelled after the test finishes and before cleanup functions run.
• Available capability: T.Chdir or B.Chdir for a scoped working-directory change in tests.
• GOEXPERIMENT=synctest is an experimental opt-in for evaluate deterministic concurrent tests with virtual time and quiescence detection. Treat the Go 1.24 API as unstable.

Compatibility

• Replacement: calls to deprecated runtime.GOROOT with locating the go executable and invoking go env GOROOT when the installation root is needed.
• Unsupported or discouraged: call deprecated math/rand.Seed; create and seed a local generator when reproducibility is required.
• Configuration support: HTTP versions through http.Server.Protocols, http.Transport.Protocols, and their HTTP/2 settings. Enable unencrypted HTTP/2 only when prior-knowledge h2c is intended.
• Platform requirement: Linux kernel 3.2 or later. Treat macOS 11 as the final supported macOS baseline for this release and remove the broken windows/arm target.
• Available capability: //go:wasmexport and -buildmode=c-shared only for supported WebAssembly host exports or WASI reactor/library builds.