This release has over 240 commits to our main repo, with important features such as Go 1.27 and LLVM 22 support to keep you current with the latest and greatest. Panics are now recoverable for runtime errors like divide-by-zero, nil dereference, and map and channel failures, which makes recover() work the way you expect. The compiler now generates type-specific hash and equal functions, and there are many GC, scheduler, and timer fixes to make concurrent code more solid. USB gets dynamic endpoint registration on RP2, SAMD21/51, and nRF52840. And there is a lot of new hardware support, with a big step forward for ESP32 (interrupts, ADC, flash XIP, and the new ESP32-C6), plus STM32H7, the Puya PY32F family, a new UEFI target, and boards like the ESP32-S3-BOX-3, M5Stack Stamp-S3A, and Pimoroni Badger 2350.
- general
- all: add LLVM 22 support, and support LLVM 19 and LLVM 20 on Fedora 43
- all: build and test using Go 1.27, and raise the max supported Go version to 1.27
- all: modernize and clean up code with Go 1.24+ in mind (#5489, #5498)
- all: use unsafe.SliceData where appropriate
- all: update golang.org/x/tools and go-llvm
- cli: add basic probe-rs support
- cli: clarify the runtime.alloc linker error with -gc=none
- main: allow the -o flag to point to a directory
- main: make the -monitor flag on flash respect the port
- main: update to espflasher 0.8.0 with fixes for esp32c3 and esp32s3
- cgo: add CGO_CFLAGS support (#5453)
- version: update to 0.42.0 for the new dev cycle
- docs: add agents.md guideline for use of ASD-STE100 (#5566)
- compiler
- compiler, runtime: make runtime, map, and channel panics recoverable
- compiler, runtime: support recover on riscv64
- compiler, runtime, reflect: generate type-specific hash/equal (#5359)
- support Go 1.27 generic methods via the x/tools upgrade
- canonicalize generic instance and method signature identities
- disambiguate function-local named types and generic instance link names (#5336)
- exclude generic methods from runtime method sets
- support file-level //go:linkname directives and the //go:linknamestd pragma
- add the //go:noheap pragma
- pass large aggregates by pointer
- use LLVM intrinsics for math trig operations
- optimize zero-sized allocations
- consistently pass layout and alignment to createAlloc
- handle nested unsigned shift being untyped after type resolution (#5497)
- store the defer list head in the defer frame and centralize deferred call records
- centralize SSA loads, stores, result handling, and LLVM function type construction
- transform, compiler: support the captures(none) attribute of LLVM 21
- compiler: make composite map hashes order dependent
- core
- reflect: add Type.ConvertibleTo and complex, rune, and integer string conversions
- reflect: implement MakeChan
- reflect: add missing iterator methods
- reflect, reflectlite: make IsRO and MakeRO package methods
- sync: add Map.CompareAndSwap and Map.CompareAndDelete
- sync: fix deadlock in the Map.Range callback
- os, syscall: add Statfs and Fstatfs stubs and Getpagesize for non-hosted targets
- os: add File.Chown on the unix path
- runtime, syscall, internal/poll, os: wasip1 poll_oneoff scheduler integration and net.FileListener (#5386)
- runtime, testing: support Goexit, SkipNow, and FailNow
- syscall: remove sliceHeader, use unsafe.SliceData more
- builder, cgo, syscall: replace fixed-size array casts with unsafe.Slice
- builder, loader: fix -ldflags -X not overriding variables with default values
- builder: build SSA before compiling packages
- builder: increase the stack size margin for automatic stack allocation
- builder: do not count non-writable SHT_NOBITS sections as RAM or bss
- builder: link stack probes on Windows amd64 and arm64, and add chkstk2.S for windows/386
- builder: add strlen to the wasm builtins
- builder: retry cached archive renames on Windows (#5462)
- loader: avoid a race condition when loading the package list, and skip object resolution
- interp: bail out of loops that iterate too many times (#5395)
- interp: fix partial store aliasing and avoid repeated object clones
- interp: defer out-of-bounds loads to runtime instead of crashing
- interp: mark pointers in aggregate call operands as external
- interp: fix switch-instruction handling for the new case-value API of LLVM 22
- transform: follow returned pointer and aggregate alloc aliases
- transform: add -print-allocs-cover and restore the -print-allocs reason output
- device: add device/uefi and device/amd64
- wasm: patch wasm_exec.js and wasm_exec_node.js from Go 1.18+ (#5483)
- net
- update the net module with a roundtrip fix for js/wasm
- runtime
- make divide-by-zero and nil dereference panics recoverable
- add a Windows vectored exception handler for recoverable panics
- make Goexit exit host threads, and encode a pending Goexit in the panic state
- make out-of-memory and fatal failures unrecoverable
- improve the hardfault handler and stack reporting on Cortex-M
- prevent timer starvation in the cores scheduler
- do not access the timer queue outside of the lock
- fix ticker not stopping when Stop races with its callback (#5487)
- wake channel waiters after releasing locks (#5513)
- implement SetFinalizer and run syscall/js finalizers without a manual GC (#5545)
- implement MemStats.NumGC
- add runtime.fastrandn (#5502)
- make arrays and struct field hashes order dependent
- add critical-section fallbacks for atomic And and Or
- gc: pause all cores before scanning the stack and globals
- gc: correct the old size calculation in block realloc
- gc: correct the leaking allocator bounds and overflow checks
- gc: move objHeader to the end of the block header
- fix the leaking GC build with the cores scheduler
- rp2040: fix -gc=leaking and -gc=none
- rp2: handle the RP2350 shared FIFO IRQ for GC (#5482)
- esp32c6: select the 80MHz PLL as the TIMG0 timer clock source
- split baremetal memory setup and the Windows PE globals scan for UEFI (#5360, #5361)
- machine
- usb: support bidirectional endpoints by dynamic registration on RP2, SAMD21/51, and nRF52840 (#5447)
- usb: generate endpoint descriptors dynamically
- usb: implement endpoint stall for nRF52840
- usb: fix a truncated string descriptor when the host requests a short maxLen (#5449)
- usb: add USBDevice.Attach and USBDevice.Detach (#5563)
- usb/cdc: fix the RP2 USB CDC TX race with the cores scheduler (#5391)
- add UART line inversion support (#5522)
- optimize RTT initialization
- device/arm: add ARM v7-M MPU support
- esp32: add interrupt support with vector table, timer alarm, and GPIO SetInterrupt
- esp32: add interrupt-based UART RX and fix the init order
- esp32: implement flash XIP (execute-in-place) support
- esp32: add ADC driver (#5595)
- esp32: fix pullup and pulldown on RTC GPIO pins
- esp32: remove dead code and fix GC root scanning
- esp32: configure UARTs to the specified pins and yield while waiting for the buffer
- esp32, esp32s3: fix the boot crash caused by the LLVM 22 lld l32r relocation bug
- esp32s3: fix register-window corruption under interrupt load
- esp32s3: add temperature reading
- esp32c6: add a minimal implementation with I2C and ADC support
- stm32: fix UART transmission, baud rate, and interrupt handling
- stm32: add an OTG FS USB driver for F4 and F7
- stm32: add STM32H7 and NUCLEO-H753ZI support
- stm32: add support for the STM32U031 chip
- stm32: make the HSE crystal frequency selectable
- stm32u5: configure the system clock to 160 MHz
- nrf: avoid a too high priority interrupt on SoftDevice
- rp2: allow SPI transmit-only without SDI (#5437)
- rp2: clear the USB buffer status before the endpoint handlers
- rp2350: fix the ROM CS control for the RP2350 ROM code
- add GP aliases for waveshare-rp2040-zero
- gba: add support for mGBA debugging
- gba: add bios interrupt flags and sound register constants (#5445)
- targets
- add minimal uefi target support with the LinkerFlavor option (#5452, #5465)
- uefi: add support for UEFI time and events, fix STOP newline conversion (#5549)
- uefi: add support for the tasks scheduler and make it the default (#5553)
- add Puya PY32F MCU support (#5106)
- add esp32s3-box-3 (#5388)
- add M5Stack Stamp-S3A (#5524)
- add Pimoroni Blinky 2350 and Badger 2350 (#5434)
- add the 'Plus' board variant of SeeedStudio XIAO nrf52840 (#5479)
- esp32: adjust memory usage, add DRAM1 sections, and export the symbols needed for wifi
- esp32c3: add the BT ROM functions to the linker
- esp32: add the espradio tag for convenience
- builder: fix esp32 XIP so large programs flash correctly, including QEMU image offsets
- wasm_exec.js: add runtime.getRandomData to the gojs imports, coerce memory offsets to unsigned, and reset _pendingEvent
- libs
- update macos-minimal-sdk to v0.1.0
- build/test
- ci: run the full smoke test once, and split the GNUmakefile (#5616)
- ci: publish a draft release from the artifacts that CI already built
- ci: stop the LLVM caches from being evicted
- ci: modify builds to use LLVM 22
- ci: add a check for compatibility with older Go and LLVM versions
- ci: add a job to make sure go.sum stays in sync with go.mod
- ci: re-add fmt-check, and remove the CircleCI configuration
- ci: adjust runner sizes for Linux, Windows, and macOS
- build: statically link the MinGW runtime in the LLVM tools on Windows
- Makefile: use ${LLVM_PROJECTDIR} during the copy phase
- GNUmakefile: disable DWARF compression for CGo objects, and update the stdlib test lists
- test: run ESP32 programs in QEMU
- test: support simavr 1.8+
- test: normalize LLVM IR when updating goldens
- test: convert TestBinarySize to a golden file test
- testdata: add regression tests for generic instances, generic aliases, and large aggregates
- test: skip flaky and Go 1.27 affected tests for now