47.0.0
Released 2026-07-20.
Added
- Wasmtime now has the WebAssembly GC proposal enabled by default.
#13594
- Wasmtime now has the WebAssembly exception-handling proposal enabled by
default.
#13603
- Cranelift now supports the compact unwind format on Mach-O platforms.
#13586
- Wasmtime now supports bounds-checked unsafe intrinsics which take spectre
mitigations into account.
#13597
- The wasmtime::Engine type now supports reflection to determine the value of
most Config options that were selected during creation.
#13671
- Support for fibers on unsupported architectures is now supported through an
opt-in compile time Cargo feature defining a C API embedders can implement.
#13620
- Embedders can now create an ArrayRef with a memcpy-style constructor.
#13716
- A new Accessor::poll_ready_for_concurrent_call API can be used to detect
when backpressure indicates that a function is ready to be invoked.
#13683
Changed
- Support for wasi-threads and Wasmtime's wasi-common crate have been removed.
For more information see the associated RFC in Wasmtime.
#13558
- The call_indirect instruction of final super types has been optimized when
the GC proposal is enabled.
#13572
- Cranelift's *_imm builder helpers have been deprecated in favor of
*imm{s,u} helpers.
#13583
- The wasmtime CLI's syntax supported for --invoke with components now
supports fully qualified WIT interface names.
#13564
- Cranelift's stack_{load,store} instructions have been removed.
#13580
- Cranelift's {band,bor,bxor}_not instructions have been removed.
#13590
- Cranelift's global_value instruction has been removed.
#13682
- The wasmtime wizer subcommand now supports specifying the initialization
function with WAVE for components.
#13582
- Wasmtime's codegen on aarch64 for the i32x4.relaxed_dot_i8x16_i7x16_add_s
wasm instruction now uses a single sdot instruction where possible.
#13640
- Wasmtime's .wasmtime{traps,addrmap} sections in *.cwasm files are now
significantly smaller.
#13628
- Wasmtime now supports removing symbols from *.cwasm files and additionally
has a documentation page about producing minimally-sized *.cwasm outputs.
#13630
- Wasmtime now suports resources in the named_imports option of bindgen!.
#13666
- Wasmtime now invokes the host's socket_addr_check callback for implicit
binds performed in WASIp3.
#13677
- Wasmtime's component-to-component sync-to-sync fused adapters have been
optimized.
#13695
- Cranelift now supports RISC-V's Zvbb extension.
#13738
Fixed
- The IPV6_V6ONLY option is now set for UDP sockets.
#13596
- Uncaught wasm exceptions at component boundaries are now turned into traps to
prevent components catching exceptions from other components.
#13613
- Addresses being sent do with WASIp3 and UDP are now validated as they are in
WASIp2.
#13631
- GC roots on component model fiber stacks are now properly traced.
#13693
- An unaligned load when reading debug state slot values has been fixed.
#13791
