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Revision tags: dev, v36.0.9, v44.0.1, v43.0.2, v36.0.8, v24.0.8, v44.0.0, v43.0.1, v42.0.2, v36.0.7, v24.0.7, v43.0.0, v42.0.1, v41.0.4, v42.0.0, v40.0.4, v36.0.6, v24.0.6, v41.0.3, v41.0.2, v41.0.1, v36.0.5, v40.0.3, v41.0.0, v36.0.4, v39.0.2, v40.0.2, v40.0.1
# 96e19700 07-Jan-2026 Nick Fitzgerald <[email protected]>

Migrate the `wasmtime` crate to `wasmtime_environ::error::*` (#12231)

* Migrate the `wasmtime` crate to `wasmtime_environ::error::*`

Instead of `anyhow::Error`.

This commit re-exports the `wasmtim

Migrate the `wasmtime` crate to `wasmtime_environ::error::*` (#12231)

* Migrate the `wasmtime` crate to `wasmtime_environ::error::*`

Instead of `anyhow::Error`.

This commit re-exports the `wasmtime_environ::error` as the `wasmtime::error`
module, updates the prelude to include these new error-handling types, redirects
our top-level `wasmtime::{Error, Result}` re-exports to re-export
`wasmtime::error::{Error, Result}`, and updates various use sites that were
directly using `anyhow` to use the new `wasmtime` versions.

This process also required updating the component macro and wit-bindgen macro to
use the new error types instead of `anyhow`.

Part of https://github.com/bytecodealliance/wasmtime/issues/12069

* Replace wasmtime::error::Thing with wasmtime::Thing where it makes sense

* cargo fmt

* Move `crate::error::Thing` to `crate::Thing` where it makes sense

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Revision tags: v40.0.0, v39.0.1, v39.0.0, v38.0.4, v37.0.3, v36.0.3, v24.0.5, v38.0.3, v38.0.2, v38.0.1, v37.0.2
# 4dd4b890 01-Oct-2025 anlavandier <[email protected]>

Fix(wit_bindgen): use declared defaults to decide on `Send` Bounds in `Wastime::world_add_to_linker` (#11761)

* feat: make FonctionConfig.default pub(crate)

Signed-off-by: Antoine Lavandier <antoin

Fix(wit_bindgen): use declared defaults to decide on `Send` Bounds in `Wastime::world_add_to_linker` (#11761)

* feat: make FonctionConfig.default pub(crate)

Signed-off-by: Antoine Lavandier <[email protected]>

* fix: use declared imports/exports defaults when deciding on Send bounds

Signed-off-by: Antoine Lavandier <[email protected]>

* fix: add Send bound on relevant test output

Signed-off-by: Antoine Lavandier <[email protected]>

* fix(tests): add test using imports to define send bounds

Signed-off-by: Antoine Lavandier <[email protected]>

* fix(fmt): make rustfmt happy

Signed-off-by: Antoine Lavandier <[email protected]>

* fix(fmt): actually make rustfmt happy this time

Signed-off-by: Antoine Lavandier <[email protected]>

---------

Signed-off-by: Antoine Lavandier <[email protected]>

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Revision tags: v37.0.1, v37.0.0, v36.0.2, v36.0.1, v36.0.0
# 1155d6df 28-Jul-2025 Alex Crichton <[email protected]>

Redesign function configuration in `bindgen!` (#11328)

* Redesign function configuration in `bindgen!`

This commit is a redesign of how function-level configuration works in
Wasmtime's `bindgen!` m

Redesign function configuration in `bindgen!` (#11328)

* Redesign function configuration in `bindgen!`

This commit is a redesign of how function-level configuration works in
Wasmtime's `bindgen!` macro. The main goal of this redesign is to
better support WASIp3 and component model async functions. Prior to this
redesign there was a mish mash of mechanisms to configure behavior of
imports/exports:

* The `async` configuration could turn everything async, nothing async,
only some imports async, or everything except some imports async.

* The `concurrent_{imports,exports}` keys were required to explicitly
opt-in to component model async signatures and applied to all
imports/exports.

* The `trappable_imports` configuration would indicate a list of imports
allowed to trap and it had special configuration for everything,
nothing, and only a certain list.

* The `tracing` and `verbose_tracing` keys could be applied to either
nothing or all functions.

Overall the previous state of configuration in `bindgen!` was clearly a
hodgepodge of systems that organically grew over time. In my personal
opinion it was in dire need of a refresh to take into account how
component-model-async ended up being implemented as well as
consolidating the one-off systems amongst all of these configuration
keys. A major motivation of this redesign, for example, was to inherit
behavior from WIT files by default. An `async` function in WIT should
not require `concurrent_*` keys to be configured, but rather it should
generate correct bindings by default.

In this commit, all of the above keys were removed. All keys have been
replaced with `imports` and `exports` configuration keys. Each behaves
the same way and looks like so:

bindgen!({
// ...
imports: {
// enable tracing for just this function
"my:local/interface/func": tracing,

// enable verbose tracing for just this function
"my:local/interface/other-func": tracing | verbose_tracing,

// this is blocking in WIT, but generate async bindings for
// it
"my:local/interface/[method]io.block": async,

// like above, but use "concurrent" bindings which have
// access to the store.
"my:local/interface/[method]io.block-again": async | store,

// everything else is, by default, trappable
default: trappable,
},
});

Effectively all the function-level configuration items are now bitflags.
These bitflags are by default inherited from the WIT files itself (e.g.
`async` functions are `async | store` by default). Further configuration
is then layered on top at the desires of the embedder. Supported keys are:

* `async` - this means that a Rust-level `async` function should be
generated. This is either `CallStyle::Async` or
`CallStyle::Concurrent` as it was prior, depending on ...

* `store` - this means that the generated function will have access to
the store on the host. This is only implemented right now for `async |
store` functions which map to `CallStyle::Concurrent`. In the future
I'd like to support just-`store` functions which means that you could
define a synchronous function with access to the store in addition to
an asynchronous function.

* `trappable` - this means that the function returns a
`wasmtime::Result<TheWitBindingType>`. If `trappable_errors` is
applicable then it means just a `Result<TheWitOkType,
TrappableErrorType>` is returned (like before)

* `tracing` - this enables `tracing!` integration for this function.

* `verbose_tracing` - this logs all argument values for this function
(including lists).

* `ignore_wit` - this ignores the WIT-level defaults of the function
(e.g. ignoring WIT `async`).

The way this then works is all modeled is that for any WIT function
being generated there are a set of flags associated with that function.
To calculate the flags the algorithm looks like:

1. Find the first matching rule in the `imports` or `exports` map
depending on if the function is imported or exported. If there is no
matching rule then use the `default` rule if present. This is the
initial set of flags for the function (or empty if nothing was
found).

2. If `ignore_wit` is present, return the flags from step 1. Otherwise
add in `async | store` if the function is `async` in WIT.

The resulting set of flags are then used to control how everything is
generated. For example the same split traits of today are still
generated and it's controlled based on the flags. Note though that the
previous `HostConcurrent` trait was renamed to `HostWithStore` to make
space for synchronous functions in this trait in the future too.

The end result of all these changes is that configuring imports/exports
now uses the exact same selection system as the `with` replacement map,
meaning there's only one system of selecting functions instead of 3.
WIT-level `async` is now respected by default meaning that bindings work
by default without further need to configure anything (unless more
functionality is desired).

One final minor change made here as well is that auto-generated
`instantiate` methods are now always synchronous and an
`instantiate_async` method is unconditionally generated for async mode.
This means that bindings always generate both functions and it's up to
the embedder to choose the appropriate one.

Closes #11246
Closes #11247

* Update expanded test expectations

prtest:full

* Fix the min platform embedding example

* Fix doc tests

* Always generate `*WithStore` traits

This helps when using the `with` mapping since that can always assume
that `HostWithStore` is available in the generated bindings, avoiding
the need to duplicate configuration options.

* Update test expectations

* Review comments

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Revision tags: v35.0.0, v24.0.4, v33.0.2, v34.0.2, v34.0.1, v33.0.1, v24.0.3, v32.0.1, v34.0.0
# beca86b0 09-Jun-2025 Alex Crichton <[email protected]>

Re-enable concurrent bindings generation tests (#10972)

* Re-enable concurrent bindings generation tests

This commit re-enables tests for bindings generation for concurrent
calls in the main repo

Re-enable concurrent bindings generation tests (#10972)

* Re-enable concurrent bindings generation tests

This commit re-enables tests for bindings generation for concurrent
calls in the main repo after all syncs have now finished with wasip3.
This additionally adds some skeleton APIs that the bindings generator
uses which are necessary to get tests passing.

* Update test expectations

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Revision tags: v33.0.0
# f81c0dc0 13-May-2025 Alex Crichton <[email protected]>

Add `T: 'static` to `Store<T>` (#10760)

* Add `T: 'static` to `Store<T>

Since the beginning the `T` type parameter on `Store<T>` has had no
bounds on it. This was intended for maximal flexibility i

Add `T: 'static` to `Store<T>` (#10760)

* Add `T: 'static` to `Store<T>

Since the beginning the `T` type parameter on `Store<T>` has had no
bounds on it. This was intended for maximal flexibility in terms of what
embedders place within a `Store<T>` and I've personally advocated that
we need to keep it this way. In the development of the WASIp3 work,
however, I've at least personally reached the conclusion that this is no
longer tenable and proceeding will require adding a `'static` bound to
data within a store.

Wasmtime today [already] carries unsafe `transmute`s to work around this
lack of `'static` bound, and while the number of `unsafe` parts is
relatively small right now we're still fundamentally lying to the
compiler about lifetime bounds internally. With the WASIp3 async work
this degree of "lying" has become even worse. Joel has written up some
examples [on Zulip] about how the Rust compiler is requiring `'static`
bounds in surprising ways. These patterns are cropping up quite
frequently in the WASIp3 work and it's becoming particularly onerous
maintaining all of the `unsafe` and ensuring that everything is in sync.

In the WASIp3 repository I've additionally [prototyped a change] which
would additionally practically require `T: 'static` in more locations.
This change is one I plan on landing in Wasmtime in the near future and
while its main motivations are for enabling WASIp3 work it is also a
much nicer system than what we have today, in my opinion.

Overall the cost of not having `T: 'static` on `Store<T>` is effectively
becoming quite costly, in particular with respect to WASIp3 work. This
is coupled with all known embedders already using `T: 'static` data
within a `Store<T>` so the expectation of the impact of this change is
not large. The main downside of this change as a result is that when and
where to place `'static` bounds is sort of a game of whack-a-mole with
the compiler. For example I changed `Store<T>` to require `'static`
here, but the rest of the change is basically "hit compile until rustc
says it's ok". There's not necessarily a huge amount of rhyme-or-reason
to where `'static` bounds crop up, which can be surprising or difficult
to work with for users.

In the end I feel that this change is necessary and one we can't shy
away from. If problems crop up we'll need to figure out how to thread
that needle at that time, but I'm coming around to thinking that
`T: 'static` is just a fundamental constraint we'll have to take on at
this time. Maybe a future version of Rust that fixes some of Joel's
examples (if they can be fixed, we're not sure of that) we could
consider relaxing this but that's left for future work.

[already]: https://github.com/bytecodealliance/wasmtime/blob/35053d6d8d1a5d4692cf636cba0c920b4a79a44b/crates/wasmtime/src/runtime/store.rs#L602-L611
[on Zulip]: https://rust-lang.zulipchat.com/#narrow/channel/122651-general/topic/.22type.20may.20not.20live.20long.20enough.22.20for.20generic.20closure/near/473862072
[prototyped a change]: https://github.com/bytecodealliance/wasip3-prototyping/pull/158

* Remove a no-longer-necessary `unsafe` block

* Update test expectations

* Fix gc-disabled builds

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# 29d04b15 07-May-2025 Alex Crichton <[email protected]>

Move the `GetHost` trait used in `bindgen!` into Wasmtime (#10746)

* Move the `GetHost` trait used in `bindgen!` into Wasmtime

Turns out we don't actually need to generate this `GetHost` trait, we

Move the `GetHost` trait used in `bindgen!` into Wasmtime (#10746)

* Move the `GetHost` trait used in `bindgen!` into Wasmtime

Turns out we don't actually need to generate this `GetHost` trait, we
can instead have it live in one location with extra documentation. There
are already extra bounds on the `Host` associated type at all call-sites
so there's no need to additionally have trait bounds in the trait
definition, meaning the trait definition is always the same and it can
move within Wasmtime.

This shouldn't have any impact on any embedders today, it's just moving
things around.

* Review comments

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# bb77f602 21-Apr-2025 Pat Hickey <[email protected]>

wasmtime-wit-bindgen: Typecheck exports at {Foo}Indices construction (#10610)

* wasmtime::component: make it possible to typecheck export funcs

* wasmtime-wit-bindgen: add typechecking on construct

wasmtime-wit-bindgen: Typecheck exports at {Foo}Indices construction (#10610)

* wasmtime::component: make it possible to typecheck export funcs

* wasmtime-wit-bindgen: add typechecking on construction of Indices struct

* wit-bindgen: reduce to a single Indices constructor which takes InstancePre

* bless bindgen output

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Revision tags: v32.0.0, v31.0.0, v30.0.2, v30.0.1, v30.0.0
# 636435f1 22-Jan-2025 Joel Dice <[email protected]>

async/stream/future support for wasmtime-wit-bindgen (#10044)

* async/stream/future support for wasmtime-wit-bindgen

I've split this out of #9582 to make review easier.

This patch adds async/strea

async/stream/future support for wasmtime-wit-bindgen (#10044)

* async/stream/future support for wasmtime-wit-bindgen

I've split this out of #9582 to make review easier.

This patch adds async/stream/future/error-context support to the host binding
generator, along with placeholder type and function definitions in the
`wasmtime` crate which the generated bindings can refer to. See
https://github.com/dicej/rfcs/blob/component-async/accepted/component-model-async.md#componentbindgen-updates
for the design and rationale.

Note that I've added temporary `[patch.crates-io]` overrides in Cargo.toml until
https://github.com/bytecodealliance/wit-bindgen/pull/1130 and
https://github.com/bytecodealliance/wasm-tools/pull/1978 have been released.

Also note that we emit a `T: 'static` bound for `AsContextMut<Data = T>` when
generating bindings with `concurrent_imports: true`. This is only because
`rustc` insists that the closure we're passing to
`LinkerInstance::func_wrap_concurrent` captures the lifetime of `T` despite my
best efforts to convince it otherwise. Alex and I suspect this is a limitation
in the compiler, and I asked about it on the rust-lang Zulip, but we haven't
been able to determine a workaround so far.

Signed-off-by: Joel Dice <[email protected]>

remove obsolete TODO comment

Signed-off-by: Joel Dice <[email protected]>

make `futures` dep optional

Signed-off-by: Joel Dice <[email protected]>

update `wasm-tools` and `wit-bindgen`

Signed-off-by: Joel Dice <[email protected]>

* run cargo vet

Signed-off-by: Joel Dice <[email protected]>

---------

Signed-off-by: Joel Dice <[email protected]>

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