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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
# c09aa380 03-Feb-2026 Joel Dice <[email protected]>

deprecate `[Typed]Func::post_return[_async]` and make them no-ops (#12498)

* deprecate `[Typed]Func::post_return[_async]` and make them no-ops

With the advent of the Component Model concurrency ABI

deprecate `[Typed]Func::post_return[_async]` and make them no-ops (#12498)

* deprecate `[Typed]Func::post_return[_async]` and make them no-ops

With the advent of the Component Model concurrency ABI and it's `task.return`
intrinsic, post-return functions have been informally deprecated and are
expected to be removed for WASI 1.0 and the corresponding stable edition of the
Component Model. Consequently, it does not make sense anymore to require
embedders to explicitly call the post-return function after using
`[Typed]Func::call[_async]`.

As of this commit, `[Typed]Func::post_return[_async]` are no-ops. Instead, the
post-return function is called automatically as part of
`[Typed]Func::call[_async]` if present, which is how
`[Typed]Func::call_concurrent` has worked all along. In addition, this commit
fixes and tests a couple of cases where the task and/or thread was being
disposed of before the post-return function was called.

* address review feedback

* test post-return function in more scenarios

Specifically, I've split the `invoke_post_return` test into multiple tests:

- using `TypedFunc::call`
- using `TypedFunc::call_async` with concurrency support enabled
- using `TypedFunc::call_async` with concurrency support disabled
- using `Func::call_async` with concurrency support disabled
- using `TypedFunc::call_concurrent`

* remove GCC/clang-specific deprecation attribute

This broke the MSVC build.

* bless bindgen output

* remove obsolete post-return functions and fields

Now that post-return calls are handled internally without requiring explicit
action by the embedder, we can avoid unnecessary bookkeeping.

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Revision tags: 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, 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, 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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# 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
# 95cc0297 16-Apr-2025 Pat Hickey <[email protected]>

Component and Instance have corresponding get_export, get_export_index (#10597)

* component::Instance: get_export gives a ComponentItem, ExportIndex pair

just like Component::export_index does

* a

Component and Instance have corresponding get_export, get_export_index (#10597)

* component::Instance: get_export gives a ComponentItem, ExportIndex pair

just like Component::export_index does

* align Instance and Component with get_export and get_export_index

* fix example

* component macro expanded: bless output

* fix component model tests

* cli only needs get_export_index

* code review: deduplicate export to typedef transformation into ComponentItem::from_export

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Revision tags: v31.0.0, v30.0.2, v30.0.1, v30.0.0, v29.0.1, v29.0.0, v28.0.1, v28.0.0, v27.0.0, v26.0.1, v25.0.3, v24.0.2, v26.0.0, v21.0.2, v22.0.1, v23.0.3, v25.0.2, v24.0.1, v25.0.1, v25.0.0
# 78b1eb4e 17-Sep-2024 Trevor Elliott <[email protected]>

Use `instrument` in generated `call_` functions (#9263)

* Add async tracing versions of the component-macro tests

* Use instrument when generating async call functions with tracing

* Update tests