Remove subtask reparenting (#12570)

This commit updates the implementation of component-model-async
primitives to remove the manual subtask reparenting process. This is
required to fix #12544 at a s

Remove subtask reparenting (#12570)

This commit updates the implementation of component-model-async
primitives to remove the manual subtask reparenting process. This is
required to fix #12544 at a semantic level because a subtask isn't ever
actually reparented, even if its parent exits. The first part of this
change is to remove the `GuestTask::subtasks` field and all relevant
manipulations of it.

This field, however, powered the `TaskExit` abstraction returned from
`call_concurrent`. This commit then subsequently deletes `TaskExit` and
all related infrastructure as it's no longer directly applicable as-is.
The rest of this change is then updating tests/bindings/etc to account
for these two changes.

The main semantic changes related to tests are:

* `wasmtime run`, with and without `--invoke`, no longer waits for all
subtasks. This instead only waits for the main task returning before
exiting. Whether or not this is the correct behavior is under
discussion in WebAssembly/component-model#608

* `wasmtime serve` has been updated to keep the store alive at least
until the response body has been fully transmitted. This is also part
of WebAssembly/component-model#608.

* Some `component-async-tests`-related tests were updated to either
avoid blocking the store as it wasn't needed or yield enough times to
ensure that the test passes.

Closes #12544

prtest:full

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Refactor how concurrency support is enabled in a `Store` (#12416)

* Document panics from using CM async machinery when CM async is not enabled

* Refactor how concurrency support is enabled in a `St

Refactor how concurrency support is enabled in a `Store` (#12416)

* Document panics from using CM async machinery when CM async is not enabled

* Refactor how concurrency support is enabled in a `Store`

This commit is an extension/refactor of #12377 and #12379. Notably this
decouples the runtime behavior of Wasmtime from enabled/disabled
WebAssembly proposals. This enables the `wasmtime serve` subcommand, for
example, to continue to disallow component-model-async by default but
continue to use `*_concurrent` under the hood.

Specifically a new `Config::concurrency_support` knob is added. This is
plumbed directly through to `Tunables` and takes over the preexisting
`component_model_concurrency` field. This field configures whether
tasks/etc are enabled at runtime for component-y things. The default
value of this configuration option is the same as `cfg!(feature =
"component-model-async")`, and this field is required if
component-model-async wasm proposals are enabled. It's intended that
eventually this'll affect on-by-default wasm features in Wasmtime
depending if the support is compiled in.

This results in a subtle shift in behavior where component-model-async
concurrency is used by default now because the feature is turned on by
default, even though the wasm features are off-by-default. This required
adjusting a few indices expected in runtime tests due to tasks/threads
being allocated in index spaces.

Finally, this additionally denies access at runtime to
`Linker::*_concurrent` when concurrent support is disabled as otherwise
the various runtime data structures won't be initialized and panics will
happen.

Closes #12393

* Add a `-Wconcurrency-support` CLI flag

Used to update disas tests to show that, when disabled, old codegen
quality is preserved

* Ungate `Config` flag

* Review comments

---------

Co-authored-by: Nick Fitzgerald <[email protected]>

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Remove need for explicit `Config::async_support` knob (#12371)

* Refactor component model host function definitions

Push the `async`-ness down one layer.

* Remove need for explicit `Config::async

Remove need for explicit `Config::async_support` knob (#12371)

* Refactor component model host function definitions

Push the `async`-ness down one layer.

* Remove need for explicit `Config::async_support` knob

This commit is an attempt to step towards reconciling "old async" and
"new async" in Wasmtime. The old async style is the original async
support in Wasmtime with `call_async`, `func_wrap_async`, etc, where the
main property is that the store is "locked" during an async operation.
Put another way, a store can only execute at most one async operation at
a time. This is in contrast to "new async" support in Wasmtime with the
component-model-async (WASIp3) support, where stores can have more than
one async operation in flight at once.

This commit does not fully reconcile these differences, but it does
remove one hurdle along the way: `Config::async_support`. Since the
beginning of Wasmtime this configuration knob has existed to explicitly
demarcate a config/engine/store as "this thing requires `async` stuff
internally." This has started to make less and less sense over time
where the line between sync and async has become more murky with WASIp3
where the two worlds comingle. The goal of this commit is to deprecate
`Config::async_support` and make the function not actually do anything.

In isolation this can't simply be done, however, because there are many
load-bearing aspects of Wasmtime that rely on this `async_support` knob.
For example once epochs + yielding are enabled it's required that all
Wasm is executed on a fiber lest it hit an epoch and not know how to
yield. That means that this commit is not a simple removal of
`async_support` but instead a refactoring/rearchitecting of how async is
used internally within Wasmtime. The high-level ideas within Wasmtime
now are:

* A `Store` has a "requires async" boolean stored within it.
* All configuration options which end up requiring async, such as
yielding with epochs, turn this boolean on.
* Creation of host functions which use async
(e.g. `func_wrap_{async,concurrent}`) will also turn this option on.
* Synchronous API entrypoints into Wasmtime ensure that this boolean is
disabled.
* Asynchronous APIs are usable at any time.

This means that the concept of an async store vs a sync store is now
gone. All stores are equally capable of executing sync/async, and the
change now is that dynamically some stores will require that async is
used with certain configuration. Additionally all panicking conditions
around `async_support` have been converted to errors instead. All
relevant APIs already returned an error and things are murky enough now
that it's not necessarily trivial to get this right at the embedder
level. In the interest of avoiding panics all detected async mismatches
are now first-class `wasmtime::Error` values.

The end result of this commit is that `Config::async_support` is a
deprecated `#[doc(hidden)]` function that does nothing. While many
internal changes happened as well as having new tests for all this sort
of behavior this is not expected to have a great impact on external
consumers. In general a deletion of `async_support(true)` is in theory
all that's required. This is intended to make it easier to think about
async/sync/etc in the future with WASIp3 and eventually reconcile
`func_wrap_async` and `func_wrap_concurrent` for example. That's left
for future refactorings however.

prtest:full

* Review comments

* Fix CI failures

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Only create `ConcurrentState` in a `Store` when CM async is enabled (#12377)

* Only create `ConcurrentState` in a `Store` when CM async is enabled

Creating the default `ConcurrentState` will create

Only create `ConcurrentState` in a `Store` when CM async is enabled (#12377)

* Only create `ConcurrentState` in a `Store` when CM async is enabled

Creating the default `ConcurrentState` will create a `FuturesUnordered` which
will allocate. By making this state optional, we can keep making progress on
https://github.com/bytecodealliance/wasmtime/issues/12069, and put off dealing
with `FuturesUnordered` until when we are ready to try and make CM async code
handle OOMs.

* Support dynamically disabling component-model-async at runtime

* fix warnings in certain cfg builds

* fix another warning

* Forcibly enable CM async for a couple wast tests

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refactor recursive reentrance checks (#12349)

* refactor recursive reentrance checks

This commit makes a few changes related to recursive reentrance checks, instance
poisoning, etc.:

- Implements

refactor recursive reentrance checks (#12349)

* refactor recursive reentrance checks

This commit makes a few changes related to recursive reentrance checks, instance
poisoning, etc.:

- Implements the more restrictive lift/lower rules described in https://github.com/WebAssembly/component-model/pull/589 such that a component instance may not lower a function lifted by one of its ancestors, nor vice-versa. Any such lower will result in a fused adapter which traps unconditionally, preventing guest-to-guest recursive reentrance without requiring data flow analysis.
- Note that this required updating several WAST tests which were violating the new rule, including some in the `tests/component-model` Git submodule, which I've updated.
- This is handled entirely in the `fact` module now; I've removed the `AlwaysTrap` case previously handled by `wasmtime-cranelift`.
- Removes `FLAG_MAY_ENTER` from `InstanceFlags`. It is no longer needed for guest-to-guest calls due to the above, and for guest-to-host-to-guest calls we can rely on either `FLAG_NEEDS_POST_RETURN` for sync-lifted functions or the `GuestTask` call stack for async-lifted functions.
- Adds a `StoreOpaque::trapped` field which is set when _any_ instance belonging to that store traps, at which point the entire store is considered poisoned, meaning no instance belonging to it may be entered. This prevents indeterminant concurrent task state left over from the trapping instance from leaking into other instances.

Note that this does _not_ include code to push and pop `GuestTask` instances for
guest-to-guest sync-to-sync calls, nor for host-to-guest calls using e.g. the
synchronous `Func::call` API, so certain intrinsics which expect a `GuestTask`
to be present such as `backpressure.inc` will still fail in such cases. I'll
address that in a later PR.

Also note that I made a small change to `wasmtime-wit-bindgen`, adding a `Send`
bound on the `T` type parameter for `store | async` functions. This allowed me
to recursively call `{Typed}Func::call_concurrent` from inside a host function,
and it doesn't have any downsides AFAICT.

Fixes #12128

* bless bindgen expansions

* bless disas tests

* address review feedback

* sync `trap.h` with `trap_encoding.rs`

...and add const assertions to `trap.rs` to help avoid future divergence.

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`wit-bindgen`: Add an option to use `anyhow::Result` instead of `wasmtime::Result` (#12331)

* wit-bindgen: Add an option to use `anyhow::Result` instead of `wasmtime::Result`

* Add option to refere

`wit-bindgen`: Add an option to use `anyhow::Result` instead of `wasmtime::Result` (#12331)

* wit-bindgen: Add an option to use `anyhow::Result` instead of `wasmtime::Result`

* Add option to reference docs

* Rename `anyhow` dev dependency to `anyhow-for-testing`

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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

show more ...

cm-async: Start to fill out `{Future,Stream}Any` (#12142)

* cm-async: Start to fill out `{Future,Stream}Any`

This commit is the first step down the road of filling out the
preexisting, but empty/bu

cm-async: Start to fill out `{Future,Stream}Any` (#12142)

* cm-async: Start to fill out `{Future,Stream}Any`

This commit is the first step down the road of filling out the
preexisting, but empty/buggy, `FutureAny` and `StreamAny` types. These
are intended to behave similarly to `ResourceAny` where the embedder
doesn't have static knowledge ahead of time about the type of the
future/stream in use. Changes made here are:

* `ComponentType for {Stream,Future}Reader<T>` now correctly typecheck
the `T`.
* Conversion to/from `*Any` types now properly typechecks the payload
type against the expected type.
* `{Future,Stream}Any` now live in their own file with the matrix of
conversions to the typed variants.
* A `close` method was added to `*Any` types.

These types are not currently directly constructible but this will
likely be relaxed in the future. Additionally the host can't actually
use these values without knowing the type, which is another restriction
that will be relaxed in the future (aka implemented).

cc #11161

* Fix tests

* Skip a test on miri

show more ...

Update wasm-tools dependencies (#12031)

* Change separator style

* Update wasm-tools dependencies

* Also update wit-bindgen
* Drop `[async]` name prefixes
* Plumb `async` as part of a function ty

Update wasm-tools dependencies (#12031)

* Change separator style

* Update wasm-tools dependencies

* Also update wit-bindgen
* Drop `[async]` name prefixes
* Plumb `async` as part of a function type

Runtime handling of async functions and new traps are to be implemented
in subsequent commits. This is just getting everything running again.

* Run clang-format, also add test

* Fix some more wast tests

---------

Co-authored-by: Sy Brand <[email protected]>

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Enable borrowing components and stores mutable at the same time (#11987)

* Use `OptionsIndex` more internally in components

This updates various runtimes bits for components to use `OptionsIndex`

Enable borrowing components and stores mutable at the same time (#11987)

* Use `OptionsIndex` more internally in components

This updates various runtimes bits for components to use `OptionsIndex`
more aggressively and ultimately deletes the old `Options` type. The
`Options` type is a heavyweight package of all possible options which is
effectively a duplication of what `OptionsIndex` points to, so that's
removed in favor of directly accessing options.

* Enable borrowing components and stores mutable at the same time

This commit adds a new, safe, function to the `Instance` type for
internal use in Wasmtime which enables simultaneously borrowing the
`Component`-within-the-`Instance` as well as the original store at the
same time. This is not possible to do in safe Rust when the store is
mutable and must be implemented with `unsafe` code.

The motivation for this commit is performance. In #11974 it was
discovered that the addition of a single `Arc::clone` was enough to
reduce throughput in the embedding by 20%. While `Arc::clone` is
generally cheap I can see how a "contended" `Arc::clone` could get quite
expensive. This particular benchmark was running multiple instances of
the same component across multiple threads which were all doing many
host calls. Each host call, after the refactoring of #10959, contained
an `Arc::clone` to the component itself. This in turn led to many
threads constantly incrementing/decrementing the `Arc::clone` count of
the same `Arc` instance.

At a high level this clone is not necessary. The component lives within
the store and cannot be mutated/deleted during execution. Safe Rust,
however, forbids access to the component and mutably using the store at
the same time. Thus, this helper function enters the picture. The goal
here is to remove the `Arc::clone` calls without requiring major surgery
or such to refactor the implementations of various functions throughout
Wasmtime. The `unsafe` block used to implement this function documents
more rationale as to why this should be safe.

* Update crates/wasmtime/src/runtime/component/instance.rs

Co-authored-by: Nick Fitzgerald <[email protected]>

---------

Co-authored-by: Nick Fitzgerald <[email protected]>

show more ...

Use `.` instead of `/` for interface members. (#11947)

* Use `.` instead of `/` for interface members.

In the `wasmtime::component::generate` macro, change the syntax for
referencing functions and

Use `.` instead of `/` for interface members. (#11947)

* Use `.` instead of `/` for interface members.

In the `wasmtime::component::generate` macro, change the syntax for
referencing functions and types inside interfaces to use `.` instead
of `/`.

For example, this changes strings like
`wasi:http/types/outgoing-body`
to
`wasi:http/types.outgoing-body`
.

This makes the syntax more consistent with the syntax of
[WIT `use` statements], which use `.` for this purpose.

And, it avoids an incompatibility with the future nested namespaces syntax
([��]), where the `/d` in `a:b/c/d` is for traversing a component export
rather than an interface member.

[WIT `use` statements]: https://github.com/WebAssembly/component-model/blob/main/design/mvp/WIT.md#wit-packages-and-use
[��]: https://github.com/WebAssembly/component-model/blob/main/design/mvp/Explainer.md#gated-features

* Use the new syntax in more places.

* Revert changes to vendored WIT files.

* Revert more changes to vendored files.

* Update syntax in more places.

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Add a new `ResourceDynamic` type (#11885)

* Move `ResourceAny` to its own submodule

In preparation for upcoming other refactorings...

* Move `Resource<T>` to its own submodule

* Move `ResourceTy

Add a new `ResourceDynamic` type (#11885)

* Move `ResourceAny` to its own submodule

In preparation for upcoming other refactorings...

* Move `Resource<T>` to its own submodule

* Move `ResourceType` to its own submodule

* Move host resource table infrastructure to its own module

* Add module documentation to resource-related modules

* Add a new `ResourceDynamic` type

This commit adds a new type `wasmtime::component::ResourceDynamic` to
the embedding API which internally is more-or-less the same as
`Resource<T>` but with different type information. This
`ResourceDynamic` specifically enables storing runtime information for
managing the type of the resource as opposed to `Resource<T>` which
requires static information.

The main goal of this type is to enable exposing resources in the C API
of Wasmtime. Currently there is no way to define different resource
types in the C API because the only option is `Resource<T>`. With this
type it will be possible to create distinct resource types in the C API
for embedders to use.

cc #11437

* Apply suggestions from code review

Co-authored-by: Joel Dice <[email protected]>

---------

Co-authored-by: Joel Dice <[email protected]>

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Rename trappable_imports to trappable in macro documentation (#11674)

add `task_exit` option to `wasmtime-wit-bindgen` (#11665)

This builds on #11662 by optionally exposing the `TaskExit` return value from
`[Typed]Func::call_concurrent` in the bindings generated for e

add `task_exit` option to `wasmtime-wit-bindgen` (#11665)

This builds on #11662 by optionally exposing the `TaskExit` return value from
`[Typed]Func::call_concurrent` in the bindings generated for exported functions.

Note that the first two commits are shared with #11662.

Fixes #11600

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

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Revamp component model stream/future host API (again) (#11515)

* Revamp component model stream/future host API (again)

This changes the host APIs for dealing with futures and streams from a
"rendez

Revamp component model stream/future host API (again) (#11515)

* Revamp component model stream/future host API (again)

This changes the host APIs for dealing with futures and streams from a
"rendezvous"-style API to a callback-oriented one.

Previously you would create e.g. a `StreamReader`/`StreamWriter` pair and call
their `read` and `write` methods, respectively, and those methods would return
`Future`s that resolved when the operation was matched with a corresponding
`write` or `read` operation on the other end.

With the new API, you instead provide a `StreamProducer` trait implementation
whe creating the stream, whose `produce` method will be called as soon as a read
happens, giving the implementation a chance to respond immediately without
making the reader wait for a rendezvous. Likewise, you can match the read end
of a stream to a `StreamConsumer` to respond immediately to writes. This model
should reduce scheduling overhead and make it easier to e.g. pipe items to/from
`AsyncWrite`/`AsyncRead` or `Sink`/`Stream` implementations without needing to
explicitly spawn background tasks. In addition, the new API provides direct
access to guest read and write buffers for `stream<u8>` operations, enabling
zero-copy operations.

Other changes:

- I've removed the `HostTaskOutput`; we were using it to run extra code with
access to the store after a host task completes, but we can do that more
elegantly inside the future using `tls::get`. This also allowed me to
simplify `Instance::poll_until` a bit.

- I've removed the `watch_{reader,writer}` functionality; it's not needed now
given that the runtime will automatically dispose of the producer or consumer
when the other end of the stream or future is closed -- no need for embedder
code to manage that.

- In order to make `UntypedWriteBuffer` `Send`, I had to wrap its raw pointer
`buf` field in a `SendSyncPtr`.

- I've removed `{Future,Stream}Writer` entirely and moved
`Instance::{future,stream}` to `{Future,Stream}Reader::new`, respectively.

- I've added a bounds check to the beginnings of `Instance::guest_read` and
`Instance::guest_write` so that we need not do it later in
`Guest{Source,Destination}::remaining`, meaning those functions can be
infallible.

Note that I haven't updated `wasmtime-wasi` yet to match; that will happen in
one or more follow-up commits.

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

* Add `Accessor::getter`, rename `with_data` to `with_getter`

* fixup bindgen invocation

Signed-off-by: Roman Volosatovs <[email protected]>

* add support for zero-length writes/reads to/from host

I've added a test to cover this; it also tests direct buffer access for
`stream<u8>`, which I realized I forgot to cover earlier. And of course there
was a bug :facepalm:.

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

* add `{Destination,Source}::remaining` methods

This can help `Stream{Producer,Consumer}` implementations determine how many
items to write or read, respectively.

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

* wasi: migrate sockets to new API

Signed-off-by: Roman Volosatovs <[email protected]>

* tests: read the socket stream until EOF

Signed-off-by: Roman Volosatovs <[email protected]>

* p3-sockets: account for cancellation

Signed-off-by: Roman Volosatovs <[email protected]>

* p3-sockets: mostly ensure byte buffer cancellation-safety

Signed-off-by: Roman Volosatovs <[email protected]>

* p3-filesystem: switch to new API

Signed-off-by: Roman Volosatovs <[email protected]>

* fixup! p3-sockets: mostly ensure byte buffer cancellation-safety

* p3-cli: switch to new API

Signed-off-by: Roman Volosatovs <[email protected]>

* p3: limit maximum buffer size

Signed-off-by: Roman Volosatovs <[email protected]>

* p3-sockets: remove reuseaddr test loop workaround

Signed-off-by: Roman Volosatovs <[email protected]>

* p3: drive I/O in `when_ready`

Signed-off-by: Roman Volosatovs <[email protected]>

* fixup! p3: drive I/O in `when_ready`

* Refine `Stream{Producer,Consumer}` APIs

Per conversations last week with Roman, Alex, and Lann, I've updated these
traits to present a lower-level API based on `poll_{consume,produce}` functions
and have documented the implementation requirements for various scenarios which
have come up in `wasmtime-wasi`, particularly around graceful cancellation. See
the doc comments for those functions for details.

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

* being integration of new API

Signed-off-by: Roman Volosatovs <[email protected]>

* update wasi/src/p3/filesystem to use new stream API

This is totally untested so far; I'll run the tests once we have everything else
compiling.

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

* update wasi/src/p3/cli to use new stream API

This is totally untested and doesn't even compile yet due to a lifetime issue I
don't have time to address yet. I'll follow up later with a fix.

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

* fix: remove `'a` bound on `&self`

Signed-off-by: Roman Volosatovs <[email protected]>

* finish `wasi:sockets` adaptation

Signed-off-by: Roman Volosatovs <[email protected]>

* finish `wasi:cli` adaptation

Note, that this removes the read optimization - let's get the
implementation complete first and optimize later

Signed-off-by: Roman Volosatovs <[email protected]>

* remove redundant loop in sockets

Signed-off-by: Roman Volosatovs <[email protected]>

* wasi: buffer on 0-length reads

Signed-off-by: Roman Volosatovs <[email protected]>

* finish `wasi:filesystem` adaptation

Signed-off-by: Roman Volosatovs <[email protected]>

* remove `MAX_BUFFER_CAPACITY`

Signed-off-by: Roman Volosatovs <[email protected]>

* refactor `Cursor` usage

Signed-off-by: Roman Volosatovs <[email protected]>

* impl Default for VecBuffer

Signed-off-by: Roman Volosatovs <[email protected]>

* refactor: use consistent import styling

Signed-off-by: Roman Volosatovs <[email protected]>

* feature-gate fs Arc accessors

Signed-off-by: Roman Volosatovs <[email protected]>

* Update test expectations

---------

Signed-off-by: Joel Dice <[email protected]>
Signed-off-by: Roman Volosatovs <[email protected]>
Co-authored-by: Alex Crichton <[email protected]>
Co-authored-by: Roman Volosatovs <[email protected]>

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Refactor `AbortHandle`, renamed to `JoinHandle` (#11414)

* Refactor `AbortHandle`, renamed to `JoinHandle`

This commit is inspired by recent discussions about providing more
guarantees around dropp

Refactor `AbortHandle`, renamed to `JoinHandle` (#11414)

* Refactor `AbortHandle`, renamed to `JoinHandle`

This commit is inspired by recent discussions about providing more
guarantees around dropping WASI resources. This commit renames
`wasmtime::component::AbortHandle` to `wasmtime::component::JoinHandle`
and additionally implements `Future for JoinHandle` to know when the
associated task's future has been dropped. The renaming is intended to
more closely align with `tokio::task::JoinHandle` where
`tokio::task::AbortHandle` is notably different and doesn't have a
`Future` implementation. The `Future` implementation helps embedders
know exactly when a value has been dropped and synchronize on that.

* Clarify lack of abort-on-drop behavior

show more ...

refactor `{Stream,Future}|{Reader,Writer}` APIs and internals (#11325)

* refactor `{Stream,Future}|{Reader,Writer}` APIs and internals

This makes a several changes to how `{Stream,Future}|{Reader,W

refactor `{Stream,Future}|{Reader,Writer}` APIs and internals (#11325)

* refactor `{Stream,Future}|{Reader,Writer}` APIs and internals

This makes a several changes to how `{Stream,Future}|{Reader,Writer}` work to
make them more efficient and, in some ways, more ergonomic:

- The background tasks have been removed, allowing reads and writes to complete without task context switching. We now only allocate and use oneshot channels lazily when the other end is not yet ready; this improves real world performance benchmarks (e.g. wasi-http request handling) considerably.

- Instances of `{Stream,Future}Reader` can now be lifted and lowered directly; no need for `Host{Stream,Future}` anymore.

- The type parameter for `Stream{Reader,Writer}` no longer refers to the buffer type -- just the payload type (i.e. `StreamReader<u8>` instead of `StreamReader<Vec<u8>>`), meaning any buffer type may be used for a given read or write operation. This also means the compiler needs help with type inference less often when calling `Instance::stream`.

- Instances of `{Stream,Future}|{Reader,Writer}` now require access to the store in order to be disposed of properly. I've added RAII wrapper structs (`WithAccessor[AndValue]`) to help with this, and also updated `Store::drop` and `Instance::run_concurrent` to ensure the store thread-local is set when dropping futures closing over `&Accessor`s.

- In order to ensure that resources containing `{Stream,Future}|{Reader,Writer}` instances are disposed of properly, I've added `LinkerInstance::resource_concurrent` and have updated `wasmtime-wit-bindgen` to use it. This gives resource drop functions access to a `StoreContextMut` via an `Accessor`, allowing the stream and future handles to be disposed of.
- In order to make this work, I had to change `Accessor::instance` from a `Instance` to an `Option<Instance>`, which is awkward but temporary since we're planning to remove `Accessor::instance` entirely once we've moved concurrent state from `ComponentInstance` to `Store`.

That problem of disposal is definitely the most awkward part of all this. In
simple cases, it's easy enough to ensure that read and write handles are
disposed of properly, but both `wasmtime-wasi` and `wasmtime-wasi-http` have
some pretty complicated functions where handles are passed between tasks and/or
stored inside resources, so it can be tricky to ensure proper disposal on all
code paths. I'm open to ideas for improving this, but I suspect we'll need new
Rust language features (e.g. linear types) to make it truly ergonomic, robust,
and efficient.

While testing the above, I discovered an issue with `Instance::poll_until` such
that it would prematurely give up and return a "deadlock" trap error, believing
that there was no further work to do, even though the future passed to it was
ready to resolve the next time it was polled. I've fixed this by polling it one
last time and only trapping if it returns pending.

Note that I've moved a few associated functions from `ConcurrentState` to
`Instance` (e.g. `guest_drop_writable` and others) since they now need access to
the store; they're unchanged otherwise. Apologies for the diff noise.

Finally, I've tweaked how `wasmtime serve` to poll the guest for content before
handing the response to Hyper, which helps performance by ensuring the first
content chunk can be sent with the same TCP packet as the beginning of the
response.

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

fix wasi p3 build and test failures

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

use `ManuallyDrop` instead of `Option` in `Dropper`

This allows us to drop its `value` field in-place, i.e. without moving it,
thereby upholding the `Pin` guarantee.

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

address review comments

- Remove `DropWithStoreAndValue` and friends; go back to taking a `fn() -> T` parameter in `Instance::future` instead
- Make `DropWithStore::drop[_with]` take `&mut self` instead of `self`
- Make `WithAccessor` and `DropWithStore` private
- Instead, I've added public `Guarded{Stream,Future}{Reader,Writer}` types for RAII
- and also `{Stream,Future}{Reader,Writer}::close[_with]` methods
- Use RAII in `FutureReader::read` and `FutureWriter::write` to ensure handles are dropped if the `Future` is dropped

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

* lower host stream/future writes in background task

This avoids unsoundness due to guest realloc calls while there are host embedder
frames on the stack.

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

* fix `tcp.rs` regressions

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

---------

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

show more ...

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

show more ...

Require `Accessor` on all future/stream functions (#11250)

* Require `Accessor` on all future/stream functions

This is a follow-up to #11238 which adds `&Accessor` arguments to all
functions for fu

Require `Accessor` on all future/stream functions (#11250)

* Require `Accessor` on all future/stream functions

This is a follow-up to #11238 which adds `&Accessor` arguments to all
functions for futures and streams. Like #11238 this is done to make
future refactorings easier for the internal implementation but the
internal implementations are not updated at this time. Many functions,
for example, do not use the argument at all just yet. The purpose of
this is to ensure host usage of these functions always provides a store
context.

This change required large refactorings of the upcoming
wasmtime-wasi-http implementation in the wasip3-prototyping repository.
That's all been sorted out now though so the changes are being pulled
back here into the Wasmtime repository as well.

This commit additionally changes the `watch_*` functions on the various
stream/future types to take `&mut self` instead of `self`-by-value. This is
mostly a stylistic change and is more API-driven than anything else.
Functionally this behaves the same as before where, while watching, the
stream/future cannot be read/written to otherwise.

* Review comments

show more ...

Gut `vm::Export` to mostly be `crate::Extern` (#11229)

* Remove `Table::from_wasmtime_table`

This commit removes the unsafe function `Table::from_wasmtime_table`.
This goes a bit further and remove

Gut `vm::Export` to mostly be `crate::Extern` (#11229)

* Remove `Table::from_wasmtime_table`

This commit removes the unsafe function `Table::from_wasmtime_table`.
This goes a bit further and removes `ExportTable` entirely as well which
means that table lookup on a `vm::Instance` directly returns a
`wasmtime::Table` without any need to translate back-and-forth.

* Remove `Tag::from_wasmtime_tag`

Like the previous commit, but for tags.

* Remove `Global::from_wasmtime_global`

Like the previous commit, but for globals.

* Remove `Memory::from_wasmtime_memory`

Like the previous commit, but for memories.

* Remove `Func::from_wasmtime_function`

Like previous commits, but for functions.

* Fix lints

* Fill out missing safety comment

* Review comments

show more ...

implement Component Model async ABI (#11127)

* implement Component Model async ABI

This commit replaces the stub functions and types in
`wasmtime::runtime::component::concurrent` and its submodules

implement Component Model async ABI (#11127)

* implement Component Model async ABI

This commit replaces the stub functions and types in
`wasmtime::runtime::component::concurrent` and its submodules with the working
implementation developed in the `wasip3-prototyping` repo. For ease of review,
it does not include any new tests; I'll add those in a follow-up commit.

Note that this builds on #11123; only the most recent commit is new.

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

* clear params pointer in `call_async` when future is dropped

This ensures that the closure we pass to `prepare_call` will never see a stale
pointer.

Note that this could potentially be made more efficient; I'm starting with a
simple solution, and we can refine from there.

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

* Remove unsafety from accessing concurrent async state

* Remove a dead variant when async is disabled

* Add tests for `tls.rs` unsafe code

* Refactor `AbortHandle`

* Don't close over the entire future in the `AbortHandle`, instead
change it to just the bare minimum state to manage aborts.
* Move aborting logic into a helper `AbortHandle::run` function which
handles the is-this-aborted-check internally.
* Refactor some logic around spawns how `AbortHandle` is
managed/created.

* Internalize some functions/types

* add FIXME comment to `states.rs`

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

* reference issue 11190 in `table.rs` TODO

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

* switch `use` directives to conventional syntax

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

* remove redundant accessor methods

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

* reference issue 11191 in `yield` TODO comments

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

* replace `dummy_waker` with `Waker::noop`

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

* remove obsolete `AsyncState::spawned_tasks` field

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

* only call post-return automatically for `call_concurrent`

This restores the original behavior of requiring explicit post-return calls for
`call[_async]` invocations.

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

* Favor function arguments before closures

* Simplify `watch` a bit

Mostly move unnecessary state out of the `Arc`.

* fix task handle leaks and add test coverage

We weren't always disposing of guest or host task handles once they became
unreachable. This adds a couple of hidden methods which integration tests may
use to guard against use-after-delete, double-delete, and leak bugs regarding
waitable handles. It also tightens up handle management in `concurrent.rs` to
ensure those tests pass.

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

* Encapsulate type erasure in stream buffers

Don't rely on all buffers to handle `TypeId` and assertions and such,
instead have a helper type which is the one location of the assertions
and everything else can stay typed.

* Remove some methods ending in underscores

* Refactor unsafety in `buffers.rs`

Mostly move away from raw pointers and instead use utilities like
`&[MaybeUninit<T>]`. Also make `WriteBuffer` an `unsafe` trait after
absorbing the `TakeBuffer` trait. Update all safety-related comments
here and there too.

* remove task on drop in `TypedFunc::call_async`

This avoids the need for an `Arc`.

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

* remove obsolete clause from `FutureReader::read` docs

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

* unhide and expand docs for `WriteBuffer` and `ReadBuffer`

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

* add optional `component-model-async-bytes` feature

This gates interop with the `bytes` crate, making it optional and non-default.

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

---------

Signed-off-by: Joel Dice <[email protected]>
Co-authored-by: Alex Crichton <[email protected]>

show more ...

Enable `allow_attributes_without_reason` (#11195)

* Enable `allow_attributes_without_reason`

This commit enables the `clippy::allow_attributes_without_reason` for
the `wasmtime` crate which previou

Enable `allow_attributes_without_reason` (#11195)

* Enable `allow_attributes_without_reason`

This commit enables the `clippy::allow_attributes_without_reason` for
the `wasmtime` crate which previously forcibly allowed it. The reason
this was allowed was that when the workspace was first migrated the
Wasmtime crate had too many instances that I was willing to fix. I've
now come back around and tried to fix everything.

In short: ideally delete `#[allow]`, otherwise use `#[expect]`,
otherwise use `#[allow]`.

prtest:full

* Adjust some directives

* Fix some warnings

* Fix stack switching size tests on unix

* Don't have a conditional `Drop` impl

* Force `testing_freelist` method to be used

Too lazy to write `#[cfg]`, but not too lazy to write a test.

show more ...

update `component-model-async` plumbing (#11123)

* [DO NOT MERGE] update `component-model-async` plumbing

This pulls in the latest Component Model async ABI code from the
`wasip3-prototyping` repo,

update `component-model-async` plumbing (#11123)

* [DO NOT MERGE] update `component-model-async` plumbing

This pulls in the latest Component Model async ABI code from the
`wasip3-prototyping` repo, including various API refactors and spec updates.

This includes all the changes to the `wasmtime` crate from `wasip3-prototyping`
_except_ that the `concurrent` submodule and child submodules contain only
non-functional stubs. For that reason, and the fact that
e.g. `Func::call_async` is now implemented in terms of `Func::call_concurrent`,
most of the component model tests are failing. This commit is not meant to be
merged as-is; a follow-up commit (to be PR'd separately) will contain the real
`concurrent` implementation, at which point the tests will pass again. I'm
splitting these into separate PRs to make review easier.

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

* Undo wit-bindgen changes

No longer necessary after other refactors

* Move back to crates.io-based wit-bindgen

* Undo upgrade of http-body-util

(deferred for future PR)

* Add back in arbitrary use of async

Looks like it may have been lost by accident

* Make imports more conventional for Wasmtime

* Some minor changes

* Privatize a component field

* Cut down a bit on #[cfg]

* Undo a no-longer-necessary `pub`

* add doc comments for `{Future,Stream,ErrorContext}Any`

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

* rename `concurrent` stub module to `concurrent_disabled`

...and avoid panicking in the stubs.

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

* fix test regression

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

* revert `call_async` and `post_return_impl` changes

These will need to wait until the `component-model-async` feature is fully
implemented.

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

* remove unused struct

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

* add `Options::callback` field

This isn't used yet, but will be used when the real `component-model-async`
implementation is merged.

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

* Remove no-longer-needed feature

* Trim reexports from Wasmtime

Some of these are no longer needed or can be avoided with small changes.
Some deps are likely needed in the next commit but they'll be best added
there.

* Update test expectations

* More trimming of Cargo.toml

* Defer `*Buffer` traits to next PR

Not needed for this PR I believe.

* Use conventional Wasmtime imports + remove dummy_waker

* Reduce duplication in `*_disabled`

* Remove some unncessary bounds

* Remove some `for<'a>` bounds where unnecessary

* Remove another bound

* Defer more functions to the next PR

`drop_fibers` is different in the next PR, so defer it to then.

* Remove some reexports no longer necessary

Bindings generation changed awhile back so these aren't needed, defer
the implementations to the next PR.

* Remove unnecessary drop

This was already moved to `run_manual_drop_routines`

* Defer a `pub(crate)` to a future PR

* Expand comments in traphandlers

* Defer some types to the next PR

* Update linker documentation

* Add `Send`/`Sync` bounds to `ComponentType`

This commit is extracted from from review of #11123 and #11127. While
not literally present in those PRs it's my own personal conclusion that
it's best to just go ahead and add these bounds at the "base" of the
component trait hierarchy. The current implementation in #11123 adds
bounds in many locations and this would remove the need to add bounds
everywhere and instead have everything inherited through the `Lift` and
`Lower` traits.

This raises the question of: why? The main conclusion that I've reached
leading to this change is that Wasmtime currently will store `R`, a
return value, on the stack during the lowering process back into linear
memory. This might involve allocation, however, meaning that wasm can be
invoked and a context switch could happen. For Wasmtime's `unsafe impl`
of `Send` and `Sync` on fibers to be sound it requires that this
stack-local variable is also `Send` and `Sync` as it's an entirely
user-provided type. Thus I've concluded that for results it's always
required for these to be both `Send` and `Sync` (or at the very least,
`Send`).

Given that I've gone ahead and updated to require both `Send` and `Sync`
for both params and results. This is not expected to actually have any
impact in practice since all primitives are already `Send`/`Sync` (minus
`Rc` impls all removed here) and all `bindgen!`-generated types are
compositions of `Send`/`Sync` primitives meaning that they're also
`Send` and `Sync`.

* Remove some now-unnecessary bounds

* Fix build after #11160

* Remove some now-unnecessary duplicate bounds

* Uncomment test that now works

* Undo accidental doc wrap

* Clarify comment on `Value` types

Don't leave `TODO` in public-facing documentation ideally

* Actually resolve the conflict (forgot to commit)

* Avoid returning boxed futures in APIs

* Defer making constructors more public to a future PR

* Make a method name more conventional

* Refactor `linear_lift_into_from_memory`

* Drop the `max_count` parameter in favor of slicing the `WasmList`
itself. Avoids situations such as what happens if `max_count` is
larger than the length of the list.
* Don't have the default implementation collect to a vector and then
push all that onto a different vector. Instead push each item
individually through `extend`.

* De-indent a block of code added

* Remove unsafety from `prepare_call`

Mostly move the parameters themselves to the closure to avoid raw
pointers/drop/etc.

This will have the consequence of in the future `call_async` is going to
now require `Params: 'static` but that seems more-or-less inevitable at
this point.

* Go back to returning box, alas.

* Apply same treatment to lift function

Make it a closure and reduce some levels of indirection of the various
functions in play.

* Refactor `lower_params` to require less context.

Relax the bounds on the closure specified since it's immediately called
and then additionally take out parameters/captures that the closure can
carry itself.

* Don't pass extraneous `Instance` parameter

This can now be inferred from `Func`.

* Clean up some SAFETY comments

* Generalize the signature of `lift_results`

* Move `lift_results` function to `Func`

Also rename the lift/lower helpers to `with_{lift,lower}_context`

* Remove parameter from `with_lift_context`

Like `with_lower_context` this is fine to capture in the closure passed
in.

* Simplify the dynamic lifting logic

Don't call `with_lift_context` in two locations, only call it once with
a dynamic parameter.

* Refactor away the `Func::lift_results_sync` helper

* Use `with_lift_context` in `call_raw`

* Simplify a call to `Func::call_unchecked_raw`

* Ungate `with_lift_context` to fix non-cm-async build

* Fix compile (bad cherry-pick conflict resolution)

* Use `with_lower_context` in `call_raw`

Trying to unify the async/concurrent paths as much as possible.

* Move params out of `call_raw`

Let closures capture the params, no need to thread it through as an
unnecessary argument.

* Clean up unsafety in `Func::call_raw`

* Accurately mark `call_raw` itself as `unsafe`, then document why
callers should be safe.
* Don't have one large `unsafe` block in `call_raw`, instead split it up
with separate safety comments.

* Move a one-off type definition closer to its use

* Avoid intermediate allocations in dynamic calls

* Simplify a future-return site

* Deduplicate checking parameter count

* Simplify a future invocation with `?`

* Simplify a variable declaration

* Simplify some function signatures

* Remove outdated safety comment

* Refactor to not require `Params: 'static` on `call_async`

* Remove no-longer-necessary SAFETY comment

* Fix typos

* Add a fast-path with no `Box` for sync host functions

Speeds up host calls by ~20% and puts them back on parity with the
beforehand numbers Wasmtime has.

* Synchronize signatures of async/concurrent dynamic calls

Use slices for both instead of vecs for one and slices for the other.
Required some slight rejiggering. Apparently one can solve a closure
problem with another closure, then one surely has no more closure
problems.

* Fix non-cm-async build

---------

Signed-off-by: Joel Dice <[email protected]>
Co-authored-by: Alex Crichton <[email protected]>

show more ...

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

show more ...

Remove `Stored` usage from `wasmtime::component::Instance` (#10913)

* Remove mutability required on a number of component methods

Powered by previous refactorings it's possible to just take
`&Store

Remove `Stored` usage from `wasmtime::component::Instance` (#10913)

* Remove mutability required on a number of component methods

Powered by previous refactorings it's possible to just take
`&StoreOpaque` in these locations.

* Move core instance map into `ComponentInstance`

This commit moves the mapping from a `RuntimeInstanceIndex` to a
`wasmtime::Instance` from `wasmtime::component::InstanceData` into the
internal `ComponentInstance` structure. This is done in preparation to
remove `InstanceData` eventually.

* Move `Component` to live in `ComponentInstance`

Previously this lived in `InstanceData` but that's just a historical
artifact of the old `wasmtime` and `wasmtime-runtime` split. Nowadays
it's possible to store `Component` directly to further move information
out of `InstanceData`.

* Move `InstanceData::imports` to `ComponentInstance`

More preparation for the removal of `InstanceData` entirely.

* Move lookup functions from `InstanceData` to `ComponentInstance`

More prep for the removal of `InstanceData`.

* Reduce some more reliance on `InstanceState`

Just removing it from some type signatures to make future removal
easier.

* Remove an unused result from a helper function

No caller needs it, so go ahead and remove it.

* Make `ComponentInstance::imports` private

This moves some methods around and documents preexisting `unsafe`
contracts to get this field private and prevent external access to it.

* Remove `InstanceData` from `Instantiator`.

Use `OwnedComponentInstance` instead.

* Remove `InstanceData`, refactor `Instance`

This commit refactors the representation of `component::Instance` to be
purely index-based to data already within a store. This makes creation
of an `Instance` free compared to before where auxiliary data needed to
be created. Note that this doesn't actually change storage within a
`Store<T>` as instances are still there, it's just that now the storage
lives in a non-`Stored`-related location.

show more ...