Stream: git-wasmtime

Topic: wasmtime / PR #14970 Enable the component model implement...

Wasmtime GitHub notifications bot (Oct 23 2026 at 21:00):

jrandolf opened PR #14970 from jrandolf:implements-default to bytecodealliance:main:

WASI 0.3.1 and later require runtimes to support implements and external-id (see #14800), so this enables the feature by default.

The one box it doesn't tick is fuzzing. As discussed on #14914, whether that's needed isn't a decision for one person, so this PR is the place to decide it. My case for not gating on it: the attributes are metadata that don't affect type checking, compilation or execution. Wasmtime copies them into its type information and returns them from ComponentExtern. The code that interprets them (ComponentExtern::is_implements, bindgen!'s named_imports and the named WASI imports) is covered by tests. The stability table keeps the :cross_mark: with a footnote saying so.

<details>
<summary>LLM summary of the changes</summary>

• Config enables CM_IMPLEMENTS whenever the component-model crate feature is on, like the component model itself, and Config::wasm_component_model_implements documents that default instead of calling the feature a work in progress.
• docs/stability-wasm-proposals.md moves implements to the on-by-default table with a footnote on its Fuzzed :cross_mark:.
• implements_enabled_by_default checks that a default Engine accepts an implements import. The .wast harness still turns the feature off unless a test asks for it, so implements-disabled.wast still checks the error.

</details>

Wasmtime GitHub notifications bot (Oct 23 2026 at 21:00):

jrandolf requested wasmtime-core-reviewers for a review on PR #14970.

Wasmtime GitHub notifications bot (Oct 23 2026 at 21:00):

jrandolf requested dicej for a review on PR #14970.

Wasmtime GitHub notifications bot (Oct 23 2026 at 21:00):

jrandolf removed the review request for wasmtime-default-reviewers from PR #14970.

Wasmtime GitHub notifications bot (Oct 23 2026 at 21:00):

jrandolf removed the review request for wasmtime-core-reviewers from PR #14970.

Wasmtime GitHub notifications bot (Oct 23 2026 at 21:00):

jrandolf requested alexcrichton for a review on PR #14970.

Wasmtime GitHub notifications bot (Oct 23 2026 at 21:00):

jrandolf requested wasmtime-default-reviewers for a review on PR #14970.

Wasmtime GitHub notifications bot (Oct 23 2026 at 21:01):

jrandolf edited PR #14970:

As discussed in #14914.

<details>
<summary>LLM summary of the changes</summary>

• Config enables CM_IMPLEMENTS whenever the component-model crate feature is on, like the component model itself, and Config::wasm_component_model_implements documents that default instead of calling the feature a work in progress.
• docs/stability-wasm-proposals.md moves implements to the on-by-default table with a footnote on its Fuzzed :cross_mark:.
• implements_enabled_by_default checks that a default Engine accepts an implements import. The .wast harness still turns the feature off unless a test asks for it, so implements-disabled.wast still checks the error.

</details>

Wasmtime GitHub notifications bot (Oct 23 2026 at 23:44):

github-actions[bot] added the label wasmtime:config on PR #14970.

Wasmtime GitHub notifications bot (Oct 23 2026 at 23:44):

github-actions[bot] added the label wasmtime:docs on PR #14970.

Wasmtime GitHub notifications bot (Oct 23 2026 at 23:44):

github-actions[bot] added the label wasmtime:api on PR #14970.

Wasmtime GitHub notifications bot (Oct 24 2026 at 01:54):

github-actions[bot] commented on PR #14970:

Label Messager: wasmtime:config

It looks like you are changing Wasmtime's configuration options. Make sure to
complete this check list:

• [ ] If you added a new Config method, you wrote extensive documentation for
  it.

  <details>

  Our documentation should be of the following form:

  ```text
  Short, simple summary sentence.

  More details. These details can be multiple paragraphs. There should be
  information about not just the method, but its parameters and results as
  well.

  Is this method fallible? If so, when can it return an error?

  Can this method panic? If so, when does it panic?

  Example

  Optional example here.
  ```

  </details>

• [ ] If you added a new Config method, or modified an existing one, you
  ensured that this configuration is exercised by the fuzz targets.

  <details>

  For example, if you expose a new strategy for allocating the next instance
  slot inside the pooling allocator, you should ensure that at least one of our
  fuzz targets exercises that new strategy.

  Often, all that is required of you is to ensure that there is a knob for this
  configuration option in [wasmtime_fuzzing::Config][fuzzing-config] (or one
  of its nested structs).

  Rarely, this may require authoring a new fuzz target to specifically test this
  configuration. See [our docs on fuzzing][fuzzing-docs] for more details.

  </details>

• [ ] If you are enabling a configuration option by default, make sure that it
  has been fuzzed for at least two weeks before turning it on by default.

[fuzzing-config]: https://github.com/bytecodealliance/wasmtime/blob/ca0e8d0a1d8cefc0496dba2f77a670571d8fdcab/crates/fuzzing/src/generators.rs#L182-L194
[fuzzing-docs]: https://docs.wasmtime.dev/contributing-fuzzing.html

---

<details>

To modify this label's message, edit the <code>.github/label-messager/wasmtime-config.md</code> file.

To add new label messages or remove existing label messages, edit the
<code>.github/label-messager.json</code> configuration file.

Learn more.

</details>

Last updated: Oct 31 2026 at 23:03 UTC