Add support for map type #12216

yordis · 2025-12-23T21:42:43Z

Context

This is adding support for map based on WebAssembly/component-model#554

References

github-actions · 2025-12-23T23:46:00Z

Subscribe to Label Action

cc @fitzgen

Details

This issue or pull request has been labeled: "wasmtime:api", "wasmtime:c-api", "wasmtime:config", "wizer"

Thus the following users have been cc'd because of the following labels:

fitzgen: wizer

To subscribe or unsubscribe from this label, edit the .github/subscribe-to-label.json configuration file.

Learn more.

github-actions · 2025-12-24T01:06:25Z

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:

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.

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 (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 for more 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.

Details

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

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

Learn more.

alexcrichton · 2026-01-07T18:09:25Z

On a skim this looks like it's all in the right direction, thanks! As as a heads up the wasm-tools deps will be updated in #12254 which'll avoid the need for git deps. I'll take a closer look once this is further along in CI passing tests

github-actions · 2026-01-08T11:46:55Z

Subscribe to Label Action

cc @fitzgen

Details

This issue or pull request has been labeled: "fuzzing"

Thus the following users have been cc'd because of the following labels:

fitzgen: fuzzing

To subscribe or unsubscribe from this label, edit the .github/subscribe-to-label.json configuration file.

Learn more.

Signed-off-by: Yordis Prieto <yordis.prieto@gmail.com>

…model This commit introduces the Map and MapEntry classes, enabling the representation of map values in the component model. The Map class allows for the creation and iteration of key/value pairs, enhancing the functionality of the wasmtime component API. Additionally, the .gitignore file is updated to exclude build artifacts from the crates/c-api directory.

yordis · 2026-01-16T20:28:54Z

.gitignore

 vendor
 examples/build
 examples/.cache
+crates/c-api/build


Is it ok to do this? I kept getting things to commit locally, so I added this

Yeah this is fine to have here, no worries

alexcrichton

This is looking quite good to me, thanks for the thorough tests!

I haven't scrutinized the trampoline generation nor the lifting/lowering yet, but I can do that once the tests added here are passing (the #[ignore] ones at least).

If you can one thing I'd also recommend is modeling as many tests as possible as a *.wast test since that's generally the easiest to run and share (albeit difficult to write and debug)

alexcrichton · 2026-01-20T20:09:48Z

crates/test-util/src/component.rs


    let mut config = Config::new();
    config.wasm_component_model(true);
+    config.wasm_features(wasmtime::WasmFeatures::CM_MAP, true);


Could this get scoped to just the tests in question using this feature?

alexcrichton · 2026-01-20T20:10:38Z

crates/test-util/src/component_fuzz.rs

+        // Note: Map types (case 21) are disabled because HashMap doesn't implement
+        // ComponentType, Lift, or Lower yet. When those implementations are added,
+        // change this to 21.


Is this still applicable?

alexcrichton · 2026-01-20T20:13:36Z

tests/misc_testsuite/component-model/types.wast

+  (type (map u32 string))
+  (type (map string u32))
+  (type (map u32 u32))
+  (type (map string (map u32 string)))


Mind splitting this out to a separate test file to avoid gating this preexsting test on the feature? It's not 100% relevant to us insofar as Wasmtime can put all the tests in one place, but in the interest of one day sharing tests with other runtimes it might be good to split things out by feature

alexcrichton · 2026-01-20T20:16:43Z

.gitignore

 vendor
 examples/build
 examples/.cache
+crates/c-api/build


Yeah this is fine to have here, no worries

yordis force-pushed the yordis/feat-map-support branch 3 times, most recently from 6b6f675 to cd2282b Compare December 23, 2025 21:53

yordis force-pushed the yordis/feat-map-support branch 5 times, most recently from db45a3a to 83dd7a7 Compare January 8, 2026 10:17

github-actions bot added the fuzzing Issues related to our fuzzing infrastructure label Jan 8, 2026

Add support for map type

b9ca740

Signed-off-by: Yordis Prieto <yordis.prieto@gmail.com>

yordis force-pushed the yordis/feat-map-support branch from 83dd7a7 to b9ca740 Compare January 8, 2026 19:19

yordis added 5 commits January 8, 2026 21:46

Add wasm_component_model_map configuration support

9a0319d

Merge branch 'main' into yordis/feat-map-support

482196e

Format code

a43b8d7

Format C code

301e19b

yordis commented Jan 16, 2026

View reviewed changes

alexcrichton reviewed Jan 20, 2026

View reviewed changes

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Add support for map type #12216

Add support for map type #12216

Uh oh!

yordis commented Dec 23, 2025 •

edited

Loading

Uh oh!

github-actions bot commented Dec 23, 2025

Uh oh!

github-actions bot commented Dec 24, 2025

Uh oh!

alexcrichton commented Jan 7, 2026

Uh oh!

github-actions bot commented Jan 8, 2026

Uh oh!

yordis Jan 16, 2026

Uh oh!

alexcrichton Jan 20, 2026

Uh oh!

alexcrichton left a comment

Uh oh!

alexcrichton Jan 20, 2026

Uh oh!

alexcrichton Jan 20, 2026

Uh oh!

alexcrichton Jan 20, 2026

Uh oh!

alexcrichton Jan 20, 2026

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants

Add support for map type #12216

Are you sure you want to change the base?

Add support for map type #12216

Uh oh!

Conversation

yordis commented Dec 23, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Context

References

Uh oh!

github-actions bot commented Dec 23, 2025

Subscribe to Label Action

Uh oh!

github-actions bot commented Dec 24, 2025

Label Messager: wasmtime:config

Uh oh!

alexcrichton commented Jan 7, 2026

Uh oh!

github-actions bot commented Jan 8, 2026

Subscribe to Label Action

Uh oh!

yordis Jan 16, 2026

Choose a reason for hiding this comment

Uh oh!

alexcrichton Jan 20, 2026

Choose a reason for hiding this comment

Uh oh!

alexcrichton left a comment

Choose a reason for hiding this comment

Uh oh!

alexcrichton Jan 20, 2026

Choose a reason for hiding this comment

Uh oh!

alexcrichton Jan 20, 2026

Choose a reason for hiding this comment

Uh oh!

alexcrichton Jan 20, 2026

Choose a reason for hiding this comment

Uh oh!

alexcrichton Jan 20, 2026

Choose a reason for hiding this comment

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants

yordis commented Dec 23, 2025 •

edited

Loading