Stream: git-wasmtime

Topic: wasmtime / issue #12154 Invalid leading byte for componen...

view this post on Zulip Wasmtime GitHub notifications bot (Dec 11 2025 at 08:46):

peter-jerry-ye opened issue #12154:

Hi, I wonder that, since the wasip3 prototyping was archived, has the changes been ported to this repo?
Because I had issue trying to run a dummy component model using async.

Test Case

dummy.zip

Steps to Reproduce

A simple wit using wasi p3:

package peter-jerry-ye:demo@0.3.0-rc-2025-09-16;

world cli {
  include wasi:http/imports@0.3.0-rc-2025-09-16;
  include wasi:cli/imports@0.3.0-rc-2025-09-16;
  export wasi:cli/run@0.3.0-rc-2025-09-16;
}

wasm-tools component embed wit --dummy-names legacy --async-stackful -t -o dummy.wat
wasm-tools component new dummy.wat -o dummy.cm.wasm
wasmtime run dummy.cm.wasm

Expected Results

It panics somewhere due to the unreachable in the dummy file

Actual Results

Error: failed to parse WebAssembly module

Caused by:
    invalid leading byte (0x43) for component defined type (at offset 0x108)

Versions and Environment

Wasmtime version or commit: wasmtime 39.0.1

Operating system: macOS 15.6.1

Architecture: arm64

Extra Info

view this post on Zulip Wasmtime GitHub notifications bot (Dec 11 2025 at 08:46):

peter-jerry-ye added the bug label to Issue #12154.

view this post on Zulip Wasmtime GitHub notifications bot (Dec 11 2025 at 11:49):

alexcrichton closed issue #12154:

Hi, I wonder that, since the wasip3 prototyping was archived, has the changes been ported to this repo?
Because I had issue trying to run a dummy component model using async.

Test Case

dummy.zip

Steps to Reproduce

A simple wit using wasi p3:

package peter-jerry-ye:demo@0.3.0-rc-2025-09-16;

world cli {
  include wasi:http/imports@0.3.0-rc-2025-09-16;
  include wasi:cli/imports@0.3.0-rc-2025-09-16;
  export wasi:cli/run@0.3.0-rc-2025-09-16;
}

wasm-tools component embed wit --dummy-names legacy --async-stackful -t -o dummy.wat
wasm-tools component new dummy.wat -o dummy.cm.wasm
wasmtime run dummy.cm.wasm

Expected Results

It panics somewhere due to the unreachable in the dummy file

Actual Results

Error: failed to parse WebAssembly module

Caused by:
    invalid leading byte (0x43) for component defined type (at offset 0x108)

Versions and Environment

Wasmtime version or commit: wasmtime 39.0.1

Operating system: macOS 15.6.1

Architecture: arm64

Extra Info

view this post on Zulip Wasmtime GitHub notifications bot (Dec 11 2025 at 11:49):

alexcrichton commented on issue #12154:

Thanks for the report! This is expected with the 39.0.1 release, and the upcoming 40.0.0 will support the new binary format for async-in-the-type component model async

Last updated: Dec 13 2025 at 19:03 UTC