Stream: git-wasmtime

Topic: wasmtime / issue #12941 Cranelift: Stack-Switching suppor...

view this post on Zulip Wasmtime GitHub notifications bot (Apr 02 2026 at 13:44):

alex28sh opened issue #12941:

Steps to Reproduce

index.zip

Run on the attached index.wasm
wasmtime -W gc,function-references,exceptions,stack-switching index.wasm

Expected Results

print test passed

Actual Results

thread '<unnamed>' (40796) panicked at /home/Aleksandr.Shefer/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/wasmtime-internal-cranelift-43.0.0/src/func_environ/gc/enabled.rs:1534:9: assertion left == right failed left: types::I128 right: types::I32 note: run with RUST_BACKTRACE=1 environment variable to display a backtrace

Versions and Environment

wasmtime 43.0.0

Operating system: Ubuntu 24.04.4

Architecture: x86_64

view this post on Zulip Wasmtime GitHub notifications bot (Apr 02 2026 at 13:44):

alex28sh added the bug label to Issue #12941.

view this post on Zulip Wasmtime GitHub notifications bot (Apr 02 2026 at 13:44):

alex28sh added the cranelift label to Issue #12941.

view this post on Zulip Wasmtime GitHub notifications bot (Apr 02 2026 at 13:46):

alex28sh edited issue #12941:

Steps to Reproduce

index.zip

Run on the attached index.wasm
wasmtime -W gc,function-references,exceptions,stack-switching index.wasm

Expected Results

print test passed

Actual Results

thread '<unnamed>' (40796) panicked at /home/Aleksandr.Shefer/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/wasmtime-internal-cranelift-43.0.0/src/func_environ/gc/enabled.rs:1534:9: assertion left == right failed left: types::I128 right: types::I32 note: run with RUST_BACKTRACE=1 environment variable to display a backtrace

Presumably, that happens because in Kotlin we are using contref typed variabled inside gc structs

Versions and Environment

wasmtime 43.0.0

Operating system: Ubuntu 24.04.4

Architecture: x86_64

view this post on Zulip Wasmtime GitHub notifications bot (Apr 02 2026 at 13:56):

alexcrichton added the wasm-proposal:stack-switching label to Issue #12941.

view this post on Zulip Wasmtime GitHub notifications bot (Apr 02 2026 at 14:00):

cfallin commented on issue #12941:

Thanks for filing the issue!

Stack switching support in Wasmtime is known to be incomplete at this time, and no one is currently staffed to work on it. We'd welcome PRs from anyone willing to improve it, though; if you'd like to send one to address this issue, we'd be happy to review it.

Last updated: Apr 12 2026 at 23:10 UTC