Testcase proposal

[cpetig]

If you need testcases run wit-bindgen test --languages rust --artifacts artifacts --rust-wit-bindgen-path crates/guest-rust/ tests/runtime in the wit-bindgen source tree. The test components end up in artifacts/*/composed-runner.rs-test.rs.wasm

The binaries should return without trap when calling run(). E.g. like wasmtime --invoke 'run()' artifacts/numbers/composed-runner.rs-test.rs.wasm

[cpetig]

examples.zip

The demo example is minimal, the strings example uses p2 stdio and allocation and complex copying logic.

[avrabe]

All four proposed fixture types now fuse and pass runtime verification as of e64404f:

• numbers — integer/float primitives ✅
• strings — string passing with allocation ✅
• lists — list<u8>, list<u32>, list<string>, list<list<string>>, list<tuple<u8,u32,u8>>, min/max f32/f64 ✅
• records — record/struct passing ✅

Key fixes that enabled this:

1. Cycle-tolerant topological sort — composed-runner components create mutual dependencies between sub-components; the resolver now tolerates these cycles instead of rejecting them
2. Provenance-based core function index lookup — correctly resolves canon lower / alias interleaving in flattened components
3. Element-size-aware list adapters — allocation uses count × element_size (not just count); recursive inner pointer fixup for list<string> and list<list<string>>
4. Return-via-pointer (retptr) adapters — multi-value returns lowered through retptr with per-field copy layouts

Tests live in meld-core/tests/wit_bindgen_runtime.rs with three tiers: CoreModule validation, Component validation, and wasmtime WASI runtime execution.

Remaining type families (variants, flags, resources, etc.) tracked in a separate issue.