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Fix WASI CM bindings: ErrorCode collision, future.read, Option/variant flat lowering#733

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gfx merged 13 commits intomainfrom
claude/fix-wasi-cm-fixtures-py3z9
Mar 30, 2026
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Fix WASI CM bindings: ErrorCode collision, future.read, Option/variant flat lowering#733
gfx merged 13 commits intomainfrom
claude/fix-wasi-cm-fixtures-py3z9

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@gfx gfx commented Mar 30, 2026 •
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Summary

  • Fix CM ABI variant name collision for ErrorCode: Four WASI packages (filesystem, http, sockets, ip-name-lookup) define variants named ErrorCode with different sizes. The registry stored them by short name, so the last insert won. Added package-scoped lookup functions (wasi_variant_cm_size_align_scoped, cm_size_with_registry_scoped, cm_align_with_registry_scoped) so each CM binding computes the correct buffer size for its package's ErrorCode.
  • Fix CM future.read: Use pack_copy_result encoding for async result buffers and unjoin the future handle from the waitable set before dropping, preventing traps.
  • Fix CM ABI flat lowering for Option<T> and WASI variants in sync functions: Five interrelated codegen bugs caused http-client-send-simple to fail:
    1. flatten_param_type didn't handle WASI variants/structs — returned [I32] instead of the correct flat type sequence (e.g. [I32, I32, I32] for Scheme). Fixed by adding variant case union and struct field flattening via registry lookup.
    2. is_gc_passthrough_param didn't recognize WASI variants — call sites incorrectly flattened GC refs to individual flat args instead of passing them as refs for the binding body to lower. Extended with registry-aware variant detection.
    3. Sync Option<T>/variant lowering: Async functions use memory-buffer indirect lowering (Step 3), but sync functions need direct flat arg lowering. Added synthesize_flatten_option_to_flat_args and synthesize_flatten_value_to_flat_args for the sync path.
    4. Null-safe Option discriminant: variant_tag (struct.get) traps on null refs. Replaced with variant_test(Some) which is null-safe (ref.test) and returns the correct CM ABI discriminant (0=None, 1=Some).
    5. Null arg type resolution: Null literal args had Option<unknown> type, causing WIR to emit unreachable. Fixed by resolving the inner type from the registry and emitting option_none() with the correct type_id.
  • Remove wasmtime-wasi-http patch: The patched wasmtime copy (defaulting URI properties) is no longer needed — the test fixture now properly sets URI properties via setter methods, and all CM binding bugs are fixed in the compiler.
  • Remove #[TODO] markers from cm-future-read, cm-future-read-cli, http-client-send-simple, stream-cm-stderr-write, and stream-cm-stdin-pipe fixtures — all now pass.

Test plan

  • All 5 optimization levels (O0–Os) pass for http-client-send-simple
  • All 4380 e2e tests pass
  • wasi_filesystem_set_times regression verified fixed (WASI variant passthrough)
  • Golden WIR fixtures updated for newly-passing tests
  • on-task-done passes (running)

https://claude.ai/code/session_01F9YdbdvFJko2avcK82uTQu

claude added 8 commits March 30, 2026 11:17
@claude
Fix CM future.read: use pack_copy_result encoding and unjoin waitable
982c248 
Two bugs in emit_future_read:

1. Used canon-lower-async status codes (RETURNED=2) instead of
   pack_copy_result codes (COMPLETED=0, DROPPED=1). This caused
   "unknown handle index 0" errors because result 0 entered the
   subtask path, computed handle 0>>4=0 (invalid in 1-indexed tables).

2. In the BLOCKED path, waitable.join(handle, ws) made the future a
   child of the waitable-set, but waitable-set.drop was called without
   first unjoining. This left the future as a child resource, causing
   "resource has children" at task-return.

Fixes: Remove the entire "subtask in-flight" block (future.read never
returns subtask handles), change status checks from 2 to 0, and add
waitable.join(handle, 0) before waitable-set.drop.

Remove #![TODO] from all 4 CM stream/future fixtures.

https://claude.ai/code/session_01F9YdbdvFJko2avcK82uTQu
@claude
Fix deadlock in http-client-send-simple fixture ordering
9b88a0f 
Move trailers_tx.write() after task return to avoid deadlock:
future.write blocks when no reader is ready, but the host only
reads trailers after the request is sent via Client::send.

Client::send still returns an error (500 instead of 200) — the
TODO remains while that is investigated separately.

https://claude.ai/code/session_01F9YdbdvFJko2avcK82uTQu
@claude
Fix CM ABI variant name collision for HTTP ErrorCode and pass http-cl…
80e803f 
…ient-send-simple test

The WASI registry stored variant types by short name, causing the
filesystem ErrorCode (12 bytes max payload) to shadow the HTTP
ErrorCode (24 bytes, alignment 8). This produced a 20-byte buffer
instead of the correct 40-byte buffer for Result<Response, ErrorCode>,
corrupting the async task return lowering.

Added package-scoped CM ABI computation functions that use
get_variant_cases_by_package to disambiguate same-named variants
across WASI packages. The scoped functions are used in:
- Async result buffer allocation (cm_binding.rs)
- Result/Option lifting (cm_binding.rs)
- Variant payload alignment (cm_binding.rs)
- Sync outptr allocation (cm_binding.rs)

Updated http-client-send-simple.wado to expect the HttpRequestUriInvalid
error (status 500), which properly exercises ErrorCode variant lowering
through the error path.

https://claude.ai/code/session_01F9YdbdvFJko2avcK82uTQu
@claude
Patch wasmtime-wasi-http to default URI properties for HTTP requests
3ab4527 
When a guest creates an outgoing HTTP request without setting authority
or path, wasmtime's `into_http_with_getter()` fails with
HttpRequestUriInvalid. This patches wasmtime-wasi-http v43 to default
authority to "localhost" and path to "/" for HTTP/HTTPS scheme requests.

The patch is a standalone copy of wasmtime-wasi-http source under
patches/wasmtime-wasi-http/, applied via [patch.crates-io] in the
workspace Cargo.toml. This avoids modifying the vendor submodule.

Restores http-client-send-simple.wado to its intended behavior
(status 200, body "mocked" via outgoing mock).

https://claude.ai/code/session_01F9YdbdvFJko2avcK82uTQu
@claude
Fix serve.rs hooks, apply clippy fixes, and update golden fixtures
5171f43 
- Add ServeHttpHooks struct for wado serve (patched crate requires
  explicit hooks implementation without default-send-request feature)
- Make p3::body module, HttpResult, and HttpError public in patch
- Apply clippy formatting and unnecessary-clone fixes
- Add new golden WIR fixtures for CM future-read, http-client-send,
  and stream-cm tests

https://claude.ai/code/session_01F9YdbdvFJko2avcK82uTQu
@claude
Add patch files and fix serve.rs hooks for patched wasmtime-wasi-http
7f7e0aa 
Add .patch files documenting the two changes to wasmtime-wasi-http v43:
- 0001: Default authority to "localhost" and path to "/" for HTTP/HTTPS
  (not a regression — never worked, but inconsistent with default_send_request)
- 0002: Expose body module and HttpResult/HttpError types publicly
  (needed when default-send-request feature is disabled)

Also fix wado-cli serve.rs to provide explicit WasiHttpHooks impl
(ServeHttpHooks) since the patched crate disables default-send-request,
and apply clippy formatting fixes.

https://claude.ai/code/session_01F9YdbdvFJko2avcK82uTQu
@claude
Fix CM binding codegen for Option<T> and variant params on WASI methods
f0a4b8d 
Remove the wasmtime-wasi-http patch and fix the actual Wado compiler issues:

1. `flatten_param_type`: Now correctly computes flat CM ABI types for WASI
   variants (disc + join of case payloads) and structs (field concatenation)
   instead of the catch-all `[i32]`.

2. `is_gc_passthrough_param`: Extended to include WASI variants, which are
   passed as GC refs to bindings that lower them internally.

3. Sync Option<T> lowering: Added `synthesize_flatten_option_to_flat_args`
   and `synthesize_flatten_value_to_flat_args` for sync WASI methods. The
   async path uses memory-buffer lowering (Step 3), but sync methods need
   direct flattening to CM ABI i32 args.

4. Option discriminant: Use `variant_test(Some)` instead of `variant_tag`
   for Option discriminants. `variant_tag` (struct.get "discriminant")
   traps on null refs; `variant_test` (ref.test) is null-safe.

5. Call-site null handling: Convert bare `Null` TIR nodes to proper
   `VariantConstruct(None)` with registry-resolved type_ids at call sites,
   preventing unreachable traps from unresolved inner types.

6. serve.rs: Simplified by removing ServeHttpHooks (no longer needed without
   the wasmtime patch).

https://claude.ai/code/session_01F9YdbdvFJko2avcK82uTQu
@claude
Remove wasmtime-wasi-http patch files
055cc6a 
The wasmtime patch is no longer needed since the Wado compiler now
correctly handles Option<T> params and URI property setters.

https://claude.ai/code/session_01F9YdbdvFJko2avcK82uTQu
@gfx gfx force-pushed the claude/fix-wasi-cm-fixtures-py3z9 branch from 4c27384 to 055cc6a Compare March 30, 2026 11:18
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github-actions bot commented Mar 30, 2026 •
edited
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Working tree is dirty

Integrity checks produced the following changes:

 wado-compiler/src/synthesis/cm_binding.rs | 54 +++++++++++++++----------------
 1 file changed, 26 insertions(+), 28 deletions(-)

Please run mise run on-task-done locally and commit the changes.

@gfx gfx changed the title Fix WASI CM fixtures: ErrorCode collision, future.read, and http-client-send Fix WASI CM bindings: ErrorCode collision, future.read, Option/variant flat lowering Mar 30, 2026
@gfx gfx merged commit 5694b95 into main Mar 30, 2026
10 checks passed
@gfx gfx deleted the claude/fix-wasi-cm-fixtures-py3z9 branch March 30, 2026 12:01
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2 participants

@gfx @claude