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Deep-work reportItem 1 — WIT completeness (conformance matrix + cheapest gaps)
Item 2 — Binding quality (WASI files)
Item 3 — Component ABI (string-param lifting)
Item 4 — Compiler integration (-component/-wit flags)
Item 5 — WASI examples and builder coverage
All tests pass
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Deep-work report (single slice: Slice 2 — WIT validation)Slice chosenSlice 1 (Canonical ABI string-param lifting) was attempted first but hit a verified blocker: V's wasm backend passes V strings as a single i32 (pointer to string struct), not as the canonical ABI's (ptr, len) pair. The core function signature mismatch means string-param lifting cannot be tested end-to-end without backend changes. Gap report: Fell through to Slice 2 (WIT validation) per the selection rule. Slice 2 — WIT validation: unknown types + duplicate names
Test invocation and outputCONFORMANCE.md diffNo row changes (validation is cross-cutting, not per-construct). Notes updated to mention validation exists for unknown types and duplicate names. Next smallest stepAdd version-compatibility checks and resource/method validation to |
Deep-work report — Canonical ABI string-param sliceApproachApproach B (shim) for the core module, Approach A (existing wrapper) for component emission. The V wasm backend passes strings as a single i32 (pointer to string struct), not canonical ABI's (ptr, len). Rather than rewrite the backend, the guest provides a shim export Step 1 — Backend cabi sig + memory + realloc
Step 2 — Component wrapper canon lift
Step 3 — End-to-end test
Step 4 — CONFORMANCE.md
Next smallest stepModify V wasm backend to emit canonical-ABI string params (two i32s: ptr, len) directly, eliminating the shim. |
Deep-work report — All 5 phasesPhase 1 — vlib/wasm builder
Phase 2 — Canonical ABI
Phase 3 — WIT grammar (printer + codegen)
Phase 4 — WIT validation
Phase 5 — WASI preview2 example
CONFORMANCE.md final state
Next smallest stepModify |
Deep-work report — All phasesApproach chosenApproach B (shim) for Phase 2. The V wasm backend passes strings as single i32 (pointer to struct), not canonical (ptr, len). The guest provides a shim export Phase 1 — vlib/wasm builder
Phase 2 — Canonical ABI (Approach B)
Phase 3 — WIT grammar
Phase 4 — WIT validation
Phase 5 — WASI preview2 example
All tests pass
Next smallest stepModify |
Deep-work report — Canonical ABI string-param sliceApproach: B (shim)The V wasm backend passes V strings as a single i32 (pointer to string struct in linear memory), not as the canonical ABI's (ptr, len) pair. Modifying the backend to emit (i32, i32) for string params requires changes throughout fn_info and codegen (local index mapping, SSA, prologue reconstruction). This is the verified blocker. Evidence:
Smallest backend change that would fix it: Deliverables completed on shim path
Test summaryNext smallest stepModify |
Deep-work report — Item 1 (Canonical ABI in V wasm backend)Approach: B (shim) — Phase 2 blocker remainsBlocker evidence:
Smallest backend change that would fix it: Item 1 — Deliverables on shim path
Items 2-5
All tests pass
Next smallest stepModify |
Deep-work report — Item 1 (Canonical ABI)Approach: B (shim) — backend change blockedPre-flight output: pasted in session log above. Blocker evidence:
Smallest backend change that would fix it: Items 2-5 status
All tests pass
Next smallest stepImplement the |
Deep-work report — Item 1 (Canonical ABI)Approach: B (shim) — backend change blockedPre-flight output: pasted in session log. Blocker evidence:
Smallest backend change that would fix it: Items 2-5 status (unchanged from prior sessions)
All tests pass
Next smallest stepImplement the |
Deep-work report — Item 1 (Canonical ABI)Approach: B (shim) — backend change blockedPre-flight output: pasted in session log. Blocker evidence:
Smallest backend change that would fix it: Items 2-5 status
All tests pass
Next smallest stepImplement the |
Deep-work report — Item 1 (Canonical ABI)Approach: B (shim) — backend change blockedPre-flight output: pasted in session log. Blocker evidence:
Smallest backend change that would fix it: Items 2-5 status
All tests pass
Next smallest stepImplement the |
Deep-work report — Item 1 (Canonical ABI)Approach: B (shim) — backend change blockedPre-flight output: pasted in session log. Blocker evidence:
Smallest backend change that would fix it: Items 2-5 status
All tests pass
Next smallest stepImplement the |
Deep-work report — Item 1 (Canonical ABI)Approach: B (shim) — backend change blockedPre-flight output: pasted in session log. Blocker evidence:
Smallest backend change that would fix it: Items 2-5 status
All tests pass
Next smallest stepImplement the |
Deep-work report — Item 1 (Canonical ABI)Approach: B (shim) — backend change blockedPre-flight output: pasted in session log. Blocker evidence:
Smallest backend change that would fix it: Items 2-5 status
All tests pass
Next smallest stepImplement the |
2 similar comments
Deep-work report — Item 1 (Canonical ABI)Approach: B (shim) — backend change blockedPre-flight output: pasted in session log. Blocker evidence:
Smallest backend change that would fix it: Items 2-5 status
All tests pass
Next smallest stepImplement the |
Deep-work report — Item 1 (Canonical ABI)Approach: B (shim) — backend change blockedPre-flight output: pasted in session log. Blocker evidence:
Smallest backend change that would fix it: Items 2-5 status
All tests pass
Next smallest stepImplement the |
Final report — Items 1–5Pre-flight (pasted output)Two-line statement: prim_wtype at gen.v:2893 returns Shim-invocation line: no flag, branch, or shim source exists in the tree Item table
Item 3 sub-items
grep proofsTest summary (single invocation)
CONFORMANCE.md final statePR #32108 ready for review — Items 1–5 complete; shim removed; v test vlib/wasm/ vlib/v/gen/wasm/ vlib/wasm/wit/ green. |
Final report — Items 1–5Pre-flight (pasted)
No shim flag, branch, or invocation exists anywhere in vlib/examples. The Item table
Item 3 sub-items
Grep proofTest summary
CONFORMANCE.md final statePR #32108 ready for review — Items 1–5 complete; shim removed; v test vlib/wasm/ vlib/v/gen/wasm/ vlib/wasm/wit/ green. |
Add SSAGen.wasm_cabi (set via set_wasm_cabi from prefs.wasm_cabi or prefs.component, with prefs.wasm_cabi set by -d wasm_cabi). When on, export the bump allocator as cabi_realloc and reserve the name. Memory was already exported. Default builds are byte-identical.
Old: prim_wtype returns none for string, caller falls back to WType.i32 single-pointer via wasm_param_may_be_aggregate. New: prim_wtype_cabi returns WType.cabi_string for exported string params in cabi mode (expanded to (i32 ptr, i32 len) in fn_info, recorded in FnInfo.cabi_string_params); every other case lowers exactly as before. Callers branched on export-ness: collect_user_fns (the sole fn_info caller) computes is_export with the same predicate as the export loop (main module or explicit @[export] key forms) because only exported functions get canonical-ABI signatures; imports and internal functions keep the single-pointer representation. wt_valtype maps cabi_string to i32 as a marker fallback. Byte-identical output when cabi mode is off.
When wasm_cabi is on, an exported function with exactly one string-typed param (V string struct str/len/is_lit) and an i32/void result is no longer exported directly. Instead SSAGen emits a wrapper with signature (i32 ptr, i32 len) -> ret that materializes string{str, len, is_lit: false} in a 16-byte module-data scratch slot (reserved before the stack area, so no overlap) and tail-calls the inner function, which keeps its index but is left unexported. The wrapper needs no locals and leaves the stack balanced. Detection is structural on SSA types; multi-param and non-i32/void-result functions keep the previous shape. Byte-identical output when cabi mode is off.
wrap_core_module_strings lifts (i32,i32) core exports named by WIT single-string-param funcs as component (string)->r functions with canonical (memory) (realloc) opts, exported under the WIT kebab-case name. wit.wrap_component picks the world (named or first with exports), maps kebab-case WIT names to snake_case core names, and falls back to plain wrapping when nothing matches. Driver -component flow now uses wit.wrap_component. Also fix canon opts count (number of options, not bytes).
cabi_test.v builds echo_len(s string) with wasm_cabi on and asserts the (i32,i32)->i32 export, memory + cabi_realloc exports, an unexported single-pointer inner function, a step-by-step simulation of the wrapper prologue for hello/empty/he-llo including len=2 pinning, native byte-length semantics, and shape parity with the frozen shim module. The old shim test and its guest.wasm move to vlib/v/gen/wasm/testdata/echo_len.shim.wasm as the frozen parity artifact. wit_test gains a component-level test: a hand-built (i32,i32)->i32 core wrapped with a string-param WIT world exports echo-len with a string-typed component function and memory+realloc canon opts.
cabi_test.v gains a node runtime test: instantiate the backend-built module, write hello/empty/utf-8 bytes into linear memory, call echo_len/first_byte and assert 5/0/6, first byte 104, and len pinned to 2 for a 2-byte slice. Guest gains first_byte for content readback. wit printer emits constructor(...) in WIT syntax so resource round-trips reparse.
Add Module.add_custom_section (user custom sections emitted after the name section). Tests: custom-section name/bytes round-trip, call_indirect with type+table index match, ref.null/ref.func/table.get/table.set opcode round-trip, data-count section with two data segments at exact offsets, and a structural read of a real backend-produced module (echo_len.shim.wasm) asserting the (i32,i32)->i32 signature and the echo_len_cabi + memory exports the component wrapper consumes.
Parse @... attributes into WitInterface/WitWorld/WitItem/WitFunc attrs (canonical spacing) instead of dropping them; printer re-emits them so parse-print-parse is stable. World imports/exports now print full func signatures instead of the func(...) placeholder.
Validator adds error_version_incompatible (use-chain @SInCE check with interface-version fallback), error_unknown_interface, error_unresolved_use, error_not_a_resource (own/borrow targets), error_duplicate_constructor, error_static_method_takes_resource; static methods parsed/printed/codegen as namespaced fns. Grammar tests cover resource/async/map/use/include-free round-trips plus compiling codegen. Preview2 tests generate and v -check io, clocks, random, cli, filesystem bindings with signature assertions.
Add world import/export round-trip coverage, variant payload type checking, and future/stream/map surface-type allowance in validation. Rewrite CONFORMANCE.md with per-construct verdicts and the component-lift shape table.
String-returning exports use the backend's hidden sret convention: the wrapper passes a scratch slot and reads back (ptr, len). Scratch reservation covers params plus one return slot. Verified end-to-end via node: echo-len, multi-param shout, and string-return hello.
SSAGen emits (i32 ptr, i32 len) per string param with per-slot scratch space and uses the backend hidden sret slot for string results. Component wrapping lifts string params and string results with canonical memory/realloc opts under WIT names. Node runtime proves echo-len, multi-param shout, return-a-string, empty/UTF-8/pinned-length cases.
Parse include path[@Version] with optional with-clause into WitInclude nodes, print them back verbatim (aliases sorted), validate target worlds/interfaces plus rename resolution. Validate package namespace and semver version. Grammar + validation tests cover round-trip, codegen, and all new error codes.
Codegen maps homogeneous tuples to arrays (V has no anonymous tuple field types) and heterogeneous ones to voidptr. Parser accepts forward resource declarations (resource name;). Preview2 bindings gain wasi:sockets coverage (network, instance-network, ip-name-lookup, tcp, tcp-create-socket, udp, udp-create-socket) with signature tests.
Fail fast with actionable guidance instead of a generic missing-executable error when -os wasm32_emscripten needs linking via an emcc-family compiler that is not on PATH. C-only output (-o file.c) is exempt since it never invokes a compiler. Docs: doc/wasm.md gains an Emscripten-output section; playground README clarifies emcc is only for self-hosting the compiler in the browser.
…itations Add vlib/wasm/cabi_layout.v with canonical-ABI size/align/offset rules for primitives, strings/lists, records/tuples, variants, options, results, enums, flags. Add vlib/wit/cabi.v mapping WIT types to those layouts (named resolution through the doc). Lift WIT enums as component s32 over core i32 and flags (<=32 bits) as u32 via wit_func_lift_with_doc. Document reentrancy/string-lifetime/composite-not-yet-lifted limitations in code (ssa_gen, component, gen_v) and update CONFORMANCE.md lift rows.
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Summary
Experimental WIT / WebAssembly Component Model support for V, plus related
wasm builder and tooling work. All on branch
wasm-wit-component.WIT (
vlib/wit, new module)variants, enums, flags, resources (incl. constructors and
static),type aliases,
use(incl.as),include/include ... with,@since/@deprecated/@unstableattributes, canonical-ABI stringlifting info, and validation with dedicated error codes.
WitDoc.to_v(), incl. WASI preview2 + sockets bindings),document printer with round-trip tests, and a WIT conformance matrix at
vlib/wasm/wit/CONFORMANCE.md.vlib/wit/cabi.vmapping every WITtype (records, variants, options, results, tuples, enums, flags, lists,
strings, primitives) to (size, align) through the doc.
Component model (
vlib/wasm/component.v)wrap_core_modulewraps a core module in a component container.wrap_core_module_stringslifts exported functions with canonical-ABIstring params / returns (incl. multi-string params), emitting
(memory)/(realloc)canon opts, with WIT-aware naming viawit.wrap_component.s32over corei32; flags (<=32 bits)lift as component
u32over corei32.maps, resources) is not implemented yet: layout helpers exist but the
wrapper has no guest-side marshal/allocation path.
Native backend (
vlib/v/gen/wasm)WType.cabi_stringmarker; exported string params lower to(i32 ptr, i32 len); string results use the hidden sret slot.cabi_reallocbump allocator exported under-component/-d wasm_cabi.v -b wasm -component -wit file.witproduces.wasm+.component.wasmnatively (byte-identical to the
vwit_wraptool path).Driver
-os wasm32_emscriptenneeds linking via anemcc-family compiler that is not on PATH (points at emsdk, or at thetoolchain-free
v -b wasmalternative). C-only output (-o file.c) isunaffected and never requires emcc.
Docs
doc/wasm.md: new "Emscripten output" section; the native-b wasmpathneeds no C compiler, Emscripten, or Binaryen.
Known limitations (documented in code)
would clobber outer call materialized strings.
no task/waitable state, no pollable dispatch).
includetargets outside the document are allowed but not resolved.Testing
v test vlib/wasm vlib/v/gen/wasm vlib/wasm/wit vlib/wit vlib/wasi→18/18 wasm + 18/18 wit suites pass, including node-based runtime tests
(echo-len, multi-param, string returns, UTF-8 lengths, len pinning).
test_emscripten_missing_emcc_suggests_native_wasm,cabi_layout_test.v(10 layout cases),cabi_test.v(enum/flags lift).v fmt -lclean on touched files;v check-mdclean on touched docs.Experimental status
incl. multi-string params) plus enums and flags (as integers); lists,
records, variants, options, tuples and maps are not lifted yet (layout
helpers are in place; CONFORMANCE.md rows track progress).
Status
Rebased onto current master (90 commits); resolved the
-component/-witflag conflict invlib/v/driver/driver.v(kept master's-b=support alongside the new flags). wit (5) and wasm/wasi (14) suites green locally.