docs(kernel): R7a survey complete — the C/C++ bug-for-bug port checklist (#1344)

Step 1 of the §0a recipe for the C/C++ port: every tree-sitter.ts branch,
extractor-config field, name-salvage helper, and gate the walker must
mirror, with file:line anchors. Locks the architecture: preParse (all seven
blanking passes) hoists to the kernel route point so none of it ports to
Rust; Metal/CUDA stay on wasm this round; one dual-language walker module.
Key asymmetries surveyed: value-refs are C-only (cpp absent from
VALUE_REF_LANGS), static-member refs are cpp-only, fn-ref spec is
cFamilySpec with addressOfOnly for cpp.

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

docs/design/ccpp-kernel-port-checklist.md

@@ -0,0 +1,116 @@
+# C/C++ kernel port (R7a) — the bug-for-bug checklist
+
+**Status:** survey COMPLETE (2026-07-17); grammars + walker + gates not started.
+This is §0a-recipe step 1's output for c/cpp: every TS-side branch the walker
+must mirror, with file:line anchors into the reference implementation. Read it
+WITH `docs/design/rust-kernel-migration-plan.md` (§0a recipe, §5 gates).
+Companion walkers to crib structure from: `codegraph-kernel/src/tsjs/` (multi-
+dialect module), `java.rs`, `go.rs` (receiver QNs), `python.rs`.
+
+## Architecture decisions (already made by the plan)
+
+1. **preParse stays TS-side and is HOISTED to the route point.**
+   `tryKernelExtract(filePath, source, lang)` currently receives RAW source
+   (`tree-sitter.ts:6707`); the wasm path applies `extractor.preParse` inside
+   `TreeSitterExtractor` (`tree-sitter.ts:488`). For kernel-routed c/cpp, apply
+   the SAME preParse before the kernel call so both arms parse identical
+   blanked bytes — all seven blanking passes (`preParseCppSource` /
+   `preParseCSource`, `languages/c-cpp.ts:698/750`) then need NO Rust port,
+   and every offset survives (they're all equal-length-space replacements).
+2. **Metal + CUDA are NOT routed this round.** They are separate `Language`
+   values riding the cpp grammar; leaving them off `DEFAULT_ROUTED` keeps them
+   on wasm — zero risk, tiny file counts. (CUDA blanking still applies to
+   c/cpp-detected files via the content gate inside preParse — that rides the
+   hoist for free.)
+3. **One walker module, dual language** (`codegraph-kernel/src/ccpp/`), flagged
+   c vs cpp like `tsjs/` flags its four dialects. Grammars: tree-sitter-c +
+   tree-sitter-cpp crates, wasm vendored from the SAME tags (sha-matched
+   parser.c + scanner, ts-cli 0.25.10). Upgrade the production wasm FIRST and
+   get the full suite green before the walker exists (isolate grammar-bump
+   effects, as R2 did for TS/JS).
+
+## Extractor configs (languages/c-cpp.ts — read the whole file when porting)
+
+**cExtractor (line 180):** functionTypes=[function_definition]; NO
+class/method/interface types; structTypes=[struct_specifier];
+enumTypes=[enum_specifier]; enumMemberTypes=[enumerator];
+typeAliasTypes=[type_definition]; importTypes=[preproc_include];
+callTypes=[call_expression]; variableTypes=[declaration];
+nameField=declarator; isConst = any child `type_qualifier` with text
+`const`; getReturnType = extractCppReturnType; resolveTypeAliasKind =
+typedef enum/struct with body → that kind (anon inner specifier takes the
+typedef's name); extractImport: `system_lib_string` → strip `<>`, else
+`string_literal>string_content`; signature = full `#include` line.
+recoverMangledName = recoverMangledCppName (post-parse salvage, PORT).
+
+**cppExtractor (line 755):** adds classTypes=[class_specifier] with
+**skipBodilessClass** (forward decls / elaborated refs mint no node, #1093);
+methodTypes=[function_definition] (method vs function decided by
+isInsideClassLikeNode); typeAliasTypes += alias_declaration (`using X = …`);
+resolveName = extractCppQualifiedMethodName (line 75: macro-recovered name
+first, else LAST `::` segment of the declarator's qualified_identifier —
+found by BFS that SKIPS parameter_list + trailing_return_type, line 13);
+getReceiverType = extractCppReceiverType (line 86: the qualifier prefix,
+`stripCppTemplateArgs`-normalized — multi-line template args must not leak
+newlines into qualifiedName, #1286/NAME_MAX); getReturnType =
+extractCppReturnType → normalizeCppReturnType (line 122: smart-ptr/optional
+unwrap to pointee, cv/template/ptr strip, last `::` segment, primitives →
+none — set CPP_NON_CLASS_RETURN line 108); getVisibility = nearest preceding
+`access_specifier` scan in the parent's children (line 785);
+isMisparsedFunction (line 811): name starts `namespace`, name ∈
+{switch,if,for,while,do,case,return}, or isMacroMisparsedTypeDecl (line 261:
+bodyless class/struct specifier in `type` + non-function_declarator
+declarator → DROP the node).
+
+**Name-salvage helpers to port exactly:** recoverCppMacroDefinedName (line
+49 — ALL-CAPS-with-underscore parsed name + first param a LONE lowercase
+type_identifier + ≥2 params + NO other lone-identifier param; gtest
+`TEST_F(Fixture, Name)` / `PYBIND11_MODULE(ext, m)` bail);
+recoverMangledCppName (line 406 — only already-mangled names, `Ret (name)`
+idiom left alone, last token before `(`, primitive/keyword guard);
+stripCppTemplateArgs (line 157 — depth-counted removal of every balanced
+`<…>`); cDeclaratorIdentifier (tree-sitter.ts:234 — declarator chain walk,
+function_declarator → null, 12-hop guard).
+
+## tree-sitter.ts branches (anchors as of `705e501`)
+
+| Line | Mechanism | Must-mirror details |
+|---|---|---|
+| 962 | cpp namespace prefix stack (#1291) | named `namespace_definition` pushes its name (C++17 `a::b` as written) onto the QN prefix while walking children; anonymous falls through bare |
+| 2795 | C file-scope variables | only when NO function ancestor; iterate declarators; accept ONLY init_declarator / pointer_declarator / array_declarator — a BARE identifier declarator is a macro-prototype misparse, skip (loses uninit scalars by design); name via cDeclaratorIdentifier; signature `= <first 100 chars>`; kind constant/variable via isConst |
+| 4313 | explicit operator calls (#1247) | callee = `function` field + ERROR-wrapped `operator_name` sibling; compact symbolic spacing (`operator *`→`operator*`, word forms keep space); receiver `->`→`.`; DROP unless receiver is `this` (bare name) or simple identifier/member chain (silent miss over wrong edge) |
+| ~4340 | field_expression method calls | `recv.method`/`ptr->method` → `recv.method`; SKIP_RECEIVERS {self,this,cls,super} → bare name; LITERAL receiver → emit nothing (#1230) |
+| 4398 | call-result receivers (#645/#608) | receiver is call_expression → `<innerCallee>().<method>` re-encode (c AND cpp in the gate list) |
+| 4534 | template-arg strip on callees | callee contains `<` and NOT `operator` → stripCppTemplateArgs (CUDA launch sites post-blank take this shape) |
+| 4545 | local fn-ptr call fan-out (#932-adjacent) | bare-identifier callee found in cppLocalFnPtrs[callerId] → emit one `calls` ref PER recorded target, suppress the local name |
+| 5173 | stack construction (#1035) | cpp `declaration` where `type` ∈ {type_identifier, template_type, qualified_identifier} and any init_declarator has `value` ∈ {argument_list, initializer_list} → extractInstantiation |
+| 5183 | fn-ptr binding recording | inside a body: `declaration>init_declarator` (identifier declarator) or `assignment_expression` (identifier left); value must be pointer_expression whose child(0) is `&`; target ∈ {identifier, template_function, qualified_identifier}, template-stripped; per-callerId map of per-local Sets (branch reassignments accumulate) |
+| 5408 | base_class_clause → extends (#1043) | per base: type_identifier / qualified_identifier / template_type, stripCppTemplateArgs'd; access-specifier keywords skipped |
+| 4740 | static member refs — **cpp only** (c not in STATIC_MEMBER_LANGS, line 345) | `Foo::BAR` value reads → `references` edge; VERIFY the MEMBER_ACCESS_TYPES shapes for qualified_identifier + the call-callee skip during the port |
+| — | value-reference edges | **c: YES** (VALUE_REF_LANGS line 401), **cpp: NO**. Port the value-ref machinery for C only (crib go.rs / tsjs — shadow prune, scope stack, MAX_VALUE_REF_NODES cap, CODEGRAPH_VALUE_REFS=0 kill) |
+| — | fn-ref capture (#756) | function-ref.ts:376: `c: cFamilySpec()`, `cpp: cFamilySpec({ addressOfOnly: true })`; note line ~582: `&Cls::m` exemption from the bare-ids-are-free-functions rule — read cFamilySpec fully when porting |
+| 355 | INSTANTIATION_KINDS | includes new_expression → cpp `new Foo(...)` instantiates (verify the cpp entry list when porting) |
+
+**Generic paths c/cpp share with ported languages** (already mirrored by
+java.rs/python.rs/go.rs — re-verify each against c/cpp fixtures rather than
+re-deriving): extractFunction/Method QN via scope stack + receiverType
+(`Recv::name` like Go), struct/enum/enum_member extraction, typedef →
+type_alias (+ resolveTypeAliasKind kind override), imports, docstrings
+(preceding `comment` nodes — docstring.rs already handles C markers incl. the
+CRLF semantics from #1329), contains edges, signature truncation in UTF-16
+units, MAX_FILE_SIZE / generated-file skips, `has_error()` → `defer:`.
+
+## Gates (per plan §5, no exceptions)
+
+- Torture fixtures: `torture.c` (fn-ptr tables, typedef enum/struct, file-scope
+  consts incl. multi-declarator, macro-prototype misparse shape, value-refs) +
+  `torture.cpp`/`torture.hpp` (namespaces incl. C++17 nested, out-of-line
+  `Cls::method` defs, templates + template bases, operators incl. spaced call
+  sites, stack construction, local fn-ptrs, UE-macro shapes THROUGH the
+  hoisted preParse, `using` aliases, anonymous namespace, access specifiers).
+- Parity sweeps + full-init dump-diffs byte-identical: redis + git (C),
+  fmt + a protobuf-class repo (C++), plus a UE-macro-heavy spot-check
+  (blanking-hoist parity) — then linux in cg1212 (expect parse 338s →
+  ~120–180s at the 2c envelope; graph counts must stay 2,048,664/6,405,964).
+- Deferral-rate guard <10%; suite; changelog rides the existing kernel entry.
+- DEFAULT_ROUTED += c, cpp only after ALL of the above.

docs/design/rust-kernel-migration-plan.md

@@ -67,7 +67,14 @@ them are the ORIGINAL plan and carry expectations that measurement later correct
       last big rock)** > backpressure ~120s (checkpoint I/O floor) > E-scan/
       settle/read-mapping (~70–90s each, approaching honest work) > the 8c
       re-run formality (est. ~15.5min).
-- [ ] **R7a. C/C++ port** — biggest single-language effort; unlocks cg1212's parse
+- [ ] **R7a. C/C++ port** — STARTED 2026-07-17: the §0a-recipe step-1 survey is
+      COMPLETE — every TS branch, quirk, and helper is enumerated with line
+      anchors in **`docs/design/ccpp-kernel-port-checklist.md`** (read it FIRST;
+      it also fixes the architecture: preParse hoisted to the route point so no
+      blanking ports to Rust, Metal/CUDA stay wasm this round, one dual-lang
+      walker module). Next: grammars (upgrade+vendor from matched tags, suite
+      green BEFORE the walker), then the walker, then the §5 gate ladder.
+      Original scope note: biggest single-language effort; unlocks cg1212's parse
       expectation (6.2m → ~1.5–2m, 23% of that wall) + CARLA/UE/llvm-class repos;
       Metal + CUDA ride along (their blanking pre-passes stay TS-side — `preParse`
       is offset-preserving and the route point can apply it before the kernel call;