Function matchGoFieldChainCall

src/resolution/name-matcher.ts:1919–1981

* Resolve a Go 2-hop field-chain call `base.field.Method(...)` (#1276): * `target.conn.Exec("insert")` where `func (target *Target) Write()` and * `type Target struct { conn *sql.DB }`. Two inference hops, both read from * source the same way #1108 does: * 1. `base`'s type from the enclosing s

(
  receiverChain: string,
  methodName: string,
  ref: UnresolvedRef,
  context: ResolutionContext
)

 * receivers, so the ref stays unresolved instead of name-guessing.
 */
function matchGoFieldChainCall(
  receiverChain: string,
  methodName: string,
  ref: UnresolvedRef,
  context: ResolutionContext
): ResolvedRef | null {
  const segs = receiverChain.split('.');
  if (segs.length !== 2 || !segs[0] || !segs[1]) return null;
  const [base, field] = segs;

  const baseType = inferLocalReceiverType(base!, ref, context);
  if (!baseType) return null;

  const fieldEsc = field!.replace(/[.*+?^${}()|[\]\\]/g, '\\$&');
  const fieldTypeRe = new RegExp(`\\b${fieldEsc}\\s+\\*?\\[?\\]?([A-Za-z_][\\w.]*)`);

  const structs = preferCallSiteFile(context.getNodesByName(baseType), ref.filePath).filter(
    (n) => (n.kind === 'struct' || n.kind === 'class') && n.language === 'go'
  );
  for (const s of structs) {
    const source = context.readFile(s.filePath);
    if (!source) continue;
    // Only the struct's own declaration lines — a same-named identifier
    // elsewhere in the file can't donate a type. Matched LINE BY LINE with
    // comments stripped: chi's `Mux` has a doc comment reading "the tree
    // router" right above `tree *node`, and a whole-block match captured
    // `router` from the prose instead of `node` from the field.
    const declLines = source.split('\n').slice(Math.max(0, s.startLine - 1), s.endLine);
    for (const rawLine of declLines) {
      const line = rawLine.replace(/\/\/.*$/, '').replace(/\/\*.*?\*\//g, '');
      const m = line.match(fieldTypeRe);
      if (!m || !m[1]) continue;
      const rawType = m[1];
      // A package-qualified field type (`http.Handler`, `sql.DB`) is only
      // followed when the package is IN-MODULE: stripping the qualifier and
      // matching the bare name would conflate a stdlib/third-party type with
      // any same-named project type — on chi, `handler http.Handler` bound
      // to an example app's unrelated local `Handler`. That is the exact
      // fabrication this matcher exists to prevent (#1276).
      if (rawType.includes('.')) {
        const pkg = rawType.split('.')[0]!;
        const mod = context.getGoModule?.();
        const imp = context
          .getImportMappings(s.filePath, 'go')
          .find((i) => i.localName === pkg);
        const inModule =
          !!mod &&
          !!imp &&
          (imp.source === mod.modulePath || imp.source.startsWith(mod.modulePath + '/'));
        if (!inModule) continue;
      }
      // Unexported (lowercase) types are idiomatic Go and stay eligible —
      // chi's `mx.tree.FindRoute()` chains through `tree *node`. A
      // mis-capture is harmless: resolveMethodOnType only returns a
      // validated `<type>::<method>` match.
      const fieldType = rawType.split('.').pop();
      if (!fieldType || !/^[A-Za-z_]/.test(fieldType) || GO_BUILTIN_FIELD_TYPES.has(fieldType)) continue;
      const resolved = resolveMethodOnType(fieldType, methodName, ref, context, 0.85, 'instance-method');