Function resolveRustModuleFile

src/resolution/import-resolver.ts:1627–1679

* Resolve a Rust module path (segments WITHOUT the leaf symbol) to the file of * the last module segment — `crate::a::b` → ` /a/b.rs` (or `.../b/mod.rs`). * Anchors on `crate` / `self` / `super`; a bare path is tried crate-relative.

(
  segments: string[],
  fromFile: string,
  context: ResolutionContext
)

 * Anchors on `crate` / `self` / `super`; a bare path is tried crate-relative.
 */
function resolveRustModuleFile(
  segments: string[],
  fromFile: string,
  context: ResolutionContext
): string | null {
  if (segments.length === 0) return null;
  const projectRoot = context.getProjectRoot();
  const fromAbs = path.join(projectRoot, fromFile);
  const toRel = (p: string) => path.relative(projectRoot, p).replace(/\\/g, '/');

  // Walk a sequence of module segments down from `startDir`, mapping each to a
  // `<seg>.rs` or `<seg>/mod.rs` file. Returns the leaf module's file, or null
  // if `startDir` is null or any segment has no file on disk.
  const resolveUnder = (startDir: string | null, rest: string[]): string | null => {
    if (!startDir) return null;
    let dir = startDir;
    let targetFile: string | null = null;
    for (const seg of rest) {
      if (seg === 'self' || seg === 'crate' || seg === 'super') continue;
      const asFile = toRel(path.join(dir, seg + '.rs'));
      const asMod = toRel(path.join(dir, seg, 'mod.rs'));
      if (context.fileExists(asFile)) targetFile = asFile;
      else if (context.fileExists(asMod)) targetFile = asMod;
      else return null;
      dir = path.join(dir, seg);
    }
    return targetFile;
  };

  const first = segments[0]!;
  if (first === 'crate') {
    return resolveUnder(rustCrateRootDir(fromAbs, context), segments.slice(1));
  }
  if (first === 'self') {
    return resolveUnder(rustSelfModuleDir(fromAbs), segments.slice(1));
  }
  if (first === 'super') {
    let supers = 0;
    while (segments[supers] === 'super') supers++;
    let dir: string | null = rustSelfModuleDir(fromAbs);
    for (let s = 0; s < supers && dir; s++) dir = path.dirname(dir);
    return resolveUnder(dir, segments.slice(supers));
  }
  // Bare path. In expression position (`submodule::item()` — the router-assembly
  // and general cross-module-call pattern) the prefix is a SUBMODULE of the
  // current module, i.e. 2018 `self::`-relative — so try self-relative FIRST.
  // Fall back to crate-relative for 2015-edition / crate-root items. External
  // crate paths (`serde::de::Error`) miss both and fall through to name-matching.
  return (
    resolveUnder(rustSelfModuleDir(fromAbs), segments) ??
    resolveUnder(rustCrateRootDir(fromAbs, context), segments)
  );
}

/**
 * Resolve a Java/Kotlin reference whose receiver is the simple name of