pub fn extract_external_declarations(
source_set_root: &Path,
source_path: &Path,
source: &str,
limits: CppExternalDeclarationLimits,
) -> CppExternalDeclarationSetExpand description
Extract declarations from one exact header source entry.
source_path is relative to source_set_root. The caller owns source-set
containment, byte limits, cancellation, and stable hashing. This function
owns only C++ syntax interpretation and its record limit.