\brief Retrieve a diagnostic associated with the given CXDiagnosticSet.
\param Diags the CXDiagnosticSet to query. \param Index the zero-based diagnostic number to retrieve.
\returns the requested diagnostic. This diagnostic must be freed via a call to \c clang_disposeDiagnostic().
See Implementation
\brief Retrieve a diagnostic associated with the given CXDiagnosticSet.
\param Diags the CXDiagnosticSet to query. \param Index the zero-based diagnostic number to retrieve.
\returns the requested diagnostic. This diagnostic must be freed via a call to \c clang_disposeDiagnostic().