fn prepare_lto(
cgcx: &CodegenContext<LlvmCodegenBackend>,
dcx: DiagCtxtHandle<'_>,
) -> Result<(Vec<CString>, Vec<(SerializedModule<ModuleBuffer>, CString)>), FatalError>
fn prepare_lto(
cgcx: &CodegenContext<LlvmCodegenBackend>,
dcx: DiagCtxtHandle<'_>,
) -> Result<(Vec<CString>, Vec<(SerializedModule<ModuleBuffer>, CString)>), FatalError>