message: Warn when using LTO
diff: @@ -162,7 +162,11 @@ fn finalize(self) {
  struct CraneliftCodegenBackend;
  impl CodegenBackend for CraneliftCodegenBackend {
  - fn init(&self, _sess: &Session) {}
  + fn init(&self, sess: &Session) {
  + if sess.lto() != rustc_session::config::Lto::No {
  + sess.warn("LTO is not supported. You may get a linker error.");
  + }
  + }
  fn metadata_loader(&self) -> Box<dyn MetadataLoader + Sync> {
  Box::new(crate::metadata::CraneliftMetadataLoader)
  