Rollup merge of #23056 - awlnx:master, r=nrc

src/libtest/lib.rs

@@ -23,6 +23,8 @@
 // running tests while providing a base that other test frameworks may
 // build off of.
 
+// Do not remove on snapshot creation. Needed for bootstrap. (Issue #22364)
+#![cfg_attr(stage0, feature(custom_attribute))]
 #![crate_name = "test"]
 #![unstable(feature = "test")]
 #![staged_api]