Rollup merge of rust-lang#87255 - RalfJung:miri-test-libcore, r=Mark-…

…Simulacrum better support for running libcore tests with Miri See rust-lang/miri-test-libstd#4 for a description of the problem that this fixes. Thanks to `@hyd-dev` for suggesting this patch!
JohnTitor · Jul 23, 2021 · 1a2b90b · 1a2b90b
2 parents aca83f1 + 6cba798
commit 1a2b90b
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diff --git a/library/alloc/src/lib.rs b/library/alloc/src/lib.rs
@@ -56,6 +56,10 @@
 //! [`Rc`]: rc
 //! [`RefCell`]: core::cell
 
+// To run liballoc tests without x.py without ending up with two copies of liballoc, Miri needs to be
+// able to "empty" this crate. See <https://github.com/rust-lang/miri-test-libstd/issues/4>.
+// rustc itself never sets the feature, so this line has no affect there.
+#![cfg(any(not(feature = "miri-test-libstd"), test, doctest))]
 #![allow(unused_attributes)]
 #![stable(feature = "alloc", since = "1.36.0")]
 #![doc(

diff --git a/library/core/src/lib.rs b/library/core/src/lib.rs
@@ -49,6 +49,10 @@
 //
 // This cfg won't affect doc tests.
 #![cfg(not(test))]
+// To run libcore tests without x.py without ending up with two copies of libcore, Miri needs to be
+// able to "empty" this crate. See <https://github.com/rust-lang/miri-test-libstd/issues/4>.
+// rustc itself never sets the feature, so this line has no affect there.
+#![cfg(any(not(feature = "miri-test-libstd"), test, doctest))]
 #![stable(feature = "core", since = "1.6.0")]
 #![doc(
     html_playground_url = "https://play.rust-lang.org/",