add '--miri' flag to 'x.py test', and make it work for 'library/core'

This does need some hacks inside libcore though

Author: RalfJung

library/alloc/Cargo.toml

@@ -36,5 +36,7 @@ compiler-builtins-c = ["compiler_builtins/c"]
 compiler-builtins-no-asm = ["compiler_builtins/no-asm"]
 compiler-builtins-mangled-names = ["compiler_builtins/mangled-names"]
 compiler-builtins-weak-intrinsics = ["compiler_builtins/weak-intrinsics"]
+# Empty the crate so Miri can run tests
+miri-test = ["core/miri-test"]
 # Make panics and failed asserts immediately abort without formatting any message
 panic_immediate_abort = []

library/core/Cargo.toml

@@ -34,3 +34,5 @@ panic_immediate_abort = []
 # Make `RefCell` store additional debugging information, which is printed out when
 # a borrow error occurs
 debug_refcell = []
+# Empty the crate so Miri can run tests
+miri-test = []

library/core/src/lib.rs

@@ -72,6 +72,8 @@
 #![doc(cfg_hide(
     not(test),
     any(not(feature = "miri-test-libstd"), test, doctest),
+    all(feature = "miri-test", not(any(test, doctest))),
+    not(all(feature = "miri-test", not(any(test, doctest)))),
     no_fp_fmt_parse,
     target_pointer_width = "16",
     target_pointer_width = "32",
@@ -282,160 +284,52 @@
 #![feature(wasm_target_feature)]
 // tidy-alphabetical-end
 
+// We want to be able to `cargo miri test` this crate, but that's tricky:
+// This will build the crate itself again, so now we have two `core` crates, one in the sysroot and
+// one built as dependency of the test crate. That leads to duplicate lang item errors. `./x.py test
+// library` avoids this by making the sysroot exactly the crates that `cargo build` produces, but
+// Miri builds the sysroot itself so that does not work.
+// Instead, we use the `miri-test` feature to indicate that we're running `cargo miri test`, and
+// with that feature we turn this crate into a re-export of the sysroot crate. We only do this when
+// building the crate that will become a dependency, not when doing the actual (doc)test build.
+#[cfg(all(feature = "miri-test", not(any(test, doctest))))]
+extern crate core as realcore;
+#[cfg(all(feature = "miri-test", not(any(test, doctest))))]
+#[stable(feature = "miri_test", since = "1.0.0")]
+pub use realcore::*;
+
+// Otherwise, we build the crate as usual. Everything that follows should have
+// `#[cfg(not(all(feature = "miri-test", not(any(test, doctest)))))]`. To avoid having to repeat the
+// same `cfg` so many times, we `include!("lib_.rs")` with the main crate contents, and `cfg` the
+// `include!`. However, some macro-related things can't be behind the `include!` so we have to
+// repeat the `cfg` for them.
+
 // allow using `core::` in intra-doc links
+#[cfg(not(all(feature = "miri-test", not(any(test, doctest)))))]
 #[allow(unused_extern_crates)]
 extern crate self as core;
 
+#[cfg(not(all(feature = "miri-test", not(any(test, doctest)))))]
 #[prelude_import]
 #[allow(unused)]
 use prelude::rust_2021::*;
 
 #[cfg(not(test))] // See #65860
+#[cfg(not(all(feature = "miri-test", not(any(test, doctest)))))]
 #[macro_use]
 mod macros;
 
-// We don't export this through #[macro_export] for now, to avoid breakage.
-// See https://github.com/rust-lang/rust/issues/82913
-#[cfg(not(test))]
-#[unstable(feature = "assert_matches", issue = "82775")]
-/// Unstable module containing the unstable `assert_matches` macro.
-pub mod assert_matches {
-    #[unstable(feature = "assert_matches", issue = "82775")]
-    pub use crate::macros::{assert_matches, debug_assert_matches};
-}
-
-#[unstable(feature = "cfg_match", issue = "115585")]
-pub use crate::macros::cfg_match;
-
-#[macro_use]
-mod internal_macros;
-
-#[path = "num/shells/int_macros.rs"]
-#[macro_use]
-mod int_macros;
-
-#[rustc_diagnostic_item = "i128_legacy_mod"]
-#[path = "num/shells/i128.rs"]
-pub mod i128;
-#[rustc_diagnostic_item = "i16_legacy_mod"]
-#[path = "num/shells/i16.rs"]
-pub mod i16;
-#[rustc_diagnostic_item = "i32_legacy_mod"]
-#[path = "num/shells/i32.rs"]
-pub mod i32;
-#[rustc_diagnostic_item = "i64_legacy_mod"]
-#[path = "num/shells/i64.rs"]
-pub mod i64;
-#[rustc_diagnostic_item = "i8_legacy_mod"]
-#[path = "num/shells/i8.rs"]
-pub mod i8;
-#[rustc_diagnostic_item = "isize_legacy_mod"]
-#[path = "num/shells/isize.rs"]
-pub mod isize;
-
-#[rustc_diagnostic_item = "u128_legacy_mod"]
-#[path = "num/shells/u128.rs"]
-pub mod u128;
-#[rustc_diagnostic_item = "u16_legacy_mod"]
-#[path = "num/shells/u16.rs"]
-pub mod u16;
-#[rustc_diagnostic_item = "u32_legacy_mod"]
-#[path = "num/shells/u32.rs"]
-pub mod u32;
-#[rustc_diagnostic_item = "u64_legacy_mod"]
-#[path = "num/shells/u64.rs"]
-pub mod u64;
-#[rustc_diagnostic_item = "u8_legacy_mod"]
-#[path = "num/shells/u8.rs"]
-pub mod u8;
-#[rustc_diagnostic_item = "usize_legacy_mod"]
-#[path = "num/shells/usize.rs"]
-pub mod usize;
-
-#[path = "num/f32.rs"]
-pub mod f32;
-#[path = "num/f64.rs"]
-pub mod f64;
-
-#[macro_use]
-pub mod num;
-
 /* The core prelude, not as all-encompassing as the std prelude */
-
+#[cfg(not(all(feature = "miri-test", not(any(test, doctest)))))]
 pub mod prelude;
 
-/* Core modules for ownership management */
-
-pub mod hint;
-pub mod intrinsics;
-pub mod mem;
-pub mod ptr;
-mod ub_checks;
-
-/* Core language traits */
-
-pub mod borrow;
-pub mod clone;
-pub mod cmp;
-pub mod convert;
-pub mod default;
-pub mod error;
-pub mod marker;
-pub mod ops;
-
-/* Core types and methods on primitives */
-
-pub mod any;
-pub mod array;
-pub mod ascii;
-pub mod asserting;
-#[unstable(feature = "async_iterator", issue = "79024")]
-pub mod async_iter;
-pub mod cell;
-pub mod char;
-pub mod ffi;
-#[unstable(feature = "core_io_borrowed_buf", issue = "117693")]
-pub mod io;
-pub mod iter;
-pub mod net;
-pub mod option;
-pub mod panic;
-pub mod panicking;
-pub mod pin;
-pub mod result;
-pub mod sync;
-
-pub mod fmt;
-pub mod hash;
-pub mod slice;
-pub mod str;
-pub mod time;
-
-pub mod unicode;
-
-/* Async */
-pub mod future;
-pub mod task;
-
-/* Heap memory allocator trait */
-#[allow(missing_docs)]
-pub mod alloc;
-
-// note: does not need to be public
-mod bool;
-mod escape;
-mod tuple;
-mod unit;
-
-#[stable(feature = "core_primitive", since = "1.43.0")]
-pub mod primitive;
-
 // Pull in the `core_arch` crate directly into core. The contents of
 // `core_arch` are in a different repository: rust-lang/stdarch.
 //
 // `core_arch` depends on core, but the contents of this module are
 // set up in such a way that directly pulling it here works such that the
 // crate uses the this crate as its core.
+#[cfg(not(all(feature = "miri-test", not(any(test, doctest)))))]
 #[path = "../../stdarch/crates/core_arch/src/mod.rs"]
 #[allow(
     missing_docs,
@@ -449,27 +343,5 @@ pub mod primitive;
 #[allow(rustdoc::bare_urls)]
 mod core_arch;
 
-#[stable(feature = "simd_arch", since = "1.27.0")]
-pub mod arch;
-
-// Pull in the `core_simd` crate directly into core. The contents of
-// `core_simd` are in a different repository: rust-lang/portable-simd.
-//
-// `core_simd` depends on core, but the contents of this module are
-// set up in such a way that directly pulling it here works such that the
-// crate uses this crate as its core.
-#[path = "../../portable-simd/crates/core_simd/src/mod.rs"]
-#[allow(missing_debug_implementations, dead_code, unsafe_op_in_unsafe_fn)]
-#[allow(rustdoc::bare_urls)]
-#[unstable(feature = "portable_simd", issue = "86656")]
-mod core_simd;
-
-#[unstable(feature = "portable_simd", issue = "86656")]
-pub mod simd {
-    #![doc = include_str!("../../portable-simd/crates/core_simd/src/core_simd_docs.md")]
-
-    #[unstable(feature = "portable_simd", issue = "86656")]
-    pub use crate::core_simd::simd::*;
-}
-
-include!("primitive_docs.rs");
+#[cfg(not(all(feature = "miri-test", not(any(test, doctest)))))]
+include!("lib_.rs");

library/core/src/lib_.rs

@@ -0,0 +1,156 @@
+// We don't export this through #[macro_export] for now, to avoid breakage.
+// See https://github.com/rust-lang/rust/issues/82913
+#[cfg(not(test))]
+#[unstable(feature = "assert_matches", issue = "82775")]
+/// Unstable module containing the unstable `assert_matches` macro.
+pub mod assert_matches {
+    #[unstable(feature = "assert_matches", issue = "82775")]
+    pub use crate::macros::{assert_matches, debug_assert_matches};
+}
+
+#[unstable(feature = "cfg_match", issue = "115585")]
+pub use crate::macros::cfg_match;
+
+#[macro_use]
+mod internal_macros;
+
+#[path = "num/shells/int_macros.rs"]
+#[macro_use]
+mod int_macros;
+
+#[rustc_diagnostic_item = "i128_legacy_mod"]
+#[path = "num/shells/i128.rs"]
+pub mod i128;
+#[rustc_diagnostic_item = "i16_legacy_mod"]
+#[path = "num/shells/i16.rs"]
+pub mod i16;
+#[rustc_diagnostic_item = "i32_legacy_mod"]
+#[path = "num/shells/i32.rs"]
+pub mod i32;
+#[rustc_diagnostic_item = "i64_legacy_mod"]
+#[path = "num/shells/i64.rs"]
+pub mod i64;
+#[rustc_diagnostic_item = "i8_legacy_mod"]
+#[path = "num/shells/i8.rs"]
+pub mod i8;
+#[rustc_diagnostic_item = "isize_legacy_mod"]
+#[path = "num/shells/isize.rs"]
+pub mod isize;
+
+#[rustc_diagnostic_item = "u128_legacy_mod"]
+#[path = "num/shells/u128.rs"]
+pub mod u128;
+#[rustc_diagnostic_item = "u16_legacy_mod"]
+#[path = "num/shells/u16.rs"]
+pub mod u16;
+#[rustc_diagnostic_item = "u32_legacy_mod"]
+#[path = "num/shells/u32.rs"]
+pub mod u32;
+#[rustc_diagnostic_item = "u64_legacy_mod"]
+#[path = "num/shells/u64.rs"]
+pub mod u64;
+#[rustc_diagnostic_item = "u8_legacy_mod"]
+#[path = "num/shells/u8.rs"]
+pub mod u8;
+#[rustc_diagnostic_item = "usize_legacy_mod"]
+#[path = "num/shells/usize.rs"]
+pub mod usize;
+
+#[path = "num/f32.rs"]
+pub mod f32;
+#[path = "num/f64.rs"]
+pub mod f64;
+
+#[macro_use]
+pub mod num;
+
+/* Core modules for ownership management */
+
+pub mod hint;
+pub mod intrinsics;
+pub mod mem;
+pub mod ptr;
+mod ub_checks;
+
+/* Core language traits */
+
+pub mod borrow;
+pub mod clone;
+pub mod cmp;
+pub mod convert;
+pub mod default;
+pub mod error;
+pub mod marker;
+pub mod ops;
+
+/* Core types and methods on primitives */
+
+pub mod any;
+pub mod array;
+pub mod ascii;
+pub mod asserting;
+#[unstable(feature = "async_iterator", issue = "79024")]
+pub mod async_iter;
+pub mod cell;
+pub mod char;
+pub mod ffi;
+#[unstable(feature = "core_io_borrowed_buf", issue = "117693")]
+pub mod io;
+pub mod iter;
+pub mod net;
+pub mod option;
+pub mod panic;
+pub mod panicking;
+pub mod pin;
+pub mod result;
+pub mod sync;
+
+pub mod fmt;
+pub mod hash;
+pub mod slice;
+pub mod str;
+pub mod time;
+
+pub mod unicode;
+
+/* Async */
+pub mod future;
+pub mod task;
+
+/* Heap memory allocator trait */
+#[allow(missing_docs)]
+pub mod alloc;
+
+// note: does not need to be public
+mod bool;
+mod escape;
+mod tuple;
+mod unit;
+
+#[stable(feature = "core_primitive", since = "1.43.0")]
+pub mod primitive;
+
+#[stable(feature = "simd_arch", since = "1.27.0")]
+pub mod arch;
+
+// Pull in the `core_simd` crate directly into core. The contents of
+// `core_simd` are in a different repository: rust-lang/portable-simd.
+//
+// `core_simd` depends on core, but the contents of this module are
+// set up in such a way that directly pulling it here works such that the
+// crate uses this crate as its core.
+#[path = "../../portable-simd/crates/core_simd/src/mod.rs"]
+#[allow(missing_debug_implementations, dead_code, unsafe_op_in_unsafe_fn)]
+#[allow(rustdoc::bare_urls)]
+#[unstable(feature = "portable_simd", issue = "86656")]
+mod core_simd;
+
+#[unstable(feature = "portable_simd", issue = "86656")]
+pub mod simd {
+    #![doc = include_str!("../../portable-simd/crates/core_simd/src/core_simd_docs.md")]
+
+    #[unstable(feature = "portable_simd", issue = "86656")]
+    pub use crate::core_simd::simd::*;
+}
+
+include!("primitive_docs.rs");