Auto merge of #132401 - matthiaskrgr:rollup-599ieqr, r=matthiaskrgr

Rollup of 5 pull requests

Successful merges:

 - #130693 (Add `minicore` test auxiliary and support `//@ add-core-stubs` directive in ui/assembly/codegen tests)
 - #132316 (CI: use free runners for 3 fast windows jobs)
 - #132354 (Add `lp64e` RISC-V ABI)
 - #132395 (coverage: Avoid ICE when `coverage_cx` is unexpectedly unavailable)
 - #132396 (CI: use free runners for x86_64-gnu-tools and x86_64-rust-for-linux)

r? `@ghost`
`@rustbot` modify labels: rollup

compiler/rustc_codegen_llvm/src/context.rs

@@ -554,6 +554,7 @@ pub(crate) fn statics_to_rauw(&self) -> &RefCell<Vec<(&'ll Value, &'ll Value)>>
 
     /// Extra state that is only available when coverage instrumentation is enabled.
     #[inline]
+    #[track_caller]
     pub(crate) fn coverage_cx(&self) -> &coverageinfo::CrateCoverageContext<'ll, 'tcx> {
         self.coverage_cx.as_ref().expect("only called when coverage instrumentation is enabled")
     }

compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs

@@ -54,7 +54,11 @@ pub(crate) fn finalize(cx: &CodegenCx<'_, '_>) {
         add_unused_functions(cx);
     }
 
-    let function_coverage_map = cx.coverage_cx().take_function_coverage_map();
+    // FIXME(#132395): Can this be none even when coverage is enabled?
+    let function_coverage_map = match cx.coverage_cx {
+        Some(ref cx) => cx.take_function_coverage_map(),
+        None => return,
+    };
     if function_coverage_map.is_empty() {
         // This module has no functions with coverage instrumentation
         return;

compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs

@@ -152,7 +152,12 @@ fn add_coverage(&mut self, instance: Instance<'tcx>, kind: &CoverageKind) {
             return;
         };
 
-        let mut coverage_map = bx.coverage_cx().function_coverage_map.borrow_mut();
+        // FIXME(#132395): Unwrapping `coverage_cx` here has led to ICEs in the
+        // wild, so keep this early-return until we understand why.
+        let mut coverage_map = match bx.coverage_cx {
+            Some(ref cx) => cx.function_coverage_map.borrow_mut(),
+            None => return,
+        };
         let func_coverage = coverage_map
             .entry(instance)
             .or_insert_with(|| FunctionCoverageCollector::new(instance, function_coverage_info));

compiler/rustc_codegen_ssa/src/back/metadata.rs

@@ -325,7 +325,8 @@ pub(crate) fn create_object_file(sess: &Session) -> Option<write::Object<'static
                 "" | "ilp32" | "lp64" => (),
                 "ilp32f" | "lp64f" => e_flags |= elf::EF_RISCV_FLOAT_ABI_SINGLE,
                 "ilp32d" | "lp64d" => e_flags |= elf::EF_RISCV_FLOAT_ABI_DOUBLE,
-                "ilp32e" => e_flags |= elf::EF_RISCV_RVE,
+                // Note that the `lp64e` is still unstable as it's not (yet) part of the ELF psABI.
+                "ilp32e" | "lp64e" => e_flags |= elf::EF_RISCV_RVE,
                 _ => bug!("unknown RISC-V ABI name"),
             }
 

compiler/rustc_target/src/spec/tests/tests_impl.rs

@@ -165,7 +165,8 @@ fn check_consistency(&self) {
                 assert_matches!(&*self.llvm_abiname, "ilp32" | "ilp32f" | "ilp32d" | "ilp32e")
             }
             "riscv64" => {
-                assert_matches!(&*self.llvm_abiname, "lp64" | "lp64f" | "lp64d" | "lp64q")
+                // Note that the `lp64e` is still unstable as it's not (yet) part of the ELF psABI.
+                assert_matches!(&*self.llvm_abiname, "lp64" | "lp64f" | "lp64d" | "lp64q" | "lp64e")
             }
             _ => {}
         }

src/bootstrap/src/core/build_steps/test.rs

@@ -1725,6 +1725,11 @@ fn run(self, builder: &Builder<'_>) {
         cmd.arg("--run-lib-path").arg(builder.sysroot_libdir(compiler, target));
         cmd.arg("--rustc-path").arg(builder.rustc(compiler));
 
+        // Minicore auxiliary lib for `no_core` tests that need `core` stubs in cross-compilation
+        // scenarios.
+        cmd.arg("--minicore-path")
+            .arg(builder.src.join("tests").join("auxiliary").join("minicore.rs"));
+
         let is_rustdoc = suite.ends_with("rustdoc-ui") || suite.ends_with("rustdoc-js");
 
         if mode == "run-make" {

src/ci/github-actions/jobs.yml

@@ -232,7 +232,7 @@ auto:
   # Tests integration with Rust for Linux.
   # Builds stage 1 compiler and tries to compile a few RfL examples with it.
   - image: x86_64-rust-for-linux
-    <<: *job-linux-8c
+    <<: *job-linux-4c
 
   - image: x86_64-gnu
     <<: *job-linux-4c
@@ -280,7 +280,7 @@ auto:
   - image: x86_64-gnu-tools
     env:
       DEPLOY_TOOLSTATES_JSON: toolstates-linux.json
-    <<: *job-linux-8c
+    <<: *job-linux-4c
 
   ####################
   #  macOS Builders  #
@@ -488,7 +488,7 @@ auto:
       SCRIPT: python x.py dist bootstrap --include-default-paths
       DIST_REQUIRE_ALL_TOOLS: 1
       CODEGEN_BACKENDS: llvm,cranelift
-    <<: *job-windows-8c
+    <<: *job-windows
 
   - image: dist-x86_64-mingw
     env:
@@ -501,10 +501,10 @@ auto:
       NO_DOWNLOAD_CI_LLVM: 1
       DIST_REQUIRE_ALL_TOOLS: 1
       CODEGEN_BACKENDS: llvm,cranelift
-    <<: *job-windows-8c
+    <<: *job-windows
 
   - image: dist-x86_64-msvc-alt
     env:
       RUST_CONFIGURE_ARGS: --build=x86_64-pc-windows-msvc --enable-extended --enable-profiler
       SCRIPT: python x.py dist bootstrap --include-default-paths
-    <<: *job-windows-8c
+    <<: *job-windows

src/tools/compiletest/src/common.rs

@@ -392,6 +392,11 @@ pub struct Config {
 
     /// Command for visual diff display, e.g. `diff-tool --color=always`.
     pub diff_command: Option<String>,
+
+    /// Path to minicore aux library, used for `no_core` tests that need `core` stubs in
+    /// cross-compilation scenarios that do not otherwise want/need to `-Zbuild-std`. Used in e.g.
+    /// ABI tests.
+    pub minicore_path: PathBuf,
 }
 
 impl Config {

src/tools/compiletest/src/directive-list.rs

@@ -3,6 +3,7 @@
 /// a best-effort approximation for diagnostics. Add new headers to this list when needed.
 const KNOWN_DIRECTIVE_NAMES: &[&str] = &[
     // tidy-alphabetical-start
+    "add-core-stubs",
     "assembly-output",
     "aux-bin",
     "aux-build",

src/tools/compiletest/src/header.rs

@@ -198,6 +198,9 @@ pub struct TestProps {
     pub no_auto_check_cfg: bool,
     /// Run tests which require enzyme being build
     pub has_enzyme: bool,
+    /// Build and use `minicore` as `core` stub for `no_core` tests in cross-compilation scenarios
+    /// that don't otherwise want/need `-Z build-std`.
+    pub add_core_stubs: bool,
 }
 
 mod directives {
@@ -243,6 +246,7 @@ mod directives {
     pub const LLVM_COV_FLAGS: &'static str = "llvm-cov-flags";
     pub const FILECHECK_FLAGS: &'static str = "filecheck-flags";
     pub const NO_AUTO_CHECK_CFG: &'static str = "no-auto-check-cfg";
+    pub const ADD_CORE_STUBS: &'static str = "add-core-stubs";
     // This isn't a real directive, just one that is probably mistyped often
     pub const INCORRECT_COMPILER_FLAGS: &'static str = "compiler-flags";
 }
@@ -300,6 +304,7 @@ pub fn new() -> Self {
             filecheck_flags: vec![],
             no_auto_check_cfg: false,
             has_enzyme: false,
+            add_core_stubs: false,
         }
     }
 
@@ -564,6 +569,8 @@ fn split_flags(flags: &str) -> Vec<String> {
                     }
 
                     config.set_name_directive(ln, NO_AUTO_CHECK_CFG, &mut self.no_auto_check_cfg);
+
+                    self.update_add_core_stubs(ln, config);
                 },
             );
 
@@ -677,6 +684,27 @@ pub fn pass_mode(&self, config: &Config) -> Option<PassMode> {
     pub fn local_pass_mode(&self) -> Option<PassMode> {
         self.pass_mode
     }
+
+    pub fn update_add_core_stubs(&mut self, ln: &str, config: &Config) {
+        let add_core_stubs = config.parse_name_directive(ln, directives::ADD_CORE_STUBS);
+        if add_core_stubs {
+            if !matches!(config.mode, Mode::Ui | Mode::Codegen | Mode::Assembly) {
+                panic!(
+                    "`add-core-stubs` is currently only supported for ui, codegen and assembly test modes"
+                );
+            }
+
+            // FIXME(jieyouxu): this check is currently order-dependent, but we should probably
+            // collect all directives in one go then perform a validation pass after that.
+            if self.local_pass_mode().is_some_and(|pm| pm == PassMode::Run) {
+                // `minicore` can only be used with non-run modes, because it's `core` prelude stubs
+                // and can't run.
+                panic!("`add-core-stubs` cannot be used to run the test binary");
+            }
+
+            self.add_core_stubs = add_core_stubs;
+        }
+    }
 }
 
 /// If the given line begins with the appropriate comment prefix for a directive,

src/tools/compiletest/src/header/tests.rs

@@ -152,6 +152,7 @@ fn build(&mut self) -> Config {
             "--git-repository=",
             "--nightly-branch=",
             "--git-merge-commit-email=",
+            "--minicore-path=",
         ];
         let mut args: Vec<String> = args.iter().map(ToString::to_string).collect();
 

src/tools/compiletest/src/lib.rs

@@ -181,7 +181,8 @@ pub fn parse_config(args: Vec<String>) -> Config {
             "compiletest-diff-tool",
             "What custom diff tool to use for displaying compiletest tests.",
             "COMMAND",
-        );
+        )
+        .reqopt("", "minicore-path", "path to minicore aux library", "PATH");
 
     let (argv0, args_) = args.split_first().unwrap();
     if args.len() == 1 || args[1] == "-h" || args[1] == "--help" {
@@ -371,7 +372,10 @@ fn make_absolute(path: PathBuf) -> PathBuf {
         git_merge_commit_email: matches.opt_str("git-merge-commit-email").unwrap(),
 
         profiler_runtime: matches.opt_present("profiler-runtime"),
+
         diff_command: matches.opt_str("compiletest-diff-tool"),
+
+        minicore_path: opt_path(matches, "minicore-path"),
     }
 }
 
@@ -409,6 +413,7 @@ pub fn log_config(config: &Config) {
     logv(c, format!("host-linker: {:?}", config.host_linker));
     logv(c, format!("verbose: {}", config.verbose));
     logv(c, format!("format: {:?}", config.format));
+    logv(c, format!("minicore_path: {:?}", config.minicore_path.display()));
     logv(c, "\n".to_string());
 }
 
@@ -885,6 +890,12 @@ fn files_related_to_test(
         related.push(path);
     }
 
+    // `minicore.rs` test auxiliary: we need to make sure tests get rerun if this changes.
+    //
+    // FIXME(jieyouxu): untangle these paths, we should provide both a path to root `tests/` or
+    // `tests/auxiliary/` and the test suite in question. `src_base` is also a terrible name.
+    related.push(config.src_base.parent().unwrap().join("auxiliary").join("minicore.rs"));
+
     related
 }
 

src/tools/compiletest/src/runtest.rs

@@ -1150,14 +1150,20 @@ fn build_all_auxiliary(&self, of: &TestPaths, aux_dir: &Path, rustc: &mut Comman
         }
     }
 
-    /// `root_testpaths` refers to the path of the original test.
+    /// `root_testpaths` refers to the path of the original test. the auxiliary and the test with an
-    /// the auxiliary and the test with an aux-build have the same `root_testpaths`.
+    /// aux-build have the same `root_testpaths`.
     fn compose_and_run_compiler(
         &self,
         mut rustc: Command,
         input: Option<String>,
         root_testpaths: &TestPaths,
     ) -> ProcRes {
+        if self.props.add_core_stubs {
+            let minicore_path = self.build_minicore();
+            rustc.arg("--extern");
+            rustc.arg(&format!("minicore={}", minicore_path.to_str().unwrap()));
+        }
+
         let aux_dir = self.aux_output_dir();
         self.build_all_auxiliary(root_testpaths, &aux_dir, &mut rustc);
 
@@ -1171,6 +1177,37 @@ fn compose_and_run_compiler(
         )
     }
 
+    /// Builds `minicore`. Returns the path to the minicore rlib within the base test output
+    /// directory.
+    fn build_minicore(&self) -> PathBuf {
+        let output_file_path = self.output_base_dir().join("libminicore.rlib");
+        let mut rustc = self.make_compile_args(
+            &self.config.minicore_path,
+            TargetLocation::ThisFile(output_file_path.clone()),
+            Emit::None,
+            AllowUnused::Yes,
+            LinkToAux::No,
+            vec![],
+        );
+
+        rustc.args(&["--crate-type", "rlib"]);
+        rustc.arg("-Cpanic=abort");
+
+        let res =
+            self.compose_and_run(rustc, self.config.compile_lib_path.to_str().unwrap(), None, None);
+        if !res.status.success() {
+            self.fatal_proc_rec(
+                &format!(
+                    "auxiliary build of {:?} failed to compile: ",
+                    self.config.minicore_path.display()
+                ),
+                &res,
+            );
+        }
+
+        output_file_path
+    }
+
     /// Builds an aux dependency.
     fn build_auxiliary(
         &self,
@@ -1662,6 +1699,15 @@ fn make_compile_args(
 
         rustc.args(&self.props.compile_flags);
 
+        // FIXME(jieyouxu): we should report a fatal error or warning if user wrote `-Cpanic=` with
+        // something that's not `abort`, however, by moving this last we should override previous
+        // `-Cpanic=`s
+        //
+        // `minicore` requires `#![no_std]` and `#![no_core]`, which means no unwinding panics.
+        if self.props.add_core_stubs {
+            rustc.arg("-Cpanic=abort");
+        }
+
         rustc
     }
 
@@ -1848,34 +1894,6 @@ fn compile_test_and_save_ir(&self) -> (ProcRes, PathBuf) {
         (proc_res, output_path)
     }
 
-    fn compile_test_and_save_assembly(&self) -> (ProcRes, PathBuf) {
-        // This works with both `--emit asm` (as default output name for the assembly)
-        // and `ptx-linker` because the latter can write output at requested location.
-        let output_path = self.output_base_name().with_extension("s");
-        let input_file = &self.testpaths.file;
-
-        // Use the `//@ assembly-output:` directive to determine how to emit assembly.
-        let emit = match self.props.assembly_output.as_deref() {
-            Some("emit-asm") => Emit::Asm,
-            Some("bpf-linker") => Emit::LinkArgsAsm,
-            Some("ptx-linker") => Emit::None, // No extra flags needed.
-            Some(other) => self.fatal(&format!("unknown 'assembly-output' directive: {other}")),
-            None => self.fatal("missing 'assembly-output' directive"),
-        };
-
-        let rustc = self.make_compile_args(
-            input_file,
-            TargetLocation::ThisFile(output_path.clone()),
-            emit,
-            AllowUnused::No,
-            LinkToAux::Yes,
-            Vec::new(),
-        );
-
-        let proc_res = self.compose_and_run_compiler(rustc, None, self.testpaths);
-        (proc_res, output_path)
-    }
-
     fn verify_with_filecheck(&self, output: &Path) -> ProcRes {
         let mut filecheck = Command::new(self.config.llvm_filecheck.as_ref().unwrap());
         filecheck.arg("--input-file").arg(output).arg(&self.testpaths.file);

src/tools/compiletest/src/runtest/assembly.rs

@@ -1,4 +1,6 @@
-use super::TestCx;
+use std::path::PathBuf;
+
+use super::{AllowUnused, Emit, LinkToAux, ProcRes, TargetLocation, TestCx};
 
 impl TestCx<'_> {
     pub(super) fn run_assembly_test(&self) {
@@ -16,4 +18,32 @@ pub(super) fn run_assembly_test(&self) {
             self.fatal_proc_rec("verification with 'FileCheck' failed", &proc_res);
         }
     }
+
+    fn compile_test_and_save_assembly(&self) -> (ProcRes, PathBuf) {
+        // This works with both `--emit asm` (as default output name for the assembly)
+        // and `ptx-linker` because the latter can write output at requested location.
+        let output_path = self.output_base_name().with_extension("s");
+        let input_file = &self.testpaths.file;
+
+        // Use the `//@ assembly-output:` directive to determine how to emit assembly.
+        let emit = match self.props.assembly_output.as_deref() {
+            Some("emit-asm") => Emit::Asm,
+            Some("bpf-linker") => Emit::LinkArgsAsm,
+            Some("ptx-linker") => Emit::None, // No extra flags needed.
+            Some(other) => self.fatal(&format!("unknown 'assembly-output' directive: {other}")),
+            None => self.fatal("missing 'assembly-output' directive"),
+        };
+
+        let rustc = self.make_compile_args(
+            input_file,
+            TargetLocation::ThisFile(output_path.clone()),
+            emit,
+            AllowUnused::No,
+            LinkToAux::Yes,
+            Vec::new(),
+        );
+
+        let proc_res = self.compose_and_run_compiler(rustc, None, self.testpaths);
+        (proc_res, output_path)
+    }
 }

tests/assembly/compiletest-self-test/use-minicore-no-run.rs

@@ -0,0 +1,5 @@
+//! `compiletest` self-test to check that `add-core-stubs` is incompatible with run pass modes.
+
+//@ add-core-stubs
+//@ run-pass
+//@ should-fail

tests/auxiliary/minicore.rs

@@ -0,0 +1,72 @@
+//! Auxiliary `minicore` prelude which stubs out `core` items for `no_core` tests that need to work
+//! in cross-compilation scenarios where no `core` is available (that don't want nor need to
+//! `-Zbuild-std`).
+//!
+//! # Important notes
+//!
+//! - `minicore` is **only** intended for `core` items, and the stubs should match the actual `core`
+//!   items.
+//!
+//! # References
+//!
+//! This is partially adapted from `rustc_codegen_cranelift`:
+//! <https://github.com/rust-lang/rust/blob/c0b5cc9003f6464c11ae1c0662c6a7e06f6f5cab/compiler/rustc_codegen_cranelift/example/mini_core.rs>.
+// ignore-tidy-linelength
+
+#![feature(no_core, lang_items, rustc_attrs)]
+#![allow(unused, improper_ctypes_definitions, internal_features)]
+#![no_std]
+#![no_core]
+
+// `core` has some exotic `marker_impls!` macro for handling the with-generics cases, but for our
+// purposes, just use a simple macro_rules macro.
+macro_rules! impl_marker_trait {
+    ($Trait:ident => [$( $ty:ident ),* $(,)?] ) => {
+        $( impl $Trait for $ty {} )*
+    }
+}
+
+#[lang = "sized"]
+pub trait Sized {}
+
+#[lang = "legacy_receiver"]
+pub trait LegacyReceiver {}
+impl<T: ?Sized> LegacyReceiver for &T {}
+impl<T: ?Sized> LegacyReceiver for &mut T {}
+
+#[lang = "copy"]
+pub trait Copy: Sized {}
+
+impl_marker_trait!(Copy => [ bool, char, isize, usize, i8, i16, i32, i64, u8, u16, u32, u64 ]);
+impl<'a, T: ?Sized> Copy for &'a T {}
+impl<T: ?Sized> Copy for *const T {}
+impl<T: ?Sized> Copy for *mut T {}
+
+#[lang = "phantom_data"]
+pub struct PhantomData<T: ?Sized>;
+impl<T: ?Sized> Copy for PhantomData<T> {}
+
+pub enum Option<T> {
+    None,
+    Some(T),
+}
+impl<T: Copy> Copy for Option<T> {}
+
+pub enum Result<T, E> {
+    Ok(T),
+    Err(E),
+}
+impl<T: Copy, E: Copy> Copy for Result<T, E> {}
+
+#[lang = "manually_drop"]
+#[repr(transparent)]
+pub struct ManuallyDrop<T: ?Sized> {
+    value: T,
+}
+impl<T: Copy + ?Sized> Copy for ManuallyDrop<T> {}
+
+#[lang = "unsafe_cell"]
+#[repr(transparent)]
+pub struct UnsafeCell<T: ?Sized> {
+    value: T,
+}

tests/codegen/compiletest-self-test/minicore-smoke-test.rs

@@ -0,0 +1,20 @@
+//! Basic smoke test for `minicore` test auxiliary.
+
+//@ add-core-stubs
+//@ compile-flags: --target=x86_64-unknown-linux-gnu
+//@ needs-llvm-components: x86
+
+#![crate_type = "lib"]
+#![feature(no_core)]
+#![no_std]
+#![no_core]
+
+extern crate minicore;
+use minicore::*;
+
+struct Meow;
+impl Copy for Meow {}
+
+// CHECK-LABEL: meow
+#[no_mangle]
+fn meow() {}

tests/ui/abi/compatibility.rs

@@ -1,4 +1,5 @@
 //@ check-pass
+//@ add-core-stubs
 //@ revisions: host
 //@ revisions: i686
 //@[i686] compile-flags: --target i686-unknown-linux-gnu
@@ -58,8 +59,10 @@
 //@ revisions: nvptx64
 //@[nvptx64] compile-flags: --target nvptx64-nvidia-cuda
 //@[nvptx64] needs-llvm-components: nvptx
-#![feature(rustc_attrs, unsized_fn_params, transparent_unions)]
+#![feature(no_core, rustc_attrs, lang_items)]
-#![cfg_attr(not(host), feature(no_core, lang_items), no_std, no_core)]
+#![feature(unsized_fn_params, transparent_unions)]
+#![no_std]
+#![no_core]
 #![allow(unused, improper_ctypes_definitions, internal_features)]
 
 // FIXME: some targets are broken in various ways.
@@ -67,67 +70,24 @@
 // sparc64: https://github.com/rust-lang/rust/issues/115336
 // mips64: https://github.com/rust-lang/rust/issues/115404
 
-#[cfg(host)]
+extern crate minicore;
-use std::{
+use minicore::*;
-    any::Any, marker::PhantomData, mem::ManuallyDrop, num::NonZero, ptr::NonNull, rc::Rc, sync::Arc,
-};
 
-/// To work cross-target this test must be no_core.
+/// To work cross-target this test must be no_core. This little prelude supplies what we need.
-/// This little prelude supplies what we need.
+///
-#[cfg(not(host))]
+/// Note that `minicore` provides a very minimal subset of `core` items (not yet complete). This
+/// prelude contains `alloc` and non-`core` (but in `std`) items that minicore does not stub out.
 mod prelude {
-    #[lang = "sized"]
+    use minicore::*;
-    pub trait Sized {}
 
-    #[lang = "legacy_receiver"]
+    // Trait stub, no `type_id` method.
-    pub trait LegacyReceiver {}
+    pub trait Any: 'static {}
-    impl<T: ?Sized> LegacyReceiver for &T {}
-    impl<T: ?Sized> LegacyReceiver for &mut T {}
-
-    #[lang = "copy"]
-    pub trait Copy: Sized {}
-    impl Copy for i32 {}
-    impl Copy for f32 {}
-    impl<T: ?Sized> Copy for &T {}
-    impl<T: ?Sized> Copy for *const T {}
-    impl<T: ?Sized> Copy for *mut T {}
 
     #[lang = "clone"]
     pub trait Clone: Sized {
         fn clone(&self) -> Self;
     }
 
-    #[lang = "phantom_data"]
-    pub struct PhantomData<T: ?Sized>;
-    impl<T: ?Sized> Copy for PhantomData<T> {}
-
-    #[lang = "unsafe_cell"]
-    #[repr(transparent)]
-    pub struct UnsafeCell<T: ?Sized> {
-        value: T,
-    }
-
-    pub trait Any: 'static {}
-
-    pub enum Option<T> {
-        None,
-        Some(T),
-    }
-    impl<T: Copy> Copy for Option<T> {}
-
-    pub enum Result<T, E> {
-        Ok(T),
-        Err(E),
-    }
-    impl<T: Copy, E: Copy> Copy for Result<T, E> {}
-
-    #[lang = "manually_drop"]
-    #[repr(transparent)]
-    pub struct ManuallyDrop<T: ?Sized> {
-        value: T,
-    }
-    impl<T: Copy + ?Sized> Copy for ManuallyDrop<T> {}
-
     #[repr(transparent)]
     #[rustc_layout_scalar_valid_range_start(1)]
     #[rustc_nonnull_optimization_guaranteed]
@@ -185,7 +145,6 @@ pub struct Arc<T: ?Sized, A = Global> {
         alloc: A,
     }
 }
-#[cfg(not(host))]
 use prelude::*;
 
 macro_rules! test_abi_compatible {

tests/ui/compiletest-self-test/minicore-smoke-test.rs

@@ -0,0 +1,20 @@
+//! Basic smoke test for `minicore` test auxiliary.
+//!
+//! This test is duplicated between ui/codegen/assembly because they have different runtest
+//! codepaths.
+
+//@ add-core-stubs
+//@ check-pass
+//@ compile-flags: --target=x86_64-unknown-linux-gnu
+//@ needs-llvm-components: x86
+
+#![crate_type = "lib"]
+#![feature(no_core)]
+#![no_std]
+#![no_core]
+
+extern crate minicore;
+use minicore::*;
+
+struct Meow;
+impl Copy for Meow {}