Library test map::test_map::test_clone_from_memory_leaks errors with using uninitialized data under valgrind and miri

[udoprog]

Steps to reproduce:

cargo test --lib

Find the resulting test binary and run it through valgrind:

valgrind target/debug/deps/hashbrown-e06c00d15197ef31 --exact map::test_map::test_clone_from_memory_leaks

This is what I get:

Valgrind error

==132117== Thread 9 map::test_map:::
==132117== Conditional jump or move depends on uninitialised value(s)
==132117==    at 0x139B47: alloc::raw_vec::RawVec<T,A>::current_memory (raw_vec.rs:256)
==132117==    by 0x1346DA: <alloc::raw_vec::RawVec<T,A> as core::ops::drop::Drop>::drop (raw_vec.rs:530)
==132117==    by 0x131AC9: core::ptr::drop_in_place<alloc::raw_vec::RawVec<i32>> (mod.rs:507)
==132117==    by 0x1318AA: core::ptr::drop_in_place<alloc::vec::Vec<i32>> (mod.rs:507)
==132117==    by 0x132749: core::ptr::drop_in_place<hashbrown::map::test_map::test_clone_from_memory_leaks::CheckedClone> (mod.rs:507)
==132117==    by 0x1302CD: core::ptr::drop_in_place<(i32,hashbrown::map::test_map::test_clone_from_memory_leaks::CheckedClone)> (mod.rs:507)
==132117==    by 0x178D4A: drop_in_place<(i32, hashbrown::map::test_map::test_clone_from_memory_leaks::CheckedClone)> (mut_ptr.rs:1469)
==132117==    by 0x178D4A: hashbrown::raw::Bucket<T>::drop (mod.rs:590)
==132117==    by 0x1CBE07: hashbrown::raw::RawTable<T,A>::clone_from_impl::{{closure}} (mod.rs:3587)
==132117==    by 0x135531: <hashbrown::scopeguard::ScopeGuard<T,F> as core::ops::drop::Drop>::drop (scopeguard.rs:70)
==132117==    by 0x1313D9: core::ptr::drop_in_place<hashbrown::scopeguard::ScopeGuard<(usize,&mut hashbrown::raw::RawTable<(i32,hashbrown::map::test_map::test_clone_from_memory_leaks::CheckedClone)>),hashbrown::raw::RawTable<(i32,hashbrown::map::test_map::test_clone_from_memory_leaks::CheckedClone)>::clone_from_impl::{{closure}}>> (mod.rs:507)
==132117==    by 0x1CB124: hashbrown::raw::RawTable<T,A>::clone_from_impl (mod.rs:3607)
==132117==    by 0x1D4532: <hashbrown::raw::RawTable<T,A> as hashbrown::raw::RawTableClone>::clone_from_spec (mod.rs:3545)
==132117== 

Miri also fails:

cargo +nightly miri test map::test_map::test_clone_from_memory_leaks

MIRI error

test map::test_map::test_clone_from_memory_leaks - should panic ... error: Undefined Behavior: using uninitialized data, but this operation requires initialized memory
    --> /home/udoprog/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/alloc/src/raw_vec.rs:235:9
     |
235  |         self.ptr.as_ptr()
     |         ^^^^^^^^ using uninitialized data, but this operation requires initialized memory
     |
     = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
     = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
     = note: BACKTRACE on thread `map::test_map::`:
     = note: inside `alloc::raw_vec::RawVec::<i32>::ptr` at /home/udoprog/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/alloc/src/raw_vec.rs:235:9: 235:17
     = note: inside `std::vec::Vec::<i32>::as_mut_ptr` at /home/udoprog/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/alloc/src/vec/mod.rs:1331:9: 1331:23
     = note: inside `<std::vec::Vec<i32> as core::ops::Drop>::drop` at /home/udoprog/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/alloc/src/vec/mod.rs:3171:62: 3171:79
     = note: inside `core::ptr::drop_in_place::<std::vec::Vec<i32>> - shim(Some(std::vec::Vec<i32>))` at /home/udoprog/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ptr/mod.rs:515:1: 515:56
     = note: inside `core::ptr::drop_in_place::<map::test_map::test_clone_from_memory_leaks::CheckedClone> - shim(Some(map::test_map::test_clone_from_memory_leaks::CheckedClone))` at /home/udoprog/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ptr/mod.rs:515:1: 515:56
     = note: inside `core::ptr::drop_in_place::<(i32, map::test_map::test_clone_from_memory_leaks::CheckedClone)> - shim(Some((i32, map::test_map::test_clone_from_memory_leaks::CheckedClone)))` at /home/udoprog/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ptr/mod.rs:515:1: 515:56
     = note: inside `core::ptr::mut_ptr::<impl *mut (i32, map::test_map::test_clone_from_memory_leaks::CheckedClone)>::drop_in_place` at /home/udoprog/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ptr/mut_ptr.rs:1473:18: 1473:37
note: inside `raw::Bucket::<(i32, map::test_map::test_clone_from_memory_leaks::CheckedClone)>::drop`
    --> src/raw/mod.rs:590:9
     |
590  |         self.as_ptr().drop_in_place();
     |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
note: inside closure
    --> src/raw/mod.rs:3587:25
     |
3587 |                         self_.bucket(i).drop();
     |                         ^^^^^^^^^^^^^^^^^^^^^^
note: inside `<scopeguard::ScopeGuard<(usize, &mut raw::RawTable<(i32, map::test_map::test_clone_from_memory_leaks::CheckedClone)>), {closure@src/raw/mod.rs:3583:48: 3583:64}> as core::ops::Drop>::drop`
    --> src/scopeguard.rs:70:9
     |
70   |         (self.dropfn)(&mut self.value);
     |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
     = note: inside `core::ptr::drop_in_place::<scopeguard::ScopeGuard<(usize, &mut raw::RawTable<(i32, map::test_map::test_clone_from_memory_leaks::CheckedClone)>), {closure@src/raw/mod.rs:3583:48: 3583:64}>> - shim(Some(scopeguard::ScopeGuard<(usize, &mut raw::RawTable<(i32, map::test_map::test_clone_from_memory_leaks::CheckedClone)>), {closure@src/raw/mod.rs:3583:48: 3583:64}>))` at /home/udoprog/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ptr/mod.rs:515:1: 515:56
note: inside `raw::RawTable::<(i32, map::test_map::test_clone_from_memory_leaks::CheckedClone)>::clone_from_impl`
    --> src/raw/mod.rs:3607:5
     |
3607 |     }
     |     ^
note: inside `<raw::RawTable<(i32, map::test_map::test_clone_from_memory_leaks::CheckedClone)> as raw::RawTableClone>::clone_from_spec`
    --> src/raw/mod.rs:3545:13
     |
3545 |             self.clone_from_impl(source);
     |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
note: inside `<raw::RawTable<(i32, map::test_map::test_clone_from_memory_leaks::CheckedClone)> as core::clone::Clone>::clone`
    --> src/raw/mod.rs:3464:17
     |
3464 |                 new_table.clone_from_spec(self);
     |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
note: inside `<map::HashMap<i32, map::test_map::test_clone_from_memory_leaks::CheckedClone> as core::clone::Clone>::clone`
    --> src/map.rs:199:20
     |
199  |             table: self.table.clone(),
     |                    ^^^^^^^^^^^^^^^^^^
note: inside `map::test_map::test_clone_from_memory_leaks`
    --> src/map.rs:8566:21
     |
8566 |         let _map2 = map1.clone();
     |                     ^^^^^^^^^^^^
note: inside closure
    --> src/map.rs:8526:38
     |
8524 |     #[test]
     |     ------- in this procedural macro expansion
8525 |     #[should_panic = "panic in clone"]
8526 |     fn test_clone_from_memory_leaks() {
     |                                      ^
     = note: this error originates in the attribute macro `test` (in Nightly builds, run with -Z macro-backtrace for more info)

I've encountered memory corruption in tests of a fork of hashbrown which might or might not be related. While trying to track down the root cause I noted that the above was also present here. I've not investigated deeper but the test case itself is implemented without unsafe.