Building with rustc 1.78 beta 4 shows the following errors:

[task 2024-04-02T03:19:49.957Z] 03:19:49    ERROR -  error: the item `libc` is imported redundantly
[task 2024-04-02T03:19:49.957Z] 03:19:49     INFO -   --> xpcom/rust/xpcom/src/refptr.rs:6:5
[task 2024-04-02T03:19:49.957Z] 03:19:49     INFO -    |
[task 2024-04-02T03:19:49.957Z] 03:19:49     INFO -  6 | use libc;
[task 2024-04-02T03:19:49.958Z] 03:19:49     INFO -    |     ^^^^ the item `libc` is already defined by prelude
[task 2024-04-02T03:19:49.958Z] 03:19:49     INFO -    |
[task 2024-04-02T03:19:49.958Z] 03:19:49     INFO -    = note: `-D unused-imports` implied by `-D warnings`
[task 2024-04-02T03:19:49.958Z] 03:19:49     INFO -    = help: to override `-D warnings` add `#[allow(unused_imports)]`
[task 2024-04-02T03:19:49.958Z] 03:19:49    ERROR -  error: could not compile `xpcom` (lib) due to 1 previous error

[task 2024-04-02T06:03:47.375Z] 06:03:47    ERROR -  error: the item `moz_task` is imported redundantly
[task 2024-04-02T06:03:47.375Z] 06:03:47     INFO -   --> xpcom/rust/gtest/moz_task/test.rs:5:5
[task 2024-04-02T06:03:47.375Z] 06:03:47     INFO -    |
[task 2024-04-02T06:03:47.375Z] 06:03:47     INFO -  5 | use moz_task;
[task 2024-04-02T06:03:47.375Z] 06:03:47     INFO -    |     ^^^^^^^^ the item `moz_task` is already defined by prelude
[task 2024-04-02T06:03:47.375Z] 06:03:47     INFO -    |
[task 2024-04-02T06:03:47.375Z] 06:03:47     INFO -    = note: `-D unused-imports` implied by `-D warnings`
[task 2024-04-02T06:03:47.375Z] 06:03:47     INFO -    = help: to override `-D warnings` add `#[allow(unused_imports)]`
[task 2024-04-02T06:03:47.375Z] 06:03:47    ERROR -  error: could not compile `moz_task-gtest` (lib) due to 1 previous error

[task 2024-04-02T03:55:39.784Z] 03:55:39    ERROR -  error: the item `Box` is imported redundantly
[task 2024-04-02T03:55:39.784Z] 03:55:39     INFO -    --> xpcom/rust/gecko_logger/src/lib.rs:13:5
[task 2024-04-02T03:55:39.784Z] 03:55:39     INFO -     |
[task 2024-04-02T03:55:39.784Z] 03:55:39     INFO -  13 | use std::boxed::Box;
[task 2024-04-02T03:55:39.784Z] 03:55:39     INFO -     |     ^^^^^^^^^^^^^^^
[task 2024-04-02T03:55:39.784Z] 03:55:39     INFO -    --> /rustc/c1195518c8ad7f37d15ecb82f39dec3da97f9c2f\library\std\src\prelude\mod.rs:115:13
[task 2024-04-02T03:55:39.784Z] 03:55:39     INFO -     |
[task 2024-04-02T03:55:39.784Z] 03:55:39     INFO -     = note: the item `Box` is already defined here
[task 2024-04-02T03:55:39.784Z] 03:55:39     INFO -     |
[task 2024-04-02T03:55:39.784Z] 03:55:39     INFO -     = note: `-D unused-imports` implied by `-D warnings`
[task 2024-04-02T03:55:39.784Z] 03:55:39     INFO -     = help: to override `-D warnings` add `#[allow(unused_imports)]`
[task 2024-04-02T03:55:39.784Z] 03:55:39    ERROR -  error: could not compile `gecko_logger` (lib) due to 1 previous error

https://hg.mozilla.org/mozilla-central/rev/5e35b6912ba6