[E0658]: panicking in constant functions is unstable

[shzhxh]

错误的提示信息如下：

error[E0658]: panicking in constant functions is unstable
   --> /home/runner/.cargo/registry/src/github.com-1ecc6299db9ec823/x86_64-0.14.7/src/addr.rs:547:5
    |
547 |     assert!(align.is_power_of_two(), "`align` must be a power of two");
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: see issue #51999 <https://github.com/rust-lang/rust/issues/51999> for more information
    = help: add `#![feature(const_panic)]` to the crate attributes to enable
    = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)

error[E0658]: panicking in constant functions is unstable
   --> /home/runner/.cargo/registry/src/github.com-1ecc6299db9ec823/x86_64-0.14.7/src/addr.rs:559:5
    |
559 |     assert!(align.is_power_of_two(), "`align` must be a power of two");
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: see issue #51999 <https://github.com/rust-lang/rust/issues/51999> for more information
    = help: add `#![feature(const_panic)]` to the crate attributes to enable
    = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)

error[E0658]: panicking in constant functions is unstable
  --> /home/runner/.cargo/registry/src/github.com-1ecc6299db9ec823/x86_64-0.14.7/src/structures/gdt.rs:75:9
   |
75 | /         assert!(
76 | |             next_free <= 8,
77 | |             "initializing a GDT from a slice requires it to be **at most** 8 elements."
78 | |         );
   | |__________^
   |
   = note: see issue #51999 <https://github.com/rust-lang/rust/issues/51999> for more information
   = help: add `#![feature(const_panic)]` to the crate attributes to enable
   = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)

error[E0658]: panicking in constant functions is unstable
   --> /home/runner/.cargo/registry/src/github.com-1ecc6299db9ec823/x86_64-0.14.7/src/structures/gdt.rs:168:17
    |
168 |                 panic!("GDT full");
    |                 ^^^^^^^^^^^^^^^^^^^
    |
    = note: see issue #51999 <https://github.com/rust-lang/rust/issues/51999> for more information
    = help: add `#![feature(const_panic)]` to the crate attributes to enable
    = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)

For more information about this error, try `rustc --explain E0658`.
error: could not compile `x86_64` due to 4 previous errors
warning: build failed, waiting for other jobs to finish...
error: build failed
Error: Process completed with exit code 101.

[shzhxh]

解决者： @elliott10
原因分析：此问题由于依赖库x86_64从0.14.6升级到0.14.7而产生。
解决方法：把工具链的版本从nightly-2021-07-27提升到nightly-2021-11-02。另外，子模块rboot的工具链也要做相应的提升。