cargo doc fails with E0080

[Warfront1]

cargo doc fails on p256 0.14.0, p384 0.14.0, p521 0.14.0, k256 0.14.0, and sm2 0.14.0-rc.15 with Rust 1.85-1.89.
Projects using Rust 1.85-1.89 that have dependencies on these are failing when executing cargo doc --document-private-items.

The following is the error message you receive from cargo doc --document-private-items:

Documenting p256 v0.14.0 (/repo/p256)
error[E0080]: it is undefined behavior to use this value
  --> p256/src/arithmetic/tables.rs:17:5
   |
17 |     const BASEPOINT_TABLE: &'static BasepointTable = &BASEPOINT_TABLE;
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value: encountered reference to mutable memory in `const`
   |
   = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
   = note: the raw bytes of the constant (size: 8, align: 8) {
               ╾─────alloc456894─────╼                         │ ╾──────╼
           }

For more information about this error, try `rustc --explain E0080`.
error: could not document `p256`

cargo build and cargo test succeed — only cargo doc fails (rustdoc evaluates the associated const to render its value).

Reproduction (Rust 1.85-1.89):

docker run --rm rust:1.85.0 bash -c '
  apt-get update -qq && apt-get install -y -qq git >/dev/null
  git clone --depth 1 https://github.com/RustCrypto/elliptic-curves.git /repo
  cd /repo/p256
  cargo doc --document-private-items
'

[tarcieri]

See #1803.

Interior mutability for associated constants like this (that in this case are pointing to a lazy static) wasn't previously allowed but was relaxed in 1.90. See rust-lang/rust#140653

So yes, we're aware versions earlier than 1.90 throw this error in certain cases. There's little we can do about it besides bump MSRV to 1.90, which is something we can potentially consider, but I was wanting to get initial releases of everything out first.

[Warfront1]

@tarcieri, I have published a PR that works around this until we can increment the MSRV.
#1910