Clippy: Wrongly suggests Option::if_let_else in const function

[Mythra]

Lint name: option_if_let_else

I tried this code:

	#[must_use]
	pub const fn new_from_parts(db_version: [u8; 10], tx_version: Option<[u8; 2]>) -> Self {
		let database_version: [u8; 8] = [
			db_version[0],
			db_version[1],
			db_version[2],
			db_version[3],
			db_version[4],
			db_version[5],
			db_version[6],
			db_version[7],
		];
		let batch_version: [u8; 2] = [db_version[8], db_version[9]];

		Self {
			database_version,
			batch_version,
			tx_version: if let Some(txv) = tx_version {
				([MaybeUninit::new(txv[0]), MaybeUninit::new(txv[1])], true)
			} else {
				([MaybeUninit::uninit(); 2], false)
			},
		}
	}

Then clippy generated a warning:

error: use Option::map_or_else instead of an if let/else
  --> <project>/src/db.rs:77:16
   |
77 |               tx_version: if let Some(txv) = tx_version {
   |  _________________________^
78 | |                 ([MaybeUninit::new(txv[0]), MaybeUninit::new(txv[1])], true)
79 | |             } else {
80 | |                 ([MaybeUninit::uninit(); 2], false)
81 | |             },
   | |_____________^ help: try: `tx_version.map_or_else(|| ([MaybeUninit::uninit(); 2], false), |txv| ([MaybeUninit::new(txv[0]), MaybeUninit::new(txv[1])], true))`
   |
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#option_if_let_else

I'm generally not a fan of this lint anyone, but I do it to hopefully be consistent with the rest of the ecosystem and juggling lints is really hard to do. However, replacing this particular code results in a failure to compile on stable as you cannot call if_let_else in a constant function. Meaning the resulting checked code fails to compile.

Meta

Rust version (rustc -Vv):

rustc 1.56.0 (09c42c458 2021-10-18)
binary: rustc
commit-hash: 09c42c45858d5f3aedfa670698275303a3d19afa
commit-date: 2021-10-18
host: x86_64-unknown-linux-gnu
release: 1.56.0
LLVM version: 13.0.0

[xFrednet]

@rustbot label +I-suggestion-causes-error

[giraffate]

The option_if_let_else was fixed not to warn in const function by #7573. Can you try currently beta (1.57.0)?

[Mythra]

Thanks! Sorry I missed that I did try looking for already existing PRs or issues but I guess not thoroughly enough! Seems to work for me on beta, thanks for the help'