non_camel_case_types does not trigger for screaming single-word

[jonhoo]

I tried this code:

#![deny(non_camel_case_types)]

pub struct FOO;

pub enum BAR {
    BAZ,
}

fn main() {}

I expected to see this happen: FOO, BAR, and BAZ should all trigger the non_camel_case_types lint (at least assuming it follows RFC430), and so the code should not compile.

Instead, this happened: The code compiled with no warnings. All three cases start triggering the lint if something like _X is added to them.

Meta

rustc --version --verbose:

rustc 1.73.0-beta.4 (9f37cd4f7 2023-09-01)
binary: rustc
commit-hash: 9f37cd4f79d289492ccaa8f28733b765498c95e5
commit-date: 2023-09-01
host: aarch64-apple-darwin
release: 1.73.0-beta.4
LLVM version: 17.0.0

[sjwang05]

@rustbot claim

[kadiwa4]

Related: #60570, which describes drawbacks of always disallowing uppercase type names

[joshtriplett]

#60570 (comment)