`uncommon_codepoints` is ignored unless specified at crate level

[Nemo157]

I tried this code:

#[allow(uncommon_codepoints)]
pub mod 𓀄 {
}

I expected to see this happen: warning-free compilation

Instead, this happened:

warning: allow(uncommon_codepoints) is ignored unless specified at crate level
 --> src/lib.rs:1:9
  |
1 | #[allow(uncommon_codepoints)]
  |         ^^^^^^^^^^^^^^^^^^^
  |
  = note: `#[warn(unused_attributes)]` on by default

warning: identifier contains uncommon Unicode codepoints
 --> src/lib.rs:2:9
  |
2 | pub mod 𓀄 {
  |         ^
  |
  = note: `#[warn(uncommon_codepoints)]` on by default

warning: allow(uncommon_codepoints) is ignored unless specified at crate level
 --> src/lib.rs:1:9
  |
1 | #[allow(uncommon_codepoints)]
  |         ^^^^^^^^^^^^^^^^^^^

Meta

Tested on 1.53 stable and 1.55.0-nightly (2021-07-01 7100b31)

[jyn514]

ignored unless specified at crate level

Relevant code:

rust/compiler/rustc_lint/src/non_ascii_idents.rs

Lines 147 to 167 in 48e4bf1

	impl EarlyLintPass for NonAsciiIdents {
	fn check_crate(&mut self, cx: &EarlyContext<'_>, _: &ast::Crate) {
	use rustc_session::lint::Level;
	use rustc_span::Span;
	use std::collections::BTreeMap;
	use unicode_security::GeneralSecurityProfile;
	let check_non_ascii_idents = cx.builder.lint_level(NON_ASCII_IDENTS).0 != Level::Allow;
	let check_uncommon_codepoints =
	cx.builder.lint_level(UNCOMMON_CODEPOINTS).0 != Level::Allow;
	let check_confusable_idents = cx.builder.lint_level(CONFUSABLE_IDENTS).0 != Level::Allow;
	let check_mixed_script_confusables =
	cx.builder.lint_level(MIXED_SCRIPT_CONFUSABLES).0 != Level::Allow;
	if !check_non_ascii_idents
	&& !check_uncommon_codepoints
	&& !check_confusable_idents
	&& !check_mixed_script_confusables
	{
	return;
	}

[larsluthman]

Has there been any decision made whether to allow changing this lint in other places than at the crate level? I like to use some of these uncommon codepoints in test function names to make certain categories of tests stand out more in the test runner output, and it's a bit annoying to have to slap #![cfg_attr(test, allow(uncommon_codepoints))] at the top of each crate instead of just adding #[allow(uncommon_codepoints)] in the macro I use to define test modules.