rust/clippy_lints/src/disallowed_script_idents.rs

113 lines
4.4 KiB
Rust

use clippy_utils::diagnostics::span_lint;
use rustc_ast::ast;
use rustc_data_structures::fx::FxHashSet;
use rustc_lint::{EarlyContext, EarlyLintPass, Level, LintContext};
use rustc_session::{declare_tool_lint, impl_lint_pass};
use unicode_script::{Script, UnicodeScript};
declare_clippy_lint! {
/// ### What it does
/// Checks for usage of unicode scripts other than those explicitly allowed
/// by the lint config.
///
/// This lint doesn't take into account non-text scripts such as `Unknown` and `Linear_A`.
/// It also ignores the `Common` script type.
/// While configuring, be sure to use official script name [aliases] from
/// [the list of supported scripts][supported_scripts].
///
/// See also: [`non_ascii_idents`].
///
/// [aliases]: http://www.unicode.org/reports/tr24/tr24-31.html#Script_Value_Aliases
/// [supported_scripts]: https://www.unicode.org/iso15924/iso15924-codes.html
///
/// ### Why is this bad?
/// It may be not desired to have many different scripts for
/// identifiers in the codebase.
///
/// Note that if you only want to allow plain English, you might want to use
/// built-in [`non_ascii_idents`] lint instead.
///
/// [`non_ascii_idents`]: https://doc.rust-lang.org/rustc/lints/listing/allowed-by-default.html#non-ascii-idents
///
/// ### Example
/// ```rust
/// // Assuming that `clippy.toml` contains the following line:
/// // allowed-scripts = ["Latin", "Cyrillic"]
/// let counter = 10; // OK, latin is allowed.
/// let счётчик = 10; // OK, cyrillic is allowed.
/// let zähler = 10; // OK, it's still latin.
/// let カウンタ = 10; // Will spawn the lint.
/// ```
#[clippy::version = "1.55.0"]
pub DISALLOWED_SCRIPT_IDENTS,
restriction,
"usage of non-allowed Unicode scripts"
}
#[derive(Clone, Debug)]
pub struct DisallowedScriptIdents {
whitelist: FxHashSet<Script>,
}
impl DisallowedScriptIdents {
pub fn new(whitelist: &[String]) -> Self {
let whitelist = whitelist
.iter()
.map(String::as_str)
.filter_map(Script::from_full_name)
.collect();
Self { whitelist }
}
}
impl_lint_pass!(DisallowedScriptIdents => [DISALLOWED_SCRIPT_IDENTS]);
impl EarlyLintPass for DisallowedScriptIdents {
fn check_crate(&mut self, cx: &EarlyContext<'_>, _: &ast::Crate) {
// Implementation is heavily inspired by the implementation of [`non_ascii_idents`] lint:
// https://github.com/rust-lang/rust/blob/master/compiler/rustc_lint/src/non_ascii_idents.rs
let check_disallowed_script_idents = cx.builder.lint_level(DISALLOWED_SCRIPT_IDENTS).0 != Level::Allow;
if !check_disallowed_script_idents {
return;
}
let symbols = cx.sess().parse_sess.symbol_gallery.symbols.lock();
// Sort by `Span` so that error messages make sense with respect to the
// order of identifier locations in the code.
let mut symbols: Vec<_> = symbols.iter().collect();
symbols.sort_unstable_by_key(|k| k.1);
for (symbol, &span) in &symbols {
// Note: `symbol.as_str()` is an expensive operation, thus should not be called
// more than once for a single symbol.
let symbol_str = symbol.as_str();
if symbol_str.is_ascii() {
continue;
}
for c in symbol_str.chars() {
// We want to iterate through all the scripts associated with this character
// and check whether at least of one scripts is in the whitelist.
let forbidden_script = c
.script_extension()
.iter()
.find(|script| !self.whitelist.contains(script));
if let Some(script) = forbidden_script {
span_lint(
cx,
DISALLOWED_SCRIPT_IDENTS,
span,
&format!(
"identifier `{symbol_str}` has a Unicode script that is not allowed by configuration: {}",
script.full_name()
),
);
// We don't want to spawn warning multiple times over a single identifier.
break;
}
}
}
}
}