use clippy_utils::diagnostics::span_lint; use clippy_utils::is_test_module_or_function; use rustc_data_structures::fx::FxHashSet; use rustc_hir::{Item, Pat, PatKind}; use rustc_lint::{LateContext, LateLintPass}; use rustc_session::impl_lint_pass; declare_clippy_lint! { /// ### What it does /// Checks for usage of disallowed names for variables, such /// as `foo`. /// /// ### Why is this bad? /// These names are usually placeholder names and should be /// avoided. /// /// ### Example /// ```no_run /// let foo = 3.14; /// ``` #[clippy::version = "pre 1.29.0"] pub DISALLOWED_NAMES, style, "usage of a disallowed/placeholder name" } #[derive(Clone, Debug)] pub struct DisallowedNames { disallow: FxHashSet, test_modules_deep: u32, } impl DisallowedNames { pub fn new(disallowed_names: &[String]) -> Self { Self { disallow: disallowed_names.iter().cloned().collect(), test_modules_deep: 0, } } fn in_test_module(&self) -> bool { self.test_modules_deep != 0 } } impl_lint_pass!(DisallowedNames => [DISALLOWED_NAMES]); impl<'tcx> LateLintPass<'tcx> for DisallowedNames { fn check_item(&mut self, cx: &LateContext<'_>, item: &Item<'_>) { if is_test_module_or_function(cx.tcx, item) { self.test_modules_deep = self.test_modules_deep.saturating_add(1); } } fn check_pat(&mut self, cx: &LateContext<'tcx>, pat: &'tcx Pat<'_>) { // Check whether we are under the `test` attribute. if self.in_test_module() { return; } if let PatKind::Binding(.., ident, _) = pat.kind { if self.disallow.contains(&ident.name.to_string()) { span_lint( cx, DISALLOWED_NAMES, ident.span, &format!("use of a disallowed/placeholder name `{}`", ident.name), ); } } } fn check_item_post(&mut self, cx: &LateContext<'_>, item: &Item<'_>) { if is_test_module_or_function(cx.tcx, item) { self.test_modules_deep = self.test_modules_deep.saturating_sub(1); } } }