//! checks for `#[inline]` on trait methods without bodies use clippy_utils::diagnostics::span_lint_and_then; use clippy_utils::sugg::DiagnosticExt; use rustc_ast::ast::Attribute; use rustc_errors::Applicability; use rustc_hir::{TraitFn, TraitItem, TraitItemKind}; use rustc_lint::{LateContext, LateLintPass}; use rustc_session::{declare_lint_pass, declare_tool_lint}; use rustc_span::{sym, Symbol}; declare_clippy_lint! { /// ### What it does /// Checks for `#[inline]` on trait methods without bodies /// /// ### Why is this bad? /// Only implementations of trait methods may be inlined. /// The inline attribute is ignored for trait methods without bodies. /// /// ### Example /// ```rust /// trait Animal { /// #[inline] /// fn name(&self) -> &'static str; /// } /// ``` #[clippy::version = "pre 1.29.0"] pub INLINE_FN_WITHOUT_BODY, correctness, "use of `#[inline]` on trait methods without bodies" } declare_lint_pass!(InlineFnWithoutBody => [INLINE_FN_WITHOUT_BODY]); impl<'tcx> LateLintPass<'tcx> for InlineFnWithoutBody { fn check_trait_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx TraitItem<'_>) { if let TraitItemKind::Fn(_, TraitFn::Required(_)) = item.kind { let attrs = cx.tcx.hir().attrs(item.hir_id()); check_attrs(cx, item.ident.name, attrs); } } } fn check_attrs(cx: &LateContext<'_>, name: Symbol, attrs: &[Attribute]) { for attr in attrs { if !attr.has_name(sym::inline) { continue; } span_lint_and_then( cx, INLINE_FN_WITHOUT_BODY, attr.span, &format!("use of `#[inline]` on trait method `{}` which has no body", name), |diag| { diag.suggest_remove_item(cx, attr.span, "remove", Applicability::MachineApplicable); }, ); } }