| use clippy_utils::diagnostics::span_lint; |
| use clippy_utils::is_from_proc_macro; |
| use rustc_data_structures::fx::FxHashSet; |
| use rustc_hir::def::{DefKind, Res}; |
| use rustc_hir::intravisit::{walk_item, Visitor}; |
| use rustc_hir::{GenericParamKind, HirId, Item, ItemKind, ItemLocalId, Node, Pat, PatKind}; |
| use rustc_lint::{LateContext, LateLintPass, LintContext}; |
| use rustc_middle::lint::in_external_macro; |
| use rustc_session::{declare_tool_lint, impl_lint_pass}; |
| use rustc_span::Span; |
| use std::borrow::Cow; |
| |
| declare_clippy_lint! { |
| /// ### What it does |
| /// Checks for idents which comprise of a single letter. |
| /// |
| /// Note: This lint can be very noisy when enabled; it may be desirable to only enable it |
| /// temporarily. |
| /// |
| /// ### Why is this bad? |
| /// In many cases it's not, but at times it can severely hinder readability. Some codebases may |
| /// wish to disallow this to improve readability. |
| /// |
| /// ### Example |
| /// ```rust,ignore |
| /// for m in movies { |
| /// let title = m.t; |
| /// } |
| /// ``` |
| /// Use instead: |
| /// ```rust,ignore |
| /// for movie in movies { |
| /// let title = movie.title; |
| /// } |
| /// ``` |
| #[clippy::version = "1.72.0"] |
| pub MIN_IDENT_CHARS, |
| restriction, |
| "disallows idents that are too short" |
| } |
| impl_lint_pass!(MinIdentChars => [MIN_IDENT_CHARS]); |
| |
| #[derive(Clone)] |
| pub struct MinIdentChars { |
| pub allowed_idents_below_min_chars: FxHashSet<String>, |
| pub min_ident_chars_threshold: u64, |
| } |
| |
| impl MinIdentChars { |
| #[expect(clippy::cast_possible_truncation)] |
| fn is_ident_too_short(&self, cx: &LateContext<'_>, str: &str, span: Span) -> bool { |
| !in_external_macro(cx.sess(), span) |
| && str.len() <= self.min_ident_chars_threshold as usize |
| && !str.starts_with('_') |
| && !str.is_empty() |
| && self.allowed_idents_below_min_chars.get(&str.to_owned()).is_none() |
| } |
| } |
| |
| impl LateLintPass<'_> for MinIdentChars { |
| fn check_item(&mut self, cx: &LateContext<'_>, item: &Item<'_>) { |
| if self.min_ident_chars_threshold == 0 { |
| return; |
| } |
| |
| walk_item(&mut IdentVisitor { conf: self, cx }, item); |
| } |
| |
| // This is necessary as `Node::Pat`s are not visited in `visit_id`. :/ |
| fn check_pat(&mut self, cx: &LateContext<'_>, pat: &Pat<'_>) { |
| if let PatKind::Binding(_, _, ident, ..) = pat.kind |
| && let str = ident.as_str() |
| && self.is_ident_too_short(cx, str, ident.span) |
| { |
| emit_min_ident_chars(self, cx, str, ident.span); |
| } |
| } |
| } |
| |
| struct IdentVisitor<'cx, 'tcx> { |
| conf: &'cx MinIdentChars, |
| cx: &'cx LateContext<'tcx>, |
| } |
| |
| impl Visitor<'_> for IdentVisitor<'_, '_> { |
| fn visit_id(&mut self, hir_id: HirId) { |
| let Self { conf, cx } = *self; |
| // FIXME(#112534) Reimplementation of `find`, as it uses indexing, which can (and will in |
| // async functions, or really anything async) panic. This should probably be fixed on the |
| // rustc side, this is just a temporary workaround. |
| let node = if hir_id.local_id == ItemLocalId::from_u32(0) { |
| // In this case, we can just use `find`, `Owner`'s `node` field is private anyway so we can't |
| // reimplement it even if we wanted to |
| cx.tcx.hir().find(hir_id) |
| } else { |
| let Some(owner) = cx.tcx.hir_owner_nodes(hir_id.owner).as_owner() else { |
| return; |
| }; |
| owner.nodes.get(hir_id.local_id).copied().flatten().map(|p| p.node) |
| }; |
| let Some(node) = node else { |
| return; |
| }; |
| let Some(ident) = node.ident() else { |
| return; |
| }; |
| |
| let str = ident.as_str(); |
| if conf.is_ident_too_short(cx, str, ident.span) { |
| if let Node::Item(item) = node |
| && let ItemKind::Use(..) = item.kind |
| { |
| return; |
| } |
| // `struct Awa<T>(T)` |
| // ^ |
| if let Node::PathSegment(path) = node { |
| if let Res::Def(def_kind, ..) = path.res |
| && let DefKind::TyParam = def_kind |
| { |
| return; |
| } |
| if matches!(path.res, Res::PrimTy(..)) || path.res.opt_def_id().is_some_and(|def_id| !def_id.is_local()) |
| { |
| return; |
| } |
| } |
| // `struct Awa<T>(T)` |
| // ^ |
| if let Node::GenericParam(generic_param) = node |
| && let GenericParamKind::Type { .. } = generic_param.kind |
| { |
| return; |
| } |
| |
| // `struct Array<T, const N: usize>([T; N])` |
| // ^ |
| if let Node::GenericParam(generic_param) = node |
| && let GenericParamKind::Const { .. } = generic_param.kind |
| { |
| return; |
| } |
| |
| if is_from_proc_macro(cx, &ident) { |
| return; |
| } |
| |
| emit_min_ident_chars(conf, cx, str, ident.span); |
| } |
| } |
| } |
| |
| fn emit_min_ident_chars(conf: &MinIdentChars, cx: &impl LintContext, ident: &str, span: Span) { |
| let help = if conf.min_ident_chars_threshold == 1 { |
| Cow::Borrowed("this ident consists of a single char") |
| } else { |
| Cow::Owned(format!( |
| "this ident is too short ({} <= {})", |
| ident.len(), |
| conf.min_ident_chars_threshold, |
| )) |
| }; |
| span_lint(cx, MIN_IDENT_CHARS, span, &help); |
| } |