| use clippy_utils::diagnostics::{span_lint, span_lint_and_then}; |
| use rustc_ast::ast::{ |
| self, Arm, AssocItem, AssocItemKind, Attribute, Block, FnDecl, Item, ItemKind, Local, Pat, PatKind, |
| }; |
| use rustc_ast::visit::{walk_block, walk_expr, walk_pat, Visitor}; |
| use rustc_lint::{EarlyContext, EarlyLintPass, LintContext}; |
| use rustc_middle::lint::in_external_macro; |
| use rustc_session::impl_lint_pass; |
| use rustc_span::symbol::{Ident, Symbol}; |
| use rustc_span::{sym, Span}; |
| use std::cmp::Ordering; |
| |
| declare_clippy_lint! { |
| /// ### What it does |
| /// Checks for names that are very similar and thus confusing. |
| /// |
| /// Note: this lint looks for similar names throughout each |
| /// scope. To allow it, you need to allow it on the scope |
| /// level, not on the name that is reported. |
| /// |
| /// ### Why is this bad? |
| /// It's hard to distinguish between names that differ only |
| /// by a single character. |
| /// |
| /// ### Example |
| /// ```ignore |
| /// let checked_exp = something; |
| /// let checked_expr = something_else; |
| /// ``` |
| #[clippy::version = "pre 1.29.0"] |
| pub SIMILAR_NAMES, |
| pedantic, |
| "similarly named items and bindings" |
| } |
| |
| declare_clippy_lint! { |
| /// ### What it does |
| /// Checks for too many variables whose name consists of a |
| /// single character. |
| /// |
| /// ### Why is this bad? |
| /// It's hard to memorize what a variable means without a |
| /// descriptive name. |
| /// |
| /// ### Example |
| /// ```ignore |
| /// let (a, b, c, d, e, f, g) = (...); |
| /// ``` |
| #[clippy::version = "pre 1.29.0"] |
| pub MANY_SINGLE_CHAR_NAMES, |
| pedantic, |
| "too many single character bindings" |
| } |
| |
| declare_clippy_lint! { |
| /// ### What it does |
| /// Checks if you have variables whose name consists of just |
| /// underscores and digits. |
| /// |
| /// ### Why is this bad? |
| /// It's hard to memorize what a variable means without a |
| /// descriptive name. |
| /// |
| /// ### Example |
| /// ```no_run |
| /// let _1 = 1; |
| /// let ___1 = 1; |
| /// let __1___2 = 11; |
| /// ``` |
| #[clippy::version = "pre 1.29.0"] |
| pub JUST_UNDERSCORES_AND_DIGITS, |
| style, |
| "unclear name" |
| } |
| |
| #[derive(Copy, Clone)] |
| pub struct NonExpressiveNames { |
| pub single_char_binding_names_threshold: u64, |
| } |
| |
| impl_lint_pass!(NonExpressiveNames => [SIMILAR_NAMES, MANY_SINGLE_CHAR_NAMES, JUST_UNDERSCORES_AND_DIGITS]); |
| |
| struct ExistingName { |
| interned: Symbol, |
| span: Span, |
| len: usize, |
| exemptions: &'static [&'static str], |
| } |
| |
| struct SimilarNamesLocalVisitor<'a, 'tcx> { |
| names: Vec<ExistingName>, |
| cx: &'a EarlyContext<'tcx>, |
| lint: NonExpressiveNames, |
| |
| /// A stack of scopes containing the single-character bindings in each scope. |
| single_char_names: Vec<Vec<Ident>>, |
| } |
| |
| impl<'a, 'tcx> SimilarNamesLocalVisitor<'a, 'tcx> { |
| fn check_single_char_names(&self) { |
| let num_single_char_names = self.single_char_names.iter().flatten().count(); |
| let threshold = self.lint.single_char_binding_names_threshold; |
| if num_single_char_names as u64 > threshold { |
| let span = self |
| .single_char_names |
| .iter() |
| .flatten() |
| .map(|ident| ident.span) |
| .collect::<Vec<_>>(); |
| span_lint( |
| self.cx, |
| MANY_SINGLE_CHAR_NAMES, |
| span, |
| format!("{num_single_char_names} bindings with single-character names in scope"), |
| ); |
| } |
| } |
| } |
| |
| // this list contains lists of names that are allowed to be similar |
| // the assumption is that no name is ever contained in multiple lists. |
| const ALLOWED_TO_BE_SIMILAR: &[&[&str]] = &[ |
| &["parsed", "parser"], |
| &["lhs", "rhs"], |
| &["tx", "rx"], |
| &["set", "get"], |
| &["args", "arms"], |
| &["qpath", "path"], |
| &["lit", "lint"], |
| &["wparam", "lparam"], |
| &["iter", "item"], |
| ]; |
| |
| /// Characters that look visually similar |
| const SIMILAR_CHARS: &[(char, char)] = &[('l', 'i'), ('l', '1'), ('i', '1'), ('u', 'v')]; |
| |
| /// Return true if two characters are visually similar |
| fn chars_are_similar(a: char, b: char) -> bool { |
| a == b || SIMILAR_CHARS.contains(&(a, b)) || SIMILAR_CHARS.contains(&(b, a)) |
| } |
| |
| struct SimilarNamesNameVisitor<'a, 'tcx, 'b>(&'b mut SimilarNamesLocalVisitor<'a, 'tcx>); |
| |
| impl<'a, 'tcx, 'b> Visitor<'tcx> for SimilarNamesNameVisitor<'a, 'tcx, 'b> { |
| fn visit_pat(&mut self, pat: &'tcx Pat) { |
| match pat.kind { |
| PatKind::Ident(_, ident, _) => { |
| if !pat.span.from_expansion() { |
| self.check_ident(ident); |
| } |
| }, |
| PatKind::Struct(_, _, ref fields, _) => { |
| for field in fields { |
| if !field.is_shorthand { |
| self.visit_pat(&field.pat); |
| } |
| } |
| }, |
| // just go through the first pattern, as either all patterns |
| // bind the same bindings or rustc would have errored much earlier |
| PatKind::Or(ref pats) => self.visit_pat(&pats[0]), |
| _ => walk_pat(self, pat), |
| } |
| } |
| } |
| |
| #[must_use] |
| fn get_exemptions(interned_name: &str) -> Option<&'static [&'static str]> { |
| ALLOWED_TO_BE_SIMILAR |
| .iter() |
| .find(|&&list| allowed_to_be_similar(interned_name, list)) |
| .copied() |
| } |
| |
| #[must_use] |
| fn allowed_to_be_similar(interned_name: &str, list: &[&str]) -> bool { |
| list.iter() |
| .any(|&name| interned_name.starts_with(name) || interned_name.ends_with(name)) |
| } |
| |
| impl<'a, 'tcx, 'b> SimilarNamesNameVisitor<'a, 'tcx, 'b> { |
| fn check_short_ident(&mut self, ident: Ident) { |
| // Ignore shadowing |
| if self |
| .0 |
| .single_char_names |
| .iter() |
| .flatten() |
| .any(|id| id.name == ident.name) |
| { |
| return; |
| } |
| |
| if let Some(scope) = &mut self.0.single_char_names.last_mut() { |
| scope.push(ident); |
| } |
| } |
| |
| fn check_ident(&mut self, ident: Ident) { |
| let interned_name = ident.name.as_str(); |
| if interned_name.chars().any(char::is_uppercase) { |
| return; |
| } |
| if interned_name.chars().all(|c| c.is_ascii_digit() || c == '_') { |
| span_lint( |
| self.0.cx, |
| JUST_UNDERSCORES_AND_DIGITS, |
| ident.span, |
| "consider choosing a more descriptive name", |
| ); |
| return; |
| } |
| if interned_name.starts_with('_') { |
| // these bindings are typically unused or represent an ignored portion of a destructuring pattern |
| return; |
| } |
| let count = interned_name.chars().count(); |
| if count < 3 { |
| if count == 1 { |
| self.check_short_ident(ident); |
| } |
| return; |
| } |
| for existing_name in &self.0.names { |
| if allowed_to_be_similar(interned_name, existing_name.exemptions) { |
| continue; |
| } |
| |
| let existing_str = existing_name.interned.as_str(); |
| |
| // The first char being different is usually enough to set identifiers apart, as long |
| // as the characters aren't too similar. |
| if !chars_are_similar( |
| interned_name.chars().next().expect("len >= 1"), |
| existing_str.chars().next().expect("len >= 1"), |
| ) { |
| continue; |
| } |
| |
| let dissimilar = match existing_name.len.cmp(&count) { |
| Ordering::Greater => existing_name.len - count != 1 || levenstein_not_1(interned_name, existing_str), |
| Ordering::Less => count - existing_name.len != 1 || levenstein_not_1(existing_str, interned_name), |
| Ordering::Equal => Self::equal_length_strs_not_similar(interned_name, existing_str), |
| }; |
| |
| if dissimilar { |
| continue; |
| } |
| |
| span_lint_and_then( |
| self.0.cx, |
| SIMILAR_NAMES, |
| ident.span, |
| "binding's name is too similar to existing binding", |
| |diag| { |
| diag.span_note(existing_name.span, "existing binding defined here"); |
| }, |
| ); |
| return; |
| } |
| self.0.names.push(ExistingName { |
| exemptions: get_exemptions(interned_name).unwrap_or(&[]), |
| interned: ident.name, |
| span: ident.span, |
| len: count, |
| }); |
| } |
| |
| fn equal_length_strs_not_similar(interned_name: &str, existing_name: &str) -> bool { |
| let mut interned_chars = interned_name.chars(); |
| let mut existing_chars = existing_name.chars(); |
| let first_i = interned_chars.next().expect("we know we have at least one char"); |
| let first_e = existing_chars.next().expect("we know we have at least one char"); |
| let eq_or_numeric = |(a, b): (char, char)| a == b || a.is_numeric() && b.is_numeric(); |
| |
| if eq_or_numeric((first_i, first_e)) { |
| let last_i = interned_chars.next_back().expect("we know we have at least two chars"); |
| let last_e = existing_chars.next_back().expect("we know we have at least two chars"); |
| if eq_or_numeric((last_i, last_e)) { |
| if interned_chars |
| .zip(existing_chars) |
| .filter(|&ie| !eq_or_numeric(ie)) |
| .count() |
| != 1 |
| { |
| return true; |
| } |
| } else { |
| let second_last_i = interned_chars |
| .next_back() |
| .expect("we know we have at least three chars"); |
| let second_last_e = existing_chars |
| .next_back() |
| .expect("we know we have at least three chars"); |
| if !eq_or_numeric((second_last_i, second_last_e)) |
| || second_last_i == '_' |
| || !interned_chars.zip(existing_chars).all(eq_or_numeric) |
| { |
| // allowed similarity foo_x, foo_y |
| // or too many chars differ (foo_x, boo_y) or (foox, booy) |
| return true; |
| } |
| } |
| } else { |
| let second_i = interned_chars.next().expect("we know we have at least two chars"); |
| let second_e = existing_chars.next().expect("we know we have at least two chars"); |
| if !eq_or_numeric((second_i, second_e)) |
| || second_i == '_' |
| || !interned_chars.zip(existing_chars).all(eq_or_numeric) |
| { |
| // allowed similarity x_foo, y_foo |
| // or too many chars differ (x_foo, y_boo) or (xfoo, yboo) |
| return true; |
| } |
| } |
| |
| false |
| } |
| } |
| |
| impl<'a, 'b> SimilarNamesLocalVisitor<'a, 'b> { |
| /// ensure scoping rules work |
| fn apply<F: for<'c> Fn(&'c mut Self)>(&mut self, f: F) { |
| let n = self.names.len(); |
| let single_char_count = self.single_char_names.len(); |
| f(self); |
| self.names.truncate(n); |
| self.single_char_names.truncate(single_char_count); |
| } |
| } |
| |
| impl<'a, 'tcx> Visitor<'tcx> for SimilarNamesLocalVisitor<'a, 'tcx> { |
| fn visit_local(&mut self, local: &'tcx Local) { |
| if let Some((init, els)) = &local.kind.init_else_opt() { |
| self.apply(|this| walk_expr(this, init)); |
| if let Some(els) = els { |
| self.apply(|this| walk_block(this, els)); |
| } |
| } |
| // add the pattern after the expression because the bindings aren't available |
| // yet in the init |
| // expression |
| SimilarNamesNameVisitor(self).visit_pat(&local.pat); |
| } |
| fn visit_block(&mut self, blk: &'tcx Block) { |
| self.single_char_names.push(vec![]); |
| |
| self.apply(|this| walk_block(this, blk)); |
| |
| self.check_single_char_names(); |
| self.single_char_names.pop(); |
| } |
| fn visit_arm(&mut self, arm: &'tcx Arm) { |
| self.single_char_names.push(vec![]); |
| |
| self.apply(|this| { |
| SimilarNamesNameVisitor(this).visit_pat(&arm.pat); |
| if let Some(body) = &arm.body { |
| this.apply(|this| walk_expr(this, body)); |
| } |
| }); |
| |
| self.check_single_char_names(); |
| self.single_char_names.pop(); |
| } |
| fn visit_item(&mut self, _: &Item) { |
| // do not recurse into inner items |
| } |
| } |
| |
| impl EarlyLintPass for NonExpressiveNames { |
| fn check_item(&mut self, cx: &EarlyContext<'_>, item: &Item) { |
| if in_external_macro(cx.sess(), item.span) { |
| return; |
| } |
| |
| if let ItemKind::Fn(box ast::Fn { |
| ref sig, |
| body: Some(ref blk), |
| .. |
| }) = item.kind |
| { |
| do_check(*self, cx, &item.attrs, &sig.decl, blk); |
| } |
| } |
| |
| fn check_impl_item(&mut self, cx: &EarlyContext<'_>, item: &AssocItem) { |
| if in_external_macro(cx.sess(), item.span) { |
| return; |
| } |
| |
| if let AssocItemKind::Fn(box ast::Fn { |
| ref sig, |
| body: Some(ref blk), |
| .. |
| }) = item.kind |
| { |
| do_check(*self, cx, &item.attrs, &sig.decl, blk); |
| } |
| } |
| } |
| |
| fn do_check(lint: NonExpressiveNames, cx: &EarlyContext<'_>, attrs: &[Attribute], decl: &FnDecl, blk: &Block) { |
| if !attrs.iter().any(|attr| attr.has_name(sym::test)) { |
| let mut visitor = SimilarNamesLocalVisitor { |
| names: Vec::new(), |
| cx, |
| lint, |
| single_char_names: vec![vec![]], |
| }; |
| |
| // initialize with function arguments |
| for arg in &decl.inputs { |
| SimilarNamesNameVisitor(&mut visitor).visit_pat(&arg.pat); |
| } |
| // walk all other bindings |
| walk_block(&mut visitor, blk); |
| |
| visitor.check_single_char_names(); |
| } |
| } |
| |
| /// Precondition: `a_name.chars().count() < b_name.chars().count()`. |
| #[must_use] |
| fn levenstein_not_1(a_name: &str, b_name: &str) -> bool { |
| debug_assert!(a_name.chars().count() < b_name.chars().count()); |
| let mut a_chars = a_name.chars(); |
| let mut b_chars = b_name.chars(); |
| while let (Some(a), Some(b)) = (a_chars.next(), b_chars.next()) { |
| if a == b { |
| continue; |
| } |
| if let Some(b2) = b_chars.next() { |
| // check if there's just one character inserted |
| return a != b2 || a_chars.ne(b_chars); |
| } |
| // tuple |
| // ntuple |
| return true; |
| } |
| // for item in items |
| true |
| } |