From 566dfd90082d709aa2d42b354349bfd2b4b895b2 Mon Sep 17 00:00:00 2001 From: Guillaume Gomez Date: Fri, 17 May 2024 18:05:46 +0200 Subject: [PATCH] Add `needless_character_iteration` lint --- CHANGELOG.md | 1 + clippy_lints/src/declared_lints.rs | 1 + clippy_lints/src/methods/mod.rs | 24 ++++ .../methods/needless_character_iteration.rs | 108 ++++++++++++++++++ .../methods/unnecessary_result_map_or_else.rs | 19 +-- clippy_lints/src/methods/utils.rs | 18 ++- tests/ui/needless_character_iteration.fixed | 51 +++++++++ tests/ui/needless_character_iteration.rs | 59 ++++++++++ tests/ui/needless_character_iteration.stderr | 67 +++++++++++ 9 files changed, 330 insertions(+), 18 deletions(-) create mode 100644 clippy_lints/src/methods/needless_character_iteration.rs create mode 100644 tests/ui/needless_character_iteration.fixed create mode 100644 tests/ui/needless_character_iteration.rs create mode 100644 tests/ui/needless_character_iteration.stderr diff --git a/CHANGELOG.md b/CHANGELOG.md index cfff0bb50a6..9f1d0e56745 100644 --- a/CHANGELOG.md +++ b/CHANGELOG.md @@ -5567,6 +5567,7 @@ Released 2018-09-13 [`needless_borrow`]: https://rust-lang.github.io/rust-clippy/master/index.html#needless_borrow [`needless_borrowed_reference`]: https://rust-lang.github.io/rust-clippy/master/index.html#needless_borrowed_reference [`needless_borrows_for_generic_args`]: https://rust-lang.github.io/rust-clippy/master/index.html#needless_borrows_for_generic_args +[`needless_character_iteration`]: https://rust-lang.github.io/rust-clippy/master/index.html#needless_character_iteration [`needless_collect`]: https://rust-lang.github.io/rust-clippy/master/index.html#needless_collect [`needless_continue`]: https://rust-lang.github.io/rust-clippy/master/index.html#needless_continue [`needless_doctest_main`]: https://rust-lang.github.io/rust-clippy/master/index.html#needless_doctest_main diff --git a/clippy_lints/src/declared_lints.rs b/clippy_lints/src/declared_lints.rs index 6850ec821e8..2e436f0f767 100644 --- a/clippy_lints/src/declared_lints.rs +++ b/clippy_lints/src/declared_lints.rs @@ -418,6 +418,7 @@ crate::methods::MAP_UNWRAP_OR_INFO, crate::methods::MUT_MUTEX_LOCK_INFO, crate::methods::NAIVE_BYTECOUNT_INFO, + crate::methods::NEEDLESS_CHARACTER_ITERATION_INFO, crate::methods::NEEDLESS_COLLECT_INFO, crate::methods::NEEDLESS_OPTION_AS_DEREF_INFO, crate::methods::NEEDLESS_OPTION_TAKE_INFO, diff --git a/clippy_lints/src/methods/mod.rs b/clippy_lints/src/methods/mod.rs index 60666445d08..b85218d3ca2 100644 --- a/clippy_lints/src/methods/mod.rs +++ b/clippy_lints/src/methods/mod.rs @@ -66,6 +66,7 @@ mod map_identity; mod map_unwrap_or; mod mut_mutex_lock; +mod needless_character_iteration; mod needless_collect; mod needless_option_as_deref; mod needless_option_take; @@ -4089,6 +4090,27 @@ "is_empty() called on strings known at compile time" } +declare_clippy_lint! { + /// ### What it does + /// Checks if an iterator is used to check if a string is ascii. + /// + /// ### Why is this bad? + /// The `str` type already implements the `is_ascii` method. + /// + /// ### Example + /// ```no_run + /// "foo".chars().all(|c| c.is_ascii()); + /// ``` + /// Use instead: + /// ```no_run + /// "foo".is_ascii(); + /// ``` + #[clippy::version = "1.80.0"] + pub NEEDLESS_CHARACTER_ITERATION, + suspicious, + "is_ascii() called on a char iterator" +} + pub struct Methods { avoid_breaking_exported_api: bool, msrv: Msrv, @@ -4254,6 +4276,7 @@ pub fn new( UNNECESSARY_RESULT_MAP_OR_ELSE, MANUAL_C_STR_LITERALS, UNNECESSARY_GET_THEN_CHECK, + NEEDLESS_CHARACTER_ITERATION, ]); /// Extracts a method call name, args, and `Span` of the method name. @@ -4461,6 +4484,7 @@ fn check_methods<'tcx>(&self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) { }, ("all", [arg]) => { unused_enumerate_index::check(cx, expr, recv, arg); + needless_character_iteration::check(cx, expr, recv, arg); if let Some(("cloned", recv2, [], _, _)) = method_call(recv) { iter_overeager_cloned::check( cx, diff --git a/clippy_lints/src/methods/needless_character_iteration.rs b/clippy_lints/src/methods/needless_character_iteration.rs new file mode 100644 index 00000000000..f4467af4de8 --- /dev/null +++ b/clippy_lints/src/methods/needless_character_iteration.rs @@ -0,0 +1,108 @@ +use rustc_errors::Applicability; +use rustc_hir::{Closure, Expr, ExprKind, HirId, StmtKind, UnOp}; +use rustc_lint::LateContext; +use rustc_middle::ty; +use rustc_span::Span; + +use super::utils::get_last_chain_binding_hir_id; +use super::NEEDLESS_CHARACTER_ITERATION; +use clippy_utils::diagnostics::span_lint_and_sugg; +use clippy_utils::source::snippet_opt; +use clippy_utils::{match_def_path, path_to_local_id, peel_blocks}; + +fn peels_expr_ref<'a, 'tcx>(mut expr: &'a Expr<'tcx>) -> &'a Expr<'tcx> { + while let ExprKind::AddrOf(_, _, e) = expr.kind { + expr = e; + } + expr +} + +fn handle_expr( + cx: &LateContext<'_>, + expr: &Expr<'_>, + first_param: HirId, + span: Span, + before_chars: Span, + revert: bool, +) { + match expr.kind { + ExprKind::MethodCall(method, receiver, [], _) => { + if method.ident.name.as_str() == "is_ascii" + && path_to_local_id(receiver, first_param) + && let char_arg_ty = cx.typeck_results().expr_ty_adjusted(receiver).peel_refs() + && *char_arg_ty.kind() == ty::Char + && let Some(snippet) = snippet_opt(cx, before_chars) + { + span_lint_and_sugg( + cx, + NEEDLESS_CHARACTER_ITERATION, + span, + "checking if a string is ascii using iterators", + "try", + format!("{}{snippet}.is_ascii()", if revert { "!" } else { "" }), + Applicability::MachineApplicable, + ); + } + }, + ExprKind::Block(block, _) => { + if block.stmts.iter().any(|stmt| !matches!(stmt.kind, StmtKind::Let(_))) { + // If there is something else than let bindings, then better not emit the lint. + return; + } + if let Some(block_expr) = block.expr + // First we ensure that this is a "binding chain" (each statement is a binding + // of the previous one) and that it is a binding of the closure argument. + && let Some(last_chain_binding_id) = + get_last_chain_binding_hir_id(first_param, block.stmts) + { + handle_expr(cx, block_expr, last_chain_binding_id, span, before_chars, revert); + } + }, + ExprKind::Unary(UnOp::Not, expr) => handle_expr(cx, expr, first_param, span, before_chars, !revert), + ExprKind::Call(fn_path, [arg]) => { + if let ExprKind::Path(path) = fn_path.kind + && let Some(fn_def_id) = cx.qpath_res(&path, fn_path.hir_id).opt_def_id() + && match_def_path(cx, fn_def_id, &["core", "char", "methods", "", "is_ascii"]) + && path_to_local_id(peels_expr_ref(arg), first_param) + && let Some(snippet) = snippet_opt(cx, before_chars) + { + span_lint_and_sugg( + cx, + NEEDLESS_CHARACTER_ITERATION, + span, + "checking if a string is ascii using iterators", + "try", + format!("{}{snippet}.is_ascii()", if revert { "!" } else { "" }), + Applicability::MachineApplicable, + ); + } + }, + _ => {}, + } +} + +pub(super) fn check(cx: &LateContext<'_>, call_expr: &Expr<'_>, recv: &Expr<'_>, closure_arg: &Expr<'_>) { + if let ExprKind::Closure(&Closure { body, .. }) = closure_arg.kind + && let body = cx.tcx.hir().body(body) + && let Some(first_param) = body.params.first() + && let ExprKind::MethodCall(method, mut recv, [], _) = recv.kind + && method.ident.name.as_str() == "chars" + && let str_ty = cx.typeck_results().expr_ty_adjusted(recv).peel_refs() + && *str_ty.kind() == ty::Str + { + let expr_start = recv.span; + while let ExprKind::MethodCall(_, new_recv, _, _) = recv.kind { + recv = new_recv; + } + let body_expr = peel_blocks(body.value); + + handle_expr( + cx, + body_expr, + first_param.pat.hir_id, + recv.span.with_hi(call_expr.span.hi()), + recv.span.with_hi(expr_start.hi()), + false, + ); + } +} diff --git a/clippy_lints/src/methods/unnecessary_result_map_or_else.rs b/clippy_lints/src/methods/unnecessary_result_map_or_else.rs index cdfaa690d5f..c14a87c1534 100644 --- a/clippy_lints/src/methods/unnecessary_result_map_or_else.rs +++ b/clippy_lints/src/methods/unnecessary_result_map_or_else.rs @@ -4,10 +4,11 @@ use clippy_utils::ty::is_type_diagnostic_item; use rustc_errors::Applicability; use rustc_hir as hir; -use rustc_hir::{Closure, Expr, ExprKind, HirId, QPath, Stmt, StmtKind}; +use rustc_hir::{Closure, Expr, ExprKind, HirId, QPath}; use rustc_lint::LateContext; use rustc_span::symbol::sym; +use super::utils::get_last_chain_binding_hir_id; use super::UNNECESSARY_RESULT_MAP_OR_ELSE; fn emit_lint(cx: &LateContext<'_>, expr: &Expr<'_>, recv: &Expr<'_>, def_arg: &Expr<'_>) { @@ -25,22 +26,6 @@ fn emit_lint(cx: &LateContext<'_>, expr: &Expr<'_>, recv: &Expr<'_>, def_arg: &E ); } -fn get_last_chain_binding_hir_id(mut hir_id: HirId, statements: &[Stmt<'_>]) -> Option { - for stmt in statements { - if let StmtKind::Let(local) = stmt.kind - && let Some(init) = local.init - && let ExprKind::Path(QPath::Resolved(_, path)) = init.kind - && let hir::def::Res::Local(local_hir_id) = path.res - && local_hir_id == hir_id - { - hir_id = local.pat.hir_id; - } else { - return None; - } - } - Some(hir_id) -} - fn handle_qpath( cx: &LateContext<'_>, expr: &Expr<'_>, diff --git a/clippy_lints/src/methods/utils.rs b/clippy_lints/src/methods/utils.rs index 34d7b9acbe4..a379f477995 100644 --- a/clippy_lints/src/methods/utils.rs +++ b/clippy_lints/src/methods/utils.rs @@ -4,7 +4,7 @@ use rustc_ast::ast; use rustc_errors::Applicability; use rustc_hir::intravisit::{walk_expr, Visitor}; -use rustc_hir::{BorrowKind, Expr, ExprKind, HirId, Mutability, Pat}; +use rustc_hir::{BorrowKind, Expr, ExprKind, HirId, Mutability, Pat, QPath, Stmt, StmtKind}; use rustc_lint::LateContext; use rustc_middle::hir::nested_filter; use rustc_middle::ty::{self, Ty}; @@ -171,3 +171,19 @@ fn is_binding(&self, expr: &Expr<'tcx>) -> bool { .any(|hir_id| path_to_local_id(expr, *hir_id)) } } + +pub(super) fn get_last_chain_binding_hir_id(mut hir_id: HirId, statements: &[Stmt<'_>]) -> Option { + for stmt in statements { + if let StmtKind::Let(local) = stmt.kind + && let Some(init) = local.init + && let ExprKind::Path(QPath::Resolved(_, path)) = init.kind + && let rustc_hir::def::Res::Local(local_hir_id) = path.res + && local_hir_id == hir_id + { + hir_id = local.pat.hir_id; + } else { + return None; + } + } + Some(hir_id) +} diff --git a/tests/ui/needless_character_iteration.fixed b/tests/ui/needless_character_iteration.fixed new file mode 100644 index 00000000000..5a5da592987 --- /dev/null +++ b/tests/ui/needless_character_iteration.fixed @@ -0,0 +1,51 @@ +#![warn(clippy::needless_character_iteration)] +#![allow(clippy::map_identity, clippy::unnecessary_operation)] + +#[derive(Default)] +struct S { + field: &'static str, +} + +impl S { + fn field(&self) -> &str { + self.field + } +} + +fn magic(_: char) {} + +fn main() { + "foo".is_ascii(); + //~^ ERROR: checking if a string is ascii using iterators + !"foo".is_ascii(); + //~^ ERROR: checking if a string is ascii using iterators + "foo".is_ascii(); + //~^ ERROR: checking if a string is ascii using iterators + !"foo".is_ascii(); + //~^ ERROR: checking if a string is ascii using iterators + + let s = String::new(); + s.is_ascii(); + //~^ ERROR: checking if a string is ascii using iterators + !"foo".to_string().is_ascii(); + //~^ ERROR: checking if a string is ascii using iterators + + "foo".is_ascii(); + !"foo".is_ascii(); + + S::default().field().is_ascii(); + //~^ ERROR: checking if a string is ascii using iterators + + // Should not lint! + "foo".chars().all(|c| { + let x = c; + magic(x); + x.is_ascii() + }); + + // Should not lint! + "foo".chars().all(|c| c.is_ascii() && c.is_alphabetic()); + + // Should not lint! + "foo".chars().map(|c| c).all(|c| !char::is_ascii(&c)); +} diff --git a/tests/ui/needless_character_iteration.rs b/tests/ui/needless_character_iteration.rs new file mode 100644 index 00000000000..f6320ff22b7 --- /dev/null +++ b/tests/ui/needless_character_iteration.rs @@ -0,0 +1,59 @@ +#![warn(clippy::needless_character_iteration)] +#![allow(clippy::map_identity, clippy::unnecessary_operation)] + +#[derive(Default)] +struct S { + field: &'static str, +} + +impl S { + fn field(&self) -> &str { + self.field + } +} + +fn magic(_: char) {} + +fn main() { + "foo".chars().all(|c| c.is_ascii()); + //~^ ERROR: checking if a string is ascii using iterators + "foo".chars().all(|c| !c.is_ascii()); + //~^ ERROR: checking if a string is ascii using iterators + "foo".chars().all(|c| char::is_ascii(&c)); + //~^ ERROR: checking if a string is ascii using iterators + "foo".chars().all(|c| !char::is_ascii(&c)); + //~^ ERROR: checking if a string is ascii using iterators + + let s = String::new(); + s.chars().all(|c| c.is_ascii()); + //~^ ERROR: checking if a string is ascii using iterators + "foo".to_string().chars().all(|c| !c.is_ascii()); + //~^ ERROR: checking if a string is ascii using iterators + + "foo".chars().all(|c| { + //~^ ERROR: checking if a string is ascii using iterators + let x = c; + x.is_ascii() + }); + "foo".chars().all(|c| { + //~^ ERROR: checking if a string is ascii using iterators + let x = c; + !x.is_ascii() + }); + + S::default().field().chars().all(|x| x.is_ascii()); + //~^ ERROR: checking if a string is ascii using iterators + + // Should not lint! + "foo".chars().all(|c| { + let x = c; + magic(x); + x.is_ascii() + }); + + // Should not lint! + "foo".chars().all(|c| c.is_ascii() && c.is_alphabetic()); + + // Should not lint! + "foo".chars().map(|c| c).all(|c| !char::is_ascii(&c)); +} diff --git a/tests/ui/needless_character_iteration.stderr b/tests/ui/needless_character_iteration.stderr new file mode 100644 index 00000000000..05055f75aa7 --- /dev/null +++ b/tests/ui/needless_character_iteration.stderr @@ -0,0 +1,67 @@ +error: checking if a string is ascii using iterators + --> tests/ui/needless_character_iteration.rs:18:5 + | +LL | "foo".chars().all(|c| c.is_ascii()); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `"foo".is_ascii()` + | + = note: `-D clippy::needless-character-iteration` implied by `-D warnings` + = help: to override `-D warnings` add `#[allow(clippy::needless_character_iteration)]` + +error: checking if a string is ascii using iterators + --> tests/ui/needless_character_iteration.rs:20:5 + | +LL | "foo".chars().all(|c| !c.is_ascii()); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `!"foo".is_ascii()` + +error: checking if a string is ascii using iterators + --> tests/ui/needless_character_iteration.rs:22:5 + | +LL | "foo".chars().all(|c| char::is_ascii(&c)); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `"foo".is_ascii()` + +error: checking if a string is ascii using iterators + --> tests/ui/needless_character_iteration.rs:24:5 + | +LL | "foo".chars().all(|c| !char::is_ascii(&c)); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `!"foo".is_ascii()` + +error: checking if a string is ascii using iterators + --> tests/ui/needless_character_iteration.rs:28:5 + | +LL | s.chars().all(|c| c.is_ascii()); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `s.is_ascii()` + +error: checking if a string is ascii using iterators + --> tests/ui/needless_character_iteration.rs:30:5 + | +LL | "foo".to_string().chars().all(|c| !c.is_ascii()); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `!"foo".to_string().is_ascii()` + +error: checking if a string is ascii using iterators + --> tests/ui/needless_character_iteration.rs:33:5 + | +LL | / "foo".chars().all(|c| { +LL | | +LL | | let x = c; +LL | | x.is_ascii() +LL | | }); + | |______^ help: try: `"foo".is_ascii()` + +error: checking if a string is ascii using iterators + --> tests/ui/needless_character_iteration.rs:38:5 + | +LL | / "foo".chars().all(|c| { +LL | | +LL | | let x = c; +LL | | !x.is_ascii() +LL | | }); + | |______^ help: try: `!"foo".is_ascii()` + +error: checking if a string is ascii using iterators + --> tests/ui/needless_character_iteration.rs:44:5 + | +LL | S::default().field().chars().all(|x| x.is_ascii()); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `S::default().field().is_ascii()` + +error: aborting due to 9 previous errors +