| use clippy_utils::diagnostics::span_lint_and_sugg; |
| use clippy_utils::is_trait_method; |
| use clippy_utils::sugg::Sugg; |
| use clippy_utils::ty::implements_trait; |
| use if_chain::if_chain; |
| use rustc_errors::Applicability; |
| use rustc_hir::{Closure, Expr, ExprKind, Mutability, Param, Pat, PatKind, Path, PathSegment, QPath}; |
| use rustc_lint::LateContext; |
| use rustc_middle::ty::{self, subst::GenericArgKind}; |
| use rustc_span::sym; |
| use rustc_span::symbol::Ident; |
| use std::iter; |
| |
| use super::UNNECESSARY_SORT_BY; |
| |
| enum LintTrigger { |
| Sort(SortDetection), |
| SortByKey(SortByKeyDetection), |
| } |
| |
| struct SortDetection { |
| vec_name: String, |
| } |
| |
| struct SortByKeyDetection { |
| vec_name: String, |
| closure_arg: String, |
| closure_body: String, |
| reverse: bool, |
| } |
| |
| /// Detect if the two expressions are mirrored (identical, except one |
| /// contains a and the other replaces it with b) |
| fn mirrored_exprs(a_expr: &Expr<'_>, a_ident: &Ident, b_expr: &Expr<'_>, b_ident: &Ident) -> bool { |
| match (&a_expr.kind, &b_expr.kind) { |
| // Two boxes with mirrored contents |
| (ExprKind::Box(left_expr), ExprKind::Box(right_expr)) => { |
| mirrored_exprs(left_expr, a_ident, right_expr, b_ident) |
| }, |
| // Two arrays with mirrored contents |
| (ExprKind::Array(left_exprs), ExprKind::Array(right_exprs)) => { |
| iter::zip(*left_exprs, *right_exprs).all(|(left, right)| mirrored_exprs(left, a_ident, right, b_ident)) |
| }, |
| // The two exprs are function calls. |
| // Check to see that the function itself and its arguments are mirrored |
| (ExprKind::Call(left_expr, left_args), ExprKind::Call(right_expr, right_args)) => { |
| mirrored_exprs(left_expr, a_ident, right_expr, b_ident) |
| && iter::zip(*left_args, *right_args).all(|(left, right)| mirrored_exprs(left, a_ident, right, b_ident)) |
| }, |
| // The two exprs are method calls. |
| // Check to see that the function is the same and the arguments are mirrored |
| // This is enough because the receiver of the method is listed in the arguments |
| ( |
| ExprKind::MethodCall(left_segment, left_receiver, left_args, _), |
| ExprKind::MethodCall(right_segment, right_receiver, right_args, _), |
| ) => { |
| left_segment.ident == right_segment.ident |
| && iter::zip(*left_args, *right_args).all(|(left, right)| mirrored_exprs(left, a_ident, right, b_ident)) |
| && mirrored_exprs(left_receiver, a_ident, right_receiver, b_ident) |
| }, |
| // Two tuples with mirrored contents |
| (ExprKind::Tup(left_exprs), ExprKind::Tup(right_exprs)) => { |
| iter::zip(*left_exprs, *right_exprs).all(|(left, right)| mirrored_exprs(left, a_ident, right, b_ident)) |
| }, |
| // Two binary ops, which are the same operation and which have mirrored arguments |
| (ExprKind::Binary(left_op, left_left, left_right), ExprKind::Binary(right_op, right_left, right_right)) => { |
| left_op.node == right_op.node |
| && mirrored_exprs(left_left, a_ident, right_left, b_ident) |
| && mirrored_exprs(left_right, a_ident, right_right, b_ident) |
| }, |
| // Two unary ops, which are the same operation and which have the same argument |
| (ExprKind::Unary(left_op, left_expr), ExprKind::Unary(right_op, right_expr)) => { |
| left_op == right_op && mirrored_exprs(left_expr, a_ident, right_expr, b_ident) |
| }, |
| // The two exprs are literals of some kind |
| (ExprKind::Lit(left_lit), ExprKind::Lit(right_lit)) => left_lit.node == right_lit.node, |
| (ExprKind::Cast(left, _), ExprKind::Cast(right, _)) => mirrored_exprs(left, a_ident, right, b_ident), |
| (ExprKind::DropTemps(left_block), ExprKind::DropTemps(right_block)) => { |
| mirrored_exprs(left_block, a_ident, right_block, b_ident) |
| }, |
| (ExprKind::Field(left_expr, left_ident), ExprKind::Field(right_expr, right_ident)) => { |
| left_ident.name == right_ident.name && mirrored_exprs(left_expr, a_ident, right_expr, right_ident) |
| }, |
| // Two paths: either one is a and the other is b, or they're identical to each other |
| ( |
| ExprKind::Path(QPath::Resolved( |
| _, |
| Path { |
| segments: left_segments, |
| .. |
| }, |
| )), |
| ExprKind::Path(QPath::Resolved( |
| _, |
| Path { |
| segments: right_segments, |
| .. |
| }, |
| )), |
| ) => { |
| (iter::zip(*left_segments, *right_segments).all(|(left, right)| left.ident == right.ident) |
| && left_segments |
| .iter() |
| .all(|seg| &seg.ident != a_ident && &seg.ident != b_ident)) |
| || (left_segments.len() == 1 |
| && &left_segments[0].ident == a_ident |
| && right_segments.len() == 1 |
| && &right_segments[0].ident == b_ident) |
| }, |
| // Matching expressions, but one or both is borrowed |
| ( |
| ExprKind::AddrOf(left_kind, Mutability::Not, left_expr), |
| ExprKind::AddrOf(right_kind, Mutability::Not, right_expr), |
| ) => left_kind == right_kind && mirrored_exprs(left_expr, a_ident, right_expr, b_ident), |
| (_, ExprKind::AddrOf(_, Mutability::Not, right_expr)) => mirrored_exprs(a_expr, a_ident, right_expr, b_ident), |
| (ExprKind::AddrOf(_, Mutability::Not, left_expr), _) => mirrored_exprs(left_expr, a_ident, b_expr, b_ident), |
| _ => false, |
| } |
| } |
| |
| fn detect_lint(cx: &LateContext<'_>, expr: &Expr<'_>, recv: &Expr<'_>, arg: &Expr<'_>) -> Option<LintTrigger> { |
| if_chain! { |
| if let Some(method_id) = cx.typeck_results().type_dependent_def_id(expr.hir_id); |
| if let Some(impl_id) = cx.tcx.impl_of_method(method_id); |
| if cx.tcx.type_of(impl_id).subst_identity().is_slice(); |
| if let ExprKind::Closure(&Closure { body, .. }) = arg.kind; |
| if let closure_body = cx.tcx.hir().body(body); |
| if let &[ |
| Param { pat: Pat { kind: PatKind::Binding(_, _, left_ident, _), .. }, ..}, |
| Param { pat: Pat { kind: PatKind::Binding(_, _, right_ident, _), .. }, .. } |
| ] = &closure_body.params; |
| if let ExprKind::MethodCall(method_path, left_expr, [right_expr], _) = closure_body.value.kind; |
| if method_path.ident.name == sym::cmp; |
| if is_trait_method(cx, closure_body.value, sym::Ord); |
| then { |
| let (closure_body, closure_arg, reverse) = if mirrored_exprs( |
| left_expr, |
| left_ident, |
| right_expr, |
| right_ident |
| ) { |
| (Sugg::hir(cx, left_expr, "..").to_string(), left_ident.name.to_string(), false) |
| } else if mirrored_exprs(left_expr, right_ident, right_expr, left_ident) { |
| (Sugg::hir(cx, left_expr, "..").to_string(), right_ident.name.to_string(), true) |
| } else { |
| return None; |
| }; |
| let vec_name = Sugg::hir(cx, recv, "..").to_string(); |
| |
| if_chain! { |
| if let ExprKind::Path(QPath::Resolved(_, Path { |
| segments: [PathSegment { ident: left_name, .. }], .. |
| })) = &left_expr.kind; |
| if left_name == left_ident; |
| if cx.tcx.get_diagnostic_item(sym::Ord).map_or(false, |id| { |
| implements_trait(cx, cx.typeck_results().expr_ty(left_expr), id, &[]) |
| }); |
| then { |
| return Some(LintTrigger::Sort(SortDetection { vec_name })); |
| } |
| } |
| |
| if !expr_borrows(cx, left_expr) { |
| return Some(LintTrigger::SortByKey(SortByKeyDetection { |
| vec_name, |
| closure_arg, |
| closure_body, |
| reverse, |
| })); |
| } |
| } |
| } |
| |
| None |
| } |
| |
| fn expr_borrows(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool { |
| let ty = cx.typeck_results().expr_ty(expr); |
| matches!(ty.kind(), ty::Ref(..)) || ty.walk().any(|arg| matches!(arg.unpack(), GenericArgKind::Lifetime(_))) |
| } |
| |
| pub(super) fn check<'tcx>( |
| cx: &LateContext<'tcx>, |
| expr: &'tcx Expr<'_>, |
| recv: &'tcx Expr<'_>, |
| arg: &'tcx Expr<'_>, |
| is_unstable: bool, |
| ) { |
| match detect_lint(cx, expr, recv, arg) { |
| Some(LintTrigger::SortByKey(trigger)) => span_lint_and_sugg( |
| cx, |
| UNNECESSARY_SORT_BY, |
| expr.span, |
| "use Vec::sort_by_key here instead", |
| "try", |
| format!( |
| "{}.sort{}_by_key(|{}| {})", |
| trigger.vec_name, |
| if is_unstable { "_unstable" } else { "" }, |
| trigger.closure_arg, |
| if trigger.reverse { |
| format!("std::cmp::Reverse({})", trigger.closure_body) |
| } else { |
| trigger.closure_body.to_string() |
| }, |
| ), |
| if trigger.reverse { |
| Applicability::MaybeIncorrect |
| } else { |
| Applicability::MachineApplicable |
| }, |
| ), |
| Some(LintTrigger::Sort(trigger)) => span_lint_and_sugg( |
| cx, |
| UNNECESSARY_SORT_BY, |
| expr.span, |
| "use Vec::sort here instead", |
| "try", |
| format!( |
| "{}.sort{}()", |
| trigger.vec_name, |
| if is_unstable { "_unstable" } else { "" }, |
| ), |
| Applicability::MachineApplicable, |
| ), |
| None => {}, |
| } |
| } |