-use clippy_utils::diagnostics::span_lint_and_then;
+use clippy_utils::diagnostics::{span_lint_and_sugg, span_lint_and_then};
use clippy_utils::source::snippet_with_applicability;
use clippy_utils::sugg::Sugg;
use clippy_utils::ty::is_type_diagnostic_item;
-use clippy_utils::{differing_macro_contexts, eq_expr_value};
+use clippy_utils::{can_mut_borrow_both, eq_expr_value, std_or_core};
use if_chain::if_chain;
use rustc_errors::Applicability;
-use rustc_hir::{Block, Expr, ExprKind, PatKind, QPath, StmtKind};
+use rustc_hir::{BinOpKind, Block, Expr, ExprKind, PatKind, QPath, Stmt, StmtKind};
use rustc_lint::{LateContext, LateLintPass};
use rustc_middle::ty;
use rustc_session::{declare_lint_pass, declare_tool_lint};
-use rustc_span::sym;
+use rustc_span::source_map::Spanned;
+use rustc_span::{sym, Span};
declare_clippy_lint! {
/// ### What it does
/// let mut b = 2;
/// std::mem::swap(&mut a, &mut b);
/// ```
+ #[clippy::version = "pre 1.29.0"]
pub MANUAL_SWAP,
complexity,
"manual swap of two variables"
/// # let mut b = 2;
/// std::mem::swap(&mut a, &mut b);
/// ```
+ #[clippy::version = "pre 1.29.0"]
pub ALMOST_SWAPPED,
correctness,
"`foo = bar; bar = foo` sequence"
fn check_block(&mut self, cx: &LateContext<'tcx>, block: &'tcx Block<'_>) {
check_manual_swap(cx, block);
check_suspicious_swap(cx, block);
+ check_xor_swap(cx, block);
}
}
+fn generate_swap_warning(cx: &LateContext<'_>, e1: &Expr<'_>, e2: &Expr<'_>, span: Span, is_xor_based: bool) {
+ let mut applicability = Applicability::MachineApplicable;
+
+ if !can_mut_borrow_both(cx, e1, e2) {
+ if let ExprKind::Index(lhs1, idx1) = e1.kind {
+ if let ExprKind::Index(lhs2, idx2) = e2.kind {
+ if eq_expr_value(cx, lhs1, lhs2) {
+ let ty = cx.typeck_results().expr_ty(lhs1).peel_refs();
+
+ if matches!(ty.kind(), ty::Slice(_))
+ || matches!(ty.kind(), ty::Array(_, _))
+ || is_type_diagnostic_item(cx, ty, sym::Vec)
+ || is_type_diagnostic_item(cx, ty, sym::VecDeque)
+ {
+ let slice = Sugg::hir_with_applicability(cx, lhs1, "<slice>", &mut applicability);
+ span_lint_and_sugg(
+ cx,
+ MANUAL_SWAP,
+ span,
+ &format!("this looks like you are swapping elements of `{}` manually", slice),
+ "try",
+ format!(
+ "{}.swap({}, {})",
+ slice.maybe_par(),
+ snippet_with_applicability(cx, idx1.span, "..", &mut applicability),
+ snippet_with_applicability(cx, idx2.span, "..", &mut applicability),
+ ),
+ applicability,
+ );
+ }
+ }
+ }
+ }
+ return;
+ }
+
+ let first = Sugg::hir_with_applicability(cx, e1, "..", &mut applicability);
+ let second = Sugg::hir_with_applicability(cx, e2, "..", &mut applicability);
+ let Some(sugg) = std_or_core(cx) else { return };
+
+ span_lint_and_then(
+ cx,
+ MANUAL_SWAP,
+ span,
+ &format!("this looks like you are swapping `{}` and `{}` manually", first, second),
+ |diag| {
+ diag.span_suggestion(
+ span,
+ "try",
+ format!("{}::mem::swap({}, {})", sugg, first.mut_addr(), second.mut_addr()),
+ applicability,
+ );
+ if !is_xor_based {
+ diag.note(&format!("or maybe you should use `{}::mem::replace`?", sugg));
+ }
+ },
+ );
+}
+
/// Implementation of the `MANUAL_SWAP` lint.
fn check_manual_swap(cx: &LateContext<'_>, block: &Block<'_>) {
for w in block.stmts.windows(3) {
if eq_expr_value(cx, tmp_init, lhs1);
if eq_expr_value(cx, rhs1, lhs2);
then {
- if let ExprKind::Field(lhs1, _) = lhs1.kind {
- if let ExprKind::Field(lhs2, _) = lhs2.kind {
- if lhs1.hir_id.owner == lhs2.hir_id.owner {
- return;
- }
- }
- }
-
- let mut applicability = Applicability::MachineApplicable;
-
- let slice = check_for_slice(cx, lhs1, lhs2);
- let (replace, what, sugg) = if let Slice::NotSwappable = slice {
- return;
- } else if let Slice::Swappable(slice, idx1, idx2) = slice {
- if let Some(slice) = Sugg::hir_opt(cx, slice) {
- (
- false,
- format!(" elements of `{}`", slice),
- format!(
- "{}.swap({}, {})",
- slice.maybe_par(),
- snippet_with_applicability(cx, idx1.span, "..", &mut applicability),
- snippet_with_applicability(cx, idx2.span, "..", &mut applicability),
- ),
- )
- } else {
- (false, String::new(), String::new())
- }
- } else if let (Some(first), Some(second)) = (Sugg::hir_opt(cx, lhs1), Sugg::hir_opt(cx, rhs1)) {
- (
- true,
- format!(" `{}` and `{}`", first, second),
- format!("std::mem::swap({}, {})", first.mut_addr(), second.mut_addr()),
- )
- } else {
- (true, String::new(), String::new())
- };
-
let span = w[0].span.to(second.span);
-
- span_lint_and_then(
- cx,
- MANUAL_SWAP,
- span,
- &format!("this looks like you are swapping{} manually", what),
- |diag| {
- if !sugg.is_empty() {
- diag.span_suggestion(
- span,
- "try",
- sugg,
- applicability,
- );
-
- if replace {
- diag.note("or maybe you should use `std::mem::replace`?");
- }
- }
- }
- );
- }
- }
- }
-}
-
-enum Slice<'a> {
- /// `slice.swap(idx1, idx2)` can be used
- ///
- /// ## Example
- ///
- /// ```rust
- /// # let mut a = vec![0, 1];
- /// let t = a[1];
- /// a[1] = a[0];
- /// a[0] = t;
- /// // can be written as
- /// a.swap(0, 1);
- /// ```
- Swappable(&'a Expr<'a>, &'a Expr<'a>, &'a Expr<'a>),
- /// The `swap` function cannot be used.
- ///
- /// ## Example
- ///
- /// ```rust
- /// # let mut a = [vec![1, 2], vec![3, 4]];
- /// let t = a[0][1];
- /// a[0][1] = a[1][0];
- /// a[1][0] = t;
- /// ```
- NotSwappable,
- /// Not a slice
- None,
-}
-
-/// Checks if both expressions are index operations into "slice-like" types.
-fn check_for_slice<'a>(cx: &LateContext<'_>, lhs1: &'a Expr<'_>, lhs2: &'a Expr<'_>) -> Slice<'a> {
- if let ExprKind::Index(lhs1, idx1) = lhs1.kind {
- if let ExprKind::Index(lhs2, idx2) = lhs2.kind {
- if eq_expr_value(cx, lhs1, lhs2) {
- let ty = cx.typeck_results().expr_ty(lhs1).peel_refs();
-
- if matches!(ty.kind(), ty::Slice(_))
- || matches!(ty.kind(), ty::Array(_, _))
- || is_type_diagnostic_item(cx, ty, sym::vec_type)
- || is_type_diagnostic_item(cx, ty, sym::vecdeque_type)
- {
- return Slice::Swappable(lhs1, idx1, idx2);
- }
- } else {
- return Slice::NotSwappable;
+ generate_swap_warning(cx, lhs1, lhs2, span, false);
}
}
}
-
- Slice::None
}
/// Implementation of the `ALMOST_SWAPPED` lint.
if_chain! {
if let StmtKind::Semi(first) = w[0].kind;
if let StmtKind::Semi(second) = w[1].kind;
- if !differing_macro_contexts(first.span, second.span);
+ if first.span.ctxt() == second.span.ctxt();
if let ExprKind::Assign(lhs0, rhs0, _) = first.kind;
if let ExprKind::Assign(lhs1, rhs1, _) = second.kind;
if eq_expr_value(cx, lhs0, rhs1);
};
let span = first.span.to(second.span);
+ let Some(sugg) = std_or_core(cx) else { return };
span_lint_and_then(cx,
- ALMOST_SWAPPED,
- span,
- &format!("this looks like you are trying to swap{}", what),
- |diag| {
- if !what.is_empty() {
- diag.span_suggestion(
- span,
- "try",
- format!(
- "std::mem::swap({}, {})",
- lhs,
- rhs,
- ),
- Applicability::MaybeIncorrect,
- );
- diag.note("or maybe you should use `std::mem::replace`?");
- }
- });
+ ALMOST_SWAPPED,
+ span,
+ &format!("this looks like you are trying to swap{}", what),
+ |diag| {
+ if !what.is_empty() {
+ diag.span_suggestion(
+ span,
+ "try",
+ format!(
+ "{}::mem::swap({}, {})",
+ sugg,
+ lhs,
+ rhs,
+ ),
+ Applicability::MaybeIncorrect,
+ );
+ diag.note(
+ &format!("or maybe you should use `{}::mem::replace`?", sugg)
+ );
+ }
+ });
}
}
}
}
+
+/// Implementation of the xor case for `MANUAL_SWAP` lint.
+fn check_xor_swap(cx: &LateContext<'_>, block: &Block<'_>) {
+ for window in block.stmts.windows(3) {
+ if_chain! {
+ if let Some((lhs0, rhs0)) = extract_sides_of_xor_assign(&window[0]);
+ if let Some((lhs1, rhs1)) = extract_sides_of_xor_assign(&window[1]);
+ if let Some((lhs2, rhs2)) = extract_sides_of_xor_assign(&window[2]);
+ if eq_expr_value(cx, lhs0, rhs1);
+ if eq_expr_value(cx, lhs2, rhs1);
+ if eq_expr_value(cx, lhs1, rhs0);
+ if eq_expr_value(cx, lhs1, rhs2);
+ then {
+ let span = window[0].span.to(window[2].span);
+ generate_swap_warning(cx, lhs0, rhs0, span, true);
+ }
+ };
+ }
+}
+
+/// Returns the lhs and rhs of an xor assignment statement.
+fn extract_sides_of_xor_assign<'a, 'hir>(stmt: &'a Stmt<'hir>) -> Option<(&'a Expr<'hir>, &'a Expr<'hir>)> {
+ if let StmtKind::Semi(expr) = stmt.kind {
+ if let ExprKind::AssignOp(
+ Spanned {
+ node: BinOpKind::BitXor,
+ ..
+ },
+ lhs,
+ rhs,
+ ) = expr.kind
+ {
+ return Some((lhs, rhs));
+ }
+ }
+ None
+}
projects / rust.git / blobdiff