+use clippy_utils::consts::{constant, Constant};
+use clippy_utils::diagnostics::{span_lint, span_lint_and_sugg, span_lint_and_then};
+use clippy_utils::source::{snippet, snippet_opt, snippet_with_applicability};
+use clippy_utils::sugg::Sugg;
+use clippy_utils::{get_parent_expr, in_constant, is_integer_const, meets_msrv, msrvs, single_segment_path};
+use clippy_utils::{higher, SpanlessEq};
use if_chain::if_chain;
-use rustc::hir::*;
-use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
-use rustc::{declare_lint_pass, declare_tool_lint};
+use rustc_ast::ast::RangeLimits;
use rustc_errors::Applicability;
-use syntax::ast::RangeLimits;
-use syntax::source_map::Spanned;
-
-use crate::utils::sugg::Sugg;
-use crate::utils::{get_trait_def_id, higher, implements_trait, SpanlessEq};
-use crate::utils::{is_integer_const, paths, snippet, snippet_opt, span_lint, span_lint_and_then};
+use rustc_hir::{BinOpKind, Expr, ExprKind, PathSegment, QPath};
+use rustc_lint::{LateContext, LateLintPass};
+use rustc_middle::ty;
+use rustc_semver::RustcVersion;
+use rustc_session::{declare_tool_lint, impl_lint_pass};
+use rustc_span::source_map::{Span, Spanned};
+use rustc_span::sym;
+use rustc_span::symbol::Ident;
+use std::cmp::Ordering;
declare_clippy_lint! {
- /// **What it does:** Checks for calling `.step_by(0)` on iterators,
- /// which never terminates.
- ///
- /// **Why is this bad?** This very much looks like an oversight, since with
- /// `loop { .. }` there is an obvious better way to endlessly loop.
- ///
- /// **Known problems:** None.
- ///
- /// **Example:**
- /// ```ignore
- /// for x in (5..5).step_by(0) {
- /// ..
- /// }
- /// ```
- pub ITERATOR_STEP_BY_ZERO,
- correctness,
- "using `Iterator::step_by(0)`, which produces an infinite iterator"
-}
-
-declare_clippy_lint! {
- /// **What it does:** Checks for zipping a collection with the range of
+ /// ### What it does
+ /// Checks for zipping a collection with the range of
/// `0.._.len()`.
///
- /// **Why is this bad?** The code is better expressed with `.enumerate()`.
+ /// ### Why is this bad?
+ /// The code is better expressed with `.enumerate()`.
///
- /// **Known problems:** None.
- ///
- /// **Example:**
+ /// ### Example
/// ```rust
/// # let x = vec![1];
/// x.iter().zip(0..x.len());
/// # let x = vec![1];
/// x.iter().enumerate();
/// ```
+ #[clippy::version = "pre 1.29.0"]
pub RANGE_ZIP_WITH_LEN,
complexity,
"zipping iterator with a range when `enumerate()` would do"
}
declare_clippy_lint! {
- /// **What it does:** Checks for exclusive ranges where 1 is added to the
+ /// ### What it does
+ /// Checks for exclusive ranges where 1 is added to the
/// upper bound, e.g., `x..(y+1)`.
///
- /// **Why is this bad?** The code is more readable with an inclusive range
+ /// ### Why is this bad?
+ /// The code is more readable with an inclusive range
/// like `x..=y`.
///
- /// **Known problems:** Will add unnecessary pair of parentheses when the
- /// expression is not wrapped in a pair but starts with a opening parenthesis
+ /// ### Known problems
+ /// Will add unnecessary pair of parentheses when the
+ /// expression is not wrapped in a pair but starts with an opening parenthesis
/// and ends with a closing one.
/// I.e., `let _ = (f()+1)..(f()+1)` results in `let _ = ((f()+1)..=f())`.
///
- /// **Example:**
+ /// Also in many cases, inclusive ranges are still slower to run than
+ /// exclusive ranges, because they essentially add an extra branch that
+ /// LLVM may fail to hoist out of the loop.
+ ///
+ /// This will cause a warning that cannot be fixed if the consumer of the
+ /// range only accepts a specific range type, instead of the generic
+ /// `RangeBounds` trait
+ /// ([#3307](https://github.com/rust-lang/rust-clippy/issues/3307)).
+ ///
+ /// ### Example
/// ```rust,ignore
/// for x..(y+1) { .. }
/// ```
/// ```rust,ignore
/// for x..=y { .. }
/// ```
+ #[clippy::version = "pre 1.29.0"]
pub RANGE_PLUS_ONE,
- complexity,
+ pedantic,
"`x..(y+1)` reads better as `x..=y`"
}
declare_clippy_lint! {
- /// **What it does:** Checks for inclusive ranges where 1 is subtracted from
+ /// ### What it does
+ /// Checks for inclusive ranges where 1 is subtracted from
/// the upper bound, e.g., `x..=(y-1)`.
///
- /// **Why is this bad?** The code is more readable with an exclusive range
+ /// ### Why is this bad?
+ /// The code is more readable with an exclusive range
/// like `x..y`.
///
- /// **Known problems:** None.
+ /// ### Known problems
+ /// This will cause a warning that cannot be fixed if
+ /// the consumer of the range only accepts a specific range type, instead of
+ /// the generic `RangeBounds` trait
+ /// ([#3307](https://github.com/rust-lang/rust-clippy/issues/3307)).
///
- /// **Example:**
+ /// ### Example
/// ```rust,ignore
/// for x..=(y-1) { .. }
/// ```
/// ```rust,ignore
/// for x..y { .. }
/// ```
+ #[clippy::version = "pre 1.29.0"]
pub RANGE_MINUS_ONE,
- complexity,
+ pedantic,
"`x..=(y-1)` reads better as `x..y`"
}
-declare_lint_pass!(Ranges => [
- ITERATOR_STEP_BY_ZERO,
+declare_clippy_lint! {
+ /// ### What it does
+ /// Checks for range expressions `x..y` where both `x` and `y`
+ /// are constant and `x` is greater or equal to `y`.
+ ///
+ /// ### Why is this bad?
+ /// Empty ranges yield no values so iterating them is a no-op.
+ /// Moreover, trying to use a reversed range to index a slice will panic at run-time.
+ ///
+ /// ### Example
+ /// ```rust,no_run
+ /// fn main() {
+ /// (10..=0).for_each(|x| println!("{}", x));
+ ///
+ /// let arr = [1, 2, 3, 4, 5];
+ /// let sub = &arr[3..1];
+ /// }
+ /// ```
+ /// Use instead:
+ /// ```rust
+ /// fn main() {
+ /// (0..=10).rev().for_each(|x| println!("{}", x));
+ ///
+ /// let arr = [1, 2, 3, 4, 5];
+ /// let sub = &arr[1..3];
+ /// }
+ /// ```
+ #[clippy::version = "1.45.0"]
+ pub REVERSED_EMPTY_RANGES,
+ correctness,
+ "reversing the limits of range expressions, resulting in empty ranges"
+}
+
+declare_clippy_lint! {
+ /// ### What it does
+ /// Checks for expressions like `x >= 3 && x < 8` that could
+ /// be more readably expressed as `(3..8).contains(x)`.
+ ///
+ /// ### Why is this bad?
+ /// `contains` expresses the intent better and has less
+ /// failure modes (such as fencepost errors or using `||` instead of `&&`).
+ ///
+ /// ### Example
+ /// ```rust
+ /// // given
+ /// let x = 6;
+ ///
+ /// assert!(x >= 3 && x < 8);
+ /// ```
+ /// Use instead:
+ /// ```rust
+ ///# let x = 6;
+ /// assert!((3..8).contains(&x));
+ /// ```
+ #[clippy::version = "1.49.0"]
+ pub MANUAL_RANGE_CONTAINS,
+ style,
+ "manually reimplementing {`Range`, `RangeInclusive`}`::contains`"
+}
+
+pub struct Ranges {
+ msrv: Option<RustcVersion>,
+}
+
+impl Ranges {
+ #[must_use]
+ pub fn new(msrv: Option<RustcVersion>) -> Self {
+ Self { msrv }
+ }
+}
+
+impl_lint_pass!(Ranges => [
RANGE_ZIP_WITH_LEN,
RANGE_PLUS_ONE,
- RANGE_MINUS_ONE
+ RANGE_MINUS_ONE,
+ REVERSED_EMPTY_RANGES,
+ MANUAL_RANGE_CONTAINS,
]);
-impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Ranges {
- fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
- if let ExprKind::MethodCall(ref path, _, ref args) = expr.kind {
- let name = path.ident.as_str();
-
- // Range with step_by(0).
- if name == "step_by" && args.len() == 2 && has_step_by(cx, &args[0]) {
- use crate::consts::{constant, Constant};
- if let Some((Constant::Int(0), _)) = constant(cx, cx.tables, &args[1]) {
- span_lint(
- cx,
- ITERATOR_STEP_BY_ZERO,
- expr.span,
- "Iterator::step_by(0) will panic at runtime",
- );
- }
- } else if name == "zip" && args.len() == 2 {
- let iter = &args[0].kind;
- let zip_arg = &args[1];
- if_chain! {
- // `.iter()` call
- if let ExprKind::MethodCall(ref iter_path, _, ref iter_args ) = *iter;
- if iter_path.ident.name == sym!(iter);
- // range expression in `.zip()` call: `0..x.len()`
- if let Some(higher::Range { start: Some(start), end: Some(end), .. }) = higher::range(cx, zip_arg);
- if is_integer_const(cx, start, 0);
- // `.len()` call
- if let ExprKind::MethodCall(ref len_path, _, ref len_args) = end.kind;
- if len_path.ident.name == sym!(len) && len_args.len() == 1;
- // `.iter()` and `.len()` called on same `Path`
- if let ExprKind::Path(QPath::Resolved(_, ref iter_path)) = iter_args[0].kind;
- if let ExprKind::Path(QPath::Resolved(_, ref len_path)) = len_args[0].kind;
- if SpanlessEq::new(cx).eq_path_segments(&iter_path.segments, &len_path.segments);
- then {
- span_lint(cx,
- RANGE_ZIP_WITH_LEN,
- expr.span,
- &format!("It is more idiomatic to use {}.iter().enumerate()",
- snippet(cx, iter_args[0].span, "_")));
- }
+impl<'tcx> LateLintPass<'tcx> for Ranges {
+ fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
+ match expr.kind {
+ ExprKind::MethodCall(path, args, _) => {
+ check_range_zip_with_len(cx, path, args, expr.span);
+ },
+ ExprKind::Binary(ref op, l, r) => {
+ if meets_msrv(self.msrv.as_ref(), &msrvs::RANGE_CONTAINS) {
+ check_possible_range_contains(cx, op.node, l, r, expr);
}
- }
+ },
+ _ => {},
}
check_exclusive_range_plus_one(cx, expr);
check_inclusive_range_minus_one(cx, expr);
+ check_reversed_empty_range(cx, expr);
+ }
+ extract_msrv_attr!(LateContext);
+}
+
+fn check_possible_range_contains(cx: &LateContext<'_>, op: BinOpKind, l: &Expr<'_>, r: &Expr<'_>, expr: &Expr<'_>) {
+ if in_constant(cx, expr.hir_id) {
+ return;
+ }
+
+ let span = expr.span;
+ let combine_and = match op {
+ BinOpKind::And | BinOpKind::BitAnd => true,
+ BinOpKind::Or | BinOpKind::BitOr => false,
+ _ => return,
+ };
+ // value, name, order (higher/lower), inclusiveness
+ if let (Some((lval, lname, name_span, lval_span, lord, linc)), Some((rval, rname, _, rval_span, rord, rinc))) =
+ (check_range_bounds(cx, l), check_range_bounds(cx, r))
+ {
+ // we only lint comparisons on the same name and with different
+ // direction
+ if lname != rname || lord == rord {
+ return;
+ }
+ let ord = Constant::partial_cmp(cx.tcx, cx.typeck_results().expr_ty(l), &lval, &rval);
+ if combine_and && ord == Some(rord) {
+ // order lower bound and upper bound
+ let (l_span, u_span, l_inc, u_inc) = if rord == Ordering::Less {
+ (lval_span, rval_span, linc, rinc)
+ } else {
+ (rval_span, lval_span, rinc, linc)
+ };
+ // we only lint inclusive lower bounds
+ if !l_inc {
+ return;
+ }
+ let (range_type, range_op) = if u_inc {
+ ("RangeInclusive", "..=")
+ } else {
+ ("Range", "..")
+ };
+ let mut applicability = Applicability::MachineApplicable;
+ let name = snippet_with_applicability(cx, name_span, "_", &mut applicability);
+ let lo = snippet_with_applicability(cx, l_span, "_", &mut applicability);
+ let hi = snippet_with_applicability(cx, u_span, "_", &mut applicability);
+ let space = if lo.ends_with('.') { " " } else { "" };
+ span_lint_and_sugg(
+ cx,
+ MANUAL_RANGE_CONTAINS,
+ span,
+ &format!("manual `{}::contains` implementation", range_type),
+ "use",
+ format!("({}{}{}{}).contains(&{})", lo, space, range_op, hi, name),
+ applicability,
+ );
+ } else if !combine_and && ord == Some(lord) {
+ // `!_.contains(_)`
+ // order lower bound and upper bound
+ let (l_span, u_span, l_inc, u_inc) = if lord == Ordering::Less {
+ (lval_span, rval_span, linc, rinc)
+ } else {
+ (rval_span, lval_span, rinc, linc)
+ };
+ if l_inc {
+ return;
+ }
+ let (range_type, range_op) = if u_inc {
+ ("Range", "..")
+ } else {
+ ("RangeInclusive", "..=")
+ };
+ let mut applicability = Applicability::MachineApplicable;
+ let name = snippet_with_applicability(cx, name_span, "_", &mut applicability);
+ let lo = snippet_with_applicability(cx, l_span, "_", &mut applicability);
+ let hi = snippet_with_applicability(cx, u_span, "_", &mut applicability);
+ let space = if lo.ends_with('.') { " " } else { "" };
+ span_lint_and_sugg(
+ cx,
+ MANUAL_RANGE_CONTAINS,
+ span,
+ &format!("manual `!{}::contains` implementation", range_type),
+ "use",
+ format!("!({}{}{}{}).contains(&{})", lo, space, range_op, hi, name),
+ applicability,
+ );
+ }
+ }
+}
+
+fn check_range_bounds(cx: &LateContext<'_>, ex: &Expr<'_>) -> Option<(Constant, Ident, Span, Span, Ordering, bool)> {
+ if let ExprKind::Binary(ref op, l, r) = ex.kind {
+ let (inclusive, ordering) = match op.node {
+ BinOpKind::Gt => (false, Ordering::Greater),
+ BinOpKind::Ge => (true, Ordering::Greater),
+ BinOpKind::Lt => (false, Ordering::Less),
+ BinOpKind::Le => (true, Ordering::Less),
+ _ => return None,
+ };
+ if let Some(id) = match_ident(l) {
+ if let Some((c, _)) = constant(cx, cx.typeck_results(), r) {
+ return Some((c, id, l.span, r.span, ordering, inclusive));
+ }
+ } else if let Some(id) = match_ident(r) {
+ if let Some((c, _)) = constant(cx, cx.typeck_results(), l) {
+ return Some((c, id, r.span, l.span, ordering.reverse(), inclusive));
+ }
+ }
+ }
+ None
+}
+
+fn match_ident(e: &Expr<'_>) -> Option<Ident> {
+ if let ExprKind::Path(ref qpath) = e.kind {
+ if let Some(seg) = single_segment_path(qpath) {
+ if seg.args.is_none() {
+ return Some(seg.ident);
+ }
+ }
+ }
+ None
+}
+
+fn check_range_zip_with_len(cx: &LateContext<'_>, path: &PathSegment<'_>, args: &[Expr<'_>], span: Span) {
+ if_chain! {
+ if path.ident.as_str() == "zip";
+ if let [iter, zip_arg] = args;
+ // `.iter()` call
+ if let ExprKind::MethodCall(iter_path, iter_args, _) = iter.kind;
+ if iter_path.ident.name == sym::iter;
+ // range expression in `.zip()` call: `0..x.len()`
+ if let Some(higher::Range { start: Some(start), end: Some(end), .. }) = higher::Range::hir(zip_arg);
+ if is_integer_const(cx, start, 0);
+ // `.len()` call
+ if let ExprKind::MethodCall(len_path, len_args, _) = end.kind;
+ if len_path.ident.name == sym::len && len_args.len() == 1;
+ // `.iter()` and `.len()` called on same `Path`
+ if let ExprKind::Path(QPath::Resolved(_, iter_path)) = iter_args[0].kind;
+ if let ExprKind::Path(QPath::Resolved(_, len_path)) = len_args[0].kind;
+ if SpanlessEq::new(cx).eq_path_segments(&iter_path.segments, &len_path.segments);
+ then {
+ span_lint(cx,
+ RANGE_ZIP_WITH_LEN,
+ span,
+ &format!("it is more idiomatic to use `{}.iter().enumerate()`",
+ snippet(cx, iter_args[0].span, "_"))
+ );
+ }
}
}
// exclusive range plus one: `x..(y+1)`
-fn check_exclusive_range_plus_one(cx: &LateContext<'_, '_>, expr: &Expr) {
+fn check_exclusive_range_plus_one(cx: &LateContext<'_>, expr: &Expr<'_>) {
if_chain! {
if let Some(higher::Range {
start,
end: Some(end),
limits: RangeLimits::HalfOpen
- }) = higher::range(cx, expr);
+ }) = higher::Range::hir(expr);
if let Some(y) = y_plus_one(cx, end);
then {
let span = if expr.span.from_expansion() {
RANGE_PLUS_ONE,
span,
"an inclusive range would be more readable",
- |db| {
- let start = start.map_or(String::new(), |x| Sugg::hir(cx, x, "x").to_string());
- let end = Sugg::hir(cx, y, "y");
+ |diag| {
+ let start = start.map_or(String::new(), |x| Sugg::hir(cx, x, "x").maybe_par().to_string());
+ let end = Sugg::hir(cx, y, "y").maybe_par();
if let Some(is_wrapped) = &snippet_opt(cx, span) {
if is_wrapped.starts_with('(') && is_wrapped.ends_with(')') {
- db.span_suggestion(
+ diag.span_suggestion(
span,
"use",
format!("({}..={})", start, end),
Applicability::MaybeIncorrect,
);
} else {
- db.span_suggestion(
+ diag.span_suggestion(
span,
"use",
format!("{}..={}", start, end),
}
// inclusive range minus one: `x..=(y-1)`
-fn check_inclusive_range_minus_one(cx: &LateContext<'_, '_>, expr: &Expr) {
+fn check_inclusive_range_minus_one(cx: &LateContext<'_>, expr: &Expr<'_>) {
if_chain! {
- if let Some(higher::Range { start, end: Some(end), limits: RangeLimits::Closed }) = higher::range(cx, expr);
+ if let Some(higher::Range { start, end: Some(end), limits: RangeLimits::Closed }) = higher::Range::hir(expr);
if let Some(y) = y_minus_one(cx, end);
then {
span_lint_and_then(
RANGE_MINUS_ONE,
expr.span,
"an exclusive range would be more readable",
- |db| {
- let start = start.map_or(String::new(), |x| Sugg::hir(cx, x, "x").to_string());
- let end = Sugg::hir(cx, y, "y");
- db.span_suggestion(
+ |diag| {
+ let start = start.map_or(String::new(), |x| Sugg::hir(cx, x, "x").maybe_par().to_string());
+ let end = Sugg::hir(cx, y, "y").maybe_par();
+ diag.span_suggestion(
expr.span,
"use",
format!("{}..{}", start, end),
}
}
-fn has_step_by(cx: &LateContext<'_, '_>, expr: &Expr) -> bool {
- // No need for `walk_ptrs_ty` here because `step_by` moves `self`, so it
- // can't be called on a borrowed range.
- let ty = cx.tables.expr_ty_adjusted(expr);
+fn check_reversed_empty_range(cx: &LateContext<'_>, expr: &Expr<'_>) {
+ fn inside_indexing_expr(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
+ matches!(
+ get_parent_expr(cx, expr),
+ Some(Expr {
+ kind: ExprKind::Index(..),
+ ..
+ })
+ )
+ }
+
+ fn is_for_loop_arg(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
+ let mut cur_expr = expr;
+ while let Some(parent_expr) = get_parent_expr(cx, cur_expr) {
+ match higher::ForLoop::hir(parent_expr) {
+ Some(higher::ForLoop { arg, .. }) if arg.hir_id == expr.hir_id => return true,
+ _ => cur_expr = parent_expr,
+ }
+ }
+
+ false
+ }
+
+ fn is_empty_range(limits: RangeLimits, ordering: Ordering) -> bool {
+ match limits {
+ RangeLimits::HalfOpen => ordering != Ordering::Less,
+ RangeLimits::Closed => ordering == Ordering::Greater,
+ }
+ }
- get_trait_def_id(cx, &paths::ITERATOR).map_or(false, |iterator_trait| implements_trait(cx, ty, iterator_trait, &[]))
+ if_chain! {
+ if let Some(higher::Range { start: Some(start), end: Some(end), limits }) = higher::Range::hir(expr);
+ let ty = cx.typeck_results().expr_ty(start);
+ if let ty::Int(_) | ty::Uint(_) = ty.kind();
+ if let Some((start_idx, _)) = constant(cx, cx.typeck_results(), start);
+ if let Some((end_idx, _)) = constant(cx, cx.typeck_results(), end);
+ if let Some(ordering) = Constant::partial_cmp(cx.tcx, ty, &start_idx, &end_idx);
+ if is_empty_range(limits, ordering);
+ then {
+ if inside_indexing_expr(cx, expr) {
+ // Avoid linting `N..N` as it has proven to be useful, see #5689 and #5628 ...
+ if ordering != Ordering::Equal {
+ span_lint(
+ cx,
+ REVERSED_EMPTY_RANGES,
+ expr.span,
+ "this range is reversed and using it to index a slice will panic at run-time",
+ );
+ }
+ // ... except in for loop arguments for backwards compatibility with `reverse_range_loop`
+ } else if ordering != Ordering::Equal || is_for_loop_arg(cx, expr) {
+ span_lint_and_then(
+ cx,
+ REVERSED_EMPTY_RANGES,
+ expr.span,
+ "this range is empty so it will yield no values",
+ |diag| {
+ if ordering != Ordering::Equal {
+ let start_snippet = snippet(cx, start.span, "_");
+ let end_snippet = snippet(cx, end.span, "_");
+ let dots = match limits {
+ RangeLimits::HalfOpen => "..",
+ RangeLimits::Closed => "..="
+ };
+
+ diag.span_suggestion(
+ expr.span,
+ "consider using the following if you are attempting to iterate over this \
+ range in reverse",
+ format!("({}{}{}).rev()", end_snippet, dots, start_snippet),
+ Applicability::MaybeIncorrect,
+ );
+ }
+ },
+ );
+ }
+ }
+ }
}
-fn y_plus_one<'t>(cx: &LateContext<'_, '_>, expr: &'t Expr) -> Option<&'t Expr> {
+fn y_plus_one<'t>(cx: &LateContext<'_>, expr: &'t Expr<'_>) -> Option<&'t Expr<'t>> {
match expr.kind {
ExprKind::Binary(
Spanned {
node: BinOpKind::Add, ..
},
- ref lhs,
- ref rhs,
+ lhs,
+ rhs,
) => {
if is_integer_const(cx, lhs, 1) {
Some(rhs)
}
}
-fn y_minus_one<'t>(cx: &LateContext<'_, '_>, expr: &'t Expr) -> Option<&'t Expr> {
+fn y_minus_one<'t>(cx: &LateContext<'_>, expr: &'t Expr<'_>) -> Option<&'t Expr<'t>> {
match expr.kind {
ExprKind::Binary(
Spanned {
node: BinOpKind::Sub, ..
},
- ref lhs,
- ref rhs,
+ lhs,
+ rhs,
) if is_integer_const(cx, rhs, 1) => Some(lhs),
_ => None,
}
projects / rust.git / blobdiff