X-Git-Url: https://git.lizzy.rs/?a=blobdiff_plain;f=clippy_lints%2Fsrc%2Franges.rs;h=b41c478c266157d5295155ffdc4103aed7847452;hb=dce274024e62a0dc20c639eaa634bf5f01008e78;hp=83c6faac04149f344ea4916f50e05d437f7411e4;hpb=8164832c4b085dd10b404392ddcab7565280806c;p=rust.git

diff --git a/clippy_lints/src/ranges.rs b/clippy_lints/src/ranges.rs
index 83c6faac041..b41c478c266 100644
--- a/clippy_lints/src/ranges.rs
+++ b/clippy_lints/src/ranges.rs
@@ -1,18 +1,22 @@
-use crate::consts::{constant, Constant};
+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_ast::ast::RangeLimits;
 use rustc_errors::Applicability;
-use rustc_hir::{BinOpKind, Expr, ExprKind, QPath};
-use rustc_lint::{LateContext, LateLintPass};
+use rustc_hir::{BinOpKind, Expr, ExprKind, PathSegment, QPath};
+use rustc_lint::{LateContext, LateLintPass, LintContext};
 use rustc_middle::ty;
-use rustc_session::{declare_lint_pass, declare_tool_lint};
-use rustc_span::source_map::Spanned;
+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;
 
-use crate::utils::sugg::Sugg;
-use crate::utils::{get_parent_expr, is_integer_const, snippet, snippet_opt, span_lint, span_lint_and_then};
-use crate::utils::{higher, SpanlessEq};
-
 declare_clippy_lint! {
     /// **What it does:** Checks for zipping a collection with the range of
     /// `0.._.len()`.
@@ -52,6 +56,11 @@
     /// 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) { .. }
@@ -72,7 +81,10 @@
     /// **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:**
     /// ```rust,ignore
@@ -83,7 +95,7 @@
     /// for x..y { .. }
     /// ```
     pub RANGE_MINUS_ONE,
-    complexity,
+    pedantic,
     "`x..=(y-1)` reads better as `x..y`"
 }
 
@@ -120,59 +132,227 @@
     "reversing the limits of range expressions, resulting in empty ranges"
 }
 
-declare_lint_pass!(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 `&&`).
+    ///
+    /// **Known problems:** None.
+    ///
+    /// **Example:**
+    ///
+    /// ```rust
+    /// // given
+    /// let x = 6;
+    ///
+    /// assert!(x >= 3 && x < 8);
+    /// ```
+    /// Use instead:
+    /// ```rust
+    ///# let x = 6;
+    /// assert!((3..8).contains(&x));
+    /// ```
+    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,
     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();
-            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(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(expr);
         if let Some(y) = y_plus_one(cx, end);
         then {
             let span = if expr.span.from_expansion() {
@@ -215,9 +395,9 @@ fn check_exclusive_range_plus_one(cx: &LateContext<'_, '_>, expr: &Expr<'_>) {
 }
 
 // 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(expr);
         if let Some(y) = y_minus_one(cx, end);
         then {
             span_lint_and_then(
@@ -240,8 +420,8 @@ fn check_inclusive_range_minus_one(cx: &LateContext<'_, '_>, expr: &Expr<'_>) {
     }
 }
 
-fn check_reversed_empty_range(cx: &LateContext<'_, '_>, expr: &Expr<'_>) {
-    fn inside_indexing_expr(cx: &LateContext<'_, '_>, expr: &Expr<'_>) -> bool {
+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 {
@@ -251,6 +431,18 @@ fn inside_indexing_expr(cx: &LateContext<'_, '_>, expr: &Expr<'_>) -> bool {
         )
     }
 
+    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::for_loop(parent_expr) {
+                Some((_, args, _, _)) if args.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,
@@ -259,28 +451,26 @@ fn is_empty_range(limits: RangeLimits, ordering: Ordering) -> bool {
     }
 
     if_chain! {
-        if let Some(higher::Range { start: Some(start), end: Some(end), limits }) = higher::range(cx, expr);
-        let ty = cx.tables.expr_ty(start);
-        if let ty::Int(_) | ty::Uint(_) = ty.kind;
-        if let Some((start_idx, _)) = constant(cx, cx.tables, start);
-        if let Some((end_idx, _)) = constant(cx, cx.tables, end);
+        if let Some(higher::Range { start: Some(start), end: Some(end), limits }) = higher::range(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) {
-                let (reason, outcome) = if ordering == Ordering::Equal {
-                    ("empty", "always yield an empty slice")
-                } else {
-                    ("reversed", "panic at run-time")
-                };
-
-                span_lint(
-                    cx,
-                    REVERSED_EMPTY_RANGES,
-                    expr.span,
-                    &format!("this range is {} and using it to index a slice will {}", reason, outcome),
-                );
-            } else {
+                // 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,
@@ -310,14 +500,14 @@ fn is_empty_range(limits: RangeLimits, ordering: Ordering) -> bool {
     }
 }
 
-fn y_plus_one<'t>(cx: &LateContext<'_, '_>, expr: &'t Expr<'_>) -> Option<&'t Expr<'t>> {
+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)
@@ -331,14 +521,14 @@ fn y_plus_one<'t>(cx: &LateContext<'_, '_>, expr: &'t Expr<'_>) -> Option<&'t Ex
     }
 }
 
-fn y_minus_one<'t>(cx: &LateContext<'_, '_>, expr: &'t Expr<'_>) -> Option<&'t Expr<'t>> {
+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,
     }