[`imprecise_flops`]: https://rust-lang.github.io/rust-clippy/master/index.html#imprecise_flops
[`inconsistent_digit_grouping`]: https://rust-lang.github.io/rust-clippy/master/index.html#inconsistent_digit_grouping
[`inconsistent_struct_constructor`]: https://rust-lang.github.io/rust-clippy/master/index.html#inconsistent_struct_constructor
+[`index_refutable_slice`]: https://rust-lang.github.io/rust-clippy/master/index.html#index_refutable_slice
[`indexing_slicing`]: https://rust-lang.github.io/rust-clippy/master/index.html#indexing_slicing
[`ineffective_bit_mask`]: https://rust-lang.github.io/rust-clippy/master/index.html#ineffective_bit_mask
[`inefficient_to_string`]: https://rust-lang.github.io/rust-clippy/master/index.html#inefficient_to_string
--- /dev/null
+use clippy_utils::consts::{constant, Constant};
+use clippy_utils::diagnostics::span_lint_and_then;
+use clippy_utils::higher::IfLet;
+use clippy_utils::ty::is_copy;
+use clippy_utils::{is_expn_of, is_lint_allowed, meets_msrv, msrvs, path_to_local};
+use if_chain::if_chain;
+use rustc_data_structures::fx::{FxHashMap, FxHashSet};
+use rustc_errors::Applicability;
+use rustc_hir as hir;
+use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor};
+use rustc_lint::{LateContext, LateLintPass, LintContext};
+use rustc_middle::hir::map::Map;
+use rustc_middle::ty;
+use rustc_semver::RustcVersion;
+use rustc_session::{declare_tool_lint, impl_lint_pass};
+use rustc_span::{symbol::Ident, Span};
+use std::convert::TryInto;
+
+declare_clippy_lint! {
+ /// ### What it does
+ /// The lint checks for slice bindings in patterns that are only used to
+ /// access individual slice values.
+ ///
+ /// ### Why is this bad?
+ /// Accessing slice values using indices can lead to panics. Using refutable
+ /// patterns can avoid these. Binding to individual values also improves the
+ /// readability as they can be named.
+ ///
+ /// ### Limitations
+ /// This lint currently only checks for immutable access inside `if let`
+ /// patterns.
+ ///
+ /// ### Example
+ /// ```rust
+ /// let slice: Option<&[u32]> = Some(&[1, 2, 3]);
+ ///
+ /// if let Some(slice) = slice {
+ /// println!("{}", slice[0]);
+ /// }
+ /// ```
+ /// Use instead:
+ /// ```rust
+ /// let slice: Option<&[u32]> = Some(&[1, 2, 3]);
+ ///
+ /// if let Some(&[first, ..]) = slice {
+ /// println!("{}", first);
+ /// }
+ /// ```
+ #[clippy::version = "1.58.0"]
+ pub INDEX_REFUTABLE_SLICE,
+ nursery,
+ "avoid indexing on slices which could be destructed"
+}
+
+#[derive(Copy, Clone)]
+pub struct IndexRefutableSlice {
+ max_suggested_slice: u64,
+ msrv: Option<RustcVersion>,
+}
+
+impl IndexRefutableSlice {
+ pub fn new(max_suggested_slice_pattern_length: u64, msrv: Option<RustcVersion>) -> Self {
+ Self {
+ max_suggested_slice: max_suggested_slice_pattern_length,
+ msrv,
+ }
+ }
+}
+
+impl_lint_pass!(IndexRefutableSlice => [INDEX_REFUTABLE_SLICE]);
+
+impl LateLintPass<'_> for IndexRefutableSlice {
+ fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>) {
+ if_chain! {
+ if !expr.span.from_expansion() || is_expn_of(expr.span, "if_chain").is_some();
+ if let Some(IfLet {let_pat, if_then, ..}) = IfLet::hir(cx, expr);
+ if !is_lint_allowed(cx, INDEX_REFUTABLE_SLICE, expr.hir_id);
+ if meets_msrv(self.msrv.as_ref(), &msrvs::SLICE_PATTERNS);
+
+ let found_slices = find_slice_values(cx, let_pat);
+ if !found_slices.is_empty();
+ let filtered_slices = filter_lintable_slices(cx, found_slices, self.max_suggested_slice, if_then);
+ if !filtered_slices.is_empty();
+ then {
+ for slice in filtered_slices.values() {
+ lint_slice(cx, slice);
+ }
+ }
+ }
+ }
+
+ extract_msrv_attr!(LateContext);
+}
+
+fn find_slice_values(cx: &LateContext<'_>, pat: &hir::Pat<'_>) -> FxHashMap<hir::HirId, SliceLintInformation> {
+ let mut removed_pat: FxHashSet<hir::HirId> = FxHashSet::default();
+ let mut slices: FxHashMap<hir::HirId, SliceLintInformation> = FxHashMap::default();
+ pat.walk_always(|pat| {
+ if let hir::PatKind::Binding(binding, value_hir_id, ident, sub_pat) = pat.kind {
+ // We'll just ignore mut and ref mut for simplicity sake right now
+ if let hir::BindingAnnotation::Mutable | hir::BindingAnnotation::RefMut = binding {
+ return;
+ }
+
+ // This block catches bindings with sub patterns. It would be hard to build a correct suggestion
+ // for them and it's likely that the user knows what they are doing in such a case.
+ if removed_pat.contains(&value_hir_id) {
+ return;
+ }
+ if sub_pat.is_some() {
+ removed_pat.insert(value_hir_id);
+ slices.remove(&value_hir_id);
+ return;
+ }
+
+ let bound_ty = cx.typeck_results().node_type(pat.hir_id);
+ if let ty::Slice(inner_ty) | ty::Array(inner_ty, _) = bound_ty.peel_refs().kind() {
+ // The values need to use the `ref` keyword if they can't be copied.
+ // This will need to be adjusted if the lint want to support multable access in the future
+ let src_is_ref = bound_ty.is_ref() && binding != hir::BindingAnnotation::Ref;
+ let needs_ref = !(src_is_ref || is_copy(cx, inner_ty));
+
+ let slice_info = slices
+ .entry(value_hir_id)
+ .or_insert_with(|| SliceLintInformation::new(ident, needs_ref));
+ slice_info.pattern_spans.push(pat.span);
+ }
+ }
+ });
+
+ slices
+}
+
+fn lint_slice(cx: &LateContext<'_>, slice: &SliceLintInformation) {
+ let used_indices = slice
+ .index_use
+ .iter()
+ .map(|(index, _)| *index)
+ .collect::<FxHashSet<_>>();
+
+ let value_name = |index| format!("{}_{}", slice.ident.name, index);
+
+ if let Some(max_index) = used_indices.iter().max() {
+ let opt_ref = if slice.needs_ref { "ref " } else { "" };
+ let pat_sugg_idents = (0..=*max_index)
+ .map(|index| {
+ if used_indices.contains(&index) {
+ format!("{}{}", opt_ref, value_name(index))
+ } else {
+ "_".to_string()
+ }
+ })
+ .collect::<Vec<_>>();
+ let pat_sugg = format!("[{}, ..]", pat_sugg_idents.join(", "));
+
+ span_lint_and_then(
+ cx,
+ INDEX_REFUTABLE_SLICE,
+ slice.ident.span,
+ "this binding can be a slice pattern to avoid indexing",
+ |diag| {
+ diag.multipart_suggestion(
+ "try using a slice pattern here",
+ slice
+ .pattern_spans
+ .iter()
+ .map(|span| (*span, pat_sugg.clone()))
+ .collect(),
+ Applicability::MaybeIncorrect,
+ );
+
+ diag.multipart_suggestion(
+ "and replace the index expressions here",
+ slice
+ .index_use
+ .iter()
+ .map(|(index, span)| (*span, value_name(*index)))
+ .collect(),
+ Applicability::MaybeIncorrect,
+ );
+
+ // The lint message doesn't contain a warning about the removed index expression,
+ // since `filter_lintable_slices` will only return slices where all access indices
+ // are known at compile time. Therefore, they can be removed without side effects.
+ },
+ );
+ }
+}
+
+#[derive(Debug)]
+struct SliceLintInformation {
+ ident: Ident,
+ needs_ref: bool,
+ pattern_spans: Vec<Span>,
+ index_use: Vec<(u64, Span)>,
+}
+
+impl SliceLintInformation {
+ fn new(ident: Ident, needs_ref: bool) -> Self {
+ Self {
+ ident,
+ needs_ref,
+ pattern_spans: Vec::new(),
+ index_use: Vec::new(),
+ }
+ }
+}
+
+fn filter_lintable_slices<'a, 'tcx>(
+ cx: &'a LateContext<'tcx>,
+ slice_lint_info: FxHashMap<hir::HirId, SliceLintInformation>,
+ max_suggested_slice: u64,
+ scope: &'tcx hir::Expr<'tcx>,
+) -> FxHashMap<hir::HirId, SliceLintInformation> {
+ let mut visitor = SliceIndexLintingVisitor {
+ cx,
+ slice_lint_info,
+ max_suggested_slice,
+ };
+
+ intravisit::walk_expr(&mut visitor, scope);
+
+ visitor.slice_lint_info
+}
+
+struct SliceIndexLintingVisitor<'a, 'tcx> {
+ cx: &'a LateContext<'tcx>,
+ slice_lint_info: FxHashMap<hir::HirId, SliceLintInformation>,
+ max_suggested_slice: u64,
+}
+
+impl<'a, 'tcx> Visitor<'tcx> for SliceIndexLintingVisitor<'a, 'tcx> {
+ type Map = Map<'tcx>;
+
+ fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
+ NestedVisitorMap::OnlyBodies(self.cx.tcx.hir())
+ }
+
+ fn visit_expr(&mut self, expr: &'tcx hir::Expr<'tcx>) {
+ if let Some(local_id) = path_to_local(expr) {
+ let Self {
+ cx,
+ ref mut slice_lint_info,
+ max_suggested_slice,
+ } = *self;
+
+ if_chain! {
+ // Check if this is even a local we're interested in
+ if let Some(use_info) = slice_lint_info.get_mut(&local_id);
+
+ let map = cx.tcx.hir();
+
+ // Checking for slice indexing
+ let parent_id = map.get_parent_node(expr.hir_id);
+ if let Some(hir::Node::Expr(parent_expr)) = map.find(parent_id);
+ if let hir::ExprKind::Index(_, index_expr) = parent_expr.kind;
+ if let Some((Constant::Int(index_value), _)) = constant(cx, cx.typeck_results(), index_expr);
+ if let Ok(index_value) = index_value.try_into();
+ if index_value < max_suggested_slice;
+
+ // Make sure that this slice index is read only
+ let maybe_addrof_id = map.get_parent_node(parent_id);
+ if let Some(hir::Node::Expr(maybe_addrof_expr)) = map.find(maybe_addrof_id);
+ if let hir::ExprKind::AddrOf(_kind, hir::Mutability::Not, _inner_expr) = maybe_addrof_expr.kind;
+ then {
+ use_info.index_use.push((index_value, map.span(parent_expr.hir_id)));
+ return;
+ }
+ }
+
+ // The slice was used for something other than indexing
+ self.slice_lint_info.remove(&local_id);
+ }
+ intravisit::walk_expr(self, expr);
+ }
+}
implicit_return::IMPLICIT_RETURN,
implicit_saturating_sub::IMPLICIT_SATURATING_SUB,
inconsistent_struct_constructor::INCONSISTENT_STRUCT_CONSTRUCTOR,
+ index_refutable_slice::INDEX_REFUTABLE_SLICE,
indexing_slicing::INDEXING_SLICING,
indexing_slicing::OUT_OF_BOUNDS_INDEXING,
infinite_iter::INFINITE_ITER,
LintId::of(floating_point_arithmetic::IMPRECISE_FLOPS),
LintId::of(floating_point_arithmetic::SUBOPTIMAL_FLOPS),
LintId::of(future_not_send::FUTURE_NOT_SEND),
+ LintId::of(index_refutable_slice::INDEX_REFUTABLE_SLICE),
LintId::of(let_if_seq::USELESS_LET_IF_SEQ),
LintId::of(missing_const_for_fn::MISSING_CONST_FOR_FN),
LintId::of(mutable_debug_assertion::DEBUG_ASSERT_WITH_MUT_CALL),
mod implicit_return;
mod implicit_saturating_sub;
mod inconsistent_struct_constructor;
+mod index_refutable_slice;
mod indexing_slicing;
mod infinite_iter;
mod inherent_impl;
store.register_late_pass(|| Box::new(size_of_in_element_count::SizeOfInElementCount));
store.register_late_pass(|| Box::new(same_name_method::SameNameMethod));
+ let max_suggested_slice_pattern_length = conf.max_suggested_slice_pattern_length;
+ store.register_late_pass(move || {
+ Box::new(index_refutable_slice::IndexRefutableSlice::new(
+ max_suggested_slice_pattern_length,
+ msrv,
+ ))
+ });
store.register_late_pass(|| Box::new(map_clone::MapClone));
store.register_late_pass(|| Box::new(map_err_ignore::MapErrIgnore));
store.register_late_pass(|| Box::new(shadow::Shadow::default()));
} else {
// find `unwrap[_err]()` calls:
if_chain! {
- if let ExprKind::MethodCall(method_name, _, args, _) = expr.kind;
- if let Some(id) = path_to_local(&args[0]);
+ if let ExprKind::MethodCall(method_name, _, [self_arg, ..], _) = expr.kind;
+ if let Some(id) = path_to_local(self_arg);
if [sym::unwrap, sym::expect, sym!(unwrap_err)].contains(&method_name.ident.name);
let call_to_unwrap = [sym::unwrap, sym::expect].contains(&method_name.ident.name);
if let Some(unwrappable) = self.unwrappables.iter()
///
/// Suppress lints whenever the suggested change would cause breakage for other crates.
(avoid_breaking_exported_api: bool = true),
- /// Lint: MANUAL_SPLIT_ONCE, MANUAL_STR_REPEAT, CLONED_INSTEAD_OF_COPIED, REDUNDANT_FIELD_NAMES, REDUNDANT_STATIC_LIFETIMES, FILTER_MAP_NEXT, CHECKED_CONVERSIONS, MANUAL_RANGE_CONTAINS, USE_SELF, MEM_REPLACE_WITH_DEFAULT, MANUAL_NON_EXHAUSTIVE, OPTION_AS_REF_DEREF, MAP_UNWRAP_OR, MATCH_LIKE_MATCHES_MACRO, MANUAL_STRIP, MISSING_CONST_FOR_FN, UNNESTED_OR_PATTERNS, FROM_OVER_INTO, PTR_AS_PTR, IF_THEN_SOME_ELSE_NONE, APPROX_CONSTANT, DEPRECATED_CFG_ATTR.
+ /// Lint: MANUAL_SPLIT_ONCE, MANUAL_STR_REPEAT, CLONED_INSTEAD_OF_COPIED, REDUNDANT_FIELD_NAMES, REDUNDANT_STATIC_LIFETIMES, FILTER_MAP_NEXT, CHECKED_CONVERSIONS, MANUAL_RANGE_CONTAINS, USE_SELF, MEM_REPLACE_WITH_DEFAULT, MANUAL_NON_EXHAUSTIVE, OPTION_AS_REF_DEREF, MAP_UNWRAP_OR, MATCH_LIKE_MATCHES_MACRO, MANUAL_STRIP, MISSING_CONST_FOR_FN, UNNESTED_OR_PATTERNS, FROM_OVER_INTO, PTR_AS_PTR, IF_THEN_SOME_ELSE_NONE, APPROX_CONSTANT, DEPRECATED_CFG_ATTR, INDEX_REFUTABLE_SLICE.
///
/// The minimum rust version that the project supports
(msrv: Option<String> = None),
///
/// Whether to apply the raw pointer heuristic to determine if a type is `Send`.
(enable_raw_pointer_heuristic_for_send: bool = true),
+ /// Lint: INDEX_REFUTABLE_SLICE.
+ ///
+ /// When Clippy suggests using a slice pattern, this is the maximum number of elements allowed in
+ /// the slice pattern that is suggested. If more elements would be necessary, the lint is suppressed.
+ /// For example, `[_, _, _, e, ..]` is a slice pattern with 4 elements.
+ (max_suggested_slice_pattern_length: u64 = 3),
}
/// Search for the configuration file.
1,46,0 { CONST_IF_MATCH }
1,45,0 { STR_STRIP_PREFIX }
1,43,0 { LOG2_10, LOG10_2 }
- 1,42,0 { MATCHES_MACRO }
+ 1,42,0 { MATCHES_MACRO, SLICE_PATTERNS }
1,41,0 { RE_REBALANCING_COHERENCE, RESULT_MAP_OR_ELSE }
1,40,0 { MEM_TAKE, NON_EXHAUSTIVE, OPTION_AS_DEREF }
1,38,0 { POINTER_CAST }
use crate::{match_def_path, must_use_attr};
+// Checks if the given type implements copy.
pub fn is_copy<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
ty.is_copy_modulo_regions(cx.tcx.at(DUMMY_SP), cx.param_env)
}
--- /dev/null
+max-suggested-slice-pattern-length = 8
--- /dev/null
+#![deny(clippy::index_refutable_slice)]
+
+fn below_limit() {
+ let slice: Option<&[u32]> = Some(&[1, 2, 3]);
+ if let Some(slice) = slice {
+ // This would usually not be linted but is included now due to the
+ // index limit in the config file
+ println!("{}", slice[7]);
+ }
+}
+
+fn above_limit() {
+ let slice: Option<&[u32]> = Some(&[1, 2, 3]);
+ if let Some(slice) = slice {
+ // This will not be linted as 8 is above the limit
+ println!("{}", slice[8]);
+ }
+}
+
+fn main() {
+ below_limit();
+ above_limit();
+}
--- /dev/null
+error: this binding can be a slice pattern to avoid indexing
+ --> $DIR/index_refutable_slice.rs:5:17
+ |
+LL | if let Some(slice) = slice {
+ | ^^^^^
+ |
+note: the lint level is defined here
+ --> $DIR/index_refutable_slice.rs:1:9
+ |
+LL | #![deny(clippy::index_refutable_slice)]
+ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+help: try using a slice pattern here
+ |
+LL | if let Some([_, _, _, _, _, _, _, slice_7, ..]) = slice {
+ | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+help: and replace the index expressions here
+ |
+LL | println!("{}", slice_7);
+ | ~~~~~~~
+
+error: aborting due to previous error
+
}
}
+fn check_index_refutable_slice() {
+ // This shouldn't trigger `clippy::index_refutable_slice` as the suggestion
+ // would only be valid from 1.42.0 onward
+ let slice: Option<&[u32]> = Some(&[1]);
+ if let Some(slice) = slice {
+ println!("{}", slice[0]);
+ }
+}
+
fn main() {
option_as_ref_deref();
match_like_matches();
match_same_arms();
match_same_arms2();
manual_strip_msrv();
+ check_index_refutable_slice();
}
-error: error reading Clippy's configuration file `$DIR/clippy.toml`: unknown field `foobar`, expected one of `avoid-breaking-exported-api`, `msrv`, `blacklisted-names`, `cognitive-complexity-threshold`, `cyclomatic-complexity-threshold`, `doc-valid-idents`, `too-many-arguments-threshold`, `type-complexity-threshold`, `single-char-binding-names-threshold`, `too-large-for-stack`, `enum-variant-name-threshold`, `enum-variant-size-threshold`, `verbose-bit-mask-threshold`, `literal-representation-threshold`, `trivial-copy-size-limit`, `pass-by-value-size-limit`, `too-many-lines-threshold`, `array-size-threshold`, `vec-box-size-threshold`, `max-trait-bounds`, `max-struct-bools`, `max-fn-params-bools`, `warn-on-all-wildcard-imports`, `disallowed-methods`, `disallowed-types`, `unreadable-literal-lint-fractions`, `upper-case-acronyms-aggressive`, `cargo-ignore-publish`, `standard-macro-braces`, `enforced-import-renames`, `allowed-scripts`, `enable-raw-pointer-heuristic-for-send`, `third-party` at line 5 column 1
+error: error reading Clippy's configuration file `$DIR/clippy.toml`: unknown field `foobar`, expected one of `avoid-breaking-exported-api`, `msrv`, `blacklisted-names`, `cognitive-complexity-threshold`, `cyclomatic-complexity-threshold`, `doc-valid-idents`, `too-many-arguments-threshold`, `type-complexity-threshold`, `single-char-binding-names-threshold`, `too-large-for-stack`, `enum-variant-name-threshold`, `enum-variant-size-threshold`, `verbose-bit-mask-threshold`, `literal-representation-threshold`, `trivial-copy-size-limit`, `pass-by-value-size-limit`, `too-many-lines-threshold`, `array-size-threshold`, `vec-box-size-threshold`, `max-trait-bounds`, `max-struct-bools`, `max-fn-params-bools`, `warn-on-all-wildcard-imports`, `disallowed-methods`, `disallowed-types`, `unreadable-literal-lint-fractions`, `upper-case-acronyms-aggressive`, `cargo-ignore-publish`, `standard-macro-braces`, `enforced-import-renames`, `allowed-scripts`, `enable-raw-pointer-heuristic-for-send`, `max-suggested-slice-pattern-length`, `third-party` at line 5 column 1
error: aborting due to previous error
--- /dev/null
+#![deny(clippy::index_refutable_slice)]
+
+enum SomeEnum<T> {
+ One(T),
+ Two(T),
+ Three(T),
+ Four(T),
+}
+
+fn lintable_examples() {
+ // Try with reference
+ let slice: Option<&[u32]> = Some(&[1, 2, 3]);
+ if let Some(slice) = slice {
+ println!("{}", slice[0]);
+ }
+
+ // Try with copy
+ let slice: Option<[u32; 3]> = Some([1, 2, 3]);
+ if let Some(slice) = slice {
+ println!("{}", slice[0]);
+ }
+
+ // Try with long slice and small indices
+ let slice: Option<[u32; 9]> = Some([1, 2, 3, 4, 5, 6, 7, 8, 9]);
+ if let Some(slice) = slice {
+ println!("{}", slice[2]);
+ println!("{}", slice[0]);
+ }
+
+ // Multiple bindings
+ let slice_wrapped: SomeEnum<[u32; 3]> = SomeEnum::One([5, 6, 7]);
+ if let SomeEnum::One(slice) | SomeEnum::Three(slice) = slice_wrapped {
+ println!("{}", slice[0]);
+ }
+
+ // Two lintable slices in one if let
+ let a_wrapped: SomeEnum<[u32; 3]> = SomeEnum::One([9, 5, 1]);
+ let b_wrapped: Option<[u32; 2]> = Some([4, 6]);
+ if let (SomeEnum::Three(a), Some(b)) = (a_wrapped, b_wrapped) {
+ println!("{} -> {}", a[2], b[1]);
+ }
+
+ // This requires the slice values to be borrowed as the slice values can only be
+ // borrowed and `String` doesn't implement copy
+ let slice: Option<[String; 2]> = Some([String::from("1"), String::from("2")]);
+ if let Some(ref slice) = slice {
+ println!("{:?}", slice[1]);
+ }
+ println!("{:?}", slice);
+
+ // This should not suggest using the `ref` keyword as the scrutinee is already
+ // a reference
+ let slice: Option<[String; 2]> = Some([String::from("1"), String::from("2")]);
+ if let Some(slice) = &slice {
+ println!("{:?}", slice[0]);
+ }
+ println!("{:?}", slice);
+}
+
+fn slice_index_above_limit() {
+ let slice: Option<&[u32]> = Some(&[1, 2, 3]);
+
+ if let Some(slice) = slice {
+ // Would cause a panic, IDK
+ println!("{}", slice[7]);
+ }
+}
+
+fn slice_is_used() {
+ let slice: Option<&[u32]> = Some(&[1, 2, 3]);
+ if let Some(slice) = slice {
+ println!("{:?}", slice.len());
+ }
+
+ let slice: Option<&[u32]> = Some(&[1, 2, 3]);
+ if let Some(slice) = slice {
+ println!("{:?}", slice.to_vec());
+ }
+
+ let opt: Option<[String; 2]> = Some([String::from("Hello"), String::from("world")]);
+ if let Some(slice) = opt {
+ if !slice.is_empty() {
+ println!("first: {}", slice[0]);
+ }
+ }
+}
+
+/// The slice is used by an external function and should therefore not be linted
+fn check_slice_as_arg() {
+ fn is_interesting<T>(slice: &[T; 2]) -> bool {
+ !slice.is_empty()
+ }
+
+ let slice_wrapped: Option<[String; 2]> = Some([String::from("Hello"), String::from("world")]);
+ if let Some(slice) = &slice_wrapped {
+ if is_interesting(slice) {
+ println!("This is interesting {}", slice[0]);
+ }
+ }
+ println!("{:?}", slice_wrapped);
+}
+
+fn check_slice_in_struct() {
+ #[derive(Debug)]
+ struct Wrapper<'a> {
+ inner: Option<&'a [String]>,
+ is_awesome: bool,
+ }
+
+ impl<'a> Wrapper<'a> {
+ fn is_super_awesome(&self) -> bool {
+ self.is_awesome
+ }
+ }
+
+ let inner = &[String::from("New"), String::from("World")];
+ let wrap = Wrapper {
+ inner: Some(inner),
+ is_awesome: true,
+ };
+
+ // Test 1: Field access
+ if let Some(slice) = wrap.inner {
+ if wrap.is_awesome {
+ println!("This is awesome! {}", slice[0]);
+ }
+ }
+
+ // Test 2: function access
+ if let Some(slice) = wrap.inner {
+ if wrap.is_super_awesome() {
+ println!("This is super awesome! {}", slice[0]);
+ }
+ }
+ println!("Complete wrap: {:?}", wrap);
+}
+
+/// This would be a nice additional feature to have in the future, but adding it
+/// now would make the PR too large. This is therefore only a test that we don't
+/// lint cases we can't make a reasonable suggestion for
+fn mutable_slice_index() {
+ // Mut access
+ let mut slice: Option<[String; 1]> = Some([String::from("Penguin")]);
+ if let Some(ref mut slice) = slice {
+ slice[0] = String::from("Mr. Penguin");
+ }
+ println!("Use after modification: {:?}", slice);
+
+ // Mut access on reference
+ let mut slice: Option<[String; 1]> = Some([String::from("Cat")]);
+ if let Some(slice) = &mut slice {
+ slice[0] = String::from("Lord Meow Meow");
+ }
+ println!("Use after modification: {:?}", slice);
+}
+
+/// The lint will ignore bindings with sub patterns as it would be hard
+/// to build correct suggestions for these instances :)
+fn binding_with_sub_pattern() {
+ let slice: Option<&[u32]> = Some(&[1, 2, 3]);
+ if let Some(slice @ [_, _, _]) = slice {
+ println!("{:?}", slice[2]);
+ }
+}
+
+fn main() {}
--- /dev/null
+error: this binding can be a slice pattern to avoid indexing
+ --> $DIR/if_let_slice_binding.rs:13:17
+ |
+LL | if let Some(slice) = slice {
+ | ^^^^^
+ |
+note: the lint level is defined here
+ --> $DIR/if_let_slice_binding.rs:1:9
+ |
+LL | #![deny(clippy::index_refutable_slice)]
+ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+help: try using a slice pattern here
+ |
+LL | if let Some([slice_0, ..]) = slice {
+ | ~~~~~~~~~~~~~
+help: and replace the index expressions here
+ |
+LL | println!("{}", slice_0);
+ | ~~~~~~~
+
+error: this binding can be a slice pattern to avoid indexing
+ --> $DIR/if_let_slice_binding.rs:19:17
+ |
+LL | if let Some(slice) = slice {
+ | ^^^^^
+ |
+help: try using a slice pattern here
+ |
+LL | if let Some([slice_0, ..]) = slice {
+ | ~~~~~~~~~~~~~
+help: and replace the index expressions here
+ |
+LL | println!("{}", slice_0);
+ | ~~~~~~~
+
+error: this binding can be a slice pattern to avoid indexing
+ --> $DIR/if_let_slice_binding.rs:25:17
+ |
+LL | if let Some(slice) = slice {
+ | ^^^^^
+ |
+help: try using a slice pattern here
+ |
+LL | if let Some([slice_0, _, slice_2, ..]) = slice {
+ | ~~~~~~~~~~~~~~~~~~~~~~~~~
+help: and replace the index expressions here
+ |
+LL ~ println!("{}", slice_2);
+LL ~ println!("{}", slice_0);
+ |
+
+error: this binding can be a slice pattern to avoid indexing
+ --> $DIR/if_let_slice_binding.rs:32:26
+ |
+LL | if let SomeEnum::One(slice) | SomeEnum::Three(slice) = slice_wrapped {
+ | ^^^^^
+ |
+help: try using a slice pattern here
+ |
+LL | if let SomeEnum::One([slice_0, ..]) | SomeEnum::Three([slice_0, ..]) = slice_wrapped {
+ | ~~~~~~~~~~~~~ ~~~~~~~~~~~~~
+help: and replace the index expressions here
+ |
+LL | println!("{}", slice_0);
+ | ~~~~~~~
+
+error: this binding can be a slice pattern to avoid indexing
+ --> $DIR/if_let_slice_binding.rs:39:29
+ |
+LL | if let (SomeEnum::Three(a), Some(b)) = (a_wrapped, b_wrapped) {
+ | ^
+ |
+help: try using a slice pattern here
+ |
+LL | if let (SomeEnum::Three([_, _, a_2, ..]), Some(b)) = (a_wrapped, b_wrapped) {
+ | ~~~~~~~~~~~~~~~
+help: and replace the index expressions here
+ |
+LL | println!("{} -> {}", a_2, b[1]);
+ | ~~~
+
+error: this binding can be a slice pattern to avoid indexing
+ --> $DIR/if_let_slice_binding.rs:39:38
+ |
+LL | if let (SomeEnum::Three(a), Some(b)) = (a_wrapped, b_wrapped) {
+ | ^
+ |
+help: try using a slice pattern here
+ |
+LL | if let (SomeEnum::Three(a), Some([_, b_1, ..])) = (a_wrapped, b_wrapped) {
+ | ~~~~~~~~~~~~
+help: and replace the index expressions here
+ |
+LL | println!("{} -> {}", a[2], b_1);
+ | ~~~
+
+error: this binding can be a slice pattern to avoid indexing
+ --> $DIR/if_let_slice_binding.rs:46:21
+ |
+LL | if let Some(ref slice) = slice {
+ | ^^^^^
+ |
+help: try using a slice pattern here
+ |
+LL | if let Some([_, ref slice_1, ..]) = slice {
+ | ~~~~~~~~~~~~~~~~~~~~
+help: and replace the index expressions here
+ |
+LL | println!("{:?}", slice_1);
+ | ~~~~~~~
+
+error: this binding can be a slice pattern to avoid indexing
+ --> $DIR/if_let_slice_binding.rs:54:17
+ |
+LL | if let Some(slice) = &slice {
+ | ^^^^^
+ |
+help: try using a slice pattern here
+ |
+LL | if let Some([slice_0, ..]) = &slice {
+ | ~~~~~~~~~~~~~
+help: and replace the index expressions here
+ |
+LL | println!("{:?}", slice_0);
+ | ~~~~~~~
+
+error: this binding can be a slice pattern to avoid indexing
+ --> $DIR/if_let_slice_binding.rs:123:17
+ |
+LL | if let Some(slice) = wrap.inner {
+ | ^^^^^
+ |
+help: try using a slice pattern here
+ |
+LL | if let Some([slice_0, ..]) = wrap.inner {
+ | ~~~~~~~~~~~~~
+help: and replace the index expressions here
+ |
+LL | println!("This is awesome! {}", slice_0);
+ | ~~~~~~~
+
+error: this binding can be a slice pattern to avoid indexing
+ --> $DIR/if_let_slice_binding.rs:130:17
+ |
+LL | if let Some(slice) = wrap.inner {
+ | ^^^^^
+ |
+help: try using a slice pattern here
+ |
+LL | if let Some([slice_0, ..]) = wrap.inner {
+ | ~~~~~~~~~~~~~
+help: and replace the index expressions here
+ |
+LL | println!("This is super awesome! {}", slice_0);
+ | ~~~~~~~
+
+error: aborting due to 10 previous errors
+
--- /dev/null
+#![deny(clippy::index_refutable_slice)]
+
+extern crate if_chain;
+use if_chain::if_chain;
+
+macro_rules! if_let_slice_macro {
+ () => {
+ // This would normally be linted
+ let slice: Option<&[u32]> = Some(&[1, 2, 3]);
+ if let Some(slice) = slice {
+ println!("{}", slice[0]);
+ }
+ };
+}
+
+fn main() {
+ // Don't lint this
+ if_let_slice_macro!();
+
+ // Do lint this
+ if_chain! {
+ let slice: Option<&[u32]> = Some(&[1, 2, 3]);
+ if let Some(slice) = slice;
+ then {
+ println!("{}", slice[0]);
+ }
+ }
+}
--- /dev/null
+error: this binding can be a slice pattern to avoid indexing
+ --> $DIR/slice_indexing_in_macro.rs:23:21
+ |
+LL | if let Some(slice) = slice;
+ | ^^^^^
+ |
+note: the lint level is defined here
+ --> $DIR/slice_indexing_in_macro.rs:1:9
+ |
+LL | #![deny(clippy::index_refutable_slice)]
+ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+help: try using a slice pattern here
+ |
+LL | if let Some([slice_0, ..]) = slice;
+ | ~~~~~~~~~~~~~
+help: and replace the index expressions here
+ |
+LL | println!("{}", slice_0);
+ | ~~~~~~~
+
+error: aborting due to previous error
+
projects / rust.git / commitdiff