diff --git a/CHANGELOG.md b/CHANGELOG.md
index b0e9ad55b4f..85f6929f924 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2162,6 +2162,7 @@ Released 2018-09-13
[`redundant_pattern`]: https://rust-lang.github.io/rust-clippy/master/index.html#redundant_pattern
[`redundant_pattern_matching`]: https://rust-lang.github.io/rust-clippy/master/index.html#redundant_pattern_matching
[`redundant_pub_crate`]: https://rust-lang.github.io/rust-clippy/master/index.html#redundant_pub_crate
+[`redundant_slicing`]: https://rust-lang.github.io/rust-clippy/master/index.html#redundant_slicing
[`redundant_static_lifetimes`]: https://rust-lang.github.io/rust-clippy/master/index.html#redundant_static_lifetimes
[`ref_in_deref`]: https://rust-lang.github.io/rust-clippy/master/index.html#ref_in_deref
[`ref_option_ref`]: https://rust-lang.github.io/rust-clippy/master/index.html#ref_option_ref
diff --git a/clippy_lints/src/lib.rs b/clippy_lints/src/lib.rs
index 4f9ebb4af3d..70fdfd22caa 100644
--- a/clippy_lints/src/lib.rs
+++ b/clippy_lints/src/lib.rs
@@ -301,6 +301,7 @@ mod redundant_closure_call;
mod redundant_else;
mod redundant_field_names;
mod redundant_pub_crate;
+mod redundant_slicing;
mod redundant_static_lifetimes;
mod ref_option_ref;
mod reference;
@@ -849,6 +850,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
&redundant_else::REDUNDANT_ELSE,
&redundant_field_names::REDUNDANT_FIELD_NAMES,
&redundant_pub_crate::REDUNDANT_PUB_CRATE,
+ &redundant_slicing::REDUNDANT_SLICING,
&redundant_static_lifetimes::REDUNDANT_STATIC_LIFETIMES,
&ref_option_ref::REF_OPTION_REF,
&reference::DEREF_ADDROF,
@@ -1229,6 +1231,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
store.register_late_pass(|| box vec_init_then_push::VecInitThenPush::default());
store.register_late_pass(move || box types::PtrAsPtr::new(msrv));
store.register_late_pass(|| box case_sensitive_file_extension_comparisons::CaseSensitiveFileExtensionComparisons);
+ store.register_late_pass(|| box redundant_slicing::RedundantSlicing);
store.register_group(true, "clippy::restriction", Some("clippy_restriction"), vec![
LintId::of(&arithmetic::FLOAT_ARITHMETIC),
@@ -1591,6 +1594,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
LintId::of(&redundant_clone::REDUNDANT_CLONE),
LintId::of(&redundant_closure_call::REDUNDANT_CLOSURE_CALL),
LintId::of(&redundant_field_names::REDUNDANT_FIELD_NAMES),
+ LintId::of(&redundant_slicing::REDUNDANT_SLICING),
LintId::of(&redundant_static_lifetimes::REDUNDANT_STATIC_LIFETIMES),
LintId::of(&reference::DEREF_ADDROF),
LintId::of(&reference::REF_IN_DEREF),
@@ -1835,6 +1839,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
LintId::of(&ptr_offset_with_cast::PTR_OFFSET_WITH_CAST),
LintId::of(&ranges::RANGE_ZIP_WITH_LEN),
LintId::of(&redundant_closure_call::REDUNDANT_CLOSURE_CALL),
+ LintId::of(&redundant_slicing::REDUNDANT_SLICING),
LintId::of(&reference::DEREF_ADDROF),
LintId::of(&reference::REF_IN_DEREF),
LintId::of(&repeat_once::REPEAT_ONCE),
diff --git a/clippy_lints/src/redundant_slicing.rs b/clippy_lints/src/redundant_slicing.rs
new file mode 100644
index 00000000000..686298b6943
--- /dev/null
+++ b/clippy_lints/src/redundant_slicing.rs
@@ -0,0 +1,56 @@
+use if_chain::if_chain;
+use rustc_errors::Applicability;
+use rustc_hir::{Expr, ExprKind, LangItem};
+use rustc_lint::{LateContext, LateLintPass};
+use rustc_middle::ty::TyS;
+use rustc_session::{declare_lint_pass, declare_tool_lint};
+
+use crate::utils::{is_type_lang_item, snippet_with_applicability, span_lint_and_sugg};
+
+declare_clippy_lint! {
+ /// **What it does:** Checks for redundant slicing expressions which use the full range, and
+ /// do not change the type.
+ ///
+ /// **Why is this bad?** It unnecessarily adds complexity to the expression.
+ ///
+ /// **Known problems:** If the type being sliced has an implementation of `Index<RangeFull>`
+ /// that actually changes anything then it can't be removed. However, this would be surprising
+ /// to people reading the code and should have a note with it.
+ ///
+ /// **Example:**
+ ///
+ /// ```ignore
+ /// fn get_slice(x: &[u32]) -> &[u32] {
+ /// &x[..]
+ /// }
+ /// ```
+ /// Use instead:
+ /// ```ignore
+ /// fn get_slice(x: &[u32]) -> &[u32] {
+ /// x
+ /// }
+ /// ```
+ pub REDUNDANT_SLICING,
+ complexity,
+ "redundant slicing of the whole range of a type"
+}
+
+declare_lint_pass!(RedundantSlicing => [REDUNDANT_SLICING]);
+
+impl LateLintPass<'_> for RedundantSlicing {
+ fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
+ if_chain! {
+ if let ExprKind::AddrOf(_, _, addressee) = expr.kind;
+ if let ExprKind::Index(indexed, range) = addressee.kind;
+ if is_type_lang_item(cx, cx.typeck_results().expr_ty_adjusted(range), LangItem::RangeFull);
+ if TyS::same_type(cx.typeck_results().expr_ty(expr), cx.typeck_results().expr_ty(indexed));
+ then {
+ let mut app = Applicability::MachineApplicable;
+ let hint = snippet_with_applicability(cx, indexed.span, "..", &mut app).into_owned();
+
+ span_lint_and_sugg(cx, REDUNDANT_SLICING, expr.span, "redundant slicing of the whole range",
+ "use the original slice instead", hint, app);
+ }
+ }
+ }
+}
diff --git a/tests/ui/redundant_slicing.rs b/tests/ui/redundant_slicing.rs
new file mode 100644
index 00000000000..922b8b4ce57
--- /dev/null
+++ b/tests/ui/redundant_slicing.rs
@@ -0,0 +1,11 @@
+#![allow(unused)]
+#![warn(clippy::redundant_slicing)]
+
+fn main() {
+ let x: &[u32] = &[0];
+ let err = &x[..];
+
+ let v = vec![0];
+ let ok = &v[..];
+ let err = &(&v[..])[..];
+}
diff --git a/tests/ui/redundant_slicing.stderr b/tests/ui/redundant_slicing.stderr
new file mode 100644
index 00000000000..9efd6484ad0
--- /dev/null
+++ b/tests/ui/redundant_slicing.stderr
@@ -0,0 +1,16 @@
+error: redundant slicing of the whole range
+ --> $DIR/redundant_slicing.rs:6:15
+ |
+LL | let err = &x[..];
+ | ^^^^^^ help: use the original slice instead: `x`
+ |
+ = note: `-D clippy::redundant-slicing` implied by `-D warnings`
+
+error: redundant slicing of the whole range
+ --> $DIR/redundant_slicing.rs:10:15
+ |
+LL | let err = &(&v[..])[..];
+ | ^^^^^^^^^^^^^ help: use the original slice instead: `(&v[..])`
+
+error: aborting due to 2 previous errors
+