lint vecs, version bump, more tests

clippy_lints/src/methods/iter_out_of_bounds.rs

@@ -1,5 +1,6 @@
 use clippy_utils::diagnostics::span_lint_and_note;
-use clippy_utils::{is_trait_method, match_def_path, paths};
+use clippy_utils::higher::VecArgs;
+use clippy_utils::{expr_or_init, is_trait_method, match_def_path, paths};
 use rustc_ast::LitKind;
 use rustc_hir::{Expr, ExprKind};
 use rustc_lint::LateContext;
@@ -8,34 +9,49 @@
 
 use super::ITER_OUT_OF_BOUNDS;
 
+fn expr_as_u128(cx: &LateContext<'_>, e: &Expr<'_>) -> Option<u128> {
+    if let ExprKind::Lit(lit) = expr_or_init(cx, e).kind
+        && let LitKind::Int(n, _) = lit.node
+    {
+        Some(n)
+    } else {
+        None
+    }
+}
+
 /// Attempts to extract the length out of an iterator expression.
 fn get_iterator_length<'tcx>(cx: &LateContext<'tcx>, iter: &'tcx Expr<'tcx>) -> Option<u128> {
-    let iter_ty = cx.typeck_results().expr_ty(iter);
+    let ty::Adt(adt, substs) = cx.typeck_results().expr_ty(iter).kind() else {
+        return None;
+    };
+    let did = adt.did();
 
-    if let ty::Adt(adt, substs) = iter_ty.kind() {
+    if match_def_path(cx, did, &paths::ARRAY_INTO_ITER) {
-        let did = adt.did();
+        // For array::IntoIter<T, const N: usize>, the length is the second generic
-
+        // parameter.
-        if match_def_path(cx, did, &paths::ARRAY_INTO_ITER) {
+        substs
-            // For array::IntoIter<T, const N: usize>, the length is the second generic
+            .const_at(1)
-            // parameter.
+            .try_eval_target_usize(cx.tcx, cx.param_env)
-            substs
+            .map(u128::from)
-                .const_at(1)
+    } else if match_def_path(cx, did, &paths::SLICE_ITER)
-                .try_eval_target_usize(cx.tcx, cx.param_env)
+        && let ExprKind::MethodCall(_, recv, ..) = iter.kind
-                .map(u128::from)
+    {
-        } else if match_def_path(cx, did, &paths::SLICE_ITER)
+        if let ty::Array(_, len) = cx.typeck_results().expr_ty(recv).peel_refs().kind() {
-            && let ExprKind::MethodCall(_, recv, ..) = iter.kind
-            && let ExprKind::Array(array) = recv.peel_borrows().kind
-        {
             // For slice::Iter<'_, T>, the receiver might be an array literal: [1,2,3].iter().skip(..)
-            array.len().try_into().ok()
+            len.try_eval_target_usize(cx.tcx, cx.param_env).map(u128::from)
-        } else if match_def_path(cx, did, &paths::ITER_EMPTY) {
+        } else if let Some(args) = VecArgs::hir(cx, expr_or_init(cx, recv)) {
-            Some(0)
+            match args {
-        } else if match_def_path(cx, did, &paths::ITER_ONCE) {
+                VecArgs::Vec(vec) => vec.len().try_into().ok(),
-            Some(1)
+                VecArgs::Repeat(_, len) => expr_as_u128(cx, len),
+            }
         } else {
             None
         }
-    } else {
+    } else if match_def_path(cx, did, &paths::ITER_EMPTY) {
+        Some(0)
+    } else if match_def_path(cx, did, &paths::ITER_ONCE) {
+        Some(1)
+    }  else {
         None
     }
 }
@@ -50,9 +66,8 @@ fn check<'tcx>(
 ) {
     if is_trait_method(cx, expr, sym::Iterator)
         && let Some(len) = get_iterator_length(cx, recv)
-        && let ExprKind::Lit(lit) = arg.kind
+        && let Some(skipped) = expr_as_u128(cx, arg)
-        && let LitKind::Int(skip, _) = lit.node
+        && skipped > len
-        && skip > len
     {
         span_lint_and_note(cx, ITER_OUT_OF_BOUNDS, expr.span, message, None, note);
     }

clippy_lints/src/methods/mod.rs

@@ -3557,7 +3557,7 @@
     /// ```rust
     /// for _ in [1, 2, 3].iter() {}
     /// ```
-    #[clippy::version = "1.73.0"]
+    #[clippy::version = "1.74.0"]
     pub ITER_OUT_OF_BOUNDS,
     suspicious,
     "calls to `.take()` or `.skip()` that are out of bounds"

tests/ui/iter_out_of_bounds.rs

@@ -1,4 +1,7 @@
+//@no-rustfix
+
 #![deny(clippy::iter_out_of_bounds)]
+#![allow(clippy::useless_vec)]
 
 fn opaque_empty_iter() -> impl Iterator<Item = ()> {
     std::iter::empty()
@@ -21,12 +24,25 @@ fn main() {
     for _ in [1, 2, 3].iter().skip(4) {}
     //~^ ERROR: this `.skip()` call skips more items than the iterator will produce
 
+    for _ in [1; 3].iter().skip(4) {}
+    //~^ ERROR: this `.skip()` call skips more items than the iterator will produce
+
     // Should not lint
     for _ in opaque_empty_iter().skip(1) {}
 
-    // Should not lint
+    for _ in vec![1, 2, 3].iter().skip(4) {}
-    let empty: [i8; 0] = [];
+    //~^ ERROR: this `.skip()` call skips more items than the iterator will produce
-    for _ in empty.iter().skip(1) {}
+
+    for _ in vec![1; 3].iter().skip(4) {}
+    //~^ ERROR: this `.skip()` call skips more items than the iterator will produce
+
+    let x = [1, 2, 3];
+    for _ in x.iter().skip(4) {}
+    //~^ ERROR: this `.skip()` call skips more items than the iterator will produce
+
+    let n = 4;
+    for _ in x.iter().skip(n) {}
+    //~^ ERROR: this `.skip()` call skips more items than the iterator will produce
 
     let empty = std::iter::empty::<i8>;
 

tests/ui/iter_out_of_bounds.stderr

@@ -1,18 +1,18 @@
 error: this `.skip()` call skips more items than the iterator will produce
-  --> $DIR/iter_out_of_bounds.rs:8:14
+  --> $DIR/iter_out_of_bounds.rs:11:14
    |
 LL |     for _ in [1, 2, 3].iter().skip(4) {
    |              ^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: this operation is useless and will create an empty iterator
 note: the lint level is defined here
-  --> $DIR/iter_out_of_bounds.rs:1:9
+  --> $DIR/iter_out_of_bounds.rs:3:9
    |
 LL | #![deny(clippy::iter_out_of_bounds)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: this `.take()` call takes more items than the iterator will produce
-  --> $DIR/iter_out_of_bounds.rs:12:19
+  --> $DIR/iter_out_of_bounds.rs:15:19
    |
 LL |     for (i, _) in [1, 2, 3].iter().take(4).enumerate() {
    |                   ^^^^^^^^^^^^^^^^^^^^^^^^
@@ -20,7 +20,7 @@ LL |     for (i, _) in [1, 2, 3].iter().take(4).enumerate() {
    = note: this operation is useless and the returned iterator will simply yield the same items
 
 error: this `.take()` call takes more items than the iterator will produce
-  --> $DIR/iter_out_of_bounds.rs:18:14
+  --> $DIR/iter_out_of_bounds.rs:21:14
    |
 LL |     for _ in (&&&&&&[1, 2, 3]).iter().take(4) {}
    |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -28,23 +28,63 @@ LL |     for _ in (&&&&&&[1, 2, 3]).iter().take(4) {}
    = note: this operation is useless and the returned iterator will simply yield the same items
 
 error: this `.skip()` call skips more items than the iterator will produce
-  --> $DIR/iter_out_of_bounds.rs:21:14
+  --> $DIR/iter_out_of_bounds.rs:24:14
    |
 LL |     for _ in [1, 2, 3].iter().skip(4) {}
    |              ^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: this operation is useless and will create an empty iterator
 
+error: this `.skip()` call skips more items than the iterator will produce
+  --> $DIR/iter_out_of_bounds.rs:27:14
+   |
+LL |     for _ in [1; 3].iter().skip(4) {}
+   |              ^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: this operation is useless and will create an empty iterator
+
 error: this `.skip()` call skips more items than the iterator will produce
   --> $DIR/iter_out_of_bounds.rs:33:14
    |
+LL |     for _ in vec![1, 2, 3].iter().skip(4) {}
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: this operation is useless and will create an empty iterator
+
+error: this `.skip()` call skips more items than the iterator will produce
+  --> $DIR/iter_out_of_bounds.rs:36:14
+   |
+LL |     for _ in vec![1; 3].iter().skip(4) {}
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: this operation is useless and will create an empty iterator
+
+error: this `.skip()` call skips more items than the iterator will produce
+  --> $DIR/iter_out_of_bounds.rs:40:14
+   |
+LL |     for _ in x.iter().skip(4) {}
+   |              ^^^^^^^^^^^^^^^^
+   |
+   = note: this operation is useless and will create an empty iterator
+
+error: this `.skip()` call skips more items than the iterator will produce
+  --> $DIR/iter_out_of_bounds.rs:44:14
+   |
+LL |     for _ in x.iter().skip(n) {}
+   |              ^^^^^^^^^^^^^^^^
+   |
+   = note: this operation is useless and will create an empty iterator
+
+error: this `.skip()` call skips more items than the iterator will produce
+  --> $DIR/iter_out_of_bounds.rs:49:14
+   |
 LL |     for _ in empty().skip(1) {}
    |              ^^^^^^^^^^^^^^^
    |
    = note: this operation is useless and will create an empty iterator
 
 error: this `.take()` call takes more items than the iterator will produce
-  --> $DIR/iter_out_of_bounds.rs:36:14
+  --> $DIR/iter_out_of_bounds.rs:52:14
    |
 LL |     for _ in empty().take(1) {}
    |              ^^^^^^^^^^^^^^^
@@ -52,7 +92,7 @@ LL |     for _ in empty().take(1) {}
    = note: this operation is useless and the returned iterator will simply yield the same items
 
 error: this `.skip()` call skips more items than the iterator will produce
-  --> $DIR/iter_out_of_bounds.rs:39:14
+  --> $DIR/iter_out_of_bounds.rs:55:14
    |
 LL |     for _ in std::iter::once(1).skip(2) {}
    |              ^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -60,12 +100,12 @@ LL |     for _ in std::iter::once(1).skip(2) {}
    = note: this operation is useless and will create an empty iterator
 
 error: this `.take()` call takes more items than the iterator will produce
-  --> $DIR/iter_out_of_bounds.rs:42:14
+  --> $DIR/iter_out_of_bounds.rs:58:14
    |
 LL |     for _ in std::iter::once(1).take(2) {}
    |              ^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: this operation is useless and the returned iterator will simply yield the same items
 
-error: aborting due to 8 previous errors
+error: aborting due to 13 previous errors
 

tests/ui/iter_skip_next.fixed

@@ -4,6 +4,7 @@
 #![allow(clippy::disallowed_names)]
 #![allow(clippy::iter_nth)]
 #![allow(clippy::useless_vec)]
+#![allow(clippy::iter_out_of_bounds)]
 #![allow(unused_mut, dead_code)]
 
 extern crate option_helpers;

tests/ui/iter_skip_next.rs

@@ -4,6 +4,7 @@
 #![allow(clippy::disallowed_names)]
 #![allow(clippy::iter_nth)]
 #![allow(clippy::useless_vec)]
+#![allow(clippy::iter_out_of_bounds)]
 #![allow(unused_mut, dead_code)]
 
 extern crate option_helpers;

tests/ui/iter_skip_next.stderr

@@ -1,5 +1,5 @@
 error: called `skip(..).next()` on an iterator
-  --> $DIR/iter_skip_next.rs:16:28
+  --> $DIR/iter_skip_next.rs:17:28
    |
 LL |     let _ = some_vec.iter().skip(42).next();
    |                            ^^^^^^^^^^^^^^^^ help: use `nth` instead: `.nth(42)`
@@ -7,37 +7,37 @@ LL |     let _ = some_vec.iter().skip(42).next();
    = note: `-D clippy::iter-skip-next` implied by `-D warnings`
 
 error: called `skip(..).next()` on an iterator
-  --> $DIR/iter_skip_next.rs:17:36
+  --> $DIR/iter_skip_next.rs:18:36
    |
 LL |     let _ = some_vec.iter().cycle().skip(42).next();
    |                                    ^^^^^^^^^^^^^^^^ help: use `nth` instead: `.nth(42)`
 
 error: called `skip(..).next()` on an iterator
-  --> $DIR/iter_skip_next.rs:18:20
+  --> $DIR/iter_skip_next.rs:19:20
    |
 LL |     let _ = (1..10).skip(10).next();
    |                    ^^^^^^^^^^^^^^^^ help: use `nth` instead: `.nth(10)`
 
 error: called `skip(..).next()` on an iterator
-  --> $DIR/iter_skip_next.rs:19:33
+  --> $DIR/iter_skip_next.rs:20:33
    |
 LL |     let _ = &some_vec[..].iter().skip(3).next();
    |                                 ^^^^^^^^^^^^^^^ help: use `nth` instead: `.nth(3)`
 
 error: called `skip(..).next()` on an iterator
-  --> $DIR/iter_skip_next.rs:27:26
+  --> $DIR/iter_skip_next.rs:28:26
    |
 LL |     let _: Vec<&str> = sp.skip(1).next().unwrap().split(' ').collect();
    |                          ^^^^^^^^^^^^^^^ help: use `nth` instead: `.nth(1)`
 
 error: called `skip(..).next()` on an iterator
-  --> $DIR/iter_skip_next.rs:29:29
+  --> $DIR/iter_skip_next.rs:30:29
    |
 LL |         let _: Vec<&str> = s.skip(1).next().unwrap().split(' ').collect();
    |                             ^^^^^^^^^^^^^^^ help: use `nth` instead: `.nth(1)`
 
 error: called `skip(..).next()` on an iterator
-  --> $DIR/iter_skip_next.rs:35:29
+  --> $DIR/iter_skip_next.rs:36:29
    |
 LL |         let _: Vec<&str> = s.skip(1).next().unwrap().split(' ').collect();
    |                             ^^^^^^^^^^^^^^^ help: use `nth` instead: `.nth(1)`

tests/ui/iter_skip_next_unfixable.rs

@@ -1,5 +1,5 @@
 #![warn(clippy::iter_skip_next)]
-#![allow(dead_code)]
+#![allow(dead_code, clippy::iter_out_of_bounds)]
 //@no-rustfix
 /// Checks implementation of `ITER_SKIP_NEXT` lint
 fn main() {