Make iter_nth work for Vecs too
This commit is contained in:
Devon Hollowood
parent
7764dc5ef4
commit
74025be59d
@ -172,6 +172,7 @@ All notable changes to this project will be documented in this file.
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[`invalid_upcast_comparisons`]: https://github.com/Manishearth/rust-clippy/wiki#invalid_upcast_comparisons
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[`items_after_statements`]: https://github.com/Manishearth/rust-clippy/wiki#items_after_statements
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[`iter_next_loop`]: https://github.com/Manishearth/rust-clippy/wiki#iter_next_loop
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[`iter_nth`]: https://github.com/Manishearth/rust-clippy/wiki#iter_nth
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[`len_without_is_empty`]: https://github.com/Manishearth/rust-clippy/wiki#len_without_is_empty
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[`len_zero`]: https://github.com/Manishearth/rust-clippy/wiki#len_zero
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[`let_and_return`]: https://github.com/Manishearth/rust-clippy/wiki#let_and_return
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@ -234,7 +235,6 @@ All notable changes to this project will be documented in this file.
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[`single_char_pattern`]: https://github.com/Manishearth/rust-clippy/wiki#single_char_pattern
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[`single_match`]: https://github.com/Manishearth/rust-clippy/wiki#single_match
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[`single_match_else`]: https://github.com/Manishearth/rust-clippy/wiki#single_match_else
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[`slice_iter_nth`]: https://github.com/Manishearth/rust-clippy/wiki#slice_iter_nth
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[`str_to_string`]: https://github.com/Manishearth/rust-clippy/wiki#str_to_string
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[`string_add`]: https://github.com/Manishearth/rust-clippy/wiki#string_add
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[`string_add_assign`]: https://github.com/Manishearth/rust-clippy/wiki#string_add_assign
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@ -78,6 +78,7 @@ name
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[invalid_upcast_comparisons](https://github.com/Manishearth/rust-clippy/wiki#invalid_upcast_comparisons) | allow | a comparison involving an upcast which is always true or false
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[items_after_statements](https://github.com/Manishearth/rust-clippy/wiki#items_after_statements) | allow | finds blocks where an item comes after a statement
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[iter_next_loop](https://github.com/Manishearth/rust-clippy/wiki#iter_next_loop) | warn | for-looping over `_.next()` which is probably not intended
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[iter_nth](https://github.com/Manishearth/rust-clippy/wiki#iter_nth) | warn | using `.iter().nth()` on a slice or Vec
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[len_without_is_empty](https://github.com/Manishearth/rust-clippy/wiki#len_without_is_empty) | warn | traits and impls that have `.len()` but not `.is_empty()`
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[len_zero](https://github.com/Manishearth/rust-clippy/wiki#len_zero) | warn | checking `.len() == 0` or `.len() > 0` (or similar) when `.is_empty()` could be used instead
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[let_and_return](https://github.com/Manishearth/rust-clippy/wiki#let_and_return) | warn | creating a let-binding and then immediately returning it like `let x = expr; x` at the end of a block
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@ -140,7 +141,6 @@ name
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[single_char_pattern](https://github.com/Manishearth/rust-clippy/wiki#single_char_pattern) | warn | using a single-character str where a char could be used, e.g. `_.split("x")`
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[single_match](https://github.com/Manishearth/rust-clippy/wiki#single_match) | warn | a match statement with a single nontrivial arm (i.e, where the other arm is `_ => {}`) is used; recommends `if let` instead
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[single_match_else](https://github.com/Manishearth/rust-clippy/wiki#single_match_else) | allow | a match statement with a two arms where the second arm's pattern is a wildcard; recommends `if let` instead
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[slice_iter_nth](https://github.com/Manishearth/rust-clippy/wiki#slice_iter_nth) | warn | using `.iter().nth()` on a slice
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[string_add](https://github.com/Manishearth/rust-clippy/wiki#string_add) | allow | using `x + ..` where x is a `String`; suggests using `push_str()` instead
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[string_add_assign](https://github.com/Manishearth/rust-clippy/wiki#string_add_assign) | allow | using `x = x + ..` where x is a `String`; suggests using `push_str()` instead
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[string_lit_as_bytes](https://github.com/Manishearth/rust-clippy/wiki#string_lit_as_bytes) | warn | calling `as_bytes` on a string literal; suggests using a byte string literal instead
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@ -349,6 +349,7 @@ pub fn register_plugins(reg: &mut rustc_plugin::Registry) {
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methods::CLONE_ON_COPY,
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methods::EXTEND_FROM_SLICE,
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methods::FILTER_NEXT,
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methods::ITER_NTH,
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methods::NEW_RET_NO_SELF,
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methods::OK_EXPECT,
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methods::OPTION_MAP_UNWRAP_OR,
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@ -357,7 +358,6 @@ pub fn register_plugins(reg: &mut rustc_plugin::Registry) {
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methods::SEARCH_IS_SOME,
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methods::SHOULD_IMPLEMENT_TRAIT,
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methods::SINGLE_CHAR_PATTERN,
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methods::SLICE_ITER_NTH,
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methods::TEMPORARY_CSTRING_AS_PTR,
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methods::WRONG_SELF_CONVENTION,
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minmax::MIN_MAX,
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@ -312,7 +312,7 @@ declare_lint! {
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"getting the inner pointer of a temporary `CString`"
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}
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/// **What it does:** This lint checks for use of `.iter().nth()` on a slice.
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/// **What it does:** This lint checks for use of `.iter().nth()` on a slice or Vec.
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///
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/// **Why is this bad?** `.get()` is more efficient and more readable.
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///
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@ -320,18 +320,20 @@ declare_lint! {
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///
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/// **Example:**
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/// ```rust
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/// let some_slice = &[0, 1, 2, 3][..];
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/// let third_elem = some_slice.iter().nth(3);
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/// let some_vec = vec![0, 1, 2, 3];
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/// let bad_vec = some_vec.iter().nth(3);
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/// let bad_slice = &some_vec[..].iter().nth(3);
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/// ```
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/// The correct use would be:
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/// ```rust
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/// let some_slice = &[0, 1, 2, 3][..];
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/// let third_elem = some_slice.get(3);
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/// let some_vec = vec![0, 1, 2, 3];
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/// let bad_vec = some_vec.get(3);
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/// let bad_slice = &some_vec[..].get(3);
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/// ```
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declare_lint! {
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pub SLICE_ITER_NTH,
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pub ITER_NTH,
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Warn,
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"using `.iter().nth()` on a slice"
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"using `.iter().nth()` on a slice or Vec"
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}
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impl LintPass for MethodsPass {
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@ -353,7 +355,7 @@ impl LintPass for MethodsPass {
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SINGLE_CHAR_PATTERN,
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SEARCH_IS_SOME,
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TEMPORARY_CSTRING_AS_PTR,
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SLICE_ITER_NTH)
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ITER_NTH)
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}
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}
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@ -387,7 +389,7 @@ impl LateLintPass for MethodsPass {
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} else if let Some(arglists) = method_chain_args(expr, &["unwrap", "as_ptr"]) {
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lint_cstring_as_ptr(cx, expr, &arglists[0][0], &arglists[1][0]);
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} else if let Some(arglists) = method_chain_args(expr, &["iter", "nth"]) {
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lint_slice_iter_nth(cx, expr, arglists[0]);
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lint_iter_nth(cx, expr, arglists[0]);
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}
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lint_or_fun_call(cx, expr, &name.node.as_str(), args);
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@ -643,14 +645,21 @@ fn lint_cstring_as_ptr(cx: &LateContext, expr: &hir::Expr, new: &hir::Expr, unwr
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#[allow(ptr_arg)]
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// Type of MethodArgs is potentially a Vec
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fn lint_slice_iter_nth(cx: &LateContext, expr: &hir::Expr, iter_args: &MethodArgs){
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// lint if the caller of `.iter().nth` is a `slice`
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fn lint_iter_nth(cx: &LateContext, expr: &hir::Expr, iter_args: &MethodArgs){
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// lint if the caller of `.iter().nth()` is a `slice`
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if let Some(_) = derefs_to_slice(cx, &iter_args[0], &cx.tcx.expr_ty(&iter_args[0])) {
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span_lint(cx,
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SLICE_ITER_NTH,
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ITER_NTH,
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expr.span,
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"called `.iter().nth()` on a slice. Calling `.get()` is both faster and more readable");
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}
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// lint if the caller of `.iter().nth()` is a `Vec`
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else if match_type(cx, cx.tcx.expr_ty(&iter_args[0]), &paths::VEC) {
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span_lint(cx,
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ITER_NTH,
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expr.span,
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"called `.iter().nth()` on a Vec. Calling `.get()` is both faster and more readable");
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}
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}
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fn derefs_to_slice(cx: &LateContext, expr: &hir::Expr, ty: &ty::Ty) -> Option<(Span, &'static str)> {
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@ -128,6 +128,16 @@ fn option_methods() {
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}
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/// Struct to generate false positives for things with .iter()
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#[derive(Copy, Clone)]
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struct HasIter;
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impl HasIter {
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fn iter(self) -> IteratorFalsePositives {
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IteratorFalsePositives { foo: 0 }
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}
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}
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/// Struct to generate false positive for Iterator-based lints
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#[derive(Copy, Clone)]
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struct IteratorFalsePositives {
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@ -154,6 +164,10 @@ impl IteratorFalsePositives {
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fn rposition(self) -> Option<u32> {
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Some(self.foo)
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}
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fn nth(self, n: usize) -> Option<u32> {
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Some(self.foo)
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}
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}
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/// Checks implementation of `FILTER_NEXT` lint
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@ -309,13 +323,17 @@ fn or_fun_call() {
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//~|SUGGESTION btree.entry(42).or_insert_with(String::new);
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}
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/// Checks implementation of `SLICE_ITER_NTH` lint
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fn slice_iter_nth() {
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/// Checks implementation of `ITER_NTH` lint
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fn iter_nth() {
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let some_vec = vec![0, 1, 2, 3];
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let bad = &some_vec[..].iter().nth(3);
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let bad_vec = some_vec.iter().nth(3);
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//~^ERROR called `.iter().nth()` on a Vec.
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let bad_slice = &some_vec[..].iter().nth(3);
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//~^ERROR called `.iter().nth()` on a slice.
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let ok = some_vec.iter().nth(3); // This should be okay, since some_vec is not a slice
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let false_positive = HasIter;
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let ok = false_positive.iter().nth(3);
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// ^This should be okay, because false_positive is not a slice or Vec
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}
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#[allow(similar_names)]
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