31 lines
1.2 KiB
Rust
31 lines
1.2 KiB
Rust
use clippy_utils::consts::{ConstEvalCtxt, Constant};
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use clippy_utils::diagnostics::span_lint_and_sugg;
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use clippy_utils::source::snippet_with_applicability;
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use clippy_utils::{is_lang_item_or_ctor, is_trait_method};
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use hir::{LangItem, OwnerNode};
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use rustc_errors::Applicability;
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use rustc_hir as hir;
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use rustc_lint::LateContext;
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use rustc_span::sym;
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use super::ITER_NTH_ZERO;
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pub(super) fn check(cx: &LateContext<'_>, expr: &hir::Expr<'_>, recv: &hir::Expr<'_>, arg: &hir::Expr<'_>) {
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if let OwnerNode::Item(item) = cx.tcx.hir_owner_node(cx.tcx.hir_get_parent_item(expr.hir_id))
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&& let def_id = item.owner_id.to_def_id()
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&& is_trait_method(cx, expr, sym::Iterator)
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&& let Some(Constant::Int(0)) = ConstEvalCtxt::new(cx).eval(arg)
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&& !is_lang_item_or_ctor(cx, def_id, LangItem::IteratorNext)
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{
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let mut app = Applicability::MachineApplicable;
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span_lint_and_sugg(
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cx,
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ITER_NTH_ZERO,
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expr.span,
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"called `.nth(0)` on a `std::iter::Iterator`, when `.next()` is equivalent",
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"try calling `.next()` instead of `.nth(0)`",
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format!("{}.next()", snippet_with_applicability(cx, recv.span, "..", &mut app)),
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app,
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);
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}
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}
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