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use clippy_utils::diagnostics::span_lint_and_sugg;
use clippy_utils::source::snippet_with_applicability;
use clippy_utils::ty::is_type_diagnostic_item;
use rustc_ast::LitKind;
use rustc_errors::Applicability;
use rustc_hir as hir;
use rustc_lint::LateContext;
use rustc_span::source_map::Spanned;
use rustc_span::sym;
use super::GET_FIRST;
pub(super) fn check<'tcx>(
cx: &LateContext<'tcx>,
expr: &'tcx hir::Expr<'_>,
recv: &'tcx hir::Expr<'_>,
arg: &'tcx hir::Expr<'_>,
) {
if let Some(method_id) = cx.typeck_results().type_dependent_def_id(expr.hir_id)
&& let Some(impl_id) = cx.tcx.impl_of_method(method_id)
&& let identity = cx.tcx.type_of(impl_id).instantiate_identity()
&& let hir::ExprKind::Lit(Spanned {
node: LitKind::Int(0, _),
..
}) = arg.kind
{
if identity.is_slice() {
let mut app = Applicability::MachineApplicable;
let slice_name = snippet_with_applicability(cx, recv.span, "..", &mut app);
span_lint_and_sugg(
cx,
GET_FIRST,
expr.span,
&format!("accessing first element with `{slice_name}.get(0)`"),
"try",
format!("{slice_name}.first()"),
app,
);
} else if is_type_diagnostic_item(cx, identity, sym::VecDeque) {
let mut app = Applicability::MachineApplicable;
let slice_name = snippet_with_applicability(cx, recv.span, "..", &mut app);
span_lint_and_sugg(
cx,
GET_FIRST,
expr.span,
&format!("accessing first element with `{slice_name}.get(0)`"),
"try",
format!("{slice_name}.front()"),
app,
);
}
}
}
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