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use clippy_utils::diagnostics::span_lint_and_sugg;
use clippy_utils::ty::is_type_diagnostic_item;
use clippy_utils::{is_expr_untyped_identity_function, is_trait_method};
use rustc_errors::Applicability;
use rustc_hir as hir;
use rustc_lint::LateContext;
use rustc_span::{sym, Span};
use super::MAP_IDENTITY;
pub(super) fn check(
cx: &LateContext<'_>,
expr: &hir::Expr<'_>,
caller: &hir::Expr<'_>,
map_arg: &hir::Expr<'_>,
name: &str,
_map_span: Span,
) {
let caller_ty = cx.typeck_results().expr_ty(caller);
if (is_trait_method(cx, expr, sym::Iterator)
|| is_type_diagnostic_item(cx, caller_ty, sym::Result)
|| is_type_diagnostic_item(cx, caller_ty, sym::Option))
&& is_expr_untyped_identity_function(cx, map_arg)
&& let Some(sugg_span) = expr.span.trim_start(caller.span)
{
span_lint_and_sugg(
cx,
MAP_IDENTITY,
sugg_span,
"unnecessary map of the identity function",
format!("remove the call to `{name}`"),
String::new(),
Applicability::MachineApplicable,
);
}
}
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