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use clippy_utils::diagnostics::span_lint_and_sugg;
use clippy_utils::method_chain_args;
use clippy_utils::source::snippet_with_applicability;
use clippy_utils::ty::is_type_diagnostic_item;
use rustc_errors::Applicability;
use rustc_hir as hir;
use rustc_lint::LateContext;
use rustc_middle::ty;
use rustc_span::symbol::sym;
use super::STRING_EXTEND_CHARS;
pub(super) fn check(cx: &LateContext<'_>, expr: &hir::Expr<'_>, recv: &hir::Expr<'_>, arg: &hir::Expr<'_>) {
let obj_ty = cx.typeck_results().expr_ty(recv).peel_refs();
if !is_type_diagnostic_item(cx, obj_ty, sym::String) {
return;
}
if let Some(arglists) = method_chain_args(arg, &["chars"]) {
let target = &arglists[0][0];
let self_ty = cx.typeck_results().expr_ty(target).peel_refs();
let ref_str = if *self_ty.kind() == ty::Str {
""
} else if is_type_diagnostic_item(cx, self_ty, sym::String) {
"&"
} else {
return;
};
let mut applicability = Applicability::MachineApplicable;
span_lint_and_sugg(
cx,
STRING_EXTEND_CHARS,
expr.span,
"calling `.extend(_.chars())`",
"try this",
format!(
"{}.push_str({}{})",
snippet_with_applicability(cx, recv.span, "..", &mut applicability),
ref_str,
snippet_with_applicability(cx, target.span, "..", &mut applicability)
),
applicability,
);
}
}
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