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|
use clippy_utils::diagnostics::span_lint_and_help;
use clippy_utils::{path_def_id, qpath_generic_tys};
use rustc_hir::{self as hir, def_id::DefId, QPath};
use rustc_lint::LateContext;
use rustc_span::{sym, Symbol};
use super::BOX_COLLECTION;
pub(super) fn check(cx: &LateContext<'_>, hir_ty: &hir::Ty<'_>, qpath: &QPath<'_>, def_id: DefId) -> bool {
if_chain! {
if Some(def_id) == cx.tcx.lang_items().owned_box();
if let Some(item_type) = get_std_collection(cx, qpath);
then {
let generic = match item_type {
sym::String => "",
_ => "<..>",
};
let box_content = format!("{item_type}{generic}");
span_lint_and_help(
cx,
BOX_COLLECTION,
hir_ty.span,
&format!(
"you seem to be trying to use `Box<{box_content}>`. Consider using just `{box_content}`"),
None,
&format!(
"`{box_content}` is already on the heap, `Box<{box_content}>` makes an extra allocation")
);
true
} else {
false
}
}
}
fn get_std_collection(cx: &LateContext<'_>, qpath: &QPath<'_>) -> Option<Symbol> {
let param = qpath_generic_tys(qpath).next()?;
let id = path_def_id(cx, param)?;
cx.tcx.get_diagnostic_name(id).filter(|&name| {
matches!(
name,
sym::HashMap
| sym::String
| sym::Vec
| sym::HashSet
| sym::VecDeque
| sym::LinkedList
| sym::BTreeMap
| sym::BTreeSet
| sym::BinaryHeap
)
})
}
|
