rust/clippy_lints/src/methods/iter_count.rs
2021-03-15 20:06:01 -05:00

50 lines
1.7 KiB
Rust

use crate::methods::derefs_to_slice;
use crate::utils::paths;
use clippy_utils::diagnostics::span_lint_and_sugg;
use clippy_utils::source::snippet_with_applicability;
use clippy_utils::ty::{is_type_diagnostic_item, match_type};
use rustc_errors::Applicability;
use rustc_hir::Expr;
use rustc_lint::LateContext;
use rustc_span::sym;
use super::ITER_COUNT;
pub(crate) fn check<'tcx>(cx: &LateContext<'tcx>, expr: &Expr<'_>, iter_args: &'tcx [Expr<'tcx>], iter_method: &str) {
let ty = cx.typeck_results().expr_ty(&iter_args[0]);
let caller_type = if derefs_to_slice(cx, &iter_args[0], ty).is_some() {
"slice"
} else if is_type_diagnostic_item(cx, ty, sym::vec_type) {
"Vec"
} else if is_type_diagnostic_item(cx, ty, sym::vecdeque_type) {
"VecDeque"
} else if is_type_diagnostic_item(cx, ty, sym::hashset_type) {
"HashSet"
} else if is_type_diagnostic_item(cx, ty, sym::hashmap_type) {
"HashMap"
} else if match_type(cx, ty, &paths::BTREEMAP) {
"BTreeMap"
} else if match_type(cx, ty, &paths::BTREESET) {
"BTreeSet"
} else if match_type(cx, ty, &paths::LINKED_LIST) {
"LinkedList"
} else if match_type(cx, ty, &paths::BINARY_HEAP) {
"BinaryHeap"
} else {
return;
};
let mut applicability = Applicability::MachineApplicable;
span_lint_and_sugg(
cx,
ITER_COUNT,
expr.span,
&format!("called `.{}().count()` on a `{}`", iter_method, caller_type),
"try",
format!(
"{}.len()",
snippet_with_applicability(cx, iter_args[0].span, "..", &mut applicability),
),
applicability,
);
}