rust/clippy_lints/src/methods/map_collect_result_unit.rs

48 lines
1.5 KiB
Rust

use clippy_utils::diagnostics::span_lint_and_sugg;
use clippy_utils::is_trait_method;
use clippy_utils::source::snippet;
use clippy_utils::ty::is_type_diagnostic_item;
use if_chain::if_chain;
use rustc_errors::Applicability;
use rustc_hir as hir;
use rustc_lint::LateContext;
use rustc_middle::ty;
use rustc_span::symbol::sym;
use super::MAP_COLLECT_RESULT_UNIT;
pub(super) fn check(
cx: &LateContext<'_>,
expr: &hir::Expr<'_>,
iter: &hir::Expr<'_>,
map_fn: &hir::Expr<'_>,
collect_recv: &hir::Expr<'_>,
) {
if_chain! {
// called on Iterator
if is_trait_method(cx, collect_recv, sym::Iterator);
// return of collect `Result<(),_>`
let collect_ret_ty = cx.typeck_results().expr_ty(expr);
if is_type_diagnostic_item(cx, collect_ret_ty, sym::result_type);
if let ty::Adt(_, substs) = collect_ret_ty.kind();
if let Some(result_t) = substs.types().next();
if result_t.is_unit();
// get parts for snippet
then {
span_lint_and_sugg(
cx,
MAP_COLLECT_RESULT_UNIT,
expr.span,
"`.map().collect()` can be replaced with `.try_for_each()`",
"try this",
format!(
"{}.try_for_each({})",
snippet(cx, iter.span, ".."),
snippet(cx, map_fn.span, "..")
),
Applicability::MachineApplicable,
);
}
}
}