105 lines
4.7 KiB
Rust
105 lines
4.7 KiB
Rust
use super::utils::clone_or_copy_needed;
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use clippy_utils::diagnostics::span_lint_and_then;
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use clippy_utils::higher::ForLoop;
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use clippy_utils::source::snippet_opt;
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use clippy_utils::ty::{get_associated_type, get_iterator_item_ty, implements_trait};
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use clippy_utils::{fn_def_id, get_parent_expr};
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use rustc_errors::Applicability;
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use rustc_hir::{def_id::DefId, Expr, ExprKind, LangItem};
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use rustc_lint::LateContext;
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use rustc_span::{sym, Symbol};
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use super::UNNECESSARY_TO_OWNED;
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pub fn check(cx: &LateContext<'_>, expr: &Expr<'_>, method_name: Symbol, receiver: &Expr<'_>) -> bool {
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if_chain! {
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if let Some(parent) = get_parent_expr(cx, expr);
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if let Some(callee_def_id) = fn_def_id(cx, parent);
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if is_into_iter(cx, callee_def_id);
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then {
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check_for_loop_iter(cx, parent, method_name, receiver, false)
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} else {
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false
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}
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}
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}
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/// Checks whether `expr` is an iterator in a `for` loop and, if so, determines whether the
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/// iterated-over items could be iterated over by reference. The reason why `check` above does not
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/// include this code directly is so that it can be called from
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/// `unnecessary_into_owned::check_into_iter_call_arg`.
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pub fn check_for_loop_iter(
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cx: &LateContext<'_>,
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expr: &Expr<'_>,
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method_name: Symbol,
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receiver: &Expr<'_>,
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cloned_before_iter: bool,
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) -> bool {
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if_chain! {
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if let Some(grandparent) = get_parent_expr(cx, expr).and_then(|parent| get_parent_expr(cx, parent));
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if let Some(ForLoop { pat, body, .. }) = ForLoop::hir(grandparent);
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let (clone_or_copy_needed, addr_of_exprs) = clone_or_copy_needed(cx, pat, body);
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if !clone_or_copy_needed;
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if let Some(receiver_snippet) = snippet_opt(cx, receiver.span);
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then {
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let snippet = if_chain! {
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if let ExprKind::MethodCall(maybe_iter_method_name, [collection], _) = receiver.kind;
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if maybe_iter_method_name.ident.name == sym::iter;
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if let Some(iterator_trait_id) = cx.tcx.get_diagnostic_item(sym::Iterator);
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let receiver_ty = cx.typeck_results().expr_ty(receiver);
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if implements_trait(cx, receiver_ty, iterator_trait_id, &[]);
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if let Some(iter_item_ty) = get_iterator_item_ty(cx, receiver_ty);
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if let Some(into_iterator_trait_id) = cx.tcx.get_diagnostic_item(sym::IntoIterator);
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let collection_ty = cx.typeck_results().expr_ty(collection);
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if implements_trait(cx, collection_ty, into_iterator_trait_id, &[]);
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if let Some(into_iter_item_ty) = get_associated_type(cx, collection_ty, into_iterator_trait_id, "Item");
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if iter_item_ty == into_iter_item_ty;
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if let Some(collection_snippet) = snippet_opt(cx, collection.span);
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then {
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collection_snippet
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} else {
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receiver_snippet
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}
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};
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span_lint_and_then(
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cx,
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UNNECESSARY_TO_OWNED,
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expr.span,
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&format!("unnecessary use of `{}`", method_name),
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|diag| {
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// If `check_into_iter_call_arg` called `check_for_loop_iter` because a call to
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// a `to_owned`-like function was removed, then the next suggestion may be
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// incorrect. This is because the iterator that results from the call's removal
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// could hold a reference to a resource that is used mutably. See
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// https://github.com/rust-lang/rust-clippy/issues/8148.
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let applicability = if cloned_before_iter {
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Applicability::MaybeIncorrect
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} else {
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Applicability::MachineApplicable
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};
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diag.span_suggestion(expr.span, "use", snippet, applicability);
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for addr_of_expr in addr_of_exprs {
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match addr_of_expr.kind {
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ExprKind::AddrOf(_, _, referent) => {
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let span = addr_of_expr.span.with_hi(referent.span.lo());
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diag.span_suggestion(span, "remove this `&`", "", applicability);
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}
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_ => unreachable!(),
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}
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}
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}
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);
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return true;
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}
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}
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false
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}
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/// Returns true if the named method is `IntoIterator::into_iter`.
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pub fn is_into_iter(cx: &LateContext<'_>, callee_def_id: DefId) -> bool {
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cx.tcx.lang_items().require(LangItem::IntoIterIntoIter) == Ok(callee_def_id)
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}
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