diff --git a/clippy_lints/src/loops/for_loop_arg.rs b/clippy_lints/src/loops/for_loop_arg.rs
deleted file mode 100644
index b33e7183984..00000000000
--- a/clippy_lints/src/loops/for_loop_arg.rs
+++ /dev/null
@@ -1,149 +0,0 @@
-use crate::utils::{
-    is_type_diagnostic_item, match_trait_method, match_type, paths, snippet, snippet_with_applicability, span_lint,
-    span_lint_and_help, span_lint_and_sugg,
-};
-use rustc_errors::Applicability;
-use rustc_hir::{Expr, ExprKind, Mutability, Pat};
-use rustc_lint::LateContext;
-use rustc_middle::ty::{self, Ty, TyS};
-use rustc_span::symbol::sym;
-
-pub(super) fn check_for_loop_arg(cx: &LateContext<'_>, pat: &Pat<'_>, arg: &Expr<'_>, expr: &Expr<'_>) {
-    let mut next_loop_linted = false; // whether or not ITER_NEXT_LOOP lint was used
-    if let ExprKind::MethodCall(ref method, _, ref args, _) = arg.kind {
-        // just the receiver, no arguments
-        if args.len() == 1 {
-            let method_name = &*method.ident.as_str();
-            // check for looping over x.iter() or x.iter_mut(), could use &x or &mut x
-            if method_name == "iter" || method_name == "iter_mut" {
-                if is_ref_iterable_type(cx, &args[0]) {
-                    lint_iter_method(cx, args, arg, method_name);
-                }
-            } else if method_name == "into_iter" && match_trait_method(cx, arg, &paths::INTO_ITERATOR) {
-                let receiver_ty = cx.typeck_results().expr_ty(&args[0]);
-                let receiver_ty_adjusted = cx.typeck_results().expr_ty_adjusted(&args[0]);
-                if TyS::same_type(receiver_ty, receiver_ty_adjusted) {
-                    let mut applicability = Applicability::MachineApplicable;
-                    let object = snippet_with_applicability(cx, args[0].span, "_", &mut applicability);
-                    span_lint_and_sugg(
-                        cx,
-                        super::EXPLICIT_INTO_ITER_LOOP,
-                        arg.span,
-                        "it is more concise to loop over containers instead of using explicit \
-                         iteration methods",
-                        "to write this more concisely, try",
-                        object.to_string(),
-                        applicability,
-                    );
-                } else {
-                    let ref_receiver_ty = cx.tcx.mk_ref(
-                        cx.tcx.lifetimes.re_erased,
-                        ty::TypeAndMut {
-                            ty: receiver_ty,
-                            mutbl: Mutability::Not,
-                        },
-                    );
-                    if TyS::same_type(receiver_ty_adjusted, ref_receiver_ty) {
-                        lint_iter_method(cx, args, arg, method_name)
-                    }
-                }
-            } else if method_name == "next" && match_trait_method(cx, arg, &paths::ITERATOR) {
-                span_lint(
-                    cx,
-                    super::ITER_NEXT_LOOP,
-                    expr.span,
-                    "you are iterating over `Iterator::next()` which is an Option; this will compile but is \
-                    probably not what you want",
-                );
-                next_loop_linted = true;
-            }
-        }
-    }
-    if !next_loop_linted {
-        check_arg_type(cx, pat, arg);
-    }
-}
-
-/// Checks for `for` loops over `Option`s and `Result`s.
-fn check_arg_type(cx: &LateContext<'_>, pat: &Pat<'_>, arg: &Expr<'_>) {
-    let ty = cx.typeck_results().expr_ty(arg);
-    if is_type_diagnostic_item(cx, ty, sym::option_type) {
-        span_lint_and_help(
-            cx,
-            super::FOR_LOOPS_OVER_FALLIBLES,
-            arg.span,
-            &format!(
-                "for loop over `{0}`, which is an `Option`. This is more readably written as an \
-                `if let` statement",
-                snippet(cx, arg.span, "_")
-            ),
-            None,
-            &format!(
-                "consider replacing `for {0} in {1}` with `if let Some({0}) = {1}`",
-                snippet(cx, pat.span, "_"),
-                snippet(cx, arg.span, "_")
-            ),
-        );
-    } else if is_type_diagnostic_item(cx, ty, sym::result_type) {
-        span_lint_and_help(
-            cx,
-            super::FOR_LOOPS_OVER_FALLIBLES,
-            arg.span,
-            &format!(
-                "for loop over `{0}`, which is a `Result`. This is more readably written as an \
-                `if let` statement",
-                snippet(cx, arg.span, "_")
-            ),
-            None,
-            &format!(
-                "consider replacing `for {0} in {1}` with `if let Ok({0}) = {1}`",
-                snippet(cx, pat.span, "_"),
-                snippet(cx, arg.span, "_")
-            ),
-        );
-    }
-}
-
-fn lint_iter_method(cx: &LateContext<'_>, args: &[Expr<'_>], arg: &Expr<'_>, method_name: &str) {
-    let mut applicability = Applicability::MachineApplicable;
-    let object = snippet_with_applicability(cx, args[0].span, "_", &mut applicability);
-    let muta = if method_name == "iter_mut" { "mut " } else { "" };
-    span_lint_and_sugg(
-        cx,
-        super::EXPLICIT_ITER_LOOP,
-        arg.span,
-        "it is more concise to loop over references to containers instead of using explicit \
-         iteration methods",
-        "to write this more concisely, try",
-        format!("&{}{}", muta, object),
-        applicability,
-    )
-}
-
-/// Returns `true` if the type of expr is one that provides `IntoIterator` impls
-/// for `&T` and `&mut T`, such as `Vec`.
-#[rustfmt::skip]
-fn is_ref_iterable_type(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
-    // no walk_ptrs_ty: calling iter() on a reference can make sense because it
-    // will allow further borrows afterwards
-    let ty = cx.typeck_results().expr_ty(e);
-    is_iterable_array(ty, cx) ||
-    is_type_diagnostic_item(cx, ty, sym::vec_type) ||
-    match_type(cx, ty, &paths::LINKED_LIST) ||
-    is_type_diagnostic_item(cx, ty, sym!(hashmap_type)) ||
-    is_type_diagnostic_item(cx, ty, sym!(hashset_type)) ||
-    is_type_diagnostic_item(cx, ty, sym!(vecdeque_type)) ||
-    match_type(cx, ty, &paths::BINARY_HEAP) ||
-    match_type(cx, ty, &paths::BTREEMAP) ||
-    match_type(cx, ty, &paths::BTREESET)
-}
-
-fn is_iterable_array<'tcx>(ty: Ty<'tcx>, cx: &LateContext<'tcx>) -> bool {
-    // IntoIterator is currently only implemented for array sizes <= 32 in rustc
-    match ty.kind() {
-        ty::Array(_, n) => n
-            .try_eval_usize(cx.tcx, cx.param_env)
-            .map_or(false, |val| (0..=32).contains(&val)),
-        _ => false,
-    }
-}