move `lints()` to `iter_count.rs`

3 files changed, 100 insertions, 88 deletions

diff --git a/clippy_lints/src/methods/iter_count.rs b/clippy_lints/src/methods/iter_count.rs
new file mode 100644
index 00000000000..ca8723cec94
--- /dev/null
+++ b/clippy_lints/src/methods/iter_count.rs
@@ -0,0 +1,51 @@
+use crate::utils::{
+    derefs_to_slice, is_type_diagnostic_item, match_trait_method, method_chain_args, paths, snippet_with_applicability,
+    span_lint_and_sugg,
+};
+use if_chain::if_chain;
+use rustc_errors::Applicability;
+use rustc_hir::Expr;
+use rustc_lint::LateContext;
+use rustc_span::sym;
+
+use super::ITER_COUNT;
+
+pub(crate) fn lints<'tcx>(cx: &LateContext<'tcx>, expr: &Expr<'_>, iter_args: &'tcx [Expr<'tcx>], is_mut: bool) {
+    let mut_str = if is_mut { "_mut" } else { "" };
+    let iter_method = if method_chain_args(expr, &[format!("iter{}", mut_str).as_str(), "count"]).is_some() {
+        "iter"
+    } else if method_chain_args(expr, &["into_iter", "count"]).is_some() {
+        "into_iter"
+    } else {
+        return;
+    };
+    if_chain! {
+        let caller_type = if derefs_to_slice(cx, &iter_args[0], cx.typeck_results().expr_ty(&iter_args[0])).is_some() {
+            Some("slice")
+        } else if is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(&iter_args[0]), sym::vec_type) {
+            Some("Vec")
+        } else if is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(&iter_args[0]), sym!(vecdeque_type)) {
+            Some("VecDeque")
+        } else if match_trait_method(cx, expr, &paths::ITERATOR) {
+            Some("std::iter::Iterator")
+        } else {
+            None
+        };
+        if let Some(caller_type) = caller_type;
+        then {
+            let mut applicability = Applicability::MachineApplicable;
+            span_lint_and_sugg(
+                cx,
+                ITER_COUNT,
+                expr.span,
+                &format!("called `.{}{}().count()` on a `{}`", iter_method, mut_str, caller_type),
+                "try",
+                format!(
+                    "{}.len()",
+                    snippet_with_applicability(cx, iter_args[0].span, "..", &mut applicability),
+                ),
+                applicability,
+            );
+        }
+    }
+}
diff --git a/clippy_lints/src/methods/mod.rs b/clippy_lints/src/methods/mod.rs
index e5509ee2c4e..d2a926d0944 100644
--- a/clippy_lints/src/methods/mod.rs
+++ b/clippy_lints/src/methods/mod.rs
@@ -4,6 +4,7 @@ mod filter_map_identity;
 mod implicit_clone;
 mod inefficient_to_string;
 mod inspect_for_each;
+mod iter_count;
 mod manual_saturating_arithmetic;
 mod option_map_unwrap_or;
 mod unnecessary_filter_map;
@@ -32,12 +33,12 @@ use crate::consts::{constant, Constant};
 use crate::utils::eager_or_lazy::is_lazyness_candidate;
 use crate::utils::usage::mutated_variables;
 use crate::utils::{
-    contains_return, contains_ty, get_parent_expr, get_trait_def_id, has_iter_method, higher, implements_trait,
-    in_macro, is_copy, is_expn_of, is_type_diagnostic_item, iter_input_pats, last_path_segment, match_def_path,
-    match_qpath, match_trait_method, match_type, meets_msrv, method_calls, method_chain_args, path_to_local_id, paths,
-    remove_blocks, return_ty, single_segment_path, snippet, snippet_with_applicability, snippet_with_macro_callsite,
-    span_lint, span_lint_and_help, span_lint_and_sugg, span_lint_and_then, strip_pat_refs, sugg, walk_ptrs_ty_depth,
-    SpanlessEq,
+    contains_return, contains_ty, derefs_to_slice, get_parent_expr, get_trait_def_id, has_iter_method, higher,
+    implements_trait, in_macro, is_copy, is_expn_of, is_type_diagnostic_item, iter_input_pats, last_path_segment,
+    match_def_path, match_qpath, match_trait_method, match_type, meets_msrv, method_calls, method_chain_args,
+    path_to_local_id, paths, remove_blocks, return_ty, single_segment_path, snippet, snippet_with_applicability,
+    snippet_with_macro_callsite, span_lint, span_lint_and_help, span_lint_and_sugg, span_lint_and_then, strip_pat_refs,
+    sugg, walk_ptrs_ty_depth, SpanlessEq,
 };
 
 declare_clippy_lint! {
@@ -1691,8 +1692,8 @@ impl<'tcx> LateLintPass<'tcx> for Methods {
                 lint_search_is_some(cx, expr, "rposition", arg_lists[1], arg_lists[0], method_spans[1])
             },
             ["extend", ..] => lint_extend(cx, expr, arg_lists[0]),
-            ["count", "into_iter" | "iter"] => lint_iter_count(cx, expr, &arg_lists[1], false),
-            ["count", "iter_mut"] => lint_iter_count(cx, expr, &arg_lists[1], true),
+            ["count", "into_iter" | "iter"] => iter_count::lints(cx, expr, &arg_lists[1], false),
+            ["count", "iter_mut"] => iter_count::lints(cx, expr, &arg_lists[1], true),
             ["nth", "iter"] => lint_iter_nth(cx, expr, &arg_lists, false),
             ["nth", "iter_mut"] => lint_iter_nth(cx, expr, &arg_lists, true),
             ["nth", "bytes"] => bytes_nth::lints(cx, expr, &arg_lists[1]),
@@ -2661,46 +2662,6 @@ fn lint_iter_next<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>, iter_
     }
 }
 
-fn lint_iter_count<'tcx>(cx: &LateContext<'tcx>, expr: &Expr<'_>, iter_args: &'tcx [Expr<'tcx>], is_mut: bool) {
-    let mut_str = if is_mut { "_mut" } else { "" };
-    let iter_method = if method_chain_args(expr, &[format!("iter{}", mut_str).as_str(), "count"]).is_some() {
-        "iter"
-    } else if method_chain_args(expr, &["into_iter", "count"]).is_some() {
-        "into_iter"
-    } else {
-        return;
-    };
-    if_chain! {
-        let caller_type = if derefs_to_slice(cx, &iter_args[0], cx.typeck_results().expr_ty(&iter_args[0])).is_some() {
-            Some("slice")
-        } else if is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(&iter_args[0]), sym::vec_type) {
-            Some("Vec")
-        } else if is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(&iter_args[0]), sym!(vecdeque_type)) {
-            Some("VecDeque")
-        } else if match_trait_method(cx, expr, &paths::ITERATOR) {
-            Some("std::iter::Iterator")
-        } else {
-            None
-        };
-        if let Some(caller_type) = caller_type;
-        then {
-            let mut applicability = Applicability::MachineApplicable;
-            span_lint_and_sugg(
-                cx,
-                ITER_COUNT,
-                expr.span,
-                &format!("called `.{}{}().count()` on a `{}`", iter_method, mut_str, caller_type),
-                "try",
-                format!(
-                    "{}.len()",
-                    snippet_with_applicability(cx, iter_args[0].span, "..", &mut applicability),
-                ),
-                applicability,
-            );
-        }
-    }
-}
-
 fn lint_iter_nth<'tcx>(
     cx: &LateContext<'tcx>,
     expr: &hir::Expr<'_>,
@@ -2841,46 +2802,6 @@ fn lint_iter_skip_next(cx: &LateContext<'_>, expr: &hir::Expr<'_>, skip_args: &[
     }
 }
 
-fn derefs_to_slice<'tcx>(
-    cx: &LateContext<'tcx>,
-    expr: &'tcx hir::Expr<'tcx>,
-    ty: Ty<'tcx>,
-) -> Option<&'tcx hir::Expr<'tcx>> {
-    fn may_slice<'a>(cx: &LateContext<'a>, ty: Ty<'a>) -> bool {
-        match ty.kind() {
-            ty::Slice(_) => true,
-            ty::Adt(def, _) if def.is_box() => may_slice(cx, ty.boxed_ty()),
-            ty::Adt(..) => is_type_diagnostic_item(cx, ty, sym::vec_type),
-            ty::Array(_, size) => size
-                .try_eval_usize(cx.tcx, cx.param_env)
-                .map_or(false, |size| size < 32),
-            ty::Ref(_, inner, _) => may_slice(cx, inner),
-            _ => false,
-        }
-    }
-
-    if let hir::ExprKind::MethodCall(ref path, _, ref args, _) = expr.kind {
-        if path.ident.name == sym::iter && may_slice(cx, cx.typeck_results().expr_ty(&args[0])) {
-            Some(&args[0])
-        } else {
-            None
-        }
-    } else {
-        match ty.kind() {
-            ty::Slice(_) => Some(expr),
-            ty::Adt(def, _) if def.is_box() && may_slice(cx, ty.boxed_ty()) => Some(expr),
-            ty::Ref(_, inner, _) => {
-                if may_slice(cx, inner) {
-                    Some(expr)
-                } else {
-                    None
-                }
-            },
-            _ => None,
-        }
-    }
-}
-
 /// lint use of `unwrap()` for `Option`s and `Result`s
 fn lint_unwrap(cx: &LateContext<'_>, expr: &hir::Expr<'_>, unwrap_args: &[hir::Expr<'_>]) {
     let obj_ty = cx.typeck_results().expr_ty(&unwrap_args[0]).peel_refs();
diff --git a/clippy_utils/src/lib.rs b/clippy_utils/src/lib.rs
index 2380ea4c7bf..ec1b189bf77 100644
--- a/clippy_utils/src/lib.rs
+++ b/clippy_utils/src/lib.rs
@@ -1802,6 +1802,46 @@ pub fn is_some_ctor(cx: &LateContext<'_>, res: Res) -> bool {
     false
 }
 
+pub fn derefs_to_slice<'tcx>(
+    cx: &LateContext<'tcx>,
+    expr: &'tcx hir::Expr<'tcx>,
+    ty: Ty<'tcx>,
+) -> Option<&'tcx hir::Expr<'tcx>> {
+    fn may_slice<'a>(cx: &LateContext<'a>, ty: Ty<'a>) -> bool {
+        match ty.kind() {
+            ty::Slice(_) => true,
+            ty::Adt(def, _) if def.is_box() => may_slice(cx, ty.boxed_ty()),
+            ty::Adt(..) => is_type_diagnostic_item(cx, ty, sym::vec_type),
+            ty::Array(_, size) => size
+                .try_eval_usize(cx.tcx, cx.param_env)
+                .map_or(false, |size| size < 32),
+            ty::Ref(_, inner, _) => may_slice(cx, inner),
+            _ => false,
+        }
+    }
+
+    if let hir::ExprKind::MethodCall(ref path, _, ref args, _) = expr.kind {
+        if path.ident.name == sym::iter && may_slice(cx, cx.typeck_results().expr_ty(&args[0])) {
+            Some(&args[0])
+        } else {
+            None
+        }
+    } else {
+        match ty.kind() {
+            ty::Slice(_) => Some(expr),
+            ty::Adt(def, _) if def.is_box() && may_slice(cx, ty.boxed_ty()) => Some(expr),
+            ty::Ref(_, inner, _) => {
+                if may_slice(cx, inner) {
+                    Some(expr)
+                } else {
+                    None
+                }
+            },
+            _ => None,
+        }
+    }
+}
+
 #[cfg(test)]
 mod test {
     use super::{reindent_multiline, without_block_comments};