Split `for_loops` tests

18 files changed, 658 insertions, 940 deletions

diff --git a/tests/ui/explicit_counter_loop.rs b/tests/ui/explicit_counter_loop.rs
index 08e6de5dc19..e02b8f62b3d 100644
--- a/tests/ui/explicit_counter_loop.rs
+++ b/tests/ui/explicit_counter_loop.rs
@@ -23,6 +23,54 @@ fn main() {
     for _v in vec {
         _index += 1;
     }
+
+    let vec = [1, 2, 3, 4];
+    // Potential false positives
+    let mut _index = 0;
+    _index = 1;
+    for _v in &vec {
+        _index += 1
+    }
+
+    let mut _index = 0;
+    _index += 1;
+    for _v in &vec {
+        _index += 1
+    }
+
+    let mut _index = 0;
+    for _v in &vec {
+        _index = 1;
+        _index += 1
+    }
+
+    let mut _index = 0;
+    for _v in &vec {
+        let mut _index = 0;
+        _index += 1
+    }
+
+    let mut _index = 0;
+    for _v in &vec {
+        _index += 1;
+        _index = 0;
+    }
+
+    let mut _index = 0;
+    if true {
+        _index = 1
+    };
+    for _v in &vec {
+        _index += 1
+    }
+
+    let mut _index = 1;
+    if false {
+        _index = 0
+    };
+    for _v in &vec {
+        _index += 1
+    }
 }
 
 mod issue_1219 {
diff --git a/tests/ui/explicit_counter_loop.stderr b/tests/ui/explicit_counter_loop.stderr
index d3f3c626bbd..0677e4d78c8 100644
--- a/tests/ui/explicit_counter_loop.stderr
+++ b/tests/ui/explicit_counter_loop.stderr
@@ -25,31 +25,31 @@ LL |     for _v in vec {
    |     ^^^^^^^^^^^^^ help: consider using: `for (_index, _v) in vec.into_iter().enumerate()`
 
 error: the variable `count` is used as a loop counter
-  --> $DIR/explicit_counter_loop.rs:62:9
+  --> $DIR/explicit_counter_loop.rs:110:9
    |
 LL |         for ch in text.chars() {
    |         ^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `for (count, ch) in text.chars().enumerate()`
 
 error: the variable `count` is used as a loop counter
-  --> $DIR/explicit_counter_loop.rs:73:9
+  --> $DIR/explicit_counter_loop.rs:121:9
    |
 LL |         for ch in text.chars() {
    |         ^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `for (count, ch) in text.chars().enumerate()`
 
 error: the variable `count` is used as a loop counter
-  --> $DIR/explicit_counter_loop.rs:131:9
+  --> $DIR/explicit_counter_loop.rs:179:9
    |
 LL |         for _i in 3..10 {
    |         ^^^^^^^^^^^^^^^ help: consider using: `for (count, _i) in (3..10).enumerate()`
 
 error: the variable `idx_usize` is used as a loop counter
-  --> $DIR/explicit_counter_loop.rs:171:9
+  --> $DIR/explicit_counter_loop.rs:219:9
    |
 LL |         for _item in slice {
    |         ^^^^^^^^^^^^^^^^^^ help: consider using: `for (idx_usize, _item) in slice.iter().enumerate()`
 
 error: the variable `idx_u32` is used as a loop counter
-  --> $DIR/explicit_counter_loop.rs:183:9
+  --> $DIR/explicit_counter_loop.rs:231:9
    |
 LL |         for _item in slice {
    |         ^^^^^^^^^^^^^^^^^^ help: consider using: `for (idx_u32, _item) in (0_u32..).zip(slice.iter())`
diff --git a/tests/ui/explicit_into_iter_loop.fixed b/tests/ui/explicit_into_iter_loop.fixed
new file mode 100644
index 00000000000..bc9ecb1e05a
--- /dev/null
+++ b/tests/ui/explicit_into_iter_loop.fixed
@@ -0,0 +1,55 @@
+//@run-rustfix
+#![warn(clippy::explicit_into_iter_loop)]
+
+fn main() {
+    // Issue #4958
+    fn _takes_iterator<T>(iterator: &T)
+    where
+        for<'a> &'a T: IntoIterator<Item = &'a String>,
+    {
+        for i in iterator {
+            println!("{}", i);
+        }
+    }
+
+    struct T;
+    impl IntoIterator for &T {
+        type Item = ();
+        type IntoIter = std::vec::IntoIter<Self::Item>;
+        fn into_iter(self) -> Self::IntoIter {
+            vec![].into_iter()
+        }
+    }
+
+    let t = T;
+    let r = &t;
+    let rr = &&t;
+
+    // This case is handled by `explicit_iter_loop`. No idea why.
+    for _ in t.into_iter() {}
+
+    for _ in r {}
+
+    // No suggestion for this.
+    // We'd have to suggest `for _ in *rr {}` which is less clear.
+    for _ in rr.into_iter() {}
+
+    // Issue #6900
+    struct S;
+    impl S {
+        #[allow(clippy::should_implement_trait)]
+        pub fn into_iter<T>(self) -> I<T> {
+            unimplemented!()
+        }
+    }
+
+    struct I<T>(T);
+    impl<T> Iterator for I<T> {
+        type Item = T;
+        fn next(&mut self) -> Option<Self::Item> {
+            unimplemented!()
+        }
+    }
+
+    for _ in S.into_iter::<u32>() {}
+}
diff --git a/tests/ui/explicit_into_iter_loop.rs b/tests/ui/explicit_into_iter_loop.rs
new file mode 100644
index 00000000000..9b610fe3d11
--- /dev/null
+++ b/tests/ui/explicit_into_iter_loop.rs
@@ -0,0 +1,55 @@
+//@run-rustfix
+#![warn(clippy::explicit_into_iter_loop)]
+
+fn main() {
+    // Issue #4958
+    fn _takes_iterator<T>(iterator: &T)
+    where
+        for<'a> &'a T: IntoIterator<Item = &'a String>,
+    {
+        for i in iterator.into_iter() {
+            println!("{}", i);
+        }
+    }
+
+    struct T;
+    impl IntoIterator for &T {
+        type Item = ();
+        type IntoIter = std::vec::IntoIter<Self::Item>;
+        fn into_iter(self) -> Self::IntoIter {
+            vec![].into_iter()
+        }
+    }
+
+    let t = T;
+    let r = &t;
+    let rr = &&t;
+
+    // This case is handled by `explicit_iter_loop`. No idea why.
+    for _ in t.into_iter() {}
+
+    for _ in r.into_iter() {}
+
+    // No suggestion for this.
+    // We'd have to suggest `for _ in *rr {}` which is less clear.
+    for _ in rr.into_iter() {}
+
+    // Issue #6900
+    struct S;
+    impl S {
+        #[allow(clippy::should_implement_trait)]
+        pub fn into_iter<T>(self) -> I<T> {
+            unimplemented!()
+        }
+    }
+
+    struct I<T>(T);
+    impl<T> Iterator for I<T> {
+        type Item = T;
+        fn next(&mut self) -> Option<Self::Item> {
+            unimplemented!()
+        }
+    }
+
+    for _ in S.into_iter::<u32>() {}
+}
diff --git a/tests/ui/explicit_into_iter_loop.stderr b/tests/ui/explicit_into_iter_loop.stderr
new file mode 100644
index 00000000000..1bd2b38a0e7
--- /dev/null
+++ b/tests/ui/explicit_into_iter_loop.stderr
@@ -0,0 +1,16 @@
+error: it is more concise to loop over containers instead of using explicit iteration methods
+  --> $DIR/explicit_into_iter_loop.rs:10:18
+   |
+LL |         for i in iterator.into_iter() {
+   |                  ^^^^^^^^^^^^^^^^^^^^ help: to write this more concisely, try: `iterator`
+   |
+   = note: `-D clippy::explicit-into-iter-loop` implied by `-D warnings`
+
+error: it is more concise to loop over containers instead of using explicit iteration methods
+  --> $DIR/explicit_into_iter_loop.rs:31:14
+   |
+LL |     for _ in r.into_iter() {}
+   |              ^^^^^^^^^^^^^ help: to write this more concisely, try: `r`
+
+error: aborting due to 2 previous errors
+
diff --git a/tests/ui/explicit_iter_loop.fixed b/tests/ui/explicit_iter_loop.fixed
new file mode 100644
index 00000000000..b0de50ed928
--- /dev/null
+++ b/tests/ui/explicit_iter_loop.fixed
@@ -0,0 +1,140 @@
+//@run-rustfix
+#![deny(clippy::explicit_iter_loop)]
+#![allow(
+    clippy::linkedlist,
+    clippy::similar_names,
+    clippy::needless_borrow,
+    clippy::deref_addrof,
+    dead_code
+)]
+
+use core::slice;
+use std::collections::*;
+
+fn main() {
+    let mut vec = vec![1, 2, 3, 4];
+
+    for _ in &vec {}
+    for _ in &mut vec {}
+
+    for _ in &vec {} // these are fine
+    for _ in &mut vec {} // these are fine
+
+    for _ in &[1, 2, 3] {}
+
+    for _ in &*(&mut [1, 2, 3]) {}
+
+    for _ in &[0; 32] {}
+    for _ in &[0; 33] {}
+
+    let ll: LinkedList<()> = LinkedList::new();
+    for _ in &ll {}
+
+    let vd: VecDeque<()> = VecDeque::new();
+    for _ in &vd {}
+
+    let bh: BinaryHeap<()> = BinaryHeap::new();
+    for _ in &bh {}
+
+    let hm: HashMap<(), ()> = HashMap::new();
+    for _ in &hm {}
+
+    let bt: BTreeMap<(), ()> = BTreeMap::new();
+    for _ in &bt {}
+
+    let hs: HashSet<()> = HashSet::new();
+    for _ in &hs {}
+
+    let bs: BTreeSet<()> = BTreeSet::new();
+    for _ in &bs {}
+
+    struct NoIntoIter();
+    impl NoIntoIter {
+        fn iter(&self) -> slice::Iter<u8> {
+            unimplemented!()
+        }
+
+        fn iter_mut(&mut self) -> slice::IterMut<u8> {
+            unimplemented!()
+        }
+    }
+    let mut x = NoIntoIter();
+    for _ in x.iter() {} // no error
+    for _ in x.iter_mut() {} // no error
+
+    struct IntoIterDiffTy;
+    impl IntoIterator for &'_ IntoIterDiffTy {
+        type Item = &'static ();
+        type IntoIter = core::slice::Iter<'static, ()>;
+        fn into_iter(self) -> Self::IntoIter {
+            unimplemented!()
+        }
+    }
+    impl IntoIterDiffTy {
+        fn iter(&self) -> core::slice::Iter<'static, i32> {
+            unimplemented!()
+        }
+    }
+    let x = IntoIterDiffTy;
+    for _ in x.iter() {}
+
+    struct IntoIterDiffSig;
+    impl IntoIterator for &'_ IntoIterDiffSig {
+        type Item = &'static ();
+        type IntoIter = core::slice::Iter<'static, ()>;
+        fn into_iter(self) -> Self::IntoIter {
+            unimplemented!()
+        }
+    }
+    impl IntoIterDiffSig {
+        fn iter(&self, _: u32) -> core::slice::Iter<'static, ()> {
+            unimplemented!()
+        }
+    }
+    let x = IntoIterDiffSig;
+    for _ in x.iter(0) {}
+
+    struct IntoIterDiffLt<'a>(&'a ());
+    impl<'a> IntoIterator for &'a IntoIterDiffLt<'_> {
+        type Item = &'a ();
+        type IntoIter = core::slice::Iter<'a, ()>;
+        fn into_iter(self) -> Self::IntoIter {
+            unimplemented!()
+        }
+    }
+    impl<'a> IntoIterDiffLt<'a> {
+        fn iter(&self) -> core::slice::Iter<'a, ()> {
+            unimplemented!()
+        }
+    }
+    let x = IntoIterDiffLt(&());
+    for _ in x.iter() {}
+
+    struct CustomType;
+    impl<'a> IntoIterator for &'a CustomType {
+        type Item = &'a u32;
+        type IntoIter = core::slice::Iter<'a, u32>;
+        fn into_iter(self) -> Self::IntoIter {
+            unimplemented!()
+        }
+    }
+    impl<'a> IntoIterator for &'a mut CustomType {
+        type Item = &'a mut u32;
+        type IntoIter = core::slice::IterMut<'a, u32>;
+        fn into_iter(self) -> Self::IntoIter {
+            unimplemented!()
+        }
+    }
+    impl CustomType {
+        fn iter(&self) -> <&'_ Self as IntoIterator>::IntoIter {
+            panic!()
+        }
+
+        fn iter_mut(&mut self) -> core::slice::IterMut<'_, u32> {
+            panic!()
+        }
+    }
+    let mut x = CustomType;
+    for _ in &x {}
+    for _ in &mut x {}
+}
diff --git a/tests/ui/explicit_iter_loop.rs b/tests/ui/explicit_iter_loop.rs
new file mode 100644
index 00000000000..33d3bada6e2
--- /dev/null
+++ b/tests/ui/explicit_iter_loop.rs
@@ -0,0 +1,140 @@
+//@run-rustfix
+#![deny(clippy::explicit_iter_loop)]
+#![allow(
+    clippy::linkedlist,
+    clippy::similar_names,
+    clippy::needless_borrow,
+    clippy::deref_addrof,
+    dead_code
+)]
+
+use core::slice;
+use std::collections::*;
+
+fn main() {
+    let mut vec = vec![1, 2, 3, 4];
+
+    for _ in vec.iter() {}
+    for _ in vec.iter_mut() {}
+
+    for _ in &vec {} // these are fine
+    for _ in &mut vec {} // these are fine
+
+    for _ in [1, 2, 3].iter() {}
+
+    for _ in (&mut [1, 2, 3]).iter() {}
+
+    for _ in [0; 32].iter() {}
+    for _ in [0; 33].iter() {}
+
+    let ll: LinkedList<()> = LinkedList::new();
+    for _ in ll.iter() {}
+
+    let vd: VecDeque<()> = VecDeque::new();
+    for _ in vd.iter() {}
+
+    let bh: BinaryHeap<()> = BinaryHeap::new();
+    for _ in bh.iter() {}
+
+    let hm: HashMap<(), ()> = HashMap::new();
+    for _ in hm.iter() {}
+
+    let bt: BTreeMap<(), ()> = BTreeMap::new();
+    for _ in bt.iter() {}
+
+    let hs: HashSet<()> = HashSet::new();
+    for _ in hs.iter() {}
+
+    let bs: BTreeSet<()> = BTreeSet::new();
+    for _ in bs.iter() {}
+
+    struct NoIntoIter();
+    impl NoIntoIter {
+        fn iter(&self) -> slice::Iter<u8> {
+            unimplemented!()
+        }
+
+        fn iter_mut(&mut self) -> slice::IterMut<u8> {
+            unimplemented!()
+        }
+    }
+    let mut x = NoIntoIter();
+    for _ in x.iter() {} // no error
+    for _ in x.iter_mut() {} // no error
+
+    struct IntoIterDiffTy;
+    impl IntoIterator for &'_ IntoIterDiffTy {
+        type Item = &'static ();
+        type IntoIter = core::slice::Iter<'static, ()>;
+        fn into_iter(self) -> Self::IntoIter {
+            unimplemented!()
+        }
+    }
+    impl IntoIterDiffTy {
+        fn iter(&self) -> core::slice::Iter<'static, i32> {
+            unimplemented!()
+        }
+    }
+    let x = IntoIterDiffTy;
+    for _ in x.iter() {}
+
+    struct IntoIterDiffSig;
+    impl IntoIterator for &'_ IntoIterDiffSig {
+        type Item = &'static ();
+        type IntoIter = core::slice::Iter<'static, ()>;
+        fn into_iter(self) -> Self::IntoIter {
+            unimplemented!()
+        }
+    }
+    impl IntoIterDiffSig {
+        fn iter(&self, _: u32) -> core::slice::Iter<'static, ()> {
+            unimplemented!()
+        }
+    }
+    let x = IntoIterDiffSig;
+    for _ in x.iter(0) {}
+
+    struct IntoIterDiffLt<'a>(&'a ());
+    impl<'a> IntoIterator for &'a IntoIterDiffLt<'_> {
+        type Item = &'a ();
+        type IntoIter = core::slice::Iter<'a, ()>;
+        fn into_iter(self) -> Self::IntoIter {
+            unimplemented!()
+        }
+    }
+    impl<'a> IntoIterDiffLt<'a> {
+        fn iter(&self) -> core::slice::Iter<'a, ()> {
+            unimplemented!()
+        }
+    }
+    let x = IntoIterDiffLt(&());
+    for _ in x.iter() {}
+
+    struct CustomType;
+    impl<'a> IntoIterator for &'a CustomType {
+        type Item = &'a u32;
+        type IntoIter = core::slice::Iter<'a, u32>;
+        fn into_iter(self) -> Self::IntoIter {
+            unimplemented!()
+        }
+    }
+    impl<'a> IntoIterator for &'a mut CustomType {
+        type Item = &'a mut u32;
+        type IntoIter = core::slice::IterMut<'a, u32>;
+        fn into_iter(self) -> Self::IntoIter {
+            unimplemented!()
+        }
+    }
+    impl CustomType {
+        fn iter(&self) -> <&'_ Self as IntoIterator>::IntoIter {
+            panic!()
+        }
+
+        fn iter_mut(&mut self) -> core::slice::IterMut<'_, u32> {
+            panic!()
+        }
+    }
+    let mut x = CustomType;
+    for _ in x.iter() {}
+    for _ in x.iter_mut() {}
+}
diff --git a/tests/ui/explicit_iter_loop.stderr b/tests/ui/explicit_iter_loop.stderr
new file mode 100644
index 00000000000..1508080a243
--- /dev/null
+++ b/tests/ui/explicit_iter_loop.stderr
@@ -0,0 +1,106 @@
+error: it is more concise to loop over references to containers instead of using explicit iteration methods
+  --> $DIR/explicit_iter_loop.rs:17:14
+   |
+LL |     for _ in vec.iter() {}
+   |              ^^^^^^^^^^ help: to write this more concisely, try: `&vec`
+   |
+note: the lint level is defined here
+  --> $DIR/explicit_iter_loop.rs:2:9
+   |
+LL | #![deny(clippy::explicit_iter_loop)]
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: it is more concise to loop over references to containers instead of using explicit iteration methods
+  --> $DIR/explicit_iter_loop.rs:18:14
+   |
+LL |     for _ in vec.iter_mut() {}
+   |              ^^^^^^^^^^^^^^ help: to write this more concisely, try: `&mut vec`
+
+error: it is more concise to loop over references to containers instead of using explicit iteration methods
+  --> $DIR/explicit_iter_loop.rs:23:14
+   |
+LL |     for _ in [1, 2, 3].iter() {}
+   |              ^^^^^^^^^^^^^^^^ help: to write this more concisely, try: `&[1, 2, 3]`
+
+error: it is more concise to loop over references to containers instead of using explicit iteration methods
+  --> $DIR/explicit_iter_loop.rs:25:14
+   |
+LL |     for _ in (&mut [1, 2, 3]).iter() {}
+   |              ^^^^^^^^^^^^^^^^^^^^^^^ help: to write this more concisely, try: `&*(&mut [1, 2, 3])`
+
+error: the method `iter` doesn't need a mutable reference
+  --> $DIR/explicit_iter_loop.rs:25:14
+   |
+LL |     for _ in (&mut [1, 2, 3]).iter() {}
+   |              ^^^^^^^^^^^^^^^^
+   |
+   = note: `-D clippy::unnecessary-mut-passed` implied by `-D warnings`
+
+error: it is more concise to loop over references to containers instead of using explicit iteration methods
+  --> $DIR/explicit_iter_loop.rs:27:14
+   |
+LL |     for _ in [0; 32].iter() {}
+   |              ^^^^^^^^^^^^^^ help: to write this more concisely, try: `&[0; 32]`
+
+error: it is more concise to loop over references to containers instead of using explicit iteration methods
+  --> $DIR/explicit_iter_loop.rs:28:14
+   |
+LL |     for _ in [0; 33].iter() {}
+   |              ^^^^^^^^^^^^^^ help: to write this more concisely, try: `&[0; 33]`
+
+error: it is more concise to loop over references to containers instead of using explicit iteration methods
+  --> $DIR/explicit_iter_loop.rs:31:14
+   |
+LL |     for _ in ll.iter() {}
+   |              ^^^^^^^^^ help: to write this more concisely, try: `&ll`
+
+error: it is more concise to loop over references to containers instead of using explicit iteration methods
+  --> $DIR/explicit_iter_loop.rs:34:14
+   |
+LL |     for _ in vd.iter() {}
+   |              ^^^^^^^^^ help: to write this more concisely, try: `&vd`
+
+error: it is more concise to loop over references to containers instead of using explicit iteration methods
+  --> $DIR/explicit_iter_loop.rs:37:14
+   |
+LL |     for _ in bh.iter() {}
+   |              ^^^^^^^^^ help: to write this more concisely, try: `&bh`
+
+error: it is more concise to loop over references to containers instead of using explicit iteration methods
+  --> $DIR/explicit_iter_loop.rs:40:14
+   |
+LL |     for _ in hm.iter() {}
+   |              ^^^^^^^^^ help: to write this more concisely, try: `&hm`
+
+error: it is more concise to loop over references to containers instead of using explicit iteration methods
+  --> $DIR/explicit_iter_loop.rs:43:14
+   |
+LL |     for _ in bt.iter() {}
+   |              ^^^^^^^^^ help: to write this more concisely, try: `&bt`
+
+error: it is more concise to loop over references to containers instead of using explicit iteration methods
+  --> $DIR/explicit_iter_loop.rs:46:14
+   |
+LL |     for _ in hs.iter() {}
+   |              ^^^^^^^^^ help: to write this more concisely, try: `&hs`
+
+error: it is more concise to loop over references to containers instead of using explicit iteration methods
+  --> $DIR/explicit_iter_loop.rs:49:14
+   |
+LL |     for _ in bs.iter() {}
+   |              ^^^^^^^^^ help: to write this more concisely, try: `&bs`
+
+error: it is more concise to loop over references to containers instead of using explicit iteration methods
+  --> $DIR/explicit_iter_loop.rs:138:14
+   |
+LL |     for _ in x.iter() {}
+   |              ^^^^^^^^ help: to write this more concisely, try: `&x`
+
+error: it is more concise to loop over references to containers instead of using explicit iteration methods
+  --> $DIR/explicit_iter_loop.rs:139:14
+   |
+LL |     for _ in x.iter_mut() {}
+   |              ^^^^^^^^^^^^ help: to write this more concisely, try: `&mut x`
+
+error: aborting due to 16 previous errors
+
diff --git a/tests/ui/for_loop_fixable.fixed b/tests/ui/for_loop_fixable.fixed
deleted file mode 100644
index 99230856446..00000000000
--- a/tests/ui/for_loop_fixable.fixed
+++ /dev/null
@@ -1,392 +0,0 @@
-//@run-rustfix
-#![allow(dead_code, unused)]
-#![allow(clippy::uninlined_format_args, clippy::useless_vec, clippy::deref_addrof)]
-
-use std::collections::*;
-
-#[warn(clippy::all)]
-struct Unrelated(Vec<u8>);
-impl Unrelated {
-    fn next(&self) -> std::slice::Iter<u8> {
-        self.0.iter()
-    }
-
-    fn iter(&self) -> std::slice::Iter<u8> {
-        self.0.iter()
-    }
-}
-
-#[warn(
-    clippy::needless_range_loop,
-    clippy::explicit_iter_loop,
-    clippy::explicit_into_iter_loop,
-    clippy::iter_next_loop,
-    clippy::for_kv_map
-)]
-#[allow(
-    clippy::linkedlist,
-    clippy::unnecessary_mut_passed,
-    clippy::similar_names,
-    clippy::needless_borrow
-)]
-#[allow(unused_variables)]
-fn main() {
-    let mut vec = vec![1, 2, 3, 4];
-
-    // See #601
-    for i in 0..10 {
-        // no error, id_col does not exist outside the loop
-        let mut id_col = vec![0f64; 10];
-        id_col[i] = 1f64;
-    }
-
-    for _v in &vec {}
-
-    for _v in &mut vec {}
-
-    let out_vec = vec![1, 2, 3];
-    for _v in out_vec {}
-
-    for _v in &vec {} // these are fine
-    for _v in &mut vec {} // these are fine
-
-    for _v in &[1, 2, 3] {}
-
-    for _v in &*(&mut [1, 2, 3]) {} // no error
-
-    for _v in &[0; 32] {}
-
-    for _v in &[0; 33] {} // no error
-
-    let ll: LinkedList<()> = LinkedList::new();
-    for _v in &ll {}
-
-    let vd: VecDeque<()> = VecDeque::new();
-    for _v in &vd {}
-
-    let bh: BinaryHeap<()> = BinaryHeap::new();
-    for _v in &bh {}
-
-    let hm: HashMap<(), ()> = HashMap::new();
-    for _v in &hm {}
-
-    let bt: BTreeMap<(), ()> = BTreeMap::new();
-    for _v in &bt {}
-
-    let hs: HashSet<()> = HashSet::new();
-    for _v in &hs {}
-
-    let bs: BTreeSet<()> = BTreeSet::new();
-    for _v in &bs {}
-
-    let u = Unrelated(vec![]);
-    for _v in u.next() {} // no error
-    for _v in u.iter() {} // no error
-
-    let mut out = vec![];
-    vec.iter().cloned().map(|x| out.push(x)).collect::<Vec<_>>();
-    let _y = vec.iter().cloned().map(|x| out.push(x)).collect::<Vec<_>>(); // this is fine
-
-    // Loop with explicit counter variable
-
-    // Potential false positives
-    let mut _index = 0;
-    _index = 1;
-    for _v in &vec {
-        _index += 1
-    }
-
-    let mut _index = 0;
-    _index += 1;
-    for _v in &vec {
-        _index += 1
-    }
-
-    let mut _index = 0;
-    if true {
-        _index = 1
-    }
-    for _v in &vec {
-        _index += 1
-    }
-
-    let mut _index = 0;
-    let mut _index = 1;
-    for _v in &vec {
-        _index += 1
-    }
-
-    let mut _index = 0;
-    for _v in &vec {
-        _index += 1;
-        _index += 1
-    }
-
-    let mut _index = 0;
-    for _v in &vec {
-        _index *= 2;
-        _index += 1
-    }
-
-    let mut _index = 0;
-    for _v in &vec {
-        _index = 1;
-        _index += 1
-    }
-
-    let mut _index = 0;
-
-    for _v in &vec {
-        let mut _index = 0;
-        _index += 1
-    }
-
-    let mut _index = 0;
-    for _v in &vec {
-        _index += 1;
-        _index = 0;
-    }
-
-    let mut _index = 0;
-    for _v in &vec {
-        for _x in 0..1 {
-            _index += 1;
-        }
-        _index += 1
-    }
-
-    let mut _index = 0;
-    for x in &vec {
-        if *x == 1 {
-            _index += 1
-        }
-    }
-
-    let mut _index = 0;
-    if true {
-        _index = 1
-    };
-    for _v in &vec {
-        _index += 1
-    }
-
-    let mut _index = 1;
-    if false {
-        _index = 0
-    };
-    for _v in &vec {
-        _index += 1
-    }
-
-    let mut index = 0;
-    {
-        let mut _x = &mut index;
-    }
-    for _v in &vec {
-        _index += 1
-    }
-
-    let mut index = 0;
-    for _v in &vec {
-        index += 1
-    }
-    println!("index: {}", index);
-
-    fn f<T>(_: &T, _: &T) -> bool {
-        unimplemented!()
-    }
-    fn g<T>(_: &mut [T], _: usize, _: usize) {
-        unimplemented!()
-    }
-    for i in 1..vec.len() {
-        if f(&vec[i - 1], &vec[i]) {
-            g(&mut vec, i - 1, i);
-        }
-    }
-
-    for mid in 1..vec.len() {
-        let (_, _) = vec.split_at(mid);
-    }
-}
-
-fn partition<T: PartialOrd + Send>(v: &mut [T]) -> usize {
-    let pivot = v.len() - 1;
-    let mut i = 0;
-    for j in 0..pivot {
-        if v[j] <= v[pivot] {
-            v.swap(i, j);
-            i += 1;
-        }
-    }
-    v.swap(i, pivot);
-    i
-}
-
-#[warn(clippy::needless_range_loop)]
-pub fn manual_copy_same_destination(dst: &mut [i32], d: usize, s: usize) {
-    // Same source and destination - don't trigger lint
-    for i in 0..dst.len() {
-        dst[d + i] = dst[s + i];
-    }
-}
-
-mod issue_2496 {
-    pub trait Handle {
-        fn new_for_index(index: usize) -> Self;
-        fn index(&self) -> usize;
-    }
-
-    pub fn test<H: Handle>() -> H {
-        for x in 0..5 {
-            let next_handle = H::new_for_index(x);
-            println!("{}", next_handle.index());
-        }
-        unimplemented!()
-    }
-}
-
-// explicit_into_iter_loop bad suggestions
-#[warn(clippy::explicit_into_iter_loop, clippy::explicit_iter_loop)]
-mod issue_4958 {
-    fn takes_iterator<T>(iterator: &T)
-    where
-        for<'a> &'a T: IntoIterator<Item = &'a String>,
-    {
-        for i in iterator {
-            println!("{}", i);
-        }
-    }
-
-    struct T;
-    impl IntoIterator for &T {
-        type Item = ();
-        type IntoIter = std::vec::IntoIter<Self::Item>;
-        fn into_iter(self) -> Self::IntoIter {
-            vec![].into_iter()
-        }
-    }
-
-    fn more_tests() {
-        let t = T;
-        let r = &t;
-        let rr = &&t;
-
-        // This case is handled by `explicit_iter_loop`. No idea why.
-        for _ in t {}
-
-        for _ in r {}
-
-        // No suggestion for this.
-        // We'd have to suggest `for _ in *rr {}` which is less clear.
-        for _ in rr.into_iter() {}
-    }
-}
-
-// explicit_into_iter_loop
-#[warn(clippy::explicit_into_iter_loop)]
-mod issue_6900 {
-    struct S;
-    impl S {
-        #[allow(clippy::should_implement_trait)]
-        pub fn into_iter<T>(self) -> I<T> {
-            unimplemented!()
-        }
-    }
-
-    struct I<T>(T);
-    impl<T> Iterator for I<T> {
-        type Item = T;
-        fn next(&mut self) -> Option<Self::Item> {
-            unimplemented!()
-        }
-    }
-
-    fn f() {
-        for _ in S.into_iter::<u32>() {
-            unimplemented!()
-        }
-    }
-}
-
-struct IntoIterDiffTy;
-impl IntoIterator for &'_ IntoIterDiffTy {
-    type Item = &'static ();
-    type IntoIter = core::slice::Iter<'static, ()>;
-    fn into_iter(self) -> Self::IntoIter {
-        unimplemented!()
-    }
-}
-impl IntoIterDiffTy {
-    fn iter(&self) -> core::slice::Iter<'static, i32> {
-        unimplemented!()
-    }
-}
-
-struct IntoIterDiffSig;
-impl IntoIterator for &'_ IntoIterDiffSig {
-    type Item = &'static ();
-    type IntoIter = core::slice::Iter<'static, ()>;
-    fn into_iter(self) -> Self::IntoIter {
-        unimplemented!()
-    }
-}
-impl IntoIterDiffSig {
-    fn iter(&self, _: u32) -> core::slice::Iter<'static, ()> {
-        unimplemented!()
-    }
-}
-
-struct IntoIterDiffLt<'a>(&'a ());
-impl<'a> IntoIterator for &'a IntoIterDiffLt<'_> {
-    type Item = &'a ();
-    type IntoIter = core::slice::Iter<'a, ()>;
-    fn into_iter(self) -> Self::IntoIter {
-        unimplemented!()
-    }
-}
-impl<'a> IntoIterDiffLt<'a> {
-    fn iter(&self) -> core::slice::Iter<'a, ()> {
-        unimplemented!()
-    }
-}
-
-struct CustomType;
-impl<'a> IntoIterator for &'a CustomType {
-    type Item = &'a u32;
-    type IntoIter = core::slice::Iter<'a, u32>;
-    fn into_iter(self) -> Self::IntoIter {
-        unimplemented!()
-    }
-}
-impl<'a> IntoIterator for &'a mut CustomType {
-    type Item = &'a mut u32;
-    type IntoIter = core::slice::IterMut<'a, u32>;
-    fn into_iter(self) -> Self::IntoIter {
-        unimplemented!()
-    }
-}
-impl CustomType {
-    fn iter(&self) -> <&'_ Self as IntoIterator>::IntoIter {
-        panic!()
-    }
-
-    fn iter_mut(&mut self) -> core::slice::IterMut<'_, u32> {
-        panic!()
-    }
-}
-
-#[warn(clippy::explicit_iter_loop)]
-fn _f() {
-    let x = IntoIterDiffTy;
-    for _ in x.iter() {}
-
-    let x = IntoIterDiffSig;
-    for _ in x.iter(0) {}
-
-    let x = IntoIterDiffLt(&());
-    for _ in x.iter() {}
-
-    let mut x = CustomType;
-    for _ in &x {}
-    for _ in &mut x {}
-}
diff --git a/tests/ui/for_loop_fixable.rs b/tests/ui/for_loop_fixable.rs
deleted file mode 100644
index 0d7fe3c0314..00000000000
--- a/tests/ui/for_loop_fixable.rs
+++ /dev/null
@@ -1,392 +0,0 @@
-//@run-rustfix
-#![allow(dead_code, unused)]
-#![allow(clippy::uninlined_format_args, clippy::useless_vec, clippy::deref_addrof)]
-
-use std::collections::*;
-
-#[warn(clippy::all)]
-struct Unrelated(Vec<u8>);
-impl Unrelated {
-    fn next(&self) -> std::slice::Iter<u8> {
-        self.0.iter()
-    }
-
-    fn iter(&self) -> std::slice::Iter<u8> {
-        self.0.iter()
-    }
-}
-
-#[warn(
-    clippy::needless_range_loop,
-    clippy::explicit_iter_loop,
-    clippy::explicit_into_iter_loop,
-    clippy::iter_next_loop,
-    clippy::for_kv_map
-)]
-#[allow(
-    clippy::linkedlist,
-    clippy::unnecessary_mut_passed,
-    clippy::similar_names,
-    clippy::needless_borrow
-)]
-#[allow(unused_variables)]
-fn main() {
-    let mut vec = vec![1, 2, 3, 4];
-
-    // See #601
-    for i in 0..10 {
-        // no error, id_col does not exist outside the loop
-        let mut id_col = vec![0f64; 10];
-        id_col[i] = 1f64;
-    }
-
-    for _v in vec.iter() {}
-
-    for _v in vec.iter_mut() {}
-
-    let out_vec = vec![1, 2, 3];
-    for _v in out_vec.into_iter() {}
-
-    for _v in &vec {} // these are fine
-    for _v in &mut vec {} // these are fine
-
-    for _v in [1, 2, 3].iter() {}
-
-    for _v in (&mut [1, 2, 3]).iter() {} // no error
-
-    for _v in [0; 32].iter() {}
-
-    for _v in [0; 33].iter() {} // no error
-
-    let ll: LinkedList<()> = LinkedList::new();
-    for _v in ll.iter() {}
-
-    let vd: VecDeque<()> = VecDeque::new();
-    for _v in vd.iter() {}
-
-    let bh: BinaryHeap<()> = BinaryHeap::new();
-    for _v in bh.iter() {}
-
-    let hm: HashMap<(), ()> = HashMap::new();
-    for _v in hm.iter() {}
-
-    let bt: BTreeMap<(), ()> = BTreeMap::new();
-    for _v in bt.iter() {}
-
-    let hs: HashSet<()> = HashSet::new();
-    for _v in hs.iter() {}
-
-    let bs: BTreeSet<()> = BTreeSet::new();
-    for _v in bs.iter() {}
-
-    let u = Unrelated(vec![]);
-    for _v in u.next() {} // no error
-    for _v in u.iter() {} // no error
-
-    let mut out = vec![];
-    vec.iter().cloned().map(|x| out.push(x)).collect::<Vec<_>>();
-    let _y = vec.iter().cloned().map(|x| out.push(x)).collect::<Vec<_>>(); // this is fine
-
-    // Loop with explicit counter variable
-
-    // Potential false positives
-    let mut _index = 0;
-    _index = 1;
-    for _v in &vec {
-        _index += 1
-    }
-
-    let mut _index = 0;
-    _index += 1;
-    for _v in &vec {
-        _index += 1
-    }
-
-    let mut _index = 0;
-    if true {
-        _index = 1
-    }
-    for _v in &vec {
-        _index += 1
-    }
-
-    let mut _index = 0;
-    let mut _index = 1;
-    for _v in &vec {
-        _index += 1
-    }
-
-    let mut _index = 0;
-    for _v in &vec {
-        _index += 1;
-        _index += 1
-    }
-
-    let mut _index = 0;
-    for _v in &vec {
-        _index *= 2;
-        _index += 1
-    }
-
-    let mut _index = 0;
-    for _v in &vec {
-        _index = 1;
-        _index += 1
-    }
-
-    let mut _index = 0;
-
-    for _v in &vec {
-        let mut _index = 0;
-        _index += 1
-    }
-
-    let mut _index = 0;
-    for _v in &vec {
-        _index += 1;
-        _index = 0;
-    }
-
-    let mut _index = 0;
-    for _v in &vec {
-        for _x in 0..1 {
-            _index += 1;
-        }
-        _index += 1
-    }
-
-    let mut _index = 0;
-    for x in &vec {
-        if *x == 1 {
-            _index += 1
-        }
-    }
-
-    let mut _index = 0;
-    if true {
-        _index = 1
-    };
-    for _v in &vec {
-        _index += 1
-    }
-
-    let mut _index = 1;
-    if false {
-        _index = 0
-    };
-    for _v in &vec {
-        _index += 1
-    }
-
-    let mut index = 0;
-    {
-        let mut _x = &mut index;
-    }
-    for _v in &vec {
-        _index += 1
-    }
-
-    let mut index = 0;
-    for _v in &vec {
-        index += 1
-    }
-    println!("index: {}", index);
-
-    fn f<T>(_: &T, _: &T) -> bool {
-        unimplemented!()
-    }
-    fn g<T>(_: &mut [T], _: usize, _: usize) {
-        unimplemented!()
-    }
-    for i in 1..vec.len() {
-        if f(&vec[i - 1], &vec[i]) {
-            g(&mut vec, i - 1, i);
-        }
-    }
-
-    for mid in 1..vec.len() {
-        let (_, _) = vec.split_at(mid);
-    }
-}
-
-fn partition<T: PartialOrd + Send>(v: &mut [T]) -> usize {
-    let pivot = v.len() - 1;
-    let mut i = 0;
-    for j in 0..pivot {
-        if v[j] <= v[pivot] {
-            v.swap(i, j);
-            i += 1;
-        }
-    }
-    v.swap(i, pivot);
-    i
-}
-
-#[warn(clippy::needless_range_loop)]
-pub fn manual_copy_same_destination(dst: &mut [i32], d: usize, s: usize) {
-    // Same source and destination - don't trigger lint
-    for i in 0..dst.len() {
-        dst[d + i] = dst[s + i];
-    }
-}
-
-mod issue_2496 {
-    pub trait Handle {
-        fn new_for_index(index: usize) -> Self;
-        fn index(&self) -> usize;
-    }
-
-    pub fn test<H: Handle>() -> H {
-        for x in 0..5 {
-            let next_handle = H::new_for_index(x);
-            println!("{}", next_handle.index());
-        }
-        unimplemented!()
-    }
-}
-
-// explicit_into_iter_loop bad suggestions
-#[warn(clippy::explicit_into_iter_loop, clippy::explicit_iter_loop)]
-mod issue_4958 {
-    fn takes_iterator<T>(iterator: &T)
-    where
-        for<'a> &'a T: IntoIterator<Item = &'a String>,
-    {
-        for i in iterator.into_iter() {
-            println!("{}", i);
-        }
-    }
-
-    struct T;
-    impl IntoIterator for &T {
-        type Item = ();
-        type IntoIter = std::vec::IntoIter<Self::Item>;
-        fn into_iter(self) -> Self::IntoIter {
-            vec![].into_iter()
-        }
-    }
-
-    fn more_tests() {
-        let t = T;
-        let r = &t;
-        let rr = &&t;
-
-        // This case is handled by `explicit_iter_loop`. No idea why.
-        for _ in t.into_iter() {}
-
-        for _ in r.into_iter() {}
-
-        // No suggestion for this.
-        // We'd have to suggest `for _ in *rr {}` which is less clear.
-        for _ in rr.into_iter() {}
-    }
-}
-
-// explicit_into_iter_loop
-#[warn(clippy::explicit_into_iter_loop)]
-mod issue_6900 {
-    struct S;
-    impl S {
-        #[allow(clippy::should_implement_trait)]
-        pub fn into_iter<T>(self) -> I<T> {
-            unimplemented!()
-        }
-    }
-
-    struct I<T>(T);
-    impl<T> Iterator for I<T> {
-        type Item = T;
-        fn next(&mut self) -> Option<Self::Item> {
-            unimplemented!()
-        }
-    }
-
-    fn f() {
-        for _ in S.into_iter::<u32>() {
-            unimplemented!()
-        }
-    }
-}
-
-struct IntoIterDiffTy;
-impl IntoIterator for &'_ IntoIterDiffTy {
-    type Item = &'static ();
-    type IntoIter = core::slice::Iter<'static, ()>;
-    fn into_iter(self) -> Self::IntoIter {
-        unimplemented!()
-    }
-}
-impl IntoIterDiffTy {
-    fn iter(&self) -> core::slice::Iter<'static, i32> {
-        unimplemented!()
-    }
-}
-
-struct IntoIterDiffSig;
-impl IntoIterator for &'_ IntoIterDiffSig {
-    type Item = &'static ();
-    type IntoIter = core::slice::Iter<'static, ()>;
-    fn into_iter(self) -> Self::IntoIter {
-        unimplemented!()
-    }
-}
-impl IntoIterDiffSig {
-    fn iter(&self, _: u32) -> core::slice::Iter<'static, ()> {
-        unimplemented!()
-    }
-}
-
-struct IntoIterDiffLt<'a>(&'a ());
-impl<'a> IntoIterator for &'a IntoIterDiffLt<'_> {
-    type Item = &'a ();
-    type IntoIter = core::slice::Iter<'a, ()>;
-    fn into_iter(self) -> Self::IntoIter {
-        unimplemented!()
-    }
-}
-impl<'a> IntoIterDiffLt<'a> {
-    fn iter(&self) -> core::slice::Iter<'a, ()> {
-        unimplemented!()
-    }
-}
-
-struct CustomType;
-impl<'a> IntoIterator for &'a CustomType {
-    type Item = &'a u32;
-    type IntoIter = core::slice::Iter<'a, u32>;
-    fn into_iter(self) -> Self::IntoIter {
-        unimplemented!()
-    }
-}
-impl<'a> IntoIterator for &'a mut CustomType {
-    type Item = &'a mut u32;
-    type IntoIter = core::slice::IterMut<'a, u32>;
-    fn into_iter(self) -> Self::IntoIter {
-        unimplemented!()
-    }
-}
-impl CustomType {
-    fn iter(&self) -> <&'_ Self as IntoIterator>::IntoIter {
-        panic!()
-    }
-
-    fn iter_mut(&mut self) -> core::slice::IterMut<'_, u32> {
-        panic!()
-    }
-}
-
-#[warn(clippy::explicit_iter_loop)]
-fn _f() {
-    let x = IntoIterDiffTy;
-    for _ in x.iter() {}
-
-    let x = IntoIterDiffSig;
-    for _ in x.iter(0) {}
-
-    let x = IntoIterDiffLt(&());
-    for _ in x.iter() {}
-
-    let mut x = CustomType;
-    for _ in x.iter() {}
-    for _ in x.iter_mut() {}
-}
diff --git a/tests/ui/for_loop_fixable.stderr b/tests/ui/for_loop_fixable.stderr
deleted file mode 100644
index 4ad23e0b9db..00000000000
--- a/tests/ui/for_loop_fixable.stderr
+++ /dev/null
@@ -1,120 +0,0 @@
-error: it is more concise to loop over references to containers instead of using explicit iteration methods
-  --> $DIR/for_loop_fixable.rs:43:15
-   |
-LL |     for _v in vec.iter() {}
-   |               ^^^^^^^^^^ help: to write this more concisely, try: `&vec`
-   |
-   = note: `-D clippy::explicit-iter-loop` implied by `-D warnings`
-
-error: it is more concise to loop over references to containers instead of using explicit iteration methods
-  --> $DIR/for_loop_fixable.rs:45:15
-   |
-LL |     for _v in vec.iter_mut() {}
-   |               ^^^^^^^^^^^^^^ help: to write this more concisely, try: `&mut vec`
-
-error: it is more concise to loop over containers instead of using explicit iteration methods
-  --> $DIR/for_loop_fixable.rs:48:15
-   |
-LL |     for _v in out_vec.into_iter() {}
-   |               ^^^^^^^^^^^^^^^^^^^ help: to write this more concisely, try: `out_vec`
-   |
-   = note: `-D clippy::explicit-into-iter-loop` implied by `-D warnings`
-
-error: it is more concise to loop over references to containers instead of using explicit iteration methods
-  --> $DIR/for_loop_fixable.rs:53:15
-   |
-LL |     for _v in [1, 2, 3].iter() {}
-   |               ^^^^^^^^^^^^^^^^ help: to write this more concisely, try: `&[1, 2, 3]`
-
-error: it is more concise to loop over references to containers instead of using explicit iteration methods
-  --> $DIR/for_loop_fixable.rs:55:15
-   |
-LL |     for _v in (&mut [1, 2, 3]).iter() {} // no error
-   |               ^^^^^^^^^^^^^^^^^^^^^^^ help: to write this more concisely, try: `&*(&mut [1, 2, 3])`
-
-error: it is more concise to loop over references to containers instead of using explicit iteration methods
-  --> $DIR/for_loop_fixable.rs:57:15
-   |
-LL |     for _v in [0; 32].iter() {}
-   |               ^^^^^^^^^^^^^^ help: to write this more concisely, try: `&[0; 32]`
-
-error: it is more concise to loop over references to containers instead of using explicit iteration methods
-  --> $DIR/for_loop_fixable.rs:59:15
-   |
-LL |     for _v in [0; 33].iter() {} // no error
-   |               ^^^^^^^^^^^^^^ help: to write this more concisely, try: `&[0; 33]`
-
-error: it is more concise to loop over references to containers instead of using explicit iteration methods
-  --> $DIR/for_loop_fixable.rs:62:15
-   |
-LL |     for _v in ll.iter() {}
-   |               ^^^^^^^^^ help: to write this more concisely, try: `&ll`
-
-error: it is more concise to loop over references to containers instead of using explicit iteration methods
-  --> $DIR/for_loop_fixable.rs:65:15
-   |
-LL |     for _v in vd.iter() {}
-   |               ^^^^^^^^^ help: to write this more concisely, try: `&vd`
-
-error: it is more concise to loop over references to containers instead of using explicit iteration methods
-  --> $DIR/for_loop_fixable.rs:68:15
-   |
-LL |     for _v in bh.iter() {}
-   |               ^^^^^^^^^ help: to write this more concisely, try: `&bh`
-
-error: it is more concise to loop over references to containers instead of using explicit iteration methods
-  --> $DIR/for_loop_fixable.rs:71:15
-   |
-LL |     for _v in hm.iter() {}
-   |               ^^^^^^^^^ help: to write this more concisely, try: `&hm`
-
-error: it is more concise to loop over references to containers instead of using explicit iteration methods
-  --> $DIR/for_loop_fixable.rs:74:15
-   |
-LL |     for _v in bt.iter() {}
-   |               ^^^^^^^^^ help: to write this more concisely, try: `&bt`
-
-error: it is more concise to loop over references to containers instead of using explicit iteration methods
-  --> $DIR/for_loop_fixable.rs:77:15
-   |
-LL |     for _v in hs.iter() {}
-   |               ^^^^^^^^^ help: to write this more concisely, try: `&hs`
-
-error: it is more concise to loop over references to containers instead of using explicit iteration methods
-  --> $DIR/for_loop_fixable.rs:80:15
-   |
-LL |     for _v in bs.iter() {}
-   |               ^^^^^^^^^ help: to write this more concisely, try: `&bs`
-
-error: it is more concise to loop over containers instead of using explicit iteration methods
-  --> $DIR/for_loop_fixable.rs:255:18
-   |
-LL |         for i in iterator.into_iter() {
-   |                  ^^^^^^^^^^^^^^^^^^^^ help: to write this more concisely, try: `iterator`
-
-error: it is more concise to loop over references to containers instead of using explicit iteration methods
-  --> $DIR/for_loop_fixable.rs:275:18
-   |
-LL |         for _ in t.into_iter() {}
-   |                  ^^^^^^^^^^^^^ help: to write this more concisely, try: `t`
-
-error: it is more concise to loop over containers instead of using explicit iteration methods
-  --> $DIR/for_loop_fixable.rs:277:18
-   |
-LL |         for _ in r.into_iter() {}
-   |                  ^^^^^^^^^^^^^ help: to write this more concisely, try: `r`
-
-error: it is more concise to loop over references to containers instead of using explicit iteration methods
-  --> $DIR/for_loop_fixable.rs:390:14
-   |
-LL |     for _ in x.iter() {}
-   |              ^^^^^^^^ help: to write this more concisely, try: `&x`
-
-error: it is more concise to loop over references to containers instead of using explicit iteration methods
-  --> $DIR/for_loop_fixable.rs:391:14
-   |
-LL |     for _ in x.iter_mut() {}
-   |              ^^^^^^^^^^^^ help: to write this more concisely, try: `&mut x`
-
-error: aborting due to 19 previous errors
-
diff --git a/tests/ui/for_loop_unfixable.rs b/tests/ui/for_loop_unfixable.rs
deleted file mode 100644
index 8e3fb99bc7c..00000000000
--- a/tests/ui/for_loop_unfixable.rs
+++ /dev/null
@@ -1,21 +0,0 @@
-// Tests from for_loop.rs that don't have suggestions
-
-#[warn(
-    clippy::needless_range_loop,
-    clippy::explicit_iter_loop,
-    clippy::explicit_into_iter_loop,
-    clippy::iter_next_loop,
-    clippy::for_kv_map
-)]
-#[allow(
-    clippy::linkedlist,
-    clippy::unnecessary_mut_passed,
-    clippy::similar_names,
-    clippy::useless_vec
-)]
-#[allow(for_loops_over_fallibles)]
-fn main() {
-    let vec = vec![1, 2, 3, 4];
-
-    for _v in vec.iter().next() {}
-}
diff --git a/tests/ui/for_loop_unfixable.stderr b/tests/ui/for_loop_unfixable.stderr
deleted file mode 100644
index 8b163a142a5..00000000000
--- a/tests/ui/for_loop_unfixable.stderr
+++ /dev/null
@@ -1,10 +0,0 @@
-error: you are iterating over `Iterator::next()` which is an Option; this will compile but is probably not what you want
-  --> $DIR/for_loop_unfixable.rs:20:15
-   |
-LL |     for _v in vec.iter().next() {}
-   |               ^^^^^^^^^^^^^^^^^
-   |
-   = note: `-D clippy::iter-next-loop` implied by `-D warnings`
-
-error: aborting due to previous error
-
diff --git a/tests/ui/iter_next_loop.rs b/tests/ui/iter_next_loop.rs
new file mode 100644
index 00000000000..548b799de44
--- /dev/null
+++ b/tests/ui/iter_next_loop.rs
@@ -0,0 +1,16 @@
+#![allow(dead_code, unused, for_loops_over_fallibles)]
+#![warn(clippy::iter_next_loop)]
+
+fn main() {
+    let x = [1, 2, 3, 4];
+    for _ in vec.iter().next() {}
+
+    struct Unrelated(&'static [u8]);
+    impl Unrelated {
+        fn next(&self) -> std::slice::Iter<u8> {
+            self.0.iter()
+        }
+    }
+    let u = Unrelated(&[0]);
+    for _v in u.next() {} // no error
+}
diff --git a/tests/ui/iter_next_loop.stderr b/tests/ui/iter_next_loop.stderr
new file mode 100644
index 00000000000..5bba0e635bb
--- /dev/null
+++ b/tests/ui/iter_next_loop.stderr
@@ -0,0 +1,9 @@
+error[E0423]: expected value, found macro `vec`
+  --> $DIR/iter_next_loop.rs:6:14
+   |
+LL |     for _ in vec.iter().next() {}
+   |              ^^^ not a value
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0423`.
diff --git a/tests/ui/needless_collect.fixed b/tests/ui/needless_collect.fixed
index b7e80af5015..17a56cdfc2f 100644
--- a/tests/ui/needless_collect.fixed
+++ b/tests/ui/needless_collect.fixed
@@ -70,6 +70,11 @@ fn main() {
         bar((0..10).collect::<Vec<_>>(), (0..10));
         baz((0..10), (), ('a'..='z'))
     }
+
+    let values = [1, 2, 3, 4];
+    let mut out = vec![];
+    values.iter().cloned().map(|x| out.push(x)).collect::<Vec<_>>();
+    let _y = values.iter().cloned().map(|x| out.push(x)).collect::<Vec<_>>(); // this is fine
 }
 
 fn foo(_: impl IntoIterator<Item = usize>) {}
diff --git a/tests/ui/needless_collect.rs b/tests/ui/needless_collect.rs
index 680b6fa5b55..8615899e979 100644
--- a/tests/ui/needless_collect.rs
+++ b/tests/ui/needless_collect.rs
@@ -70,6 +70,11 @@ fn main() {
         bar((0..10).collect::<Vec<_>>(), (0..10).collect::<Vec<_>>());
         baz((0..10), (), ('a'..='z').collect::<Vec<_>>())
     }
+
+    let values = [1, 2, 3, 4];
+    let mut out = vec![];
+    values.iter().cloned().map(|x| out.push(x)).collect::<Vec<_>>();
+    let _y = values.iter().cloned().map(|x| out.push(x)).collect::<Vec<_>>(); // this is fine
 }
 
 fn foo(_: impl IntoIterator<Item = usize>) {}
diff --git a/tests/ui/needless_range_loop.rs b/tests/ui/needless_range_loop.rs
index 329cdc1f06b..1935ccb94bd 100644
--- a/tests/ui/needless_range_loop.rs
+++ b/tests/ui/needless_range_loop.rs
@@ -82,6 +82,29 @@ fn main() {
     for i in 0..2 {
         println!("{}", test[i]);
     }
+
+    // See #601
+    for i in 0..10 {
+        // no error, id_col does not exist outside the loop
+        let mut id_col = [0f64; 10];
+        id_col[i] = 1f64;
+    }
+
+    fn f<T>(_: &T, _: &T) -> bool {
+        unimplemented!()
+    }
+    fn g<T>(_: &mut [T], _: usize, _: usize) {
+        unimplemented!()
+    }
+    for i in 1..vec.len() {
+        if f(&vec[i - 1], &vec[i]) {
+            g(&mut vec, i - 1, i);
+        }
+    }
+
+    for mid in 1..vec.len() {
+        let (_, _) = vec.split_at(mid);
+    }
 }
 
 struct Test {
@@ -94,3 +117,38 @@ impl std::ops::Index<usize> for Test {
         &self.inner[index]
     }
 }
+
+fn partition<T: PartialOrd + Send>(v: &mut [T]) -> usize {
+    let pivot = v.len() - 1;
+    let mut i = 0;
+    for j in 0..pivot {
+        if v[j] <= v[pivot] {
+            v.swap(i, j);
+            i += 1;
+        }
+    }
+    v.swap(i, pivot);
+    i
+}
+
+pub fn manual_copy_same_destination(dst: &mut [i32], d: usize, s: usize) {
+    // Same source and destination - don't trigger lint
+    for i in 0..dst.len() {
+        dst[d + i] = dst[s + i];
+    }
+}
+
+mod issue_2496 {
+    pub trait Handle {
+        fn new_for_index(index: usize) -> Self;
+        fn index(&self) -> usize;
+    }
+
+    pub fn test<H: Handle>() -> H {
+        for x in 0..5 {
+            let next_handle = H::new_for_index(x);
+            println!("{}", next_handle.index());
+        }
+        unimplemented!()
+    }
+}