reversed_empty_ranges: don't lint N..N except in for loop arg

5 files changed, 22 insertions, 33 deletions

diff --git a/tests/ui/reversed_empty_ranges_fixable.fixed b/tests/ui/reversed_empty_ranges_fixable.fixed
index 332c0427ef6..79e482eec30 100644
--- a/tests/ui/reversed_empty_ranges_fixable.fixed
+++ b/tests/ui/reversed_empty_ranges_fixable.fixed
@@ -4,8 +4,6 @@
 const ANSWER: i32 = 42;
 
 fn main() {
-    let arr = [1, 2, 3, 4, 5];
-
     // These should be linted:
 
     (21..=42).rev().for_each(|x| println!("{}", x));
@@ -14,16 +12,18 @@ fn main() {
     for _ in (-42..=-21).rev() {}
     for _ in (21u32..42u32).rev() {}
 
-    let _ = &[] as &[i32];
-
     // These should be ignored as they are not empty ranges:
 
     (21..=42).for_each(|x| println!("{}", x));
     (21..42).for_each(|x| println!("{}", x));
 
+    let arr = [1, 2, 3, 4, 5];
     let _ = &arr[1..=3];
     let _ = &arr[1..3];
 
     for _ in 21..=42 {}
     for _ in 21..42 {}
+
+    // This range is empty but should be ignored, see issue #5689
+    let _ = &arr[0..0];
 }
diff --git a/tests/ui/reversed_empty_ranges_fixable.rs b/tests/ui/reversed_empty_ranges_fixable.rs
index 901ec8bcc09..b2e8bf33771 100644
--- a/tests/ui/reversed_empty_ranges_fixable.rs
+++ b/tests/ui/reversed_empty_ranges_fixable.rs
@@ -4,8 +4,6 @@
 const ANSWER: i32 = 42;
 
 fn main() {
-    let arr = [1, 2, 3, 4, 5];
-
     // These should be linted:
 
     (42..=21).for_each(|x| println!("{}", x));
@@ -14,16 +12,18 @@ fn main() {
     for _ in -21..=-42 {}
     for _ in 42u32..21u32 {}
 
-    let _ = &arr[3..3];
-
     // These should be ignored as they are not empty ranges:
 
     (21..=42).for_each(|x| println!("{}", x));
     (21..42).for_each(|x| println!("{}", x));
 
+    let arr = [1, 2, 3, 4, 5];
     let _ = &arr[1..=3];
     let _ = &arr[1..3];
 
     for _ in 21..=42 {}
     for _ in 21..42 {}
+
+    // This range is empty but should be ignored, see issue #5689
+    let _ = &arr[0..0];
 }
diff --git a/tests/ui/reversed_empty_ranges_fixable.stderr b/tests/ui/reversed_empty_ranges_fixable.stderr
index 9a646fd9939..de83c4f3d63 100644
--- a/tests/ui/reversed_empty_ranges_fixable.stderr
+++ b/tests/ui/reversed_empty_ranges_fixable.stderr
@@ -1,5 +1,5 @@
 error: this range is empty so it will yield no values
-  --> $DIR/reversed_empty_ranges_fixable.rs:11:5
+  --> $DIR/reversed_empty_ranges_fixable.rs:9:5
    |
 LL |     (42..=21).for_each(|x| println!("{}", x));
    |     ^^^^^^^^^
@@ -11,7 +11,7 @@ LL |     (21..=42).rev().for_each(|x| println!("{}", x));
    |     ^^^^^^^^^^^^^^^
 
 error: this range is empty so it will yield no values
-  --> $DIR/reversed_empty_ranges_fixable.rs:12:13
+  --> $DIR/reversed_empty_ranges_fixable.rs:10:13
    |
 LL |     let _ = (ANSWER..21).filter(|x| x % 2 == 0).take(10).collect::<Vec<_>>();
    |             ^^^^^^^^^^^^
@@ -22,7 +22,7 @@ LL |     let _ = (21..ANSWER).rev().filter(|x| x % 2 == 0).take(10).collect::<Ve
    |             ^^^^^^^^^^^^^^^^^^
 
 error: this range is empty so it will yield no values
-  --> $DIR/reversed_empty_ranges_fixable.rs:14:14
+  --> $DIR/reversed_empty_ranges_fixable.rs:12:14
    |
 LL |     for _ in -21..=-42 {}
    |              ^^^^^^^^^
@@ -33,7 +33,7 @@ LL |     for _ in (-42..=-21).rev() {}
    |              ^^^^^^^^^^^^^^^^^
 
 error: this range is empty so it will yield no values
-  --> $DIR/reversed_empty_ranges_fixable.rs:15:14
+  --> $DIR/reversed_empty_ranges_fixable.rs:13:14
    |
 LL |     for _ in 42u32..21u32 {}
    |              ^^^^^^^^^^^^
@@ -43,11 +43,5 @@ help: consider using the following if you are attempting to iterate over this ra
 LL |     for _ in (21u32..42u32).rev() {}
    |              ^^^^^^^^^^^^^^^^^^^^
 
-error: this range is empty and using it to index a slice will always yield an empty slice
-  --> $DIR/reversed_empty_ranges_fixable.rs:17:18
-   |
-LL |     let _ = &arr[3..3];
-   |              ----^^^^- help: if you want an empty slice, use: `[] as &[i32]`
-
-error: aborting due to 5 previous errors
+error: aborting due to 4 previous errors
 
diff --git a/tests/ui/reversed_empty_ranges_unfixable.rs b/tests/ui/reversed_empty_ranges_unfixable.rs
index 561a35625f0..264d3d1e95a 100644
--- a/tests/ui/reversed_empty_ranges_unfixable.rs
+++ b/tests/ui/reversed_empty_ranges_unfixable.rs
@@ -4,11 +4,12 @@ const ANSWER: i32 = 42;
 const SOME_NUM: usize = 3;
 
 fn main() {
-    let _ = (42 + 10..42 + 10).map(|x| x / 2).find(|&x| x == 21);
-
     let arr = [1, 2, 3, 4, 5];
     let _ = &arr[3usize..=1usize];
     let _ = &arr[SOME_NUM..1];
 
     for _ in ANSWER..ANSWER {}
+
+    // Should not be linted, see issue #5689
+    let _ = (42 + 10..42 + 10).map(|x| x / 2).find(|&x| x == 21);
 }
diff --git a/tests/ui/reversed_empty_ranges_unfixable.stderr b/tests/ui/reversed_empty_ranges_unfixable.stderr
index 240188cbb46..f23d4eb0f9c 100644
--- a/tests/ui/reversed_empty_ranges_unfixable.stderr
+++ b/tests/ui/reversed_empty_ranges_unfixable.stderr
@@ -1,28 +1,22 @@
-error: this range is empty so it will yield no values
-  --> $DIR/reversed_empty_ranges_unfixable.rs:7:13
-   |
-LL |     let _ = (42 + 10..42 + 10).map(|x| x / 2).find(|&x| x == 21);
-   |             ^^^^^^^^^^^^^^^^^^
-   |
-   = note: `-D clippy::reversed-empty-ranges` implied by `-D warnings`
-
 error: this range is reversed and using it to index a slice will panic at run-time
-  --> $DIR/reversed_empty_ranges_unfixable.rs:10:18
+  --> $DIR/reversed_empty_ranges_unfixable.rs:8:18
    |
 LL |     let _ = &arr[3usize..=1usize];
    |                  ^^^^^^^^^^^^^^^
+   |
+   = note: `-D clippy::reversed-empty-ranges` implied by `-D warnings`
 
 error: this range is reversed and using it to index a slice will panic at run-time
-  --> $DIR/reversed_empty_ranges_unfixable.rs:11:18
+  --> $DIR/reversed_empty_ranges_unfixable.rs:9:18
    |
 LL |     let _ = &arr[SOME_NUM..1];
    |                  ^^^^^^^^^^^
 
 error: this range is empty so it will yield no values
-  --> $DIR/reversed_empty_ranges_unfixable.rs:13:14
+  --> $DIR/reversed_empty_ranges_unfixable.rs:11:14
    |
 LL |     for _ in ANSWER..ANSWER {}
    |              ^^^^^^^^^^^^^^
 
-error: aborting due to 4 previous errors
+error: aborting due to 3 previous errors