From 70704db36fd07353de58c9330397d0137afdeebe Mon Sep 17 00:00:00 2001
From: ThibsG <Thibs@debian.com>
Date: Fri, 15 Jan 2021 18:51:00 +0100
Subject: [PATCH 1/2] Do not lint when range is completely included into
 another one

---
 clippy_lints/src/matches.rs           | 12 +++++++++++-
 tests/ui/match_overlapping_arm.rs     | 12 ++++++++++++
 tests/ui/match_overlapping_arm.stderr | 26 +-------------------------
 3 files changed, 24 insertions(+), 26 deletions(-)

diff --git a/clippy_lints/src/matches.rs b/clippy_lints/src/matches.rs
index 04b35835c6b8..90c63f32c135 100644
--- a/clippy_lints/src/matches.rs
+++ b/clippy_lints/src/matches.rs
@@ -1544,7 +1544,17 @@ where
                 }
             },
             (&Kind::End(a, _), &Kind::Start(b, _)) if a != Bound::Included(b) => (),
-            _ => return Some((a.range(), b.range())),
+            _ => {
+                // skip if the range `a` is completely included into the range `b`
+                if let Ordering::Equal | Ordering::Less = a.cmp(&b) {
+                    let kind_a = Kind::End(a.range().node.1, a.range());
+                    let kind_b = Kind::End(b.range().node.1, b.range());
+                    if let Ordering::Equal | Ordering::Greater = kind_a.cmp(&kind_b) {
+                        return None;
+                    }
+                }
+                return Some((a.range(), b.range()));
+            },
         }
     }
 
diff --git a/tests/ui/match_overlapping_arm.rs b/tests/ui/match_overlapping_arm.rs
index 97789bb766f8..3e40f2187bf5 100644
--- a/tests/ui/match_overlapping_arm.rs
+++ b/tests/ui/match_overlapping_arm.rs
@@ -57,6 +57,18 @@ fn overlapping() {
         _ => (),
     }
 
+    match 42 {
+        5..7 => println!("5 .. 7"),
+        0..10 => println!("0 .. 10"),
+        _ => (),
+    }
+
+    match 42 {
+        5..10 => println!("5 .. 10"),
+        0..=10 => println!("0 ... 10"),
+        _ => (),
+    }
+
     /*
     // FIXME(JohnTitor): uncomment this once rustfmt knows half-open patterns
     match 42 {
diff --git a/tests/ui/match_overlapping_arm.stderr b/tests/ui/match_overlapping_arm.stderr
index eb20d5405a95..74259cd88c78 100644
--- a/tests/ui/match_overlapping_arm.stderr
+++ b/tests/ui/match_overlapping_arm.stderr
@@ -23,30 +23,6 @@ note: overlaps with this
 LL |         FOO..=11 => println!("0 ... 11"),
    |         ^^^^^^^^
 
-error: some ranges overlap
-  --> $DIR/match_overlapping_arm.rs:26:9
-   |
-LL |         0..=5 => println!("0 ... 5"),
-   |         ^^^^^
-   |
-note: overlaps with this
-  --> $DIR/match_overlapping_arm.rs:25:9
-   |
-LL |         2 => println!("2"),
-   |         ^
-
-error: some ranges overlap
-  --> $DIR/match_overlapping_arm.rs:32:9
-   |
-LL |         0..=2 => println!("0 ... 2"),
-   |         ^^^^^
-   |
-note: overlaps with this
-  --> $DIR/match_overlapping_arm.rs:31:9
-   |
-LL |         2 => println!("2"),
-   |         ^
-
 error: some ranges overlap
   --> $DIR/match_overlapping_arm.rs:55:9
    |
@@ -59,5 +35,5 @@ note: overlaps with this
 LL |         0..=11 => println!("0 ... 11"),
    |         ^^^^^^
 
-error: aborting due to 5 previous errors
+error: aborting due to 3 previous errors
 

From 051891173d4018abfb353235c912e8cd649f73e3 Mon Sep 17 00:00:00 2001
From: ThibsG <Thibs@debian.com>
Date: Sun, 24 Jan 2021 12:28:59 +0100
Subject: [PATCH 2/2] Add more tests for `match_overlapping_arm` lint

---
 tests/ui/match_overlapping_arm.rs     | 18 ++++++++++++++++++
 tests/ui/match_overlapping_arm.stderr | 26 +++++++++++++++++++++++++-
 2 files changed, 43 insertions(+), 1 deletion(-)

diff --git a/tests/ui/match_overlapping_arm.rs b/tests/ui/match_overlapping_arm.rs
index 3e40f2187bf5..44c51e8112a7 100644
--- a/tests/ui/match_overlapping_arm.rs
+++ b/tests/ui/match_overlapping_arm.rs
@@ -69,6 +69,24 @@ fn overlapping() {
         _ => (),
     }
 
+    match 42 {
+        0..14 => println!("0 .. 14"),
+        5..10 => println!("5 .. 10"),
+        _ => (),
+    }
+
+    match 42 {
+        5..14 => println!("5 .. 14"),
+        0..=10 => println!("0 ... 10"),
+        _ => (),
+    }
+
+    match 42 {
+        0..7 => println!("0 .. 7"),
+        0..=10 => println!("0 ... 10"),
+        _ => (),
+    }
+
     /*
     // FIXME(JohnTitor): uncomment this once rustfmt knows half-open patterns
     match 42 {
diff --git a/tests/ui/match_overlapping_arm.stderr b/tests/ui/match_overlapping_arm.stderr
index 74259cd88c78..f25a66d634e8 100644
--- a/tests/ui/match_overlapping_arm.stderr
+++ b/tests/ui/match_overlapping_arm.stderr
@@ -35,5 +35,29 @@ note: overlaps with this
 LL |         0..=11 => println!("0 ... 11"),
    |         ^^^^^^
 
-error: aborting due to 3 previous errors
+error: some ranges overlap
+  --> $DIR/match_overlapping_arm.rs:80:9
+   |
+LL |         0..=10 => println!("0 ... 10"),
+   |         ^^^^^^
+   |
+note: overlaps with this
+  --> $DIR/match_overlapping_arm.rs:79:9
+   |
+LL |         5..14 => println!("5 .. 14"),
+   |         ^^^^^
+
+error: some ranges overlap
+  --> $DIR/match_overlapping_arm.rs:85:9
+   |
+LL |         0..7 => println!("0 .. 7"),
+   |         ^^^^
+   |
+note: overlaps with this
+  --> $DIR/match_overlapping_arm.rs:86:9
+   |
+LL |         0..=10 => println!("0 ... 10"),
+   |         ^^^^^^
+
+error: aborting due to 5 previous errors