New lint: manual_midpoint

tests/ui/manual_midpoint.fixed

@@ -0,0 +1,74 @@
+#![warn(clippy::manual_midpoint)]
+
+macro_rules! mac {
+    ($a: expr, $b: expr) => {
+        ($a + $b) / 2
+    };
+}
+
+macro_rules! add {
+    ($a: expr, $b: expr) => {
+        ($a + $b)
+    };
+}
+
+macro_rules! two {
+    () => {
+        2
+    };
+}
+
+#[clippy::msrv = "1.84"]
+fn older_msrv() {
+    let a: u32 = 10;
+    let _ = (a + 5) / 2;
+}
+
+#[clippy::msrv = "1.85"]
+fn main() {
+    let a: u32 = 10;
+    let _ = u32::midpoint(a, 5); //~ ERROR: manual implementation of `midpoint`
+
+    let f: f32 = 10.0;
+    let _ = f32::midpoint(f, 5.0); //~ ERROR: manual implementation of `midpoint`
+
+    let _: u32 = 5 + u32::midpoint(8, 8) + 2; //~ ERROR: manual implementation of `midpoint`
+    let _: u32 = const { u32::midpoint(8, 8) }; //~ ERROR: manual implementation of `midpoint`
+    let _: f64 = const { f64::midpoint(8.0f64, 8.) }; //~ ERROR: manual implementation of `midpoint`
+    let _: u32 = u32::midpoint(u32::default(), u32::default()); //~ ERROR: manual implementation of `midpoint`
+    let _: u32 = u32::midpoint(two!(), two!()); //~ ERROR: manual implementation of `midpoint`
+
+    // Do not lint in presence of an addition with more than 2 operands
+    let _: u32 = (10 + 20 + 30) / 2;
+
+    // Do not lint if whole or part is coming from a macro
+    let _ = mac!(10, 20);
+    let _: u32 = add!(10u32, 20u32) / 2;
+    let _: u32 = (10 + 20) / two!();
+
+    // Do not lint if a literal is not present
+    let _ = (f + 5.0) / (1.0 + 1.0);
+
+    // Do not lint on signed integer types
+    let i: i32 = 10;
+    let _ = (i + 5) / 2;
+
+    // Do not lint on (x+1)/2 or (1+x)/2 as this looks more like a `div_ceil()` operation
+    let _ = (i + 1) / 2;
+    let _ = (1 + i) / 2;
+
+    // But if we see (x+1.0)/2.0 or (x+1.0)/2.0, it is probably a midpoint operation
+    let _ = f32::midpoint(f, 1.0); //~ ERROR: manual implementation of `midpoint`
+    let _ = f32::midpoint(1.0, f); //~ ERROR: manual implementation of `midpoint`
+}
+
+#[clippy::msrv = "1.86"]
+fn older_signed_midpoint(i: i32) {
+    // Do not lint
+    let _ = (i + 10) / 2;
+}
+
+#[clippy::msrv = "1.87"]
+fn signed_midpoint(i: i32) {
+    let _ = i32::midpoint(i, 10); //~ ERROR: manual implementation of `midpoint`
+}

tests/ui/manual_midpoint.rs

@@ -0,0 +1,74 @@
+#![warn(clippy::manual_midpoint)]
+
+macro_rules! mac {
+    ($a: expr, $b: expr) => {
+        ($a + $b) / 2
+    };
+}
+
+macro_rules! add {
+    ($a: expr, $b: expr) => {
+        ($a + $b)
+    };
+}
+
+macro_rules! two {
+    () => {
+        2
+    };
+}
+
+#[clippy::msrv = "1.84"]
+fn older_msrv() {
+    let a: u32 = 10;
+    let _ = (a + 5) / 2;
+}
+
+#[clippy::msrv = "1.85"]
+fn main() {
+    let a: u32 = 10;
+    let _ = (a + 5) / 2; //~ ERROR: manual implementation of `midpoint`
+
+    let f: f32 = 10.0;
+    let _ = (f + 5.0) / 2.0; //~ ERROR: manual implementation of `midpoint`
+
+    let _: u32 = 5 + (8 + 8) / 2 + 2; //~ ERROR: manual implementation of `midpoint`
+    let _: u32 = const { (8 + 8) / 2 }; //~ ERROR: manual implementation of `midpoint`
+    let _: f64 = const { (8.0f64 + 8.) / 2. }; //~ ERROR: manual implementation of `midpoint`
+    let _: u32 = (u32::default() + u32::default()) / 2; //~ ERROR: manual implementation of `midpoint`
+    let _: u32 = (two!() + two!()) / 2; //~ ERROR: manual implementation of `midpoint`
+
+    // Do not lint in presence of an addition with more than 2 operands
+    let _: u32 = (10 + 20 + 30) / 2;
+
+    // Do not lint if whole or part is coming from a macro
+    let _ = mac!(10, 20);
+    let _: u32 = add!(10u32, 20u32) / 2;
+    let _: u32 = (10 + 20) / two!();
+
+    // Do not lint if a literal is not present
+    let _ = (f + 5.0) / (1.0 + 1.0);
+
+    // Do not lint on signed integer types
+    let i: i32 = 10;
+    let _ = (i + 5) / 2;
+
+    // Do not lint on (x+1)/2 or (1+x)/2 as this looks more like a `div_ceil()` operation
+    let _ = (i + 1) / 2;
+    let _ = (1 + i) / 2;
+
+    // But if we see (x+1.0)/2.0 or (x+1.0)/2.0, it is probably a midpoint operation
+    let _ = (f + 1.0) / 2.0; //~ ERROR: manual implementation of `midpoint`
+    let _ = (1.0 + f) / 2.0; //~ ERROR: manual implementation of `midpoint`
+}
+
+#[clippy::msrv = "1.86"]
+fn older_signed_midpoint(i: i32) {
+    // Do not lint
+    let _ = (i + 10) / 2;
+}
+
+#[clippy::msrv = "1.87"]
+fn signed_midpoint(i: i32) {
+    let _ = (i + 10) / 2; //~ ERROR: manual implementation of `midpoint`
+}

tests/ui/manual_midpoint.stderr

@@ -0,0 +1,65 @@
+error: manual implementation of `midpoint` which can overflow
+  --> tests/ui/manual_midpoint.rs:30:13
+   |
+LL |     let _ = (a + 5) / 2;
+   |             ^^^^^^^^^^^ help: use `u32::midpoint` instead: `u32::midpoint(a, 5)`
+   |
+   = note: `-D clippy::manual-midpoint` implied by `-D warnings`
+   = help: to override `-D warnings` add `#[allow(clippy::manual_midpoint)]`
+
+error: manual implementation of `midpoint` which can overflow
+  --> tests/ui/manual_midpoint.rs:33:13
+   |
+LL |     let _ = (f + 5.0) / 2.0;
+   |             ^^^^^^^^^^^^^^^ help: use `f32::midpoint` instead: `f32::midpoint(f, 5.0)`
+
+error: manual implementation of `midpoint` which can overflow
+  --> tests/ui/manual_midpoint.rs:35:22
+   |
+LL |     let _: u32 = 5 + (8 + 8) / 2 + 2;
+   |                      ^^^^^^^^^^^ help: use `u32::midpoint` instead: `u32::midpoint(8, 8)`
+
+error: manual implementation of `midpoint` which can overflow
+  --> tests/ui/manual_midpoint.rs:36:26
+   |
+LL |     let _: u32 = const { (8 + 8) / 2 };
+   |                          ^^^^^^^^^^^ help: use `u32::midpoint` instead: `u32::midpoint(8, 8)`
+
+error: manual implementation of `midpoint` which can overflow
+  --> tests/ui/manual_midpoint.rs:37:26
+   |
+LL |     let _: f64 = const { (8.0f64 + 8.) / 2. };
+   |                          ^^^^^^^^^^^^^^^^^^ help: use `f64::midpoint` instead: `f64::midpoint(8.0f64, 8.)`
+
+error: manual implementation of `midpoint` which can overflow
+  --> tests/ui/manual_midpoint.rs:38:18
+   |
+LL |     let _: u32 = (u32::default() + u32::default()) / 2;
+   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `u32::midpoint` instead: `u32::midpoint(u32::default(), u32::default())`
+
+error: manual implementation of `midpoint` which can overflow
+  --> tests/ui/manual_midpoint.rs:39:18
+   |
+LL |     let _: u32 = (two!() + two!()) / 2;
+   |                  ^^^^^^^^^^^^^^^^^^^^^ help: use `u32::midpoint` instead: `u32::midpoint(two!(), two!())`
+
+error: manual implementation of `midpoint` which can overflow
+  --> tests/ui/manual_midpoint.rs:61:13
+   |
+LL |     let _ = (f + 1.0) / 2.0;
+   |             ^^^^^^^^^^^^^^^ help: use `f32::midpoint` instead: `f32::midpoint(f, 1.0)`
+
+error: manual implementation of `midpoint` which can overflow
+  --> tests/ui/manual_midpoint.rs:62:13
+   |
+LL |     let _ = (1.0 + f) / 2.0;
+   |             ^^^^^^^^^^^^^^^ help: use `f32::midpoint` instead: `f32::midpoint(1.0, f)`
+
+error: manual implementation of `midpoint` which can overflow
+  --> tests/ui/manual_midpoint.rs:73:13
+   |
+LL |     let _ = (i + 10) / 2;
+   |             ^^^^^^^^^^^^ help: use `i32::midpoint` instead: `i32::midpoint(i, 10)`
+
+error: aborting due to 10 previous errors
+

tests/ui/option_if_let_else.fixed

@@ -4,6 +4,7 @@
     clippy::equatable_if_let,
     clippy::let_unit_value,
     clippy::redundant_locals,
+    clippy::manual_midpoint,
     clippy::manual_unwrap_or_default,
     clippy::manual_unwrap_or
 )]

tests/ui/option_if_let_else.rs

@@ -4,6 +4,7 @@
     clippy::equatable_if_let,
     clippy::let_unit_value,
     clippy::redundant_locals,
+    clippy::manual_midpoint,
     clippy::manual_unwrap_or_default,
     clippy::manual_unwrap_or
 )]

tests/ui/option_if_let_else.stderr

@@ -1,5 +1,5 @@
 error: use Option::map_or instead of an if let/else
-  --> tests/ui/option_if_let_else.rs:12:5
+  --> tests/ui/option_if_let_else.rs:13:5
    |
 LL | /     if let Some(x) = string {
 LL | |
@@ -13,19 +13,19 @@ LL | |     }
    = help: to override `-D warnings` add `#[allow(clippy::option_if_let_else)]`
 
 error: use Option::map_or instead of an if let/else
-  --> tests/ui/option_if_let_else.rs:31:13
+  --> tests/ui/option_if_let_else.rs:32:13
    |
 LL |     let _ = if let Some(s) = *string { s.len() } else { 0 };
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `string.map_or(0, |s| s.len())`
 
 error: use Option::map_or instead of an if let/else
-  --> tests/ui/option_if_let_else.rs:33:13
+  --> tests/ui/option_if_let_else.rs:34:13
    |
 LL |     let _ = if let Some(s) = &num { s } else { &0 };
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `num.as_ref().map_or(&0, |s| s)`
 
 error: use Option::map_or instead of an if let/else
-  --> tests/ui/option_if_let_else.rs:35:13
+  --> tests/ui/option_if_let_else.rs:36:13
    |
 LL |       let _ = if let Some(s) = &mut num {
    |  _____________^
@@ -47,13 +47,13 @@ LL ~     });
    |
 
 error: use Option::map_or instead of an if let/else
-  --> tests/ui/option_if_let_else.rs:42:13
+  --> tests/ui/option_if_let_else.rs:43:13
    |
 LL |     let _ = if let Some(ref s) = num { s } else { &0 };
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `num.as_ref().map_or(&0, |s| s)`
 
 error: use Option::map_or instead of an if let/else
-  --> tests/ui/option_if_let_else.rs:44:13
+  --> tests/ui/option_if_let_else.rs:45:13
    |
 LL |       let _ = if let Some(mut s) = num {
    |  _____________^
@@ -75,7 +75,7 @@ LL ~     });
    |
 
 error: use Option::map_or instead of an if let/else
-  --> tests/ui/option_if_let_else.rs:51:13
+  --> tests/ui/option_if_let_else.rs:52:13
    |
 LL |       let _ = if let Some(ref mut s) = num {
    |  _____________^
@@ -97,7 +97,7 @@ LL ~     });
    |
 
 error: use Option::map_or instead of an if let/else
-  --> tests/ui/option_if_let_else.rs:61:5
+  --> tests/ui/option_if_let_else.rs:62:5
    |
 LL | /     if let Some(x) = arg {
 LL | |
@@ -118,7 +118,7 @@ LL +     })
    |
 
 error: use Option::map_or_else instead of an if let/else
-  --> tests/ui/option_if_let_else.rs:75:13
+  --> tests/ui/option_if_let_else.rs:76:13
    |
 LL |       let _ = if let Some(x) = arg {
    |  _____________^
@@ -131,7 +131,7 @@ LL | |     };
    | |_____^ help: try: `arg.map_or_else(side_effect, |x| x)`
 
 error: use Option::map_or_else instead of an if let/else
-  --> tests/ui/option_if_let_else.rs:85:13
+  --> tests/ui/option_if_let_else.rs:86:13
    |
 LL |       let _ = if let Some(x) = arg {
    |  _____________^
@@ -154,7 +154,7 @@ LL ~     }, |x| x * x * x * x);
    |
 
 error: use Option::map_or_else instead of an if let/else
-  --> tests/ui/option_if_let_else.rs:119:13
+  --> tests/ui/option_if_let_else.rs:120:13
    |
 LL | /             if let Some(idx) = s.find('.') {
 LL | |
@@ -165,7 +165,7 @@ LL | |             }
    | |_____________^ help: try: `s.find('.').map_or_else(|| vec![s.to_string()], |idx| vec![s[..idx].to_string(), s[idx..].to_string()])`
 
 error: use Option::map_or_else instead of an if let/else
-  --> tests/ui/option_if_let_else.rs:131:5
+  --> tests/ui/option_if_let_else.rs:132:5
    |
 LL | /     if let Ok(binding) = variable {
 LL | |
@@ -189,13 +189,13 @@ LL +     })
    |
 
 error: use Option::map_or instead of an if let/else
-  --> tests/ui/option_if_let_else.rs:156:13
+  --> tests/ui/option_if_let_else.rs:157:13
    |
 LL |     let _ = if let Some(x) = optional { x + 2 } else { 5 };
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `optional.map_or(5, |x| x + 2)`
 
 error: use Option::map_or instead of an if let/else
-  --> tests/ui/option_if_let_else.rs:167:13
+  --> tests/ui/option_if_let_else.rs:168:13
    |
 LL |       let _ = if let Some(x) = Some(0) {
    |  _____________^
@@ -217,13 +217,13 @@ LL ~         });
    |
 
 error: use Option::map_or instead of an if let/else
-  --> tests/ui/option_if_let_else.rs:196:13
+  --> tests/ui/option_if_let_else.rs:197:13
    |
 LL |     let _ = if let Some(x) = Some(0) { s.len() + x } else { s.len() };
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `Some(0).map_or(s.len(), |x| s.len() + x)`
 
 error: use Option::map_or instead of an if let/else
-  --> tests/ui/option_if_let_else.rs:201:13
+  --> tests/ui/option_if_let_else.rs:202:13
    |
 LL |       let _ = if let Some(x) = Some(0) {
    |  _____________^
@@ -245,7 +245,7 @@ LL ~     });
    |
 
 error: use Option::map_or instead of an if let/else
-  --> tests/ui/option_if_let_else.rs:241:13
+  --> tests/ui/option_if_let_else.rs:242:13
    |
 LL |       let _ = match s {
    |  _____________^
@@ -256,7 +256,7 @@ LL | |     };
    | |_____^ help: try: `s.map_or(1, |string| string.len())`
 
 error: use Option::map_or instead of an if let/else
-  --> tests/ui/option_if_let_else.rs:246:13
+  --> tests/ui/option_if_let_else.rs:247:13
    |
 LL |       let _ = match Some(10) {
    |  _____________^
@@ -267,7 +267,7 @@ LL | |     };
    | |_____^ help: try: `Some(10).map_or(5, |a| a + 1)`
 
 error: use Option::map_or instead of an if let/else
-  --> tests/ui/option_if_let_else.rs:253:13
+  --> tests/ui/option_if_let_else.rs:254:13
    |
 LL |       let _ = match res {
    |  _____________^
@@ -278,7 +278,7 @@ LL | |     };
    | |_____^ help: try: `res.map_or(1, |a| a + 1)`
 
 error: use Option::map_or instead of an if let/else
-  --> tests/ui/option_if_let_else.rs:258:13
+  --> tests/ui/option_if_let_else.rs:259:13
    |
 LL |       let _ = match res {
    |  _____________^
@@ -289,13 +289,13 @@ LL | |     };
    | |_____^ help: try: `res.map_or(1, |a| a + 1)`
 
 error: use Option::map_or instead of an if let/else
-  --> tests/ui/option_if_let_else.rs:263:13
+  --> tests/ui/option_if_let_else.rs:264:13
    |
 LL |     let _ = if let Ok(a) = res { a + 1 } else { 5 };
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `res.map_or(5, |a| a + 1)`
 
 error: use Option::map_or instead of an if let/else
-  --> tests/ui/option_if_let_else.rs:281:17
+  --> tests/ui/option_if_let_else.rs:282:17
    |
 LL |           let _ = match initial {
    |  _________________^
@@ -306,7 +306,7 @@ LL | |         };
    | |_________^ help: try: `initial.as_ref().map_or(42, |value| do_something(value))`
 
 error: use Option::map_or instead of an if let/else
-  --> tests/ui/option_if_let_else.rs:289:17
+  --> tests/ui/option_if_let_else.rs:290:17
    |
 LL |           let _ = match initial {
    |  _________________^
@@ -317,7 +317,7 @@ LL | |         };
    | |_________^ help: try: `initial.as_mut().map_or(42, |value| do_something2(value))`
 
 error: use Option::map_or_else instead of an if let/else
-  --> tests/ui/option_if_let_else.rs:313:24
+  --> tests/ui/option_if_let_else.rs:314:24
    |
 LL |       let mut _hashmap = if let Some(hm) = &opt {
    |  ________________________^
@@ -329,7 +329,7 @@ LL | |     };
    | |_____^ help: try: `opt.as_ref().map_or_else(HashMap::new, |hm| hm.clone())`
 
 error: use Option::map_or_else instead of an if let/else
-  --> tests/ui/option_if_let_else.rs:320:19
+  --> tests/ui/option_if_let_else.rs:321:19
    |
 LL |     let mut _hm = if let Some(hm) = &opt { hm.clone() } else { new_map!() };
    |                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `opt.as_ref().map_or_else(|| new_map!(), |hm| hm.clone())`

tests/ui/suspicious_operation_groupings.fixed

@@ -1,7 +1,7 @@
 //@compile-flags: -Zdeduplicate-diagnostics=yes
 
 #![warn(clippy::suspicious_operation_groupings)]
-#![allow(dead_code, unused_parens, clippy::eq_op)]
+#![allow(dead_code, unused_parens, clippy::eq_op, clippy::manual_midpoint)]
 
 struct Vec3 {
     x: f64,

tests/ui/suspicious_operation_groupings.rs

@@ -1,7 +1,7 @@
 //@compile-flags: -Zdeduplicate-diagnostics=yes
 
 #![warn(clippy::suspicious_operation_groupings)]
-#![allow(dead_code, unused_parens, clippy::eq_op)]
+#![allow(dead_code, unused_parens, clippy::eq_op, clippy::manual_midpoint)]
 
 struct Vec3 {
     x: f64,