A new lint for shared code in if blocks

* Added expression check for shared_code_in_if_blocks
* Finishing touches for the shared_code_in_if_blocks lint
* Applying PR suggestions
* Update lints yay
* Moved test into subfolder

tests/ui/checked_unwrap/complex_conditionals.rs

@@ -1,5 +1,5 @@
 #![deny(clippy::panicking_unwrap, clippy::unnecessary_unwrap)]
-#![allow(clippy::if_same_then_else)]
+#![allow(clippy::if_same_then_else, clippy::shared_code_in_if_blocks)]
 
 fn test_complex_conditions() {
     let x: Result<(), ()> = Ok(());

tests/ui/if_same_then_else.rs

@@ -5,7 +5,8 @@
     clippy::never_loop,
     clippy::no_effect,
     clippy::unused_unit,
-    clippy::zero_divided_by_zero
+    clippy::zero_divided_by_zero,
+    clippy::shared_code_in_if_blocks
 )]
 
 struct Foo {

tests/ui/if_same_then_else.stderr

@@ -1,19 +1,5 @@
 error: this `if` has identical blocks
-  --> $DIR/if_same_then_else.rs:28:12
-   |
-LL |       } else {
-   |  ____________^
-LL | |         //~ ERROR same body as `if` block
-LL | |         Foo { bar: 42 };
-LL | |         0..10;
-...  |
-LL | |         foo();
-LL | |     }
-   | |_____^
-   |
-   = note: `-D clippy::if-same-then-else` implied by `-D warnings`
-note: same as this
-  --> $DIR/if_same_then_else.rs:20:13
+  --> $DIR/if_same_then_else.rs:21:13
    |
 LL |       if true {
    |  _____________^
@@ -24,79 +10,80 @@ LL | |         ..;
 LL | |         foo();
 LL | |     } else {
    | |_____^
-
-error: this `if` has identical blocks
-  --> $DIR/if_same_then_else.rs:66:12
-   |
-LL |       } else {
-   |  ____________^
-LL | |         //~ ERROR same body as `if` block
-LL | |         0.0
-LL | |     };
-   | |_____^
    |
+   = note: `-D clippy::if-same-then-else` implied by `-D warnings`
 note: same as this
-  --> $DIR/if_same_then_else.rs:64:21
-   |
-LL |       let _ = if true {
-   |  _____________________^
-LL | |         0.0
-LL | |     } else {
-   | |_____^
-
-error: this `if` has identical blocks
-  --> $DIR/if_same_then_else.rs:73:12
+  --> $DIR/if_same_then_else.rs:29:12
    |
 LL |       } else {
    |  ____________^
 LL | |         //~ ERROR same body as `if` block
-LL | |         -0.0
-LL | |     };
-   | |_____^
-   |
-note: same as this
-  --> $DIR/if_same_then_else.rs:71:21
-   |
-LL |       let _ = if true {
-   |  _____________________^
-LL | |         -0.0
-LL | |     } else {
-   | |_____^
-
-error: this `if` has identical blocks
-  --> $DIR/if_same_then_else.rs:89:12
-   |
-LL |       } else {
-   |  ____________^
-LL | |         //~ ERROR same body as `if` block
-LL | |         42
-LL | |     };
-   | |_____^
-   |
-note: same as this
-  --> $DIR/if_same_then_else.rs:87:21
-   |
-LL |       let _ = if true {
-   |  _____________________^
-LL | |         42
-LL | |     } else {
-   | |_____^
-
-error: this `if` has identical blocks
-  --> $DIR/if_same_then_else.rs:101:12
-   |
-LL |       } else {
-   |  ____________^
-LL | |         //~ ERROR same body as `if` block
-LL | |         let bar = if true { 42 } else { 43 };
-LL | |
+LL | |         Foo { bar: 42 };
+LL | |         0..10;
 ...  |
-LL | |         bar + 1;
+LL | |         foo();
 LL | |     }
    | |_____^
+
+error: this `if` has identical blocks
+  --> $DIR/if_same_then_else.rs:65:21
+   |
+LL |       let _ = if true {
+   |  _____________________^
+LL | |         0.0
+LL | |     } else {
+   | |_____^
    |
 note: same as this
-  --> $DIR/if_same_then_else.rs:94:13
+  --> $DIR/if_same_then_else.rs:67:12
+   |
+LL |       } else {
+   |  ____________^
+LL | |         //~ ERROR same body as `if` block
+LL | |         0.0
+LL | |     };
+   | |_____^
+
+error: this `if` has identical blocks
+  --> $DIR/if_same_then_else.rs:72:21
+   |
+LL |       let _ = if true {
+   |  _____________________^
+LL | |         -0.0
+LL | |     } else {
+   | |_____^
+   |
+note: same as this
+  --> $DIR/if_same_then_else.rs:74:12
+   |
+LL |       } else {
+   |  ____________^
+LL | |         //~ ERROR same body as `if` block
+LL | |         -0.0
+LL | |     };
+   | |_____^
+
+error: this `if` has identical blocks
+  --> $DIR/if_same_then_else.rs:88:21
+   |
+LL |       let _ = if true {
+   |  _____________________^
+LL | |         42
+LL | |     } else {
+   | |_____^
+   |
+note: same as this
+  --> $DIR/if_same_then_else.rs:90:12
+   |
+LL |       } else {
+   |  ____________^
+LL | |         //~ ERROR same body as `if` block
+LL | |         42
+LL | |     };
+   | |_____^
+
+error: this `if` has identical blocks
+  --> $DIR/if_same_then_else.rs:95:13
    |
 LL |       if true {
    |  _____________^
@@ -107,6 +94,19 @@ LL | |         while foo() {
 LL | |         bar + 1;
 LL | |     } else {
    | |_____^
+   |
+note: same as this
+  --> $DIR/if_same_then_else.rs:102:12
+   |
+LL |       } else {
+   |  ____________^
+LL | |         //~ ERROR same body as `if` block
+LL | |         let bar = if true { 42 } else { 43 };
+LL | |
+...  |
+LL | |         bar + 1;
+LL | |     }
+   | |_____^
 
 error: aborting due to 5 previous errors
 

tests/ui/if_same_then_else2.rs

@@ -5,7 +5,8 @@
     clippy::collapsible_if,
     clippy::ifs_same_cond,
     clippy::needless_return,
-    clippy::single_element_loop
+    clippy::single_element_loop,
+    clippy::shared_code_in_if_blocks
 )]
 
 fn if_same_then_else2() -> Result<&'static str, ()> {

tests/ui/if_same_then_else2.stderr

@@ -24,8 +24,31 @@ LL | |             if foo.is_some() {
 LL | |         }
 LL | |     } else {
    | |_____^
+   |
+   = note: `-D clippy::if-same-then-else` implied by `-D warnings`
+note: same as this
+  --> $DIR/if_same_then_else2.rs:21:12
+   |
+LL |       } else {
+   |  ____________^
+LL | |         //~ ERROR same body as `if` block
+LL | |         for _ in &[42] {
+LL | |             let foo: &Option<_> = &Some::<u8>(42);
+...  |
+LL | |         }
+LL | |     }
+   | |_____^
 
 error: this `if` has identical blocks
+  --> $DIR/if_same_then_else2.rs:33:13
+   |
+LL |       if true {
+   |  _____________^
+LL | |         if let Some(a) = Some(42) {}
+LL | |     } else {
+   | |_____^
+   |
+note: same as this
   --> $DIR/if_same_then_else2.rs:35:12
    |
 LL |       } else {
@@ -34,17 +57,17 @@ LL | |         //~ ERROR same body as `if` block
 LL | |         if let Some(a) = Some(42) {}
 LL | |     }
    | |_____^
-   |
-note: same as this
-  --> $DIR/if_same_then_else2.rs:33:13
+
+error: this `if` has identical blocks
+  --> $DIR/if_same_then_else2.rs:40:13
    |
 LL |       if true {
    |  _____________^
-LL | |         if let Some(a) = Some(42) {}
+LL | |         if let (1, .., 3) = (1, 2, 3) {}
 LL | |     } else {
    | |_____^
-
-error: this `if` has identical blocks
+   |
+note: same as this
   --> $DIR/if_same_then_else2.rs:42:12
    |
 LL |       } else {
@@ -53,17 +76,17 @@ LL | |         //~ ERROR same body as `if` block
 LL | |         if let (1, .., 3) = (1, 2, 3) {}
 LL | |     }
    | |_____^
-   |
-note: same as this
-  --> $DIR/if_same_then_else2.rs:40:13
-   |
-LL |       if true {
-   |  _____________^
-LL | |         if let (1, .., 3) = (1, 2, 3) {}
-LL | |     } else {
-   | |_____^
 
 error: this `if` has identical blocks
+  --> $DIR/if_same_then_else2.rs:90:21
+   |
+LL |       let _ = if true {
+   |  _____________________^
+LL | |         f32::NAN
+LL | |     } else {
+   | |_____^
+   |
+note: same as this
   --> $DIR/if_same_then_else2.rs:92:12
    |
 LL |       } else {
@@ -72,17 +95,17 @@ LL | |         //~ ERROR same body as `if` block
 LL | |         f32::NAN
 LL | |     };
    | |_____^
-   |
-note: same as this
-  --> $DIR/if_same_then_else2.rs:90:21
-   |
-LL |       let _ = if true {
-   |  _____________________^
-LL | |         f32::NAN
-LL | |     } else {
-   | |_____^
 
 error: this `if` has identical blocks
+  --> $DIR/if_same_then_else2.rs:97:13
+   |
+LL |       if true {
+   |  _____________^
+LL | |         Ok("foo")?;
+LL | |     } else {
+   | |_____^
+   |
+note: same as this
   --> $DIR/if_same_then_else2.rs:99:12
    |
 LL |       } else {
@@ -91,27 +114,8 @@ LL | |         //~ ERROR same body as `if` block
 LL | |         Ok("foo")?;
 LL | |     }
    | |_____^
-   |
-note: same as this
-  --> $DIR/if_same_then_else2.rs:97:13
-   |
-LL |       if true {
-   |  _____________^
-LL | |         Ok("foo")?;
-LL | |     } else {
-   | |_____^
 
 error: this `if` has identical blocks
-  --> $DIR/if_same_then_else2.rs:124:12
-   |
-LL |       } else {
-   |  ____________^
-LL | |         let foo = "";
-LL | |         return Ok(&foo[0..]);
-LL | |     }
-   | |_____^
-   |
-note: same as this
   --> $DIR/if_same_then_else2.rs:121:20
    |
 LL |       } else if true {
@@ -120,6 +124,16 @@ LL | |         let foo = "";
 LL | |         return Ok(&foo[0..]);
 LL | |     } else {
    | |_____^
+   |
+note: same as this
+  --> $DIR/if_same_then_else2.rs:124:12
+   |
+LL |       } else {
+   |  ____________^
+LL | |         let foo = "";
+LL | |         return Ok(&foo[0..]);
+LL | |     }
+   | |_____^
 
 error: aborting due to 6 previous errors
 

tests/ui/let_if_seq.rs

@@ -2,7 +2,8 @@
     unused_variables,
     unused_assignments,
     clippy::similar_names,
-    clippy::blacklisted_name
+    clippy::blacklisted_name,
+    clippy::shared_code_in_if_blocks
 )]
 #![warn(clippy::useless_let_if_seq)]
 

tests/ui/let_if_seq.stderr

@@ -1,5 +1,5 @@
 error: `if _ { .. } else { .. }` is an expression
-  --> $DIR/let_if_seq.rs:64:5
+  --> $DIR/let_if_seq.rs:65:5
    |
 LL | /     let mut foo = 0;
 LL | |     if f() {
@@ -11,7 +11,7 @@ LL | |     }
    = note: you might not need `mut` at all
 
 error: `if _ { .. } else { .. }` is an expression
-  --> $DIR/let_if_seq.rs:69:5
+  --> $DIR/let_if_seq.rs:70:5
    |
 LL | /     let mut bar = 0;
 LL | |     if f() {
@@ -25,7 +25,7 @@ LL | |     }
    = note: you might not need `mut` at all
 
 error: `if _ { .. } else { .. }` is an expression
-  --> $DIR/let_if_seq.rs:77:5
+  --> $DIR/let_if_seq.rs:78:5
    |
 LL | /     let quz;
 LL | |     if f() {
@@ -36,7 +36,7 @@ LL | |     }
    | |_____^ help: it is more idiomatic to write: `let quz = if f() { 42 } else { 0 };`
 
 error: `if _ { .. } else { .. }` is an expression
-  --> $DIR/let_if_seq.rs:106:5
+  --> $DIR/let_if_seq.rs:107:5
    |
 LL | /     let mut baz = 0;
 LL | |     if f() {

tests/ui/shared_code_in_if_blocks/shared_at_bot.rs

@@ -0,0 +1,47 @@
+#![allow(dead_code)]
+#![deny(clippy::if_same_then_else, clippy::shared_code_in_if_blocks)]
+
+// This tests the shared_code_in_if_blocks lint at the end of blocks
+
+fn simple_examples() {
+    // TODO xFrednet 2021-01-06: Test with const literals at the end
+    let x = 1;
+
+    let _ = if x == 7 {
+        println!("Branch I");
+        let start_value = 0;
+        println!("=^.^=");
+
+        // Same but not moveable due to `start_value`
+        let _ = start_value;
+
+        // The rest is self contained and moveable => Only lint the rest
+        let result = false;
+        println!("Block end!");
+        result
+    } else {
+        println!("Branch II");
+        let start_value = 8;
+        println!("xD");
+
+        // Same but not moveable due to `start_value`
+        let _ = start_value;
+
+        // The rest is self contained and moveable => Only lint the rest
+        let result = false;
+        println!("Block end!");
+        result
+    };
+}
+
+/// Simple examples where the move can cause some problems due to moved values
+fn simple_but_suggestion_is_invalid() {
+    // TODO xFrednet 2021-01-12: This
+}
+
+/// Tests where the blocks are not linted due to the used value scope
+fn not_moveable_due_to_value_scope() {
+    // TODO xFrednet 2021-01-12: This
+}
+
+fn main() {}

tests/ui/shared_code_in_if_blocks/shared_at_top.rs

@@ -0,0 +1,83 @@
+#![allow(dead_code, clippy::eval_order_dependence)]
+#![deny(clippy::if_same_then_else, clippy::shared_code_in_if_blocks)]
+
+// This tests the shared_code_in_if_blocks lint at the start of blocks
+
+fn simple_examples() {
+    let x = 0;
+
+    // Simple
+    if true {
+        println!("Hello World!");
+        println!("I'm branch nr: 1");
+    } else {
+        println!("Hello World!");
+        println!("I'm branch nr: 2");
+    }
+
+    // Else if
+    if x == 0 {
+        let y = 9;
+        println!("The value y was set to: `{}`", y);
+        let _z = y;
+
+        println!("I'm the true start index of arrays");
+    } else if x == 1 {
+        let y = 9;
+        println!("The value y was set to: `{}`", y);
+        let _z = y;
+
+        println!("I start counting from 1 so my array starts from `1`");
+    } else {
+        let y = 9;
+        println!("The value y was set to: `{}`", y);
+        let _z = y;
+
+        println!("Ha, Pascal allows you to start the array where you want")
+    }
+
+    // Return a value
+    let _ = if x == 7 {
+        let y = 16;
+        println!("What can I say except: \"you're welcome?\"");
+        let _ = y;
+        x
+    } else {
+        let y = 16;
+        println!("Thank you");
+        y
+    };
+}
+
+/// Simple examples where the move can cause some problems due to moved values
+fn simple_but_suggestion_is_invalid() {
+    let x = 10;
+
+    // Can't be automatically moved because used_value_name is getting used again
+    let used_value_name = 19;
+    if x == 10 {
+        let used_value_name = "Different type";
+        println!("Str: {}", used_value_name);
+        let _ = 1;
+    } else {
+        let used_value_name = "Different type";
+        println!("Str: {}", used_value_name);
+        let _ = 2;
+    }
+    let _ = used_value_name;
+
+    // This can be automatically moved as `can_be_overridden` is not used again
+    let can_be_overridden = 8;
+    let _ = can_be_overridden;
+    if x == 11 {
+        let can_be_overridden = "Move me";
+        println!("I'm also moveable");
+        let _ = 111;
+    } else {
+        let can_be_overridden = "Move me";
+        println!("I'm also moveable");
+        let _ = 222;
+    }
+}
+
+fn main() {}

tests/ui/shared_code_in_if_blocks/shared_at_top_and_bot.rs

@@ -0,0 +1,22 @@
+#![allow(dead_code)]
+#![deny(clippy::if_same_then_else, clippy::shared_code_in_if_blocks)]
+
+// shared_code_in_if_blocks at the top and bottom of the if blocks
+
+fn main() {
+    // TODO xFrednet 2021-01-12: This
+}
+
+// General TODOs By xFrednet:
+
+// 
+// * Make a test with overlapping eq regions (else ifs)
+// * Test if as function parameter, tuple constructor, index, while loop condition
+// * Test where only the expression is the same
+// * Test where the block only has an expression
+// * Test with let on a previous line let _ = \n if...
+// * Tests with unreadable formatting (Inline if, Not indented)
+// * Test multiline condition if x == 9 \n x == 8 {}
+// * Test if for return/break (Only move to front)
+// * Test in inline closures
+// * Test with structs and tuples

tests/ui/shared_code_in_if_blocks/valid_if_blocks.rs

@@ -0,0 +1,157 @@
+#![allow(dead_code, clippy::eval_order_dependence)]
+#![deny(clippy::if_same_then_else, clippy::shared_code_in_if_blocks)]
+
+// This tests the shared_code_in_if_blocks lint at the start of blocks
+
+// Tests with value references are includes in "shared_code_at_bot.rs"
+
+fn valid_examples() {
+    let x = 2;
+
+    // The edge statements are different
+    if x == 9 {
+        let y = 1 << 5;
+
+        println!("This is the same: vvv");
+        let _z = y;
+        println!("The block expression is different");
+
+        println!("Different end 1");
+    } else {
+        let y = 1 << 7;
+
+        println!("This is the same: vvv");
+        let _z = y;
+        println!("The block expression is different");
+
+        println!("Different end 2");
+    }
+
+    // No else
+    if x == 2 {
+        println!("Hello world!");
+        println!("Hello back, how are you?");
+
+        // This is different vvvv
+        println!("Howdy stranger =^.^=");
+
+        println!("Bye Bye World");
+    } else if x == 9 {
+        println!("Hello world!");
+        println!("Hello back, how are you?");
+
+        // This is different vvvv
+        println!("Hello reviewer :D");
+
+        println!("Bye Bye World");
+    }
+
+    // Overlapping statements only in else if blocks -> Don't lint
+    if x == 0 {
+        println!("I'm important!")
+    } else if x == 17 {
+        println!("I share code in else if");
+
+        println!("x is 17");
+    } else {
+        println!("I share code in else if");
+
+        println!("x is nether x nor 17");
+    }
+
+    // Mutability is different
+    if x == 13 {
+        let mut y = 9;
+        println!("Value y is: {}", y);
+        y += 16;
+        let _z1 = y;
+    } else {
+        let y = 9;
+        println!("Value y is: {}", y);
+        let _z2 = y;
+    }
+
+    // Same blocks but at start and bottom so no `if_same_then_else` lint
+    if x == 418 {
+        let y = 9;
+        let z = 8;
+        let _ = (x, y, z);
+        // Don't tell the programmer, my code is also in the else block
+    } else if x == 419 {
+        println!("+-----------+");
+        println!("|           |");
+        println!("|  O     O  |");
+        println!("|     °     |");
+        println!("|  \\_____/  |");
+        println!("|           |");
+        println!("+-----------+");
+    } else {
+        let y = 9;
+        let z = 8;
+        let _ = (x, y, z);
+        // I'm so much better than the x == 418 block. Trust me
+    }
+}
+
+/// This makes sure that the `if_same_then_else` masks the `shared_code_in_if_blocks` lint
+fn trigger_other_lint() {
+    let x = 0;
+    let y = 1;
+
+    // Same block
+    if x == 0 {
+        let u = 19;
+        println!("How are u today?");
+        let _ = "This is a string";
+    } else {
+        let u = 19;
+        println!("How are u today?");
+        let _ = "This is a string";
+    }
+
+    // More complex same blocks
+    if x == 17 {
+        #[derive(Debug)]
+        struct Duck {
+            num: u64,
+        };
+        let pet = Duck { num: 18 };
+        println!("{:?}", pet);
+    } else {
+        #[derive(Debug)]
+        struct Duck {
+            num: u64,
+        };
+        let pet = Duck { num: 18 };
+        println!("{:?}", pet);
+    }
+
+    // Only same expression
+    let _ = if x == 6 { 7 } else { 7 };
+
+    // Same in else if block
+    let _ = if x == 67 {
+        println!("Well I'm the most important block");
+        "I'm a pretty string"
+    } else if x == 68 {
+        println!("I'm a doppelgänger");
+        // Don't listen to my clone below
+
+        if y == 90 {
+            "=^.^="
+        } else {
+            ":D"
+        }
+    } else {
+        // Don't listen to my clone above
+        println!("I'm a doppelgänger");
+
+        if y == 90 {
+            "=^.^="
+        } else {
+            ":D"
+        }
+    };
+}
+
+fn main() {}