3 files changed, 143 insertions, 3 deletions

diff --git a/tests/ui/identity_op.fixed b/tests/ui/identity_op.fixed
index b18d8560f6f..18b7401768d 100644
--- a/tests/ui/identity_op.fixed
+++ b/tests/ui/identity_op.fixed
@@ -149,7 +149,7 @@ fn main() {
 
     2 * { a };
     //~^ ERROR: this operation has no effect
-    (({ a } + 4));
+    ({ a } + 4);
     //~^ ERROR: this operation has no effect
     1;
     //~^ ERROR: this operation has no effect
@@ -212,3 +212,43 @@ fn issue_12050() {
         //~^ ERROR: this operation has no effect
     }
 }
+
+fn issue_13470() {
+    let x = 1i32;
+    let y = 1i32;
+    // Removes the + 0i32 while keeping the parentheses around x + y so the cast operation works
+    let _: u64 = (x + y) as u64;
+    //~^ ERROR: this operation has no effect
+    // both of the next two lines should look the same after rustfix
+    let _: u64 = 1u64 & (x + y) as u64;
+    //~^ ERROR: this operation has no effect
+    // Same as above, but with extra redundant parenthesis
+    let _: u64 = 1u64 & (x + y) as u64;
+    //~^ ERROR: this operation has no effect
+    // Should maintain parenthesis even if the surrounding expr has the same precedence
+    let _: u64 = 5u64 + (x + y) as u64;
+    //~^ ERROR: this operation has no effect
+
+    // If we don't maintain the parens here, the behavior changes
+    let _ = -(x + y);
+    //~^ ERROR: this operation has no effect
+    // Maintain parenthesis if the parent expr is of higher precedence
+    let _ = 2i32 * (x + y);
+    //~^ ERROR: this operation has no effect
+    // No need for parenthesis if the parent expr is of equal precedence
+    let _ = 2i32 + x + y;
+    //~^ ERROR: this operation has no effect
+    // But make sure that inner parens still exist
+    let z = 1i32;
+    let _ = 2 + x + (y * z);
+    //~^ ERROR: this operation has no effect
+    // Maintain parenthesis if the parent expr is of lower precedence
+    // This is for clarity, and clippy will not warn on these being unnecessary
+    let _ = 2i32 + (x * y);
+    //~^ ERROR: this operation has no effect
+
+    let x = 1i16;
+    let y = 1i16;
+    let _: u64 = 1u64 + (x as i32 + y as i32) as u64;
+    //~^ ERROR: this operation has no effect
+}
diff --git a/tests/ui/identity_op.rs b/tests/ui/identity_op.rs
index f1f01b42447..55483f4e5fb 100644
--- a/tests/ui/identity_op.rs
+++ b/tests/ui/identity_op.rs
@@ -212,3 +212,43 @@ fn issue_12050() {
         //~^ ERROR: this operation has no effect
     }
 }
+
+fn issue_13470() {
+    let x = 1i32;
+    let y = 1i32;
+    // Removes the + 0i32 while keeping the parentheses around x + y so the cast operation works
+    let _: u64 = (x + y + 0i32) as u64;
+    //~^ ERROR: this operation has no effect
+    // both of the next two lines should look the same after rustfix
+    let _: u64 = 1u64 & (x + y + 0i32) as u64;
+    //~^ ERROR: this operation has no effect
+    // Same as above, but with extra redundant parenthesis
+    let _: u64 = 1u64 & ((x + y) + 0i32) as u64;
+    //~^ ERROR: this operation has no effect
+    // Should maintain parenthesis even if the surrounding expr has the same precedence
+    let _: u64 = 5u64 + ((x + y) + 0i32) as u64;
+    //~^ ERROR: this operation has no effect
+
+    // If we don't maintain the parens here, the behavior changes
+    let _ = -(x + y + 0i32);
+    //~^ ERROR: this operation has no effect
+    // Maintain parenthesis if the parent expr is of higher precedence
+    let _ = 2i32 * (x + y + 0i32);
+    //~^ ERROR: this operation has no effect
+    // No need for parenthesis if the parent expr is of equal precedence
+    let _ = 2i32 + (x + y + 0i32);
+    //~^ ERROR: this operation has no effect
+    // But make sure that inner parens still exist
+    let z = 1i32;
+    let _ = 2 + (x + (y * z) + 0);
+    //~^ ERROR: this operation has no effect
+    // Maintain parenthesis if the parent expr is of lower precedence
+    // This is for clarity, and clippy will not warn on these being unnecessary
+    let _ = 2i32 + (x * y * 1i32);
+    //~^ ERROR: this operation has no effect
+
+    let x = 1i16;
+    let y = 1i16;
+    let _: u64 = 1u64 + ((x as i32 + y as i32) as u64 + 0u64);
+    //~^ ERROR: this operation has no effect
+}
diff --git a/tests/ui/identity_op.stderr b/tests/ui/identity_op.stderr
index 9fff86b86f9..856bebfa1ff 100644
--- a/tests/ui/identity_op.stderr
+++ b/tests/ui/identity_op.stderr
@@ -221,7 +221,7 @@ error: this operation has no effect
   --> tests/ui/identity_op.rs:152:5
    |
 LL |     1 * ({ a } + 4);
-   |     ^^^^^^^^^^^^^^^ help: consider reducing it to: `(({ a } + 4))`
+   |     ^^^^^^^^^^^^^^^ help: consider reducing it to: `({ a } + 4)`
 
 error: this operation has no effect
   --> tests/ui/identity_op.rs:154:5
@@ -313,5 +313,65 @@ error: this operation has no effect
 LL |         let _: i32 = **&&*&x + 0;
    |                      ^^^^^^^^^^^ help: consider reducing it to: `***&&*&x`
 
-error: aborting due to 52 previous errors
+error: this operation has no effect
+  --> tests/ui/identity_op.rs:220:18
+   |
+LL |     let _: u64 = (x + y + 0i32) as u64;
+   |                  ^^^^^^^^^^^^^^ help: consider reducing it to: `(x + y)`
+
+error: this operation has no effect
+  --> tests/ui/identity_op.rs:223:25
+   |
+LL |     let _: u64 = 1u64 & (x + y + 0i32) as u64;
+   |                         ^^^^^^^^^^^^^^ help: consider reducing it to: `(x + y)`
+
+error: this operation has no effect
+  --> tests/ui/identity_op.rs:226:25
+   |
+LL |     let _: u64 = 1u64 & ((x + y) + 0i32) as u64;
+   |                         ^^^^^^^^^^^^^^^^ help: consider reducing it to: `(x + y)`
+
+error: this operation has no effect
+  --> tests/ui/identity_op.rs:229:25
+   |
+LL |     let _: u64 = 5u64 + ((x + y) + 0i32) as u64;
+   |                         ^^^^^^^^^^^^^^^^ help: consider reducing it to: `(x + y)`
+
+error: this operation has no effect
+  --> tests/ui/identity_op.rs:233:14
+   |
+LL |     let _ = -(x + y + 0i32);
+   |              ^^^^^^^^^^^^^^ help: consider reducing it to: `(x + y)`
+
+error: this operation has no effect
+  --> tests/ui/identity_op.rs:236:20
+   |
+LL |     let _ = 2i32 * (x + y + 0i32);
+   |                    ^^^^^^^^^^^^^^ help: consider reducing it to: `(x + y)`
+
+error: this operation has no effect
+  --> tests/ui/identity_op.rs:239:20
+   |
+LL |     let _ = 2i32 + (x + y + 0i32);
+   |                    ^^^^^^^^^^^^^^ help: consider reducing it to: `x + y`
+
+error: this operation has no effect
+  --> tests/ui/identity_op.rs:243:17
+   |
+LL |     let _ = 2 + (x + (y * z) + 0);
+   |                 ^^^^^^^^^^^^^^^^^ help: consider reducing it to: `x + (y * z)`
+
+error: this operation has no effect
+  --> tests/ui/identity_op.rs:247:20
+   |
+LL |     let _ = 2i32 + (x * y * 1i32);
+   |                    ^^^^^^^^^^^^^^ help: consider reducing it to: `(x * y)`
+
+error: this operation has no effect
+  --> tests/ui/identity_op.rs:252:25
+   |
+LL |     let _: u64 = 1u64 + ((x as i32 + y as i32) as u64 + 0u64);
+   |                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider reducing it to: `(x as i32 + y as i32) as u64`
+
+error: aborting due to 62 previous errors