introduce rc_clone_in_vec_init lint

tests/ui/rc_clone_in_vec_init/arc.rs

@@ -0,0 +1,49 @@
+#![warn(clippy::rc_clone_in_vec_init)]
+use std::sync::{Arc, Mutex};
+
+fn main() {}
+
+fn should_warn_simple_case() {
+    let v = vec![Arc::new("x".to_string()); 2];
+}
+
+fn should_warn_complex_case() {
+    let v = vec![
+        std::sync::Arc::new(Mutex::new({
+            let x = 1;
+            dbg!(x);
+            x
+        }));
+        2
+    ];
+}
+
+fn should_not_warn_custom_arc() {
+    #[derive(Clone)]
+    struct Arc;
+
+    impl Arc {
+        fn new() -> Self {
+            Arc
+        }
+    }
+
+    let v = vec![Arc::new(); 2];
+}
+
+fn should_not_warn_vec_from_elem_but_not_arc() {
+    let v = vec![String::new(); 2];
+    let v1 = vec![1; 2];
+    let v2 = vec![
+        Box::new(std::sync::Arc::new({
+            let y = 3;
+            dbg!(y);
+            y
+        }));
+        2
+    ];
+}
+
+fn should_not_warn_vec_macro_but_not_from_elem() {
+    let v = vec![Arc::new("x".to_string())];
+}

tests/ui/rc_clone_in_vec_init/arc.stderr

@@ -0,0 +1,30 @@
+error: calling `Arc::new` in `vec![elem; len]`
+  --> $DIR/arc.rs:7:13
+   |
+LL |     let v = vec![Arc::new("x".to_string()); 2];
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: `-D clippy::rc-clone-in-vec-init` implied by `-D warnings`
+   = note: each element will point to the same `Arc` instance
+   = help: if this is intentional, consider extracting the `Arc` initialization to a variable
+   = help: or if not, initialize each element individually
+
+error: calling `Arc::new` in `vec![elem; len]`
+  --> $DIR/arc.rs:11:13
+   |
+LL |       let v = vec![
+   |  _____________^
+LL | |         std::sync::Arc::new(Mutex::new({
+LL | |             let x = 1;
+LL | |             dbg!(x);
+...  |
+LL | |         2
+LL | |     ];
+   | |_____^
+   |
+   = note: each element will point to the same `Arc` instance
+   = help: if this is intentional, consider extracting the `Arc` initialization to a variable
+   = help: or if not, initialize each element individually
+
+error: aborting due to 2 previous errors
+

tests/ui/rc_clone_in_vec_init/rc.rs

@@ -0,0 +1,50 @@
+#![warn(clippy::rc_clone_in_vec_init)]
+use std::rc::Rc;
+use std::sync::Mutex;
+
+fn main() {}
+
+fn should_warn_simple_case() {
+    let v = vec![Rc::new("x".to_string()); 2];
+}
+
+fn should_warn_complex_case() {
+    let v = vec![
+        std::rc::Rc::new(Mutex::new({
+            let x = 1;
+            dbg!(x);
+            x
+        }));
+        2
+    ];
+}
+
+fn should_not_warn_custom_arc() {
+    #[derive(Clone)]
+    struct Rc;
+
+    impl Rc {
+        fn new() -> Self {
+            Rc
+        }
+    }
+
+    let v = vec![Rc::new(); 2];
+}
+
+fn should_not_warn_vec_from_elem_but_not_rc() {
+    let v = vec![String::new(); 2];
+    let v1 = vec![1; 2];
+    let v2 = vec![
+        Box::new(std::rc::Rc::new({
+            let y = 3;
+            dbg!(y);
+            y
+        }));
+        2
+    ];
+}
+
+fn should_not_warn_vec_macro_but_not_from_elem() {
+    let v = vec![Rc::new("x".to_string())];
+}

tests/ui/rc_clone_in_vec_init/rc.stderr

@@ -0,0 +1,30 @@
+error: calling `Rc::new` in `vec![elem; len]`
+  --> $DIR/rc.rs:8:13
+   |
+LL |     let v = vec![Rc::new("x".to_string()); 2];
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: `-D clippy::rc-clone-in-vec-init` implied by `-D warnings`
+   = note: each element will point to the same `Rc` instance
+   = help: if this is intentional, consider extracting the `Rc` initialization to a variable
+   = help: or if not, initialize each element individually
+
+error: calling `Rc::new` in `vec![elem; len]`
+  --> $DIR/rc.rs:12:13
+   |
+LL |       let v = vec![
+   |  _____________^
+LL | |         std::rc::Rc::new(Mutex::new({
+LL | |             let x = 1;
+LL | |             dbg!(x);
+...  |
+LL | |         2
+LL | |     ];
+   | |_____^
+   |
+   = note: each element will point to the same `Rc` instance
+   = help: if this is intentional, consider extracting the `Rc` initialization to a variable
+   = help: or if not, initialize each element individually
+
+error: aborting due to 2 previous errors
+