Merge commit 'd5e2a7aca5' into clippyup

tests/ui/uninit_vec.rs

@@ -7,6 +7,11 @@ struct MyVec {
     vec: Vec<u8>,
 }
 
+union MyOwnMaybeUninit {
+    value: u8,
+    uninit: (),
+}
+
 fn main() {
     // with_capacity() -> set_len() should be detected
     let mut vec: Vec<u8> = Vec::with_capacity(1000);
@@ -97,4 +102,26 @@ fn main() {
     unsafe {
         vec.set_len(0);
     }
+
+    // ZSTs should not be detected
+    let mut vec: Vec<()> = Vec::with_capacity(1000);
+    unsafe {
+        vec.set_len(10);
+    }
+
+    // unions should not be detected
+    let mut vec: Vec<MyOwnMaybeUninit> = Vec::with_capacity(1000);
+    unsafe {
+        vec.set_len(10);
+    }
+
+    polymorphic::<()>();
+
+    fn polymorphic<T>() {
+        // We are conservative around polymorphic types.
+        let mut vec: Vec<T> = Vec::with_capacity(1000);
+        unsafe {
+            vec.set_len(10);
+        }
+    }
 }