Test a type with drop glue but no Drop impl

Author: dtolnay

src/test/ui/lint/lint-const-item-mutation.rs

@@ -18,10 +18,16 @@ impl Drop for Mutable {
     }
 }
 
+struct Mutable2 { // this one has drop glue but not a Drop impl
+    msg: &'static str,
+    other: String,
+}
+
 const ARRAY: [u8; 1] = [25];
 const MY_STRUCT: MyStruct = MyStruct { field: true, inner_array: ['a'], raw_ptr: 2 as *mut u8 };
 const RAW_PTR: *mut u8 = 1 as *mut u8;
 const MUTABLE: Mutable = Mutable { msg: "" };
+const MUTABLE2: Mutable2 = Mutable2 { msg: "", other: String::new() };
 
 fn main() {
     ARRAY[0] = 5; //~ WARN attempting to modify
@@ -41,4 +47,5 @@ fn main() {
     }
 
     MUTABLE.msg = "wow"; // no warning, because Drop observes the mutation
+    MUTABLE2.msg = "wow"; //~ WARN attempting to modify
 }

src/test/ui/lint/lint-const-item-mutation.stderr

@@ -1,45 +1,45 @@
 warning: attempting to modify a `const` item
-  --> $DIR/lint-const-item-mutation.rs:27:5
+  --> $DIR/lint-const-item-mutation.rs:33:5
    |
 LL |     ARRAY[0] = 5;
    |     ^^^^^^^^^^^^
    |
    = note: `#[warn(const_item_mutation)]` on by default
    = note: each usage of a `const` item creates a new temporary - the original `const` item will not be modified
 note: `const` item defined here
-  --> $DIR/lint-const-item-mutation.rs:21:1
+  --> $DIR/lint-const-item-mutation.rs:26:1
    |
 LL | const ARRAY: [u8; 1] = [25];
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 warning: attempting to modify a `const` item
-  --> $DIR/lint-const-item-mutation.rs:28:5
+  --> $DIR/lint-const-item-mutation.rs:34:5
    |
 LL |     MY_STRUCT.field = false;
    |     ^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: each usage of a `const` item creates a new temporary - the original `const` item will not be modified
 note: `const` item defined here
-  --> $DIR/lint-const-item-mutation.rs:22:1
+  --> $DIR/lint-const-item-mutation.rs:27:1
    |
 LL | const MY_STRUCT: MyStruct = MyStruct { field: true, inner_array: ['a'], raw_ptr: 2 as *mut u8 };
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 warning: attempting to modify a `const` item
-  --> $DIR/lint-const-item-mutation.rs:29:5
+  --> $DIR/lint-const-item-mutation.rs:35:5
    |
 LL |     MY_STRUCT.inner_array[0] = 'b';
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: each usage of a `const` item creates a new temporary - the original `const` item will not be modified
 note: `const` item defined here
-  --> $DIR/lint-const-item-mutation.rs:22:1
+  --> $DIR/lint-const-item-mutation.rs:27:1
    |
 LL | const MY_STRUCT: MyStruct = MyStruct { field: true, inner_array: ['a'], raw_ptr: 2 as *mut u8 };
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 warning: taking a mutable reference to a `const` item
-  --> $DIR/lint-const-item-mutation.rs:30:5
+  --> $DIR/lint-const-item-mutation.rs:36:5
    |
 LL |     MY_STRUCT.use_mut();
    |     ^^^^^^^^^^^^^^^^^^^
@@ -52,38 +52,51 @@ note: mutable reference created due to call to this method
 LL |     fn use_mut(&mut self) {}
    |     ^^^^^^^^^^^^^^^^^^^^^
 note: `const` item defined here
-  --> $DIR/lint-const-item-mutation.rs:22:1
+  --> $DIR/lint-const-item-mutation.rs:27:1
    |
 LL | const MY_STRUCT: MyStruct = MyStruct { field: true, inner_array: ['a'], raw_ptr: 2 as *mut u8 };
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 warning: taking a mutable reference to a `const` item
-  --> $DIR/lint-const-item-mutation.rs:31:5
+  --> $DIR/lint-const-item-mutation.rs:37:5
    |
 LL |     &mut MY_STRUCT;
    |     ^^^^^^^^^^^^^^
    |
    = note: each usage of a `const` item creates a new temporary
    = note: the mutable reference will refer to this temporary, not the original `const` item
 note: `const` item defined here
-  --> $DIR/lint-const-item-mutation.rs:22:1
+  --> $DIR/lint-const-item-mutation.rs:27:1
    |
 LL | const MY_STRUCT: MyStruct = MyStruct { field: true, inner_array: ['a'], raw_ptr: 2 as *mut u8 };
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 warning: taking a mutable reference to a `const` item
-  --> $DIR/lint-const-item-mutation.rs:32:5
+  --> $DIR/lint-const-item-mutation.rs:38:5
    |
 LL |     (&mut MY_STRUCT).use_mut();
    |     ^^^^^^^^^^^^^^^^
    |
    = note: each usage of a `const` item creates a new temporary
    = note: the mutable reference will refer to this temporary, not the original `const` item
 note: `const` item defined here
-  --> $DIR/lint-const-item-mutation.rs:22:1
+  --> $DIR/lint-const-item-mutation.rs:27:1
    |
 LL | const MY_STRUCT: MyStruct = MyStruct { field: true, inner_array: ['a'], raw_ptr: 2 as *mut u8 };
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-warning: 6 warnings emitted
+warning: attempting to modify a `const` item
+  --> $DIR/lint-const-item-mutation.rs:50:5
+   |
+LL |     MUTABLE2.msg = "wow";
+   |     ^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: each usage of a `const` item creates a new temporary - the original `const` item will not be modified
+note: `const` item defined here
+  --> $DIR/lint-const-item-mutation.rs:30:1
+   |
+LL | const MUTABLE2: Mutable2 = Mutable2 { msg: "", other: String::new() };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+warning: 7 warnings emitted