Tweak E0740

7 files changed, 45 insertions, 45 deletions

diff --git a/tests/ui/union/field_checks.rs b/tests/ui/union/field_checks.rs
index d5d1e44ac85..bb4eccb4cf8 100644
--- a/tests/ui/union/field_checks.rs
+++ b/tests/ui/union/field_checks.rs
@@ -21,15 +21,15 @@ union U24<T> { // OK
 }
 
 union U3 {
-    a: String, //~ ERROR unions cannot contain fields that may need dropping
+    a: String, //~ ERROR field must implement `Copy` or be wrapped in `ManuallyDrop<...>` to be used in a union
 }
 
 union U32 { // field that does not drop but is not `Copy`, either
-    a: std::cell::RefCell<i32>, //~ ERROR unions cannot contain fields that may need dropping
+    a: std::cell::RefCell<i32>, //~ ERROR field must implement `Copy` or be wrapped in `ManuallyDrop<...>` to be used in a union
 }
 
 union U4<T> {
-    a: T, //~ ERROR unions cannot contain fields that may need dropping
+    a: T, //~ ERROR field must implement `Copy` or be wrapped in `ManuallyDrop<...>` to be used in a union
 }
 
 union U5 { // Having a drop impl is OK
@@ -41,11 +41,11 @@ impl Drop for U5 {
 }
 
 union U5Nested { // a nested union that drops is NOT OK
-    nest: U5, //~ ERROR unions cannot contain fields that may need dropping
+    nest: U5, //~ ERROR field must implement `Copy` or be wrapped in `ManuallyDrop<...>` to be used in a union
 }
 
 union U5Nested2 { // for now we don't special-case empty arrays
-    nest: [U5; 0], //~ ERROR unions cannot contain fields that may need dropping
+    nest: [U5; 0], //~ ERROR field must implement `Copy` or be wrapped in `ManuallyDrop<...>` to be used in a union
 }
 
 union U6 { // OK
diff --git a/tests/ui/union/field_checks.stderr b/tests/ui/union/field_checks.stderr
index 1f97e97ac6e..32407a74970 100644
--- a/tests/ui/union/field_checks.stderr
+++ b/tests/ui/union/field_checks.stderr
@@ -1,59 +1,59 @@
-error[E0740]: unions cannot contain fields that may need dropping
+error[E0740]: field must implement `Copy` or be wrapped in `ManuallyDrop<...>` to be used in a union
   --> $DIR/field_checks.rs:24:5
    |
 LL |     a: String,
    |     ^^^^^^^^^
    |
-   = note: a type is guaranteed not to need dropping when it implements `Copy`, or when it is the special `ManuallyDrop<_>` type
-help: when the type does not implement `Copy`, wrap it inside a `ManuallyDrop<_>` and ensure it is manually dropped
+   = note: union fields must not have drop side-effects, which is currently enforced via either `Copy` or `ManuallyDrop<...>`
+help: wrap the field type in `ManuallyDrop<...>`
    |
 LL |     a: std::mem::ManuallyDrop<String>,
    |        +++++++++++++++++++++++      +
 
-error[E0740]: unions cannot contain fields that may need dropping
+error[E0740]: field must implement `Copy` or be wrapped in `ManuallyDrop<...>` to be used in a union
   --> $DIR/field_checks.rs:28:5
    |
 LL |     a: std::cell::RefCell<i32>,
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-   = note: a type is guaranteed not to need dropping when it implements `Copy`, or when it is the special `ManuallyDrop<_>` type
-help: when the type does not implement `Copy`, wrap it inside a `ManuallyDrop<_>` and ensure it is manually dropped
+   = note: union fields must not have drop side-effects, which is currently enforced via either `Copy` or `ManuallyDrop<...>`
+help: wrap the field type in `ManuallyDrop<...>`
    |
 LL |     a: std::mem::ManuallyDrop<std::cell::RefCell<i32>>,
    |        +++++++++++++++++++++++                       +
 
-error[E0740]: unions cannot contain fields that may need dropping
+error[E0740]: field must implement `Copy` or be wrapped in `ManuallyDrop<...>` to be used in a union
   --> $DIR/field_checks.rs:32:5
    |
 LL |     a: T,
    |     ^^^^
    |
-   = note: a type is guaranteed not to need dropping when it implements `Copy`, or when it is the special `ManuallyDrop<_>` type
-help: when the type does not implement `Copy`, wrap it inside a `ManuallyDrop<_>` and ensure it is manually dropped
+   = note: union fields must not have drop side-effects, which is currently enforced via either `Copy` or `ManuallyDrop<...>`
+help: wrap the field type in `ManuallyDrop<...>`
    |
 LL |     a: std::mem::ManuallyDrop<T>,
    |        +++++++++++++++++++++++ +
 
-error[E0740]: unions cannot contain fields that may need dropping
+error[E0740]: field must implement `Copy` or be wrapped in `ManuallyDrop<...>` to be used in a union
   --> $DIR/field_checks.rs:44:5
    |
 LL |     nest: U5,
    |     ^^^^^^^^
    |
-   = note: a type is guaranteed not to need dropping when it implements `Copy`, or when it is the special `ManuallyDrop<_>` type
-help: when the type does not implement `Copy`, wrap it inside a `ManuallyDrop<_>` and ensure it is manually dropped
+   = note: union fields must not have drop side-effects, which is currently enforced via either `Copy` or `ManuallyDrop<...>`
+help: wrap the field type in `ManuallyDrop<...>`
    |
 LL |     nest: std::mem::ManuallyDrop<U5>,
    |           +++++++++++++++++++++++  +
 
-error[E0740]: unions cannot contain fields that may need dropping
+error[E0740]: field must implement `Copy` or be wrapped in `ManuallyDrop<...>` to be used in a union
   --> $DIR/field_checks.rs:48:5
    |
 LL |     nest: [U5; 0],
    |     ^^^^^^^^^^^^^
    |
-   = note: a type is guaranteed not to need dropping when it implements `Copy`, or when it is the special `ManuallyDrop<_>` type
-help: when the type does not implement `Copy`, wrap it inside a `ManuallyDrop<_>` and ensure it is manually dropped
+   = note: union fields must not have drop side-effects, which is currently enforced via either `Copy` or `ManuallyDrop<...>`
+help: wrap the field type in `ManuallyDrop<...>`
    |
 LL |     nest: std::mem::ManuallyDrop<[U5; 0]>,
    |           +++++++++++++++++++++++       +
diff --git a/tests/ui/union/issue-41073.rs b/tests/ui/union/issue-41073.rs
index 4dfdc606bb4..f7a82b4e7cf 100644
--- a/tests/ui/union/issue-41073.rs
+++ b/tests/ui/union/issue-41073.rs
@@ -1,5 +1,5 @@
 union Test {
-    a: A, //~ ERROR unions cannot contain fields that may need dropping
+    a: A, //~ ERROR field must implement `Copy` or be wrapped in `ManuallyDrop<...>` to be used in a union
     b: B
 }
 
diff --git a/tests/ui/union/issue-41073.stderr b/tests/ui/union/issue-41073.stderr
index b3887fa0f90..ae1c4dfed9a 100644
--- a/tests/ui/union/issue-41073.stderr
+++ b/tests/ui/union/issue-41073.stderr
@@ -1,11 +1,11 @@
-error[E0740]: unions cannot contain fields that may need dropping
+error[E0740]: field must implement `Copy` or be wrapped in `ManuallyDrop<...>` to be used in a union
   --> $DIR/issue-41073.rs:2:5
    |
 LL |     a: A,
    |     ^^^^
    |
-   = note: a type is guaranteed not to need dropping when it implements `Copy`, or when it is the special `ManuallyDrop<_>` type
-help: when the type does not implement `Copy`, wrap it inside a `ManuallyDrop<_>` and ensure it is manually dropped
+   = note: union fields must not have drop side-effects, which is currently enforced via either `Copy` or `ManuallyDrop<...>`
+help: wrap the field type in `ManuallyDrop<...>`
    |
 LL |     a: std::mem::ManuallyDrop<A>,
    |        +++++++++++++++++++++++ +
diff --git a/tests/ui/union/union-with-drop-fields.mirunsafeck.stderr b/tests/ui/union/union-with-drop-fields.mirunsafeck.stderr
index 93fe996d2a4..9861a21cb3d 100644
--- a/tests/ui/union/union-with-drop-fields.mirunsafeck.stderr
+++ b/tests/ui/union/union-with-drop-fields.mirunsafeck.stderr
@@ -1,35 +1,35 @@
-error[E0740]: unions cannot contain fields that may need dropping
+error[E0740]: field must implement `Copy` or be wrapped in `ManuallyDrop<...>` to be used in a union
   --> $DIR/union-with-drop-fields.rs:11:5
    |
 LL |     a: String,
    |     ^^^^^^^^^
    |
-   = note: a type is guaranteed not to need dropping when it implements `Copy`, or when it is the special `ManuallyDrop<_>` type
-help: when the type does not implement `Copy`, wrap it inside a `ManuallyDrop<_>` and ensure it is manually dropped
+   = note: union fields must not have drop side-effects, which is currently enforced via either `Copy` or `ManuallyDrop<...>`
+help: wrap the field type in `ManuallyDrop<...>`
    |
 LL |     a: std::mem::ManuallyDrop<String>,
    |        +++++++++++++++++++++++      +
 
-error[E0740]: unions cannot contain fields that may need dropping
+error[E0740]: field must implement `Copy` or be wrapped in `ManuallyDrop<...>` to be used in a union
   --> $DIR/union-with-drop-fields.rs:19:5
    |
 LL |     a: S,
    |     ^^^^
    |
-   = note: a type is guaranteed not to need dropping when it implements `Copy`, or when it is the special `ManuallyDrop<_>` type
-help: when the type does not implement `Copy`, wrap it inside a `ManuallyDrop<_>` and ensure it is manually dropped
+   = note: union fields must not have drop side-effects, which is currently enforced via either `Copy` or `ManuallyDrop<...>`
+help: wrap the field type in `ManuallyDrop<...>`
    |
 LL |     a: std::mem::ManuallyDrop<S>,
    |        +++++++++++++++++++++++ +
 
-error[E0740]: unions cannot contain fields that may need dropping
+error[E0740]: field must implement `Copy` or be wrapped in `ManuallyDrop<...>` to be used in a union
   --> $DIR/union-with-drop-fields.rs:24:5
    |
 LL |     a: T,
    |     ^^^^
    |
-   = note: a type is guaranteed not to need dropping when it implements `Copy`, or when it is the special `ManuallyDrop<_>` type
-help: when the type does not implement `Copy`, wrap it inside a `ManuallyDrop<_>` and ensure it is manually dropped
+   = note: union fields must not have drop side-effects, which is currently enforced via either `Copy` or `ManuallyDrop<...>`
+help: wrap the field type in `ManuallyDrop<...>`
    |
 LL |     a: std::mem::ManuallyDrop<T>,
    |        +++++++++++++++++++++++ +
diff --git a/tests/ui/union/union-with-drop-fields.rs b/tests/ui/union/union-with-drop-fields.rs
index a7a8b69e784..9720830fb1f 100644
--- a/tests/ui/union/union-with-drop-fields.rs
+++ b/tests/ui/union/union-with-drop-fields.rs
@@ -8,7 +8,7 @@ union U {
 }
 
 union W {
-    a: String, //~ ERROR unions cannot contain fields that may need dropping
+    a: String, //~ ERROR field must implement `Copy` or be wrapped in `ManuallyDrop<...>` to be used in a union
     b: String, // OK, only one field is reported
 }
 
@@ -16,12 +16,12 @@ struct S(String);
 
 // `S` doesn't implement `Drop` trait, but still has non-trivial destructor
 union Y {
-    a: S, //~ ERROR unions cannot contain fields that may need dropping
+    a: S, //~ ERROR field must implement `Copy` or be wrapped in `ManuallyDrop<...>` to be used in a union
 }
 
 // We don't know if `T` is trivially-destructable or not until trans
 union J<T> {
-    a: T, //~ ERROR unions cannot contain fields that may need dropping
+    a: T, //~ ERROR field must implement `Copy` or be wrapped in `ManuallyDrop<...>` to be used in a union
 }
 
 union H<T: Copy> {
diff --git a/tests/ui/union/union-with-drop-fields.thirunsafeck.stderr b/tests/ui/union/union-with-drop-fields.thirunsafeck.stderr
index 93fe996d2a4..9861a21cb3d 100644
--- a/tests/ui/union/union-with-drop-fields.thirunsafeck.stderr
+++ b/tests/ui/union/union-with-drop-fields.thirunsafeck.stderr
@@ -1,35 +1,35 @@
-error[E0740]: unions cannot contain fields that may need dropping
+error[E0740]: field must implement `Copy` or be wrapped in `ManuallyDrop<...>` to be used in a union
   --> $DIR/union-with-drop-fields.rs:11:5
    |
 LL |     a: String,
    |     ^^^^^^^^^
    |
-   = note: a type is guaranteed not to need dropping when it implements `Copy`, or when it is the special `ManuallyDrop<_>` type
-help: when the type does not implement `Copy`, wrap it inside a `ManuallyDrop<_>` and ensure it is manually dropped
+   = note: union fields must not have drop side-effects, which is currently enforced via either `Copy` or `ManuallyDrop<...>`
+help: wrap the field type in `ManuallyDrop<...>`
    |
 LL |     a: std::mem::ManuallyDrop<String>,
    |        +++++++++++++++++++++++      +
 
-error[E0740]: unions cannot contain fields that may need dropping
+error[E0740]: field must implement `Copy` or be wrapped in `ManuallyDrop<...>` to be used in a union
   --> $DIR/union-with-drop-fields.rs:19:5
    |
 LL |     a: S,
    |     ^^^^
    |
-   = note: a type is guaranteed not to need dropping when it implements `Copy`, or when it is the special `ManuallyDrop<_>` type
-help: when the type does not implement `Copy`, wrap it inside a `ManuallyDrop<_>` and ensure it is manually dropped
+   = note: union fields must not have drop side-effects, which is currently enforced via either `Copy` or `ManuallyDrop<...>`
+help: wrap the field type in `ManuallyDrop<...>`
    |
 LL |     a: std::mem::ManuallyDrop<S>,
    |        +++++++++++++++++++++++ +
 
-error[E0740]: unions cannot contain fields that may need dropping
+error[E0740]: field must implement `Copy` or be wrapped in `ManuallyDrop<...>` to be used in a union
   --> $DIR/union-with-drop-fields.rs:24:5
    |
 LL |     a: T,
    |     ^^^^
    |
-   = note: a type is guaranteed not to need dropping when it implements `Copy`, or when it is the special `ManuallyDrop<_>` type
-help: when the type does not implement `Copy`, wrap it inside a `ManuallyDrop<_>` and ensure it is manually dropped
+   = note: union fields must not have drop side-effects, which is currently enforced via either `Copy` or `ManuallyDrop<...>`
+help: wrap the field type in `ManuallyDrop<...>`
    |
 LL |     a: std::mem::ManuallyDrop<T>,
    |        +++++++++++++++++++++++ +