5 files changed, 91 insertions, 14 deletions
diff --git a/tests/ui/enum-discriminant/eval-error.rs b/tests/ui/enum-discriminant/eval-error.rs
new file mode 100644
index 00000000000..f2c3b581627
--- /dev/null
+++ b/tests/ui/enum-discriminant/eval-error.rs
@@ -0,0 +1,37 @@
+union Foo {
+    a: str,
+    //~^ ERROR the size for values of type `str` cannot be known at compilation time
+    //~| ERROR field must implement `Copy` or be wrapped in `ManuallyDrop<...>`
+}
+
+enum Bar {
+    Boo = {
+        let _: Option<Foo> = None;
+        0
+    },
+}
+
+union Foo2 {}
+//~^ ERROR unions cannot have zero fields
+
+enum Bar2 {
+    Boo = {
+        let _: Option<Foo2> = None;
+        0
+    },
+}
+
+#[repr(u8, packed)]
+//~^ ERROR attribute should be applied to a struct or union
+enum Foo3 {
+    A
+}
+
+enum Bar3 {
+    Boo = {
+        let _: Option<Foo3> = None;
+        0
+    },
+}
+
+fn main() {}
diff --git a/tests/ui/enum-discriminant/eval-error.stderr b/tests/ui/enum-discriminant/eval-error.stderr
new file mode 100644
index 00000000000..0f12308de3c
--- /dev/null
+++ b/tests/ui/enum-discriminant/eval-error.stderr
@@ -0,0 +1,51 @@
+error: unions cannot have zero fields
+  --> $DIR/eval-error.rs:14:1
+   |
+LL | union Foo2 {}
+   | ^^^^^^^^^^^^^
+
+error[E0517]: attribute should be applied to a struct or union
+  --> $DIR/eval-error.rs:24:12
+   |
+LL |   #[repr(u8, packed)]
+   |              ^^^^^^
+LL |
+LL | / enum Foo3 {
+LL | |     A
+LL | | }
+   | |_- not a struct or union
+
+error[E0277]: the size for values of type `str` cannot be known at compilation time
+  --> $DIR/eval-error.rs:2:8
+   |
+LL |     a: str,
+   |        ^^^ doesn't have a size known at compile-time
+   |
+   = help: the trait `Sized` is not implemented for `str`
+   = note: no field of a union may have a dynamically sized type
+   = help: change the field's type to have a statically known size
+help: borrowed types always have a statically known size
+   |
+LL |     a: &str,
+   |        +
+help: the `Box` type always has a statically known size and allocates its contents in the heap
+   |
+LL |     a: Box<str>,
+   |        ++++   +
+
+error[E0740]: field must implement `Copy` or be wrapped in `ManuallyDrop<...>` to be used in a union
+  --> $DIR/eval-error.rs:2:5
+   |
+LL |     a: str,
+   |     ^^^^^^
+   |
+   = 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<str>,
+   |        +++++++++++++++++++++++   +
+
+error: aborting due to 4 previous errors
+
+Some errors have detailed explanations: E0277, E0517, E0740.
+For more information about an error, try `rustc --explain E0277`.
diff --git a/tests/ui/layout/base-layout-is-sized-ice-123078.rs b/tests/ui/layout/base-layout-is-sized-ice-123078.rs
index b1c33e15075..15f11145f84 100644
--- a/tests/ui/layout/base-layout-is-sized-ice-123078.rs
+++ b/tests/ui/layout/base-layout-is-sized-ice-123078.rs
@@ -8,7 +8,6 @@ struct S {
 }
 
 const C: S = unsafe { std::mem::transmute(()) };
-//~^ ERROR cannot transmute between types of different sizes, or dependently-sized types
 const _: [(); {
     C;
     0
diff --git a/tests/ui/layout/base-layout-is-sized-ice-123078.stderr b/tests/ui/layout/base-layout-is-sized-ice-123078.stderr
index 455bd2cbf8b..9181368533a 100644
--- a/tests/ui/layout/base-layout-is-sized-ice-123078.stderr
+++ b/tests/ui/layout/base-layout-is-sized-ice-123078.stderr
@@ -16,16 +16,6 @@ help: the `Box` type always has a statically known size and allocates its conten
 LL |     a: Box<[u8]>,
    |        ++++    +
 
-error[E0512]: cannot transmute between types of different sizes, or dependently-sized types
-  --> $DIR/base-layout-is-sized-ice-123078.rs:10:23
-   |
-LL | const C: S = unsafe { std::mem::transmute(()) };
-   |                       ^^^^^^^^^^^^^^^^^^^
-   |
-   = note: source type: `()` (0 bits)
-   = note: target type: `S` (size can vary because of [u8])
-
-error: aborting due to 2 previous errors
+error: aborting due to 1 previous error
 
-Some errors have detailed explanations: E0277, E0512.
-For more information about an error, try `rustc --explain E0277`.
+For more information about this error, try `rustc --explain E0277`.
diff --git a/tests/ui/layout/debug.stderr b/tests/ui/layout/debug.stderr
index 1fc55511384..319c0de26a9 100644
--- a/tests/ui/layout/debug.stderr
+++ b/tests/ui/layout/debug.stderr
@@ -590,7 +590,7 @@ LL | type Impossible = (str, str);
    = help: the trait `Sized` is not implemented for `str`
    = note: only the last element of a tuple may have a dynamically sized type
 
-error: the type `EmptyUnion` has an unknown layout
+error: the type has an unknown layout
   --> $DIR/debug.rs:83:1
    |
 LL | union EmptyUnion {}