4 files changed, 80 insertions, 0 deletions
diff --git a/src/test/ui/packed-struct/packed-struct-generic-transmute.rs b/src/test/ui/packed-struct/packed-struct-generic-transmute.rs
new file mode 100644
index 000000000..c6264b6d2
--- /dev/null
+++ b/src/test/ui/packed-struct/packed-struct-generic-transmute.rs
@@ -0,0 +1,27 @@
+// This assumes the packed and non-packed structs are different sizes.
+
+// the error points to the start of the file, not the line with the
+// transmute
+
+// error-pattern: cannot transmute between types of different sizes, or dependently-sized types
+
+use std::mem;
+
+#[repr(packed)]
+struct Foo<T,S> {
+    bar: T,
+    baz: S
+}
+
+struct Oof<T, S> {
+    rab: T,
+    zab: S
+}
+
+fn main() {
+    let foo = Foo { bar: [1u8, 2, 3, 4, 5], baz: 10i32 };
+    unsafe {
+        let oof: Oof<[u8; 5], i32> = mem::transmute(foo);
+        println!("{:?} {:?}", &oof.rab[..], oof.zab);
+    }
+}
diff --git a/src/test/ui/packed-struct/packed-struct-generic-transmute.stderr b/src/test/ui/packed-struct/packed-struct-generic-transmute.stderr
new file mode 100644
index 000000000..744c832db
--- /dev/null
+++ b/src/test/ui/packed-struct/packed-struct-generic-transmute.stderr
@@ -0,0 +1,12 @@
+error[E0512]: cannot transmute between types of different sizes, or dependently-sized types
+  --> $DIR/packed-struct-generic-transmute.rs:24:38
+   |
+LL |         let oof: Oof<[u8; 5], i32> = mem::transmute(foo);
+   |                                      ^^^^^^^^^^^^^^
+   |
+   = note: source type: `Foo<[u8; 5], i32>` (72 bits)
+   = note: target type: `Oof<[u8; 5], i32>` (96 bits)
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0512`.
diff --git a/src/test/ui/packed-struct/packed-struct-transmute.rs b/src/test/ui/packed-struct/packed-struct-transmute.rs
new file mode 100644
index 000000000..a7d284025
--- /dev/null
+++ b/src/test/ui/packed-struct/packed-struct-transmute.rs
@@ -0,0 +1,29 @@
+// This assumes the packed and non-packed structs are different sizes.
+
+// the error points to the start of the file, not the line with the
+// transmute
+
+// normalize-stderr-test "\d+ bits" -> "N bits"
+// error-pattern: cannot transmute between types of different sizes, or dependently-sized types
+
+use std::mem;
+
+#[repr(packed)]
+struct Foo {
+    bar: u8,
+    baz: usize
+}
+
+#[derive(Debug)]
+struct Oof {
+    rab: u8,
+    zab: usize
+}
+
+fn main() {
+    let foo = Foo { bar: 1, baz: 10 };
+    unsafe {
+        let oof: Oof = mem::transmute(foo);
+        println!("{:?}", oof);
+    }
+}
diff --git a/src/test/ui/packed-struct/packed-struct-transmute.stderr b/src/test/ui/packed-struct/packed-struct-transmute.stderr
new file mode 100644
index 000000000..80a8919f7
--- /dev/null
+++ b/src/test/ui/packed-struct/packed-struct-transmute.stderr
@@ -0,0 +1,12 @@
+error[E0512]: cannot transmute between types of different sizes, or dependently-sized types
+  --> $DIR/packed-struct-transmute.rs:26:24
+   |
+LL |         let oof: Oof = mem::transmute(foo);
+   |                        ^^^^^^^^^^^^^^
+   |
+   = note: source type: `Foo` (N bits)
+   = note: target type: `Oof` (N bits)
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0512`.