1 files changed, 69 insertions, 0 deletions
diff --git a/src/test/ui/print_type_sizes/packed.rs b/src/test/ui/print_type_sizes/packed.rs
new file mode 100644
index 000000000..269cc3cc2
--- /dev/null
+++ b/src/test/ui/print_type_sizes/packed.rs
@@ -0,0 +1,69 @@
+// compile-flags: -Z print-type-sizes
+// build-pass
+// ignore-pass
+// ^-- needed because `--pass check` does not emit the output needed.
+//     FIXME: consider using an attribute instead of side-effects.
+
+// This file illustrates how packing is handled; it should cause
+// the elimination of padding that would normally be introduced
+// to satisfy alignment desirata.
+//
+// It avoids using u64/i64 because on some targets that is only 4-byte
+// aligned (while on most it is 8-byte aligned) and so the resulting
+// padding and overall computed sizes can be quite different.
+
+#![allow(dead_code)]
+#![feature(start)]
+
+#[derive(Default)]
+#[repr(packed)]
+struct Packed1 {
+    a: u8,
+    b: u8,
+    g: i32,
+    c: u8,
+    h: i16,
+    d: u8,
+}
+
+#[derive(Default)]
+#[repr(packed(2))]
+struct Packed2 {
+    a: u8,
+    b: u8,
+    g: i32,
+    c: u8,
+    h: i16,
+    d: u8,
+}
+
+#[derive(Default)]
+#[repr(packed(2))]
+#[repr(C)]
+struct Packed2C {
+    a: u8,
+    b: u8,
+    g: i32,
+    c: u8,
+    h: i16,
+    d: u8,
+}
+
+#[derive(Default)]
+struct Padded {
+    a: u8,
+    b: u8,
+    g: i32,
+    c: u8,
+    h: i16,
+    d: u8,
+}
+
+#[start]
+fn start(_: isize, _: *const *const u8) -> isize {
+    let _c: Packed1 = Default::default();
+    let _d: Packed2 = Default::default();
+    let _e: Packed2C = Default::default();
+    let _f: Padded = Default::default();
+    0
+}