1 files changed, 173 insertions, 0 deletions
diff --git a/src/test/ui/structs-enums/type-sizes.rs b/src/test/ui/structs-enums/type-sizes.rs
new file mode 100644
index 000000000..73a11a5e7
--- /dev/null
+++ b/src/test/ui/structs-enums/type-sizes.rs
@@ -0,0 +1,173 @@
+// run-pass
+
+#![allow(non_camel_case_types)]
+#![allow(dead_code)]
+#![feature(never_type)]
+
+use std::mem::size_of;
+use std::num::NonZeroU8;
+
+struct t {a: u8, b: i8}
+struct u {a: u8, b: i8, c: u8}
+struct v {a: u8, b: i8, c: v2, d: u32}
+struct v2 {u: char, v: u8}
+struct w {a: isize, b: ()}
+struct x {a: isize, b: (), c: ()}
+struct y {x: isize}
+
+enum e1 {
+    a(u8, u32), b(u32), c
+}
+enum e2 {
+    a(u32), b
+}
+
+#[repr(C, u8)]
+enum e3 {
+    a([u16; 0], u8), b
+}
+
+struct ReorderedStruct {
+    a: u8,
+    b: u16,
+    c: u8
+}
+
+enum ReorderedEnum {
+    A(u8, u16, u8),
+    B(u8, u16, u8),
+}
+
+enum ReorderedEnum2 {
+    A(u8, u32, u8),
+    B(u16, u8, u16, u8),
+
+    // 0x100 niche variants.
+    _00, _01, _02, _03, _04, _05, _06, _07, _08, _09, _0A, _0B, _0C, _0D, _0E, _0F,
+    _10, _11, _12, _13, _14, _15, _16, _17, _18, _19, _1A, _1B, _1C, _1D, _1E, _1F,
+    _20, _21, _22, _23, _24, _25, _26, _27, _28, _29, _2A, _2B, _2C, _2D, _2E, _2F,
+    _30, _31, _32, _33, _34, _35, _36, _37, _38, _39, _3A, _3B, _3C, _3D, _3E, _3F,
+    _40, _41, _42, _43, _44, _45, _46, _47, _48, _49, _4A, _4B, _4C, _4D, _4E, _4F,
+    _50, _51, _52, _53, _54, _55, _56, _57, _58, _59, _5A, _5B, _5C, _5D, _5E, _5F,
+    _60, _61, _62, _63, _64, _65, _66, _67, _68, _69, _6A, _6B, _6C, _6D, _6E, _6F,
+    _70, _71, _72, _73, _74, _75, _76, _77, _78, _79, _7A, _7B, _7C, _7D, _7E, _7F,
+    _80, _81, _82, _83, _84, _85, _86, _87, _88, _89, _8A, _8B, _8C, _8D, _8E, _8F,
+    _90, _91, _92, _93, _94, _95, _96, _97, _98, _99, _9A, _9B, _9C, _9D, _9E, _9F,
+    _A0, _A1, _A2, _A3, _A4, _A5, _A6, _A7, _A8, _A9, _AA, _AB, _AC, _AD, _AE, _AF,
+    _B0, _B1, _B2, _B3, _B4, _B5, _B6, _B7, _B8, _B9, _BA, _BB, _BC, _BD, _BE, _BF,
+    _C0, _C1, _C2, _C3, _C4, _C5, _C6, _C7, _C8, _C9, _CA, _CB, _CC, _CD, _CE, _CF,
+    _D0, _D1, _D2, _D3, _D4, _D5, _D6, _D7, _D8, _D9, _DA, _DB, _DC, _DD, _DE, _DF,
+    _E0, _E1, _E2, _E3, _E4, _E5, _E6, _E7, _E8, _E9, _EA, _EB, _EC, _ED, _EE, _EF,
+    _F0, _F1, _F2, _F3, _F4, _F5, _F6, _F7, _F8, _F9, _FA, _FB, _FC, _FD, _FE, _FF,
+}
+
+enum EnumEmpty {}
+
+enum EnumSingle1 {
+    A,
+}
+
+enum EnumSingle2 {
+    A = 42 as isize,
+}
+
+enum EnumSingle3 {
+    A,
+    B(!),
+}
+
+#[repr(u8)]
+enum EnumSingle4 {
+    A,
+}
+
+#[repr(u8)]
+enum EnumSingle5 {
+    A = 42 as u8,
+}
+
+enum EnumWithMaybeUninhabitedVariant<T> {
+    A(&'static ()),
+    B(&'static (), T),
+    C,
+}
+
+enum NicheFilledEnumWithAbsentVariant {
+    A(&'static ()),
+    B((), !),
+    C,
+}
+
+enum Option2<A, B> {
+    Some(A, B),
+    None
+}
+
+// Two layouts are considered for `CanBeNicheFilledButShouldnt`:
+//   Niche-filling:
+//     { u32 (4 bytes), NonZeroU8 + tag in niche (1 byte), padding (3 bytes) }
+//   Tagged:
+//     { tag (1 byte), NonZeroU8 (1 byte), padding (2 bytes), u32 (4 bytes) }
+// Both are the same size (due to padding),
+// but the tagged layout is better as the tag creates a niche with 254 invalid values,
+// allowing types like `Option<Option<CanBeNicheFilledButShouldnt>>` to fit into 8 bytes.
+pub enum CanBeNicheFilledButShouldnt {
+    A(NonZeroU8, u32),
+    B
+}
+pub enum AlwaysTaggedBecauseItHasNoNiche {
+    A(u8, u32),
+    B
+}
+
+pub fn main() {
+    assert_eq!(size_of::<u8>(), 1 as usize);
+    assert_eq!(size_of::<u32>(), 4 as usize);
+    assert_eq!(size_of::<char>(), 4 as usize);
+    assert_eq!(size_of::<i8>(), 1 as usize);
+    assert_eq!(size_of::<i32>(), 4 as usize);
+    assert_eq!(size_of::<t>(), 2 as usize);
+    assert_eq!(size_of::<u>(), 3 as usize);
+    // Alignment causes padding before the char and the u32.
+
+    assert_eq!(size_of::<v>(),
+                16 as usize);
+    assert_eq!(size_of::<isize>(), size_of::<usize>());
+    assert_eq!(size_of::<w>(), size_of::<isize>());
+    assert_eq!(size_of::<x>(), size_of::<isize>());
+    assert_eq!(size_of::<isize>(), size_of::<y>());
+
+    // Make sure enum types are the appropriate size, mostly
+    // around ensuring alignment is handled properly
+
+    assert_eq!(size_of::<e1>(), 8 as usize);
+    assert_eq!(size_of::<e2>(), 8 as usize);
+    assert_eq!(size_of::<e3>(), 4 as usize);
+    assert_eq!(size_of::<ReorderedStruct>(), 4);
+    assert_eq!(size_of::<ReorderedEnum>(), 6);
+    assert_eq!(size_of::<ReorderedEnum2>(), 8);
+
+
+    assert_eq!(size_of::<EnumEmpty>(), 0);
+    assert_eq!(size_of::<EnumSingle1>(), 0);
+    assert_eq!(size_of::<EnumSingle2>(), 0);
+    assert_eq!(size_of::<EnumSingle3>(), 0);
+    assert_eq!(size_of::<EnumSingle4>(), 1);
+    assert_eq!(size_of::<EnumSingle5>(), 1);
+
+    assert_eq!(size_of::<EnumWithMaybeUninhabitedVariant<!>>(),
+               size_of::<EnumWithMaybeUninhabitedVariant<()>>());
+    assert_eq!(size_of::<NicheFilledEnumWithAbsentVariant>(), size_of::<&'static ()>());
+
+    assert_eq!(size_of::<Option<Option<(bool, &())>>>(), size_of::<(bool, &())>());
+    assert_eq!(size_of::<Option<Option<(&(), bool)>>>(), size_of::<(bool, &())>());
+    assert_eq!(size_of::<Option<Option2<bool, &()>>>(), size_of::<(bool, &())>());
+    assert_eq!(size_of::<Option<Option2<&(), bool>>>(), size_of::<(bool, &())>());
+
+    assert_eq!(size_of::<CanBeNicheFilledButShouldnt>(), 8);
+    assert_eq!(size_of::<Option<CanBeNicheFilledButShouldnt>>(), 8);
+    assert_eq!(size_of::<Option<Option<CanBeNicheFilledButShouldnt>>>(), 8);
+    assert_eq!(size_of::<AlwaysTaggedBecauseItHasNoNiche>(), 8);
+    assert_eq!(size_of::<Option<AlwaysTaggedBecauseItHasNoNiche>>(), 8);
+    assert_eq!(size_of::<Option<Option<AlwaysTaggedBecauseItHasNoNiche>>>(), 8);
+}