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-rw-r--r--tests/ui/structs-enums/enum-non-c-like-repr-c-and-int.rs173
1 files changed, 173 insertions, 0 deletions
diff --git a/tests/ui/structs-enums/enum-non-c-like-repr-c-and-int.rs b/tests/ui/structs-enums/enum-non-c-like-repr-c-and-int.rs
new file mode 100644
index 000000000..7d15d607d
--- /dev/null
+++ b/tests/ui/structs-enums/enum-non-c-like-repr-c-and-int.rs
@@ -0,0 +1,173 @@
+// run-pass
+// This test deserializes an enum in-place by transmuting to a union that
+// should have the same layout, and manipulating the tag and payloads
+// independently. This verifies that `repr(some_int)` has a stable representation,
+// and that we don't miscompile these kinds of manipulations.
+
+use std::time::Duration;
+use std::mem;
+
+#[repr(C, u8)]
+#[derive(Copy, Clone, Eq, PartialEq, Debug)]
+enum MyEnum {
+ A(u32), // Single primitive value
+ B { x: u8, y: i16, z: u8 }, // Composite, and the offsets of `y` and `z`
+ // depend on tag being internal
+ C, // Empty
+ D(Option<u32>), // Contains an enum
+ E(Duration), // Contains a struct
+}
+
+#[repr(C)]
+struct MyEnumRepr {
+ tag: MyEnumTag,
+ payload: MyEnumPayload,
+}
+
+#[repr(C)]
+#[allow(non_snake_case)]
+union MyEnumPayload {
+ A: MyEnumVariantA,
+ B: MyEnumVariantB,
+ D: MyEnumVariantD,
+ E: MyEnumVariantE,
+}
+
+#[repr(u8)] #[derive(Copy, Clone)] enum MyEnumTag { A, B, C, D, E }
+#[repr(C)] #[derive(Copy, Clone)] struct MyEnumVariantA(u32);
+#[repr(C)] #[derive(Copy, Clone)] struct MyEnumVariantB {x: u8, y: i16, z: u8 }
+#[repr(C)] #[derive(Copy, Clone)] struct MyEnumVariantD(Option<u32>);
+#[repr(C)] #[derive(Copy, Clone)] struct MyEnumVariantE(Duration);
+
+fn main() {
+ let result: Vec<Result<MyEnum, ()>> = vec![
+ Ok(MyEnum::A(17)),
+ Ok(MyEnum::B { x: 206, y: 1145, z: 78 }),
+ Ok(MyEnum::C),
+ Err(()),
+ Ok(MyEnum::D(Some(407))),
+ Ok(MyEnum::D(None)),
+ Ok(MyEnum::E(Duration::from_secs(100))),
+ Err(()),
+ ];
+
+ // Binary serialized version of the above (little-endian)
+ let input: Vec<u8> = vec![
+ 0, 17, 0, 0, 0,
+ 1, 206, 121, 4, 78,
+ 2,
+ 8, /* invalid tag value */
+ 3, 0, 151, 1, 0, 0,
+ 3, 1,
+ 4, 100, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, /* incomplete value */
+ ];
+
+ let mut output = vec![];
+ let mut buf = &input[..];
+
+ unsafe {
+ // This should be safe, because we don't match on it unless it's fully formed,
+ // and it doesn't have a destructor.
+ //
+ // MyEnum is repr(C, u8) so it is guaranteed to have a separate discriminant and each
+ // variant can be zero initialized.
+ let mut dest: MyEnum = mem::zeroed();
+ while buf.len() > 0 {
+ match parse_my_enum(&mut dest, &mut buf) {
+ Ok(()) => output.push(Ok(dest)),
+ Err(()) => output.push(Err(())),
+ }
+ }
+ }
+
+ assert_eq!(output, result);
+}
+
+fn parse_my_enum<'a>(dest: &'a mut MyEnum, buf: &mut &[u8]) -> Result<(), ()> {
+ unsafe {
+ // Should be correct to do this transmute.
+ let dest: &'a mut MyEnumRepr = mem::transmute(dest);
+ let tag = read_u8(buf)?;
+
+ dest.tag = match tag {
+ 0 => MyEnumTag::A,
+ 1 => MyEnumTag::B,
+ 2 => MyEnumTag::C,
+ 3 => MyEnumTag::D,
+ 4 => MyEnumTag::E,
+ _ => return Err(()),
+ };
+
+ match dest.tag {
+ MyEnumTag::A => {
+ dest.payload.A.0 = read_u32_le(buf)?;
+ }
+ MyEnumTag::B => {
+ dest.payload.B.x = read_u8(buf)?;
+ dest.payload.B.y = read_u16_le(buf)? as i16;
+ dest.payload.B.z = read_u8(buf)?;
+ }
+ MyEnumTag::C => {
+ /* do nothing */
+ }
+ MyEnumTag::D => {
+ let is_some = read_u8(buf)? == 0;
+ if is_some {
+ dest.payload.D.0 = Some(read_u32_le(buf)?);
+ } else {
+ dest.payload.D.0 = None;
+ }
+ }
+ MyEnumTag::E => {
+ let secs = read_u64_le(buf)?;
+ let nanos = read_u32_le(buf)?;
+ dest.payload.E.0 = Duration::new(secs, nanos);
+ }
+ }
+ Ok(())
+ }
+}
+
+
+
+// reader helpers
+
+fn read_u64_le(buf: &mut &[u8]) -> Result<u64, ()> {
+ if buf.len() < 8 { return Err(()) }
+ let val = (buf[0] as u64) << 0
+ | (buf[1] as u64) << 8
+ | (buf[2] as u64) << 16
+ | (buf[3] as u64) << 24
+ | (buf[4] as u64) << 32
+ | (buf[5] as u64) << 40
+ | (buf[6] as u64) << 48
+ | (buf[7] as u64) << 56;
+ *buf = &buf[8..];
+ Ok(val)
+}
+
+fn read_u32_le(buf: &mut &[u8]) -> Result<u32, ()> {
+ if buf.len() < 4 { return Err(()) }
+ let val = (buf[0] as u32) << 0
+ | (buf[1] as u32) << 8
+ | (buf[2] as u32) << 16
+ | (buf[3] as u32) << 24;
+ *buf = &buf[4..];
+ Ok(val)
+}
+
+fn read_u16_le(buf: &mut &[u8]) -> Result<u16, ()> {
+ if buf.len() < 2 { return Err(()) }
+ let val = (buf[0] as u16) << 0
+ | (buf[1] as u16) << 8;
+ *buf = &buf[2..];
+ Ok(val)
+}
+
+fn read_u8(buf: &mut &[u8]) -> Result<u8, ()> {
+ if buf.len() < 1 { return Err(()) }
+ let val = buf[0];
+ *buf = &buf[1..];
+ Ok(val)
+}