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Rollup merge of rust-lang#56887 - emilio:enum-field-reordering, r=eddyb
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Disable field reordering for repr(int).

This fixes the problem that the test in rust-lang#56619 uncovers.

Closes rust-lang#56619.
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@pietroalbini
pietroalbini authored Dec 20, 2018
2 parents 7c7e21a + d84bdba commit e12e472
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Showing 4 changed files with 33 additions and 26 deletions.
5 changes: 3 additions & 2 deletions src/librustc/ty/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -2061,9 +2061,10 @@ impl ReprOptions {
}

/// Returns `true` if this `#[repr()]` should inhibit struct field reordering
/// optimizations, such as with repr(C) or repr(packed(1)).
/// optimizations, such as with repr(C), repr(packed(1)), or repr(<int>).
pub fn inhibit_struct_field_reordering_opt(&self) -> bool {
!(self.flags & ReprFlags::IS_UNOPTIMISABLE).is_empty() || (self.pack == 1)
self.flags.intersects(ReprFlags::IS_UNOPTIMISABLE) || self.pack == 1 ||
self.int.is_some()
}

/// Returns true if this `#[repr()]` should inhibit union abi optimisations
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18 changes: 10 additions & 8 deletions src/test/run-pass/structs-enums/enum-non-c-like-repr-c-and-int.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -20,11 +20,12 @@ use std::mem;
#[repr(C, u8)]
#[derive(Copy, Clone, Eq, PartialEq, Debug)]
enum MyEnum {
A(u32), // Single primitive value
B { x: u8, y: i16 }, // Composite, and the offset of `y` depends on tag being internal
C, // Empty
D(Option<u32>), // Contains an enum
E(Duration), // Contains a struct
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)]
Expand All @@ -44,14 +45,14 @@ union MyEnumPayload {

#[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 }
#[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 }),
Ok(MyEnum::B { x: 206, y: 1145, z: 78 }),
Ok(MyEnum::C),
Err(()),
Ok(MyEnum::D(Some(407))),
Expand All @@ -63,7 +64,7 @@ fn main() {
// Binary serialized version of the above (little-endian)
let input: Vec<u8> = vec![
0, 17, 0, 0, 0,
1, 206, 121, 4,
1, 206, 121, 4, 78,
2,
8, /* invalid tag value */
3, 0, 151, 1, 0, 0,
Expand Down Expand Up @@ -112,6 +113,7 @@ fn parse_my_enum<'a>(dest: &'a mut MyEnum, buf: &mut &[u8]) -> Result<(), ()> {
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 */
Expand Down
18 changes: 10 additions & 8 deletions src/test/run-pass/structs-enums/enum-non-c-like-repr-c.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -20,11 +20,12 @@ use std::mem;
#[repr(C)]
#[derive(Copy, Clone, Eq, PartialEq, Debug)]
enum MyEnum {
A(u32), // Single primitive value
B { x: u8, y: i16 }, // Composite, and the offset of `y` depends on tag being internal
C, // Empty
D(Option<u32>), // Contains an enum
E(Duration), // Contains a struct
A(u32), // Single primitive value
B { x: u8, y: i16, z: u8 }, // Composite, and the offset of `y` and `z`
// depend on tag being internal
C, // Empty
D(Option<u32>), // Contains an enum
E(Duration), // Contains a struct
}

#[repr(C)]
Expand All @@ -44,14 +45,14 @@ union MyEnumPayload {

#[repr(C)] #[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 }
#[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 }),
Ok(MyEnum::B { x: 206, y: 1145, z: 78 }),
Ok(MyEnum::C),
Err(()),
Ok(MyEnum::D(Some(407))),
Expand All @@ -63,7 +64,7 @@ fn main() {
// Binary serialized version of the above (little-endian)
let input: Vec<u8> = vec![
0, 17, 0, 0, 0,
1, 206, 121, 4,
1, 206, 121, 4, 78,
2,
8, /* invalid tag value */
3, 0, 151, 1, 0, 0,
Expand Down Expand Up @@ -112,6 +113,7 @@ fn parse_my_enum<'a>(dest: &'a mut MyEnum, buf: &mut &[u8]) -> Result<(), ()> {
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 */
Expand Down
18 changes: 10 additions & 8 deletions src/test/run-pass/structs-enums/enum-non-c-like-repr-int.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -20,11 +20,12 @@ use std::mem;
#[repr(u8)]
#[derive(Copy, Clone, Eq, PartialEq, Debug)]
enum MyEnum {
A(u32), // Single primitive value
B { x: u8, y: i16 }, // Composite, and the offset of `y` depends on tag being internal
C, // Empty
D(Option<u32>), // Contains an enum
E(Duration), // Contains a struct
A(u32), // Single primitive value
B { x: u8, y: i16, z: u8 }, // Composite, and the offset of `y` and `z`
// depend on tag being internal
C, // Empty
D(Option<u32>), // Contains an enum
E(Duration), // Contains a struct
}

#[allow(non_snake_case)]
Expand All @@ -39,15 +40,15 @@ union MyEnumRepr {

#[repr(u8)] #[derive(Copy, Clone)] enum MyEnumTag { A, B, C, D, E }
#[repr(C)] #[derive(Copy, Clone)] struct MyEnumVariantA(MyEnumTag, u32);
#[repr(C)] #[derive(Copy, Clone)] struct MyEnumVariantB { tag: MyEnumTag, x: u8, y: i16 }
#[repr(C)] #[derive(Copy, Clone)] struct MyEnumVariantB { tag: MyEnumTag, x: u8, y: i16, z: u8 }
#[repr(C)] #[derive(Copy, Clone)] struct MyEnumVariantC(MyEnumTag);
#[repr(C)] #[derive(Copy, Clone)] struct MyEnumVariantD(MyEnumTag, Option<u32>);
#[repr(C)] #[derive(Copy, Clone)] struct MyEnumVariantE(MyEnumTag, Duration);

fn main() {
let result: Vec<Result<MyEnum, ()>> = vec![
Ok(MyEnum::A(17)),
Ok(MyEnum::B { x: 206, y: 1145 }),
Ok(MyEnum::B { x: 206, y: 1145, z: 78 }),
Ok(MyEnum::C),
Err(()),
Ok(MyEnum::D(Some(407))),
Expand All @@ -59,7 +60,7 @@ fn main() {
// Binary serialized version of the above (little-endian)
let input: Vec<u8> = vec![
0, 17, 0, 0, 0,
1, 206, 121, 4,
1, 206, 121, 4, 78,
2,
8, /* invalid tag value */
3, 0, 151, 1, 0, 0,
Expand Down Expand Up @@ -108,6 +109,7 @@ fn parse_my_enum<'a>(dest: &'a mut MyEnum, buf: &mut &[u8]) -> Result<(), ()> {
MyEnumTag::B => {
dest.B.x = read_u8(buf)?;
dest.B.y = read_u16_le(buf)? as i16;
dest.B.z = read_u8(buf)?;
}
MyEnumTag::C => {
/* do nothing */
Expand Down

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