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might_permit_raw_init: also check aggregate fields
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RalfJung committed Sep 26, 2020
1 parent e599b53 commit 6f881b3
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Showing 2 changed files with 57 additions and 6 deletions.
23 changes: 19 additions & 4 deletions compiler/rustc_target/src/abi/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -1135,16 +1135,31 @@ impl<'a, Ty> TyAndLayout<'a, Ty> {
Abi::Scalar(s) => scalar_allows_raw_init(s),
Abi::ScalarPair(s1, s2) => scalar_allows_raw_init(s1) && scalar_allows_raw_init(s2),
Abi::Vector { element: s, count } => *count == 0 || scalar_allows_raw_init(s),
Abi::Aggregate { .. } => true, // Cannot be excluded *right now*.
Abi::Aggregate { .. } => true, // Fields are checked below.
};
if !valid {
// This is definitely not okay.
trace!("might_permit_raw_init({:?}, zero={}): not valid", self.layout, zero);
return Ok(false);
}

// If we have not found an error yet, we need to recursively descend.
// FIXME(#66151): For now, we are conservative and do not do this.
// If we have not found an error yet, we need to recursively descend into fields.
match &self.fields {
FieldsShape::Primitive | FieldsShape::Union { .. } => {}
FieldsShape::Array { .. } => {
// FIXME(#66151): For now, we are conservative and do not check arrays.
}
FieldsShape::Arbitrary { offsets, .. } => {
for idx in 0..offsets.len() {
let field = self.field(cx, idx).to_result()?;
if !field.might_permit_raw_init(cx, zero)? {
// We found a field that is unhappy with this kind of initialization.
return Ok(false);
}
}
}
}

// FIXME(#66151): For now, we are conservative and do not check `self.variants`.
Ok(true)
}
}
40 changes: 38 additions & 2 deletions src/test/ui/intrinsics/panic-uninitialized-zeroed.rs
Original file line number Diff line number Diff line change
Expand Up @@ -3,7 +3,7 @@

// This test checks panic emitted from `mem::{uninitialized,zeroed}`.

#![feature(never_type)]
#![feature(never_type, arbitrary_enum_discriminant)]
#![allow(deprecated, invalid_value)]

use std::{
Expand All @@ -24,6 +24,20 @@ enum Bar {}
#[allow(dead_code)]
enum OneVariant { Variant(i32) }

#[allow(dead_code, non_camel_case_types)]
enum OneVariant_NonZero {
Variant(i32, i32, num::NonZeroI32),
DeadVariant(Bar),
}

// An `Aggregate` abi enum where 0 is not a valid discriminant.
#[allow(dead_code)]
#[repr(i32)]
enum NoNullVariant {
Variant1(i32, i32) = 1,
Variant2(i32, i32) = 2,
}

// An enum with ScalarPair layout
#[allow(dead_code)]
enum LR {
Expand Down Expand Up @@ -125,6 +139,7 @@ fn main() {
"attempted to zero-initialize type `std::mem::ManuallyDrop<LR_NonZero>`, \
which is invalid"
);
*/

test_panic_msg(
|| mem::uninitialized::<(NonNull<u32>, u32, u32)>(),
Expand All @@ -136,7 +151,28 @@ fn main() {
"attempted to zero-initialize type `(std::ptr::NonNull<u32>, u32, u32)`, \
which is invalid"
);
*/

test_panic_msg(
|| mem::uninitialized::<OneVariant_NonZero>(),
"attempted to leave type `OneVariant_NonZero` uninitialized, \
which is invalid"
);
test_panic_msg(
|| mem::zeroed::<OneVariant_NonZero>(),
"attempted to zero-initialize type `OneVariant_NonZero`, \
which is invalid"
);

test_panic_msg(
|| mem::uninitialized::<NoNullVariant>(),
"attempted to leave type `NoNullVariant` uninitialized, \
which is invalid"
);
test_panic_msg(
|| mem::zeroed::<NoNullVariant>(),
"attempted to zero-initialize type `NoNullVariant`, \
which is invalid"
);

// Types that can be zero, but not uninit.
test_panic_msg(
Expand Down

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