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Make size_of_val and min_align_of_val intrinsics unsafe #80711

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Jan 5, 2021
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Make size_of_val and min_align_of_val intrinsics unsafe #80711

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2 changes: 0 additions & 2 deletions compiler/rustc_typeck/src/check/intrinsic.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -63,8 +63,6 @@ pub fn intrinsic_operation_unsafety(intrinsic: Symbol) -> hir::Unsafety {
| sym::min_align_of
| sym::needs_drop
| sym::caller_location
| sym::size_of_val
| sym::min_align_of_val
| sym::add_with_overflow
| sym::sub_with_overflow
| sym::mul_with_overflow
Expand Down
16 changes: 11 additions & 5 deletions library/core/src/mem/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,7 @@
//! types, initializing and manipulating memory.

#![stable(feature = "rust1", since = "1.0.0")]
#![cfg_attr(bootstrap, allow(unused_unsafe))]

use crate::clone;
use crate::cmp;
Expand Down Expand Up @@ -333,7 +334,8 @@ pub const fn size_of<T>() -> usize {
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_const_unstable(feature = "const_size_of_val", issue = "46571")]
pub const fn size_of_val<T: ?Sized>(val: &T) -> usize {
intrinsics::size_of_val(val)
// SAFETY: `val` is a reference, so it's a valid raw pointer
unsafe { intrinsics::size_of_val(val) }
}

/// Returns the size of the pointed-to value in bytes.
Expand Down Expand Up @@ -381,7 +383,8 @@ pub const fn size_of_val<T: ?Sized>(val: &T) -> usize {
#[unstable(feature = "layout_for_ptr", issue = "69835")]
#[rustc_const_unstable(feature = "const_size_of_val_raw", issue = "46571")]
pub const unsafe fn size_of_val_raw<T: ?Sized>(val: *const T) -> usize {
intrinsics::size_of_val(val)
// SAFETY: the caller must provide a valid raw pointer
unsafe { intrinsics::size_of_val(val) }
}

/// Returns the [ABI]-required minimum alignment of a type.
Expand Down Expand Up @@ -425,7 +428,8 @@ pub fn min_align_of<T>() -> usize {
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_deprecated(reason = "use `align_of_val` instead", since = "1.2.0")]
pub fn min_align_of_val<T: ?Sized>(val: &T) -> usize {
intrinsics::min_align_of_val(val)
// SAFETY: val is a reference, so it's a valid raw pointer
unsafe { intrinsics::min_align_of_val(val) }
}

/// Returns the [ABI]-required minimum alignment of a type.
Expand Down Expand Up @@ -469,7 +473,8 @@ pub const fn align_of<T>() -> usize {
#[rustc_const_unstable(feature = "const_align_of_val", issue = "46571")]
#[allow(deprecated)]
pub const fn align_of_val<T: ?Sized>(val: &T) -> usize {
intrinsics::min_align_of_val(val)
// SAFETY: val is a reference, so it's a valid raw pointer
unsafe { intrinsics::min_align_of_val(val) }
}

/// Returns the [ABI]-required minimum alignment of the type of the value that `val` points to.
Expand Down Expand Up @@ -513,7 +518,8 @@ pub const fn align_of_val<T: ?Sized>(val: &T) -> usize {
#[unstable(feature = "layout_for_ptr", issue = "69835")]
#[rustc_const_unstable(feature = "const_align_of_val_raw", issue = "46571")]
pub const unsafe fn align_of_val_raw<T: ?Sized>(val: *const T) -> usize {
intrinsics::min_align_of_val(val)
// SAFETY: the caller must provide a valid raw pointer
unsafe { intrinsics::min_align_of_val(val) }
}

/// Returns `true` if dropping values of type `T` matters.
Expand Down