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Constify Box<T, A> methods

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This commit is contained in:
woppopo 2021-12-23 22:03:12 +09:00
parent 69ac533527
commit eb4fc640b0
5 changed files with 224 additions and 32 deletions
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23
library/alloc/src/alloc.rs
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@ -323,17 +323,21 @@ unsafe fn exchange_malloc(size: usize, align: usize) -> *mut u8 {
#[cfg_attr(not(test), lang = "box_free")]
#[inline]
#[rustc_const_unstable(feature = "const_box", issue = "none")]
// This signature has to be the same as `Box`, otherwise an ICE will happen.
// When an additional parameter to `Box` is added (like `A: Allocator`), this has to be added here as
// well.
// For example if `Box` is changed to `struct Box<T: ?Sized, A: Allocator>(Unique<T>, A)`,
// this function has to be changed to `fn box_free<T: ?Sized, A: Allocator>(Unique<T>, A)` as well.
pub(crate) unsafe fn box_free<T: ?Sized, A: Allocator>(ptr: Unique<T>, alloc: A) {
pub(crate) const unsafe fn box_free<T: ?Sized, A: ~const Allocator + ~const Drop>(
ptr: Unique<T>,
alloc: A,
) {
unsafe {
let size = size_of_val(ptr.as_ref());
let align = min_align_of_val(ptr.as_ref());
let layout = Layout::from_size_align_unchecked(size, align);
alloc.deallocate(ptr.cast().into(), layout)
alloc.deallocate(From::from(ptr.cast()), layout)
}
}
@ -361,13 +365,22 @@ extern "Rust" {
/// [`set_alloc_error_hook`]: ../../std/alloc/fn.set_alloc_error_hook.html
/// [`take_alloc_error_hook`]: ../../std/alloc/fn.take_alloc_error_hook.html
#[stable(feature = "global_alloc", since = "1.28.0")]
#[rustc_const_unstable(feature = "const_box", issue = "none")]
#[cfg(all(not(no_global_oom_handling), not(test)))]
#[rustc_allocator_nounwind]
#[cold]
pub fn handle_alloc_error(layout: Layout) -> ! {
unsafe {
__rust_alloc_error_handler(layout.size(), layout.align());
pub const fn handle_alloc_error(layout: Layout) -> ! {
const fn ct_error(_: Layout) -> ! {
panic!("allocation failed");
}
fn rt_error(layout: Layout) -> ! {
unsafe {
__rust_alloc_error_handler(layout.size(), layout.align());
}
}
unsafe { core::intrinsics::const_eval_select((layout,), ct_error, rt_error) }
}
// For alloc test `std::alloc::handle_alloc_error` can be used directly.