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Add #[must_use] to alloc functions that would leak memory #90427

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Merged
merged 1 commit into from
Oct 31, 2021
Merged

Add #[must_use] to alloc functions that would leak memory #90427

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3 changes: 3 additions & 0 deletions library/alloc/src/alloc.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -81,6 +81,7 @@ pub use std::alloc::Global;
/// }
/// ```
#[stable(feature = "global_alloc", since = "1.28.0")]
#[must_use = "losing the pointer will leak memory"]
#[inline]
pub unsafe fn alloc(layout: Layout) -> *mut u8 {
unsafe { __rust_alloc(layout.size(), layout.align()) }
Expand Down Expand Up @@ -117,6 +118,7 @@ pub unsafe fn dealloc(ptr: *mut u8, layout: Layout) {
///
/// See [`GlobalAlloc::realloc`].
#[stable(feature = "global_alloc", since = "1.28.0")]
#[must_use = "losing the pointer will leak memory"]
#[inline]
pub unsafe fn realloc(ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 {
unsafe { __rust_realloc(ptr, layout.size(), layout.align(), new_size) }
Expand Down Expand Up @@ -150,6 +152,7 @@ pub unsafe fn realloc(ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8
/// }
/// ```
#[stable(feature = "global_alloc", since = "1.28.0")]
#[must_use = "losing the pointer will leak memory"]
#[inline]
pub unsafe fn alloc_zeroed(layout: Layout) -> *mut u8 {
unsafe { __rust_alloc_zeroed(layout.size(), layout.align()) }
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1 change: 1 addition & 0 deletions library/alloc/src/sync.rs
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Expand Up @@ -804,6 +804,7 @@ impl<T: ?Sized> Arc<T> {
/// let x_ptr = Arc::into_raw(x);
/// assert_eq!(unsafe { &*x_ptr }, "hello");
/// ```
#[must_use = "losing the pointer will leak memory"]
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This one feels like it could lead to false positives. This is Arc, so you can get the data back via another instance.

not sure if it happens in practice though. I think I used that once to simulate
increment_strong_count? Not sure.

#[stable(feature = "rc_raw", since = "1.17.0")]
pub fn into_raw(this: Self) -> *const T {
let ptr = Self::as_ptr(&this);
Expand Down