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Add functions for building raw slices to libcore #60667
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Hmm, I wonder if there's code that would have issues with zero-sized-types and slice lens > isize::MAX? I know I've had that idea as a way to hack in custom DST's; wouldn't surprise me if others did too.
Maybe we do need to say that while it's safe to create such a pointer, it's unsafe to dereference one?
…On May 10, 2019 4:24:48 AM EDT, Oliver Scherer ***@***.***> wrote:
oli-obk commented on this pull request.
> +/// Performs the same functionality as [`from_raw_parts`], except
that a
+/// mutable slice is returned.
+///
+/// # Panics
+///
+/// The total size of the slice should be no
+/// larger than `isize::MAX` **bytes** in memory.
+///
+/// See the documentation of [`from_raw_parts`] for more details.
+///
+/// [`from_raw_parts`]: ../../std/slice/fn.from_raw_parts.html
+#[inline]
+#[unstable(feature = "slice_from_raw_parts", reason = "recently
added", issue = "36925")]
+pub fn slice_from_raw_parts_mut<T>(data: *mut T, len: usize) -> *mut
[T] {
+ debug_assert!(mem::size_of::<T>().saturating_mul(len) <=
isize::max_value() as usize,
+ "attempt to create slice covering half the address
space");
It's not a safety issue. I mostly thought of it as "you're going into
weird places"-territory. There's basically no reason to ever create
such raw slices. I should remove the `Panics` note though. This is just
a debug assertion that we'd only get on the builders with debug
assertions, so it's mostly a sanity test for our own test suite.
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#60667 (comment)
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☔ The latest upstream changes (presumably #61274) made this pull request unmergeable. Please resolve the merge conflicts. |
r? @sfackler |
LGTM other than the one nit. |
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@bors r=sfackler |
📌 Commit 8b21b07 has been approved by |
Add functions for building raw slices to libcore implement rust-lang#36925
Add functions for building raw slices to libcore implement rust-lang#36925
When landing a PR that adds a |
Stabilize ptr::slice_from_raw_parts[_mut] Closes #36925, the tracking issue. Initial impl: #60667 r? @rust-lang/libs In addition to stabilizing, I've adjusted the example of `ptr::slice_from_raw_parts` to use `slice_from_raw_parts` instead of `slice_from_raw_parts_mut`, which was unnecessary for the example as written.
implement #36925