Improve boxed docs #34740
Improve boxed docs #34740
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| /// ``` | ||
| /// let mut x = 5; | ||
| /// let ptr = &mut x as *mut i32; | ||
| /// let b = unsafe { Box::from_raw(ptr) }; |
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It would be better if this example didn't demonstrate code that is likely to cause a segfault. The typical use case for this is when you start off with a Box, convert it to a raw pointer with into_raw, and then need to restore it.
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I see. Just by curiosity: why would it likely cause a segfault in here?
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The Box ends up being a pointer to the stack, and is then freed when the
Box is dropped.
On Saturday, July 9, 2016, Guillaume Gomez [email protected] wrote:
In src/liballoc/boxed.rs
#34740 (comment):@@ -249,6 +249,14 @@ impl<T: ?Sized> Box {
/// This function is unsafe because improper use may lead to
/// memory problems. For example, a double-free may occur if the
/// function is called twice on the same raw pointer.
- ///
- /// # Examples
- ///
- /// ```
- /// let mut x = 5;
- /// let ptr = &mut x as *mut i32;
- /// let b = unsafe { Box::from_raw(ptr) };
I see. Just by curiosity: why would it likely cause a segfault in here?
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Updated. |
| /// use std::any::Any; | ||
| /// | ||
| /// fn print_if_string(value: Box<Any + Send>) { | ||
| /// match value.downcast::<String>() { |
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@frewsxcv: Thanks! |
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@bors: r+ rollup |
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📌 Commit 1ef7bdc has been approved by |
…abnik Improve boxed docs Fixes rust-lang#29343. r? @steveklabnik
Fixes #29343.
r? @steveklabnik