Add a `Result::into_ok_or_err` method to extract a `T` from `Result<T, T>`
When updating code to handle the semi-recent deprecation of `compare_and_swap` in favor of `compare_exchange`, which returns `Result<T, T>`, I wanted this. I've also wanted it with code using `slice::binary_search` before.
The name (and perhaps the documentation) is the hardest part here, but this name seems consistent with the other Result methods, and equivalently memorable.
Document that `assert!` format arguments are evaluated lazily
It can be useful to do some computation in `assert!` format arguments, in order to get better error messages. For example:
```rust
assert!(
some_condition,
"The state is invalid. Details: {}",
expensive_call_to_get_debugging_info(),
);
```
It seems like `assert!` only evaluates the format arguments if the assertion fails, which is useful but doesn't appear to be documented anywhere. This PR documents the behavior and adds some tests.
To digit simplification
I found out the other day that all the ascii digits have the first four bits as one would hope them to. (Eg. char `2` ends `0b0010`). There are two bits to indicate it's in the digit range ( `0b0011_0000`). If it is a true digit then all the higher bits aside from these two will be 0 (as ascii is the lowest part of the unicode u32 spectrum). So XORing with `0b11_0000` should mean we either get the number 0-9 or alternativly we get a larger number in the u32 space. If we get something that's not 0-9 then it will be discarded as it will be greater than the radix.
The code seems so fast though that there's quite a lot of noise in the benchmarks so it's not that easy to prove conclusively that it's faster as well as less instructions.
The non-fast path I was toying with as well wondering if we could do this as then we'd only have one return and less instructions still:
```
match self {
'a'..='z' => self as u32 - 'a' as u32 + 10,
'A'..='Z' => self as u32 - 'A' as u32 + 10,
_ => { radix = 10; self as u32 ^ ASCII_DIGIT_MASK},
}
```
Here's the [godbolt](https://godbolt.org/z/883c9n).
( H/T to ``@byteshadow`` for pointing out xor was what I needed)
Quotes the arg and not quotes the arg have different effect on Windows when the program called
are msys2/cygwin program.
Refer to https://github.com/msys2/MSYS2-packages/issues/2176
Signed-off-by: Yonggang Luo <luoyonggang@gmail.com>
It can be useful to do some computation in `assert!` format arguments, in order to get better error messages. For example:
```rust
assert!(
some_condition,
"The state is invalid. Details: {}",
expensive_call_to_get_debugging_info(),
);
```
It seems like `assert!` only evaluates the format arguments if the assertion fails, which is useful but doesn't appear to be documented anywhere. This PR documents the behavior and adds some tests.
BTree: remove outdated traces of coercions
The introduction of `marker::ValMut` (#75200) meant iterators no longer see mutable keys but their code still pretends it does. And settle on the majority style `Some(unsafe {…})` over `unsafe { Some(…) }`.
r? `@Mark-Simulacrum`
Initialize BTree nodes directly in the heap
We can avoid any stack-local nodes entirely by using `Box::new_uninit`, and since the nodes are mostly `MaybeUninit` fields, we only need a couple of actual writes before `assume_init`. This should help with the stack overflows in #81444, and may also improve performance in general.
r? `@Mark-Simulacrum`
cc `@ssomers`
Added tests to drain an empty vec
Discovered this kind of issue in an unrelated library.
The author copied the tests from here and AFAIK, there are no tests for this particular case.
https://github.com/LeonineKing1199/minivec/pull/19
Signed-off-by: Hanif Bin Ariffin <hanif.ariffin.4326@gmail.com>
Add docs for shared_from_slice From impls
The advantage of making these docs is mostly in pointing out that these
functions all make new allocations and copy/clone/move the source into them.
These docs are on the function, and not the `impl` block, to avoid showing
the "[+] show undocumented items" button.
CC #51430
Fix doc test for Vec::retain(), now passes clippy::eval_order_dependence
Doc test for Vec::retain() works correctly but is flagged by clippy::eval_order_dependence. Fix avoids the issue by using an iterator instead of an index.
Discovered this kind of issue in an unrelated library.
The author copied the tests from here and AFAIK, there are no tests for this particular case.
Signed-off-by: Hanif Bin Ariffin <hanif.ariffin.4326@gmail.com>
use RWlock when accessing os::env
Multiple threads modifying the current process environment is fairly uncommon. Optimize for the more common read case.
r? ````@m-ou-se````
Increment `self.index` before calling `Iterator::self.a.__iterator_ge…
…`t_unchecked` in `Zip` `TrustedRandomAccess` specialization
Otherwise if `Iterator::self.a.__iterator_get_unchecked` panics the
index would not have been incremented yet and another call to
`Iterator::next` would read from the same index again, which is not
allowed according to the API contract of `TrustedRandomAccess` for
`!Clone`.
Fixes https://github.com/rust-lang/rust/issues/81740
The advantage of making these docs is mostly in pointing out that these
functions all make new allocations and copy/clone/move the source into them.
These docs are on the function, and not the `impl` block, to avoid showing
the "[+] show undocumented items" button.
CC #51430
