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kandi X-RAY | rust Summary
kandi X-RAY | rust Summary
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First, I tried something like this:...
ANSWERAnswered 2022-Apr-12 at 00:43
It is definitely an interesting one.
They are similar - but not quite the same.
resize() is a member of
rotate_right(), on the other hand, is a method of slices.
Vec derefs to
[T], so most of the time this does not matter. But actually, while this call:
When trying to run the command using nextjs npm run dev shows error - failed to load SWC binary see more info here: https://nextjs.org/docs/messages/failed-loading-swc.
I've tried uninstalling node and reinstalling it again with version 16.13 but without success, on the vercel page, but unsuccessful so far. Any tips?
Also, I noticed it's a current issue on NextJS discussion page and it has to do with the new Rust-base compiler which is faster than Babel....
ANSWERAnswered 2021-Nov-20 at 13:57
This worked as suggeted by nextJS docs but it takes away Rust compiler and all its benefits... Here is what I did for those who eventually get stuck...
Step 1. add this line or edit next.json.js
In the current stable Rust, is there a way to write a function equivalent to BTreeMap::pop_last?
The best I could come up with is:...
ANSWERAnswered 2022-Mar-15 at 16:55
Is there a way to work around this issue without imposing additional constraints on map key and value types?
It doesn't appear doable in safe Rust, at least not with reasonable algorithmic complexity. (See Aiden4's answer for a solution that does it by re-building the whole map.)
But if you're allowed to use unsafe, and if you're determined enough that you want to delve into it, this code could do it:
Consider following code...
ANSWERAnswered 2022-Mar-03 at 21:14
You are correct, this is due to match ergonomics. The first case should hopefully be self explanatory, but the second and third cases can be a bit counter-intuitive.
In the second case:
(x,)is a non-reference pattern (see the second example in the RFC). The
ttuple reference is dereferenced, and
xis bound as a
refas it also is a non-reference pattern. Note that
t.0was a reference to begin with, thus resulting in
xbeing a double reference.
(&y,)is also a non-reference pattern. The
ttuple is dereferenced again to a
&yis a reference pattern being matched to a
yis bound with
movemode and is an
In the third case:
Using the same reasoning as the second case,
uis dereferenced via
Derefcoercion to an
x, a non-reference pattern, is bound in
Again with the same reasoning as the second case,
uis dereferenced to an
&yreference pattern is then matched to an
i32, a non-reference, which causes an error.
I have been using the
#[tokio::main] macro in one of my programs. After importing
main and using it unqualified, I encountered an unexpected error.
ANSWERAnswered 2022-Feb-15 at 23:57
#[main] is an old, unstable attribute that was mostly removed from the language in 1.53.0. However, the removal missed one line, with the result you see: the attribute had no effect, but it could be used on stable Rust without an error, and conflicted with imported attributes named
main. This was a bug, not intended behaviour. It has been fixed as of
1.59.0-beta.8. Your example with
use tokio::main; and
#[main] can now run without error.
Before it was removed, the unstable
#[main] was used to specify the entry point of a program. Alex Crichton described the behaviour of it and related attributes in a 2016 comment on GitHub:
Ah yes, we've got three entry points. I.. think this is how they work:
#[start], the receiver of
char **argv. This is literally the symbol
main(or what is called by that symbol generated in the compiler).
- Next, there's
#[lang = "start"]. If no
#[start]exists in the crate graph then the compiler generates a
mainfunction that calls this. This functions receives argc/argv along with a third argument that is a function pointer to the
#[main]function (defined below). Importantly,
#[lang = "start"]can be located in a library. For example it's located in the standard library (libstd).
#[main], the main function for an executable. This is passed no arguments and is called by
#[lang = "start"](if it decides to). The standard library uses this to initialize itself and then call the Rust program. This, if not specified, defaults to
fn mainat the top.
So to answer your question, this isn't the same as
#[start]. To answer your other (possibly not yet asked) question, yes we have too many entry points.
build[s] a package's documentation, using specified custom flags
build[s] a package's documentation
What is the difference between the two? From what I understand
cargo rustdoc is just like
cargo doc, but it allows for more lints—for instance:
ANSWERAnswered 2022-Jan-11 at 21:00
Their relationship is like between
cargo build and
cargo doc performs all the usual work, for an entire workspace, including dependencies (by default).
cargo rustdoc allows you to pass flags directly to rustdoc, and only works for a single crate.
Here is the execution code for
cargo rustdoc. Here is the code for
cargo doc. The only differences is that
cargo rustdoc always specify to not check dependencies while
cargo doc allows you to choose (by default it does, but you can specify the flag
--no-deps), and that
cargo rustc allows you to pass flags directly to rustdoc with the flags after the
I want to run an example via Cargo but I am facing an error:...
ANSWERAnswered 2021-Dec-14 at 14:09
Update the Rust to satisfy the new edition 2021.
rustup default nightly && rustup update
Thanks to @ken.
Yes, you can use the
stable channel too!
But I love
Is there a more idiomatic way to express something like the following?...
ANSWERAnswered 2022-Jan-27 at 07:32
There are many ways to do it. One of the simplest (and arguably most readable) is something like this:
I'm trying to adapt some layers of existing C++ code to be used by Rust and apparently the way is through a C API.
For example, one function might return a struct as an object...
ANSWERAnswered 2022-Jan-21 at 01:15
extern "C" on both sides +
#[repr(C)] on the Rust side + only using C-compatible types for interfacing between C++ and Rust, should work.
These two loops are equivalent in C++ and Rust:...
ANSWERAnswered 2022-Jan-12 at 10:20
Overflow in the iterator state.
The C++ version will loop forever when given a large enough input:
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