https://github.com/qryxip/rhs_first_assign

An attribute macro to hack compound assignment
https://github.com/qryxip/rhs_first_assign

Last synced: 24 days ago
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An attribute macro to hack compound assignment

• Host: GitHub
• URL: https://github.com/qryxip/rhs_first_assign
• Owner: qryxip
• License: apache-2.0
• Created: 2020-01-22T10:12:05.000Z (almost 5 years ago)
• Default Branch: master
• Last Pushed: 2020-02-17T10:21:56.000Z (almost 5 years ago)
• Last Synced: 2024-11-18T15:11:38.072Z (about 1 month ago)
• Language: Rust
• Homepage:
• Size: 13.7 KB
• Stars: 1
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE-APACHE

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README

        
# rhs\_first\_assign

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An attribute macro to hack compound assignment.

## Motivation

```rust

use std::num::Wrapping;

fn main() {

    let mut xs = vec![Wrapping(1), Wrapping(2)];

    // OK

    xs[1] = xs[0] + xs[1];

    // Error

    xs[1] += xs[0];

}

```

```

error[E0502]: cannot borrow `xs` as immutable because it is also borrowed as mutable

  --> src/main.rs:10:14

   |

10 |     xs[1] += xs[0];

   |     ---------^^---

   |     |        |

   |     |        immutable borrow occurs here

   |     mutable borrow occurs here

   |     mutable borrow later used here

```

## Usage

```rust

use rhs_first_assign::rhs_first_assign;

use std::num::Wrapping;

#[rhs_first_assign]

fn main() {

    let mut xs = vec![Wrapping(1), Wrapping(2)];

    xs[1] = xs[0] + xs[1];

    xs[1] += xs[0];

}

```

↓

```rust

use std::num::Wrapping;

fn main() {

    let mut xs = vec![Wrapping(1), Wrapping(2)];

    xs[1] = xs[0] + xs[1];

    {

        let __rhs_first_assign_rhs_l11_c10 = xs[0];

        xs[1] += __rhs_first_assign_rhs_l11_c10;

    };

}

```

## License

Licensed under [MIT](https://opensource.org/licenses/MIT) OR [Apache-2.0](http://www.apache.org/licenses/LICENSE-2.0).