What changed in Go, Rust and Solidity this week.

package main

import (
	"encoding/json"
	"fmt"
)

func main() {
	// The existing json package is still available in Go 1.27.1.
	// It will be rewritten to use the new v2 API in a future release.
	data, _ := json.Marshal(map[string]int{"a": 1})
	fmt.Println(string(data))
}

// This program demonstrates the new crates announced in This Week in Rust 655.
// They are not part of the standard library, so we just list their names.
fn main() {
    let crates = [
        "stdx",
        "OmniScope",
        "Asterinas",
        "Oryxis SSH",
        "Ratatui",
        "@utoo/pack",
    ];
    println!("New crates and tools announced:");
    for c in &crates {
        println!("- {}", c);
    }
}

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.37;

// This contract demonstrates that delete on a memory bytes array element
// clears only the targeted byte, not the whole 32‑byte word.
contract Main {
    function clearByte(uint index) external pure returns (bytes memory) {
        bytes memory data = new bytes(5);
        // set all bytes to 0xFF for visibility
        for (uint i = 0; i < data.length; i++) {
            data[i] = 0xFF;
        }
        // delete the element at `index`
        delete data[index];
        return data;
    }
}

Tests

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.37;

import "./main.sol";

contract MainTest {
    Main main;

    constructor() {
        main = new Main();
    }

    function test_singleByteCleared() public {
        bytes memory result = main.clearByte(2);
        // bytes[2] should be 0x00, others remain 0xFF
        require(result[2] == 0x00, "byte not cleared");
        require(result[0] == 0xFF, "other byte altered");
        require(result[1] == 0xFF, "other byte altered");
        require(result[3] == 0xFF, "other byte altered");
        require(result[4] == 0xFF, "other byte altered");
    }
}

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.37;

// This contract demonstrates the 0.8.37 delete‑byte‑array‑element fix.
// It creates a memory bytes array, sets each element to 0x01,
// deletes the middle element, and returns the array.
contract Demo {
    function deleteMiddle() external pure returns (bytes memory) {
        bytes memory b = new bytes(3);
        b[0] = 0x01;
        b[1] = 0x01;
        b[2] = 0x01;
        delete b[1]; // only b[1] should become 0x00
        return b;
    }
}

Tests

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.37;
import "./main.sol";

contract DemoTest {
    Demo demo;

    constructor() {
        demo = new Demo();
    }

    function test_deleteLeavesOtherBytes() external {
        bytes memory result = demo.deleteMiddle();
        require(result.length == 3, "wrong length");
        require(result[0] == 0x01, "b[0] altered");
        require(result[1] == 0x00, "b[1] not zeroed");
        require(result[2] == 0x01, "b[2] altered");
    }
}