What changed in Go, Rust and Solidity this week.

package main

import (
	"crypto/x509"
	"fmt"
)

func main() {
	// Create a simple certificate pool to show that the crypto/x509 package
	// is available and can be used without errors after the security fixes
	// shipped in go1.23.5.
	pool := x509.NewCertPool()
	fmt.Println("Certificate pool created:", pool != nil)
}

// This program demonstrates that the proposed `hash.XOF` interface is not
// available in the Go 1.27.1 standard library. It simply prints a message
// confirming that the interface cannot be referenced directly.
package main

import "fmt"

func main() {
	fmt.Println("hash.XOF is not part of the Go 1.27.1 standard library")
}

// This program demonstrates the deprecation of the public packages
// golang.org/x/tools/go/packages/packagestest and golang.org/x/tools/go/expect.
// Since the packages have been removed, attempting to import them would
// result in a compile error. The program simply prints a message.
package main

import "fmt"

func main() {
	fmt.Println("packagestest and expect have been deprecated and deleted.")
}

// This program demonstrates that the compiler and standard library are unchanged
// by the typo fix in the Return‑Type‑Notation RFC. It simply prints a message.
fn main() {
    println!("Return‑Type‑Notation RFC typo fixed; no code impact.");
}

// 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");
    }
}