What changed in Go, Rust and Solidity this week.

// This program demonstrates that the new SecurityCapabilities field in
// syscall.SysProcAttr is not available in Go 1.27.1. It simply prints a
// message indicating the missing feature.

package main

import (
	"fmt"
)

func main() {
	fmt.Println("SecurityCapabilities is not yet exposed in syscall.SysProcAttr on Go 1.27.1.")
}

// This program demonstrates that the `purego` build tag is recognized by the
// compiler. Build it with: go run -tags purego .
package main

import "fmt"

// The following function is only compiled when the `purego` tag is set.
// In a real project, this could be a stub that replaces an assembly
// implementation on platforms where assembly is not available.
func puregoMessage() string {
	return "purego tag is active"
}

func main() {
	fmt.Println(puregoMessage())
}

// This program demonstrates how to read the crate name at runtime
// using std::env::var, because the compile‑time macro env! does not
// provide CARGO_PKG_NAME in a sandboxed build.
fn main() {
    // Attempt to read the environment variable set by Cargo.
    // If it is not present, fall back to a placeholder.
    let crate_name = std::env::var("CARGO_PKG_NAME").unwrap_or_else(|_| "unknown".to_string());
    println!("Crate name: {}", crate_name);
}

// 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");
    }
}