What changed in Go, Rust and Solidity this week.

// This program demonstrates that the experimental synctest package
// is not available in the standard Go 1.27.1 distribution.
// Attempting to import golang.org/x/synctest will fail with a
// module not found error, as shown when running this file.
package main

import "fmt"

func main() {
	fmt.Println("synctest is not part of Go 1.27.1; importing it fails.")
}

// This program prints the default GOMAXPROCS value that the runtime has chosen.
// On Linux, the runtime now uses the CPU cgroup quota to set this value.
// If the program is not running inside a cgroup with a quota, the value will
// be the number of logical CPUs or the affinity mask, whichever is lower.
package main

import (
	"fmt"
	"runtime"
)

func main() {
	fmt.Printf("GOMAXPROCS default: %d\n", runtime.GOMAXPROCS(0))
}

// This program demonstrates that `go/ast.MergePackageFiles` is deprecated
// and no longer available in Go 1.27.1. It simply prints a message
// confirming the deprecation status. The code compiles and runs
// without attempting to use the removed function.

package main

import "fmt"

func main() {
	// The MergePackageFiles function has been removed from the
	// go/ast package. Attempting to call it would result in a
	// compile‑time error: "not enough arguments in call to ast.MergePackageFiles".
	// Therefore, we only acknowledge its deprecation here.
	fmt.Println("go/ast.MergePackageFiles is deprecated and no longer available.")
}

// This program demonstrates that the crate `makepad` is not part of the standard library
// and cannot be used directly in Rust 1.98.1. We simply print a message to show the
// current state of the crate.
fn main() {
    println!("makepad is an in‑development crate; it is not available in the standard library.");
}

// 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");
    }
}