What changed in Go, Rust and Solidity this week.

// This program demonstrates that the //go:wasmexport directive is ignored
// in Go 1.27.1. The function is not exported to a WebAssembly module,
// so we simply call it directly from Go and print the result.

package main

import "fmt"

//go:wasmexport add
func add(a, b int32) int32 { return a + b }

func main() {
	// Call the function directly; it behaves normally in Go.
	res := add(3, 4)
	fmt.Printf("add(3, 4) = %d\n", res)
}

// This program demonstrates the new generic type alias feature introduced in Go 1.24.
// It defines a generic alias for a map type and uses it to store and retrieve values.
package main

import "fmt"

// Generic type alias: a map from K to V, where K must be comparable.
type MyMap[K comparable, V any] = map[K]V

func main() {
	// Create a MyMap[int, string] and populate it.
	m := MyMap[int, string]{}
	m[1] = "one"
	m[2] = "two"

	// Print the map contents.
	for k, v := range m {
		fmt.Printf("%d -> %s\n", k, v)
	}
}

// This program demonstrates that Rust 1.98.1 (edition 2024) does not
// support target modifier flags.  It simply prints a message indicating
// that the feature is unavailable in this version.

fn main() {
    println!("Target modifiers are not available in Rust 1.98.1 (edition 2024).");
}

// 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");
    }
}