The unary "+" in "((x) /= (2 % x)) + (-y)" reports an error

[haoyang9804]

Description

The unary "+" in "((x) /= (2 % x)) + (-y)" reports an error, but x = ((x) /= (2 % x)) + (-y) does not.

Environment

• Compiler version: 0.8.27-develop.2024.6.25+commit.ce4be6e1.Darwin.appleclang

Steps to Reproduce

pragma solidity ^0.8.0;

contract Test {
  function f(int32 x) external pure returns (int32) {
    int32 y = 1;
    ((x) /= (2 % x)) + (-y);
    return 2;
  }
}

Compiling the above program raises an error complaining that + is disallowed in ((x) /= (2 % x)) + (-y);. However, when I change this expression statement into x = ((x) /= (2 % x)) + (-y);, the compiler does not raise the error. According to my understanding of Solidity type system, expr /= expr is an assignment expression, and its value equals the value of the left-hand-side identifier. I think + can connect the assignment expression and an identifier expression (-y).

[ekpyron]

Thanks for reporting, this is definitely an unintended regression introduced in 0.8.20!