Why was the statement (j++); forbidden?

Question

The following code is wrong (see it on ideone):

public class Test
{
    public static void Main()
    {
        int j = 5;
        (j++);      // if we remove th         


        

Answer 1

In the C# language specification

Expression statements are used to evaluate expressions. Expressions that can be used as statements include method invocations, object allocations using the new operator, assignments using = and the compound assignment operators, increment and decrement operations using the ++ and -- operators and await expressions.

Putting parentheses around a statement creates a new so-called parenthesized expression. From the specification:

A parenthesized-expression consists of an expression enclosed in parentheses. ... A parenthesized-expression is evaluated by evaluating the expression within the parentheses. If the expression within the parentheses denotes a namespace or type, a compile-time error occurs. Otherwise, the result of the parenthesized-expression is the result of the evaluation of the contained expression.

Since parenthesized expressions are not listed as a valid expression statement, it is not a valid statement according to the specification. Why the designers chose to do it this way is anyone's guess but my bet is because parentheses do no useful work if the entire statement is contained in parentheses: stmt and (stmt) are exactly the same.