Question

For example

using(var something = GetSomething())
{
    something.DoSomething();
    if(something.IsX()) return true;
}
return false;

Answer 1

Yes, absolutely. The Dispose method is called however the using statement is executed, unless it was an abrupt whole-process termination. The most common cases are:

• A return within the block
• An exception being thrown (and not caught) within the block
• Reaching the end of the block naturally

Basically a using statement is mostly syntactic sugar for a try/finally block – and finally has all the same properties.

EDIT: From section 8.13 of the C# 4 specification:

A using statement is stranslated into three parts: acquisition, usage, and disposal. Usage of the resource is implicitly enclosed in a try statement that includes a finally clause. This finally clause disposes of the resource.

The finally statement is described in section 8.10 of the specification:

The statements of a finally block are always executed when control leaves a try statement. This is true whether the control transfer occurs as a result of normal execution; as a result of executing a break, continue, goto or return statement; or as a result of propagating an exception out of the try statement.