alignment unintuitive for expressions split on multiple lines

Alignment of multi-line expressions is done using automatic indentation with 4 spaces. It does not respect user's indentation or, better, the expected behavior described later below. Right now, one obtains:

some_expression = a +
    b -
    c;

Based on general (feeling) rules of indentation in the C++ editor, I would expect alignment of many items of an expression to be done to the column of the first item, when splitting an expression on multiple lines. Like in:

some_expression = a +
                  b -
                  c;

or, depending where the user places the signs:

some_expression = a
                + b 
                - c;

Parenthesized expressions are treated correctly right now:

some_expression = (a +
                   b -
                   c);

So do expressions containing pipe operators:

some_stream << a
            << b;

I understand that this could be a question of taste, but I believe that the way I would like it is also the way of least surprise. At a minimum, user's indentation setting should be respected.

Thank you very much for the attention.