Brace-initialized initializerlists – as supported since C++11 – are malformed. The expected behavior is as for old ( ) initialization.

Example:

class Example
{
public:
    Example(int a) : m_value{a} // Initialization using { }
    {
        /* Ctor body */
    }

private:
    int m_value;
};

Using auto format breaks the formatting:

    Example(int a) : m_value
    {
        a 
    }
    {
        /* Ctor body */
    }

The m_value{a} is separated into new lines.

Using normal ( ) for initializer lists – m_value(a) – works fine.