Test case:

struct A
{
    A (const A &);
};

struct B
{
    A a;
    enum Mode { };
    Mode m:8;
};

struct C
{
    C();
    B b;
};

C fn()
{
    return C();
}


The test compiles fine with 4.7, fails with 4.8 (20130205 (experimental)) but only in C++11 mode:

g++ -c -std=c++11 t.ii
t.ii: In constructor ‘B::B(B&&)’:
t.ii:6:8: error: invalid conversion from ‘unsigned char’ to ‘B::Mode’ [-fpermissive]
 struct B
        ^
t.ii: In constructor ‘C::C(C&&)’:
t.ii:13:8: note: synthesized method ‘B::B(B&&)’ first required here 
 struct C
        ^
t.ii: In function ‘C fn()’:
t.ii:21:14: note: synthesized method ‘C::C(C&&)’ first required here 
     return C();
              ^


Google ref: b/8152830