This may or may not have been an intended change:

-----
enum A = 1;

enum E
{
    A = A
}

void main()
{
}
-----

$ dmd test.d
test.d(7): Error: enum member test.E.A circular reference to enum member

The workaround is simple for module-scoped enums, use the [dot] expression to look up module-scoped symbols:

-----
enum A = 1;

enum E
{
    A = .A  // works
}

void main()
{
}
-----

However the following code does not have an easy workaround:

-----
void main()
{
    enum A = 1;

    enum E
    {
        // circular reference, cannot use ".A" here
        // because "A" is not in module scope
        A = A  
    }
}
-----

Above you would likely have to introduce an alias such as:

-----
void main()
{
    enum A = 1;
    alias thisA = A;
    enum E
    {
        A = thisA  // ok
    }
}
-----

If this regression was intended we're going to have to properly document it, both in the docs and in the upcoming changelog.

The regression was found in DGui, where some enum members have the same name as WinAPI constants, but were purposefully wrapped in the enum to make the constants typed:

enum EdgeType : uint
{
    RAISED_OUTER = BDR_RAISEDOUTER,
    RAISED_INNER = BDR_RAISEDINNER,

    SUNKEN_OUTER = BDR_SUNKENOUTER,
    SUNKEN_INNER = BDR_SUNKENINNER,

    BUMP        = EDGE_BUMP,
    ETCHED      = EDGE_ETCHED,
    EDGE_RAISED = EDGE_RAISED,  // issue here
    SUNKEN      = EDGE_SUNKEN,
}