https://issues.dlang.org/show_bug.cgi?id=16607

          Issue ID: 16607
           Summary: [REG2.072b1] "forward reference" error with structs
                    nested in struct templates
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Keywords: rejects-valid
          Severity: regression
          Priority: P1
         Component: dmd
          Assignee: nobody@puremagic.com
          Reporter: thecybershadow@gmail.com

//////// test.d ////////
struct A(T)
{
    T t;

    struct C
    {
    }
}

struct B
{
    A!(typeof(this))* a;
}
////////////////////////

Compiler output:

test.d(5): Error: struct test.A!(B).A.C has forward references
test.d(12): Error: template instance test.A!(B) error instantiating

Introduced in https://github.com/D-Programming-Language/dmd/pull/5500

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