Compiling this with the latest DMD (fca8ba6f445fe99b55a6953722815c16d68344fa): void main() { char[][] a; const(char)[][] b = a; } Yields this error: test.d(4): Error: cannot implicitly convert expression (a) of type char[][] to const(char)[][] This used to compile fine in DMD 2.057.
Not a bug. See issue 4251.
Not an invalid request.
Sorry for the noise. The compile error in Tango that motivates this bug report could be type checked by implementing the enhancement in issue 7208, but the example code given here is obviously invalid.