Example code: uint[] toArray(string s) { return cast(uint[])s; } version(BigEndian) static assert(toArray("\xdd\xcc\xbb\xaa")[0] == 0xddccbbaa); else static assert(toArray("\xdd\xcc\xbb\xaa")[0] == 0xaabbccdd); // The following code works, of course: static this() { version(BigEndian) assert(toArray("\xdd\xcc\xbb\xaa")[0] == 0xddccbbaa); else assert(toArray("\xdd\xcc\xbb\xaa")[0] == 0xaabbccdd); }
This test case generated wrong code in 2.053 and earlier, but it actually should have been accepts-invalid. Since 2.054 it generates test.d(3): Error: array cast from string to uint[] is not supported at compile t ime test.d(8): Error: cannot evaluate toArray("\xdd\xcc\xbb\xaa") at compile time test.d(8): Error: static assert (toArray("\xdd\xcc\xbb\xaa")[0u] == -1430532899 u) is not evaluatable at compile time https://github.com/D-Programming-Language/dmd/commit/5d6df984d50862f25b481790ad4ef86b0afd6c9a Also the spec now states that such casts are not legal in CTFE.