On 2/1/15 9:42 AM, Stefan Frijters wrote:
So recently I ran into this discrepancy between the behaviour of dmd
(and gdc) and ldc2:
void test(int[] data)
in { assert(data, "data must be non-null."); }
Note, this will soon fail to compile. use assert(data.ptr) instead.
body { }
void main() {
import std.stdio;
int[1] data1;
writeln(data1); // [0]
test(data1); // Passes
assert(data1.ptr !is null);
int[0] data0;
writeln(data0); // []
test(data0); // Passes with dmd and gdc, fails with ldc2 (2.066.1)
assert(data0.ptr !is null); // Passes with dmd and gdc, fails with ldc2
}
I reported this as an issue at
https://github.com/ldc-developers/ldc/issues/831 and was asked to check
for a more definite answer. So, in light of recent developments of
trying to tighten up the D spec, does anyone have any insight what the
correct behaviour should be, and can it be locked down in the spec?
Currently the D spec says [1]:
---
Static Arrays
int[3] s;
These are analogous to C arrays. Static arrays are distinguished by
having a length fixed at compile time.
The total size of a static array cannot exceed 16Mb. A dynamic array
should be used instead for such large arrays.
A static array with a dimension of 0 is allowed, but no space is
allocated for it. It's useful as the last member of a variable length
struct, or as the degenerate case of a template expansion.
The lynch pin here is that "it's useful as the last member of a variable
length struct." If it's given the address of 0, then it's no longer
useful there, so it should take an address of where it is defined.
I'd say this is definitely a bug (and the docs should be clearer on this).
-Steve
