On Tuesday, 5 June 2018 at 13:27:35 UTC, Steven Schveighoffer
wrote:
On 6/5/18 6:40 AM, Simen Kjærås wrote:
On Tuesday, 5 June 2018 at 09:36:22 UTC, Gopan wrote:
void main()
{
immutable n = __ctfe ? 1 : 2;
int[n] a;
assert(a.length == n); // fails, wat
}
That's gotta be a bug - that should give a 'variable n cannot
be read at compile time' error. The fact that n is immutable
shouldn't be enough to use it at compile time. Filed as
https://issues.dlang.org/show_bug.cgi?id=18945.
Indeed it is a bug. Interesting to see what the compiler sees
as its AST:
import object;
void main()
{
immutable immutable(int) n = __ctfe ? 1 : 2;
int[1] a = 0;
assert(1LU == cast(ulong)n);
return 0;
}
This is what -vcg-ast spits out.
Note the int[1].
-Steve
This is not bug just not very intuitive.
Since you are declaring a static array the value of n needs to
known at compiletime.
so it'll try to evaluate n at an compile-time context in which n
is 1.
however when code-generation for the function is done __ctfe will
be false.
Causing the n variable to be initialized to 2.
Therefore n will not be equal to a.length.
