When is a dynamic array really a static array?

[Steven Schveighoffer]

On 12/31/19 12:24 PM, Temtaime wrote:
> On Tuesday, 31 December 2019 at 13:35:42 UTC, Paul Backus wrote:
>> On Tuesday, 31 December 2019 at 11:20:31 UTC, Patrick Schluter wrote:
>>> Is it really a bug?
>>
>> Yes. Perhaps this example will convince you:
>>
>> void foo(size_t N)(int[N] arr)
>> {
>>     arr[0] = 42;
>> }
>>
>> void foo()(int[] arr)
>> {
>>     arr[0] = 42;
>> }
>>
>> void main()
>> {
>>     int[16] x;
>>     foo(x[]);
>>     assert(x[0] == 42); // fails
>> }
> 
> void foo(size_t N)(int[N] arr) does nothing. I doubt this is a bug too.

int[N] foo(size_t N)(int[N] arr)
{
    arr[0] = 42;
    return arr;
}

Better?

The use case that spurred this discovery is this:

ubyte[16] hash;

string hexStr = toHexString(hash); // slices a temporary that is 
immediately removed from scope

The fix should be:

string hexStr = toHexString(hash[]);

But it doesn't do anything different. In order to do it correctly, you 
have to literally declare another variable, or cast. Hell, I don't even 
know if the cast will work!

-Steve