A couple of questions about arrays and slices

[Cecil Ward]

On Thursday, 22 June 2023 at 05:21:52 UTC, Cecil Ward wrote:
> On Thursday, 22 June 2023 at 01:44:22 UTC, Jonathan M Davis 
> wrote:
>> On Wednesday, June 21, 2023 7:05:28 PM MDT Paul Backus via 
>> Digitalmars-d-learn wrote:
>>> [...]
>>
>> To add to that, it _has_ to know the element type, because 
>> aside from anything related to a type's size, it bit-blits the 
>> type's init value onto the new elements when it increases the 
>> length of the dynamic array.
>>
>> You'd probably be dealing with bytes if you were explicitly 
>> asking for memory and the like (e.g. with malloc), but a 
>> dynamic array is properly typed, and everything you do with it 
>> in @safe code is going to deal with it as properly typed. For 
>> it to be otherwise would require @system casts.
>>
>> - Jonathan M Davis
>
> Thankyou Jonathan!

I just had a fight with LDC over the following code when I tried 
out reserve. I have an associative array that maps strings to 
‘ordinals’ ie uints that are unique, and the compiler hates the 
call to reserve.

==



struct decls_t
	{
	uint                 		n_entries = 0;
	uint[ dstring ]		ordinals;	// Associative array maps variable 
names to ordinals
	}

static decls_t Decls;

enum NPreAllocEntries = 32;
Decls.ordinals.reserve( NPreAllocEntries );

source>(82): Error: none of the overloads of template 
`object.reserve` are callable using argument types 
`!()(uint[dstring], ulong)`
/opt/compiler-explorer/ldc1.32.1/ldc2-1.32.1-linux-x86_64/bin/../import/object.d(3983):        Candidate is: `reserve(T)(ref T[] arr, size_t newcapacity)`
Compiler returned: 1