betterC generate dynamic array throw Error: TypeInfo cannot be used with -betterC

[learnfirst1]

On Wednesday, 17 October 2018 at 16:50:36 UTC, Paul Backus wrote:
> You can't append to an array in betterC code, because making 
> space for the new elements requires allocating memory, and that 
> uses the GC.
>
> In theory, since you're only using the GC during CTFE, it 
> shouldn't be a problem, but the D compiler doesn't *know* 
> that's what you're doing, so it has to assume the function 
> could be called at runtime--which would be an error.


The test2 is not build as source code,  like you can use std.* in 
butterC ctfe function even it use GC.

for example you can use this function in betterC if it not build 
as source code(include from include path):

	string add_prefix(string exp) {
	    string reg = "^" ~ exp;
	    return reg ;
	}


the dynamic array append working for basic type but not for 
struct.

so I guess this is a dmd front bug.