On Tuesday, 3 August 2021 at 21:40:09 UTC, james.p.leblanc wrote:
I am getting linker errors with this stripped-down example:
-------------------------------------------
**my_main.d:**
import std.stdio;
import std.complex;
import my_module;
void main(){
my_TYPE xxx;
writeln(xxx);
}
-------------------------------------------
**my_module.d:**
module my_module;
import std.complex;
alias my_TYPE = Complex!double; *// this causes link error:
"undefined reference"*
/* alias my_TYPE = double; */ *// this works fine*
------------------------------------------
Why does the linker fail when I alias to the Complex!double ...
but would work fine when alias to the double ??
Any help to understand what is greatly appreciated.
James
The alias to Complex!double is a template instantiation. A
template instantiation creates a symbol that needs to be linked.
So you need to compile my_module.d along with my_main.d.
```
dmd my_main.d my_module.d
```
Or alternatively:
```
dmd -i my_main.d
```
double is a built-in type, so that alias doesn't create any
symbols that need linking.
An alias in and of itself is a compile-time-only construct, but
the symbols you assign it might require linking something.
