Using GtK

[Iain Buclaw]

On Monday, 23 August 2021 at 20:21:13 UTC, Ruby The Roobster 
wrote:
> gdc -I/usr/include/gtkd-3 -L-ldl -L-libgtkd-3 test.d
>

You're using command-line arguments as if you are compiling with 
dmd.

On gcc `-L-libgtkd-3` means "add _directory_ ./-libgtkd-3 to the 
list of directories to be searched for `-l`".

https://gcc.gnu.org/onlinedocs/gcc-11.2.0/gcc/Directory-Options.html#index-L

Correct invocation:

gdc -I/usr/include/gtkd-3 -ldl -lgtkd-3 test.d