D Language Foundation July 2025 Quarterly Meeting Summary

[Bastiaan Veelo]

On Sunday, 11 January 2026 at 14:56:07 UTC, Mike Parker wrote:
> __Link errors in LDC__
>
> Bastiaan's second issue was an LDC linking problem after 
> upgrading the front end. He didn’t expect a full answer on the 
> call and would need to work on a reduction.
[...]
> He said the error mentioned "conflicting weak external 
> definition". He'd only seen it a few times and had forgotten 
> the context.

What turned out to be the issue was that I was using the "include 
imports" flag (`-i`) wrong. We have a lot of library code in a 
grab bag that various programs include from, and the -i flag 
relieves us from having to otherwise manage or define 
dependencies. None of these modules were in a D package though, 
and thus the -i flag was effective on *all* imports, also those 
imported from Dub packages and their dependencies. Dub already 
takes care of linking in Dub packages, so those modules would be 
linked twice. This would occasionally cause link errors but not 
always, and the errors would appear and disappear with different 
compilers and compiler versions. Understanding only half of the 
problem, I was using exclusions (`-i=-dub_package`) to patch over 
these errors, which doesn't scale, is flaky and is obviously not 
how you are meant to use this.

The solution was to move our library modules into a D package, 
and use only one flag with the package name (`-i=d_package`).

-- Bastiaan.