GPL Interpretation on load [Was: [bug #61594] suggest new $(hash ...) function]

[rsbecker]

On December 1, 2021 9:06 AM, Tim Murphy wrote:

<big snip>
> -load $(XTRA_OUTPUTDIR)/hash$(XTRA_EXT)

This thread brings up a question. The load function checks for GPL 
compatibility.

      /* Assert that the GPL license symbol is defined.  */
      symp = (load_func_t) dlsym (dlp, "plugin_is_GPL_compatible");
      if (! symp)
        OS (fatal, flocp,
             _("Loaded object %s is not declared to be GPL compatible"),
             ldname);

I am wondering why that is the case. A DLL that is loaded by GNU Make is not 
necessarily subject to GPLv2 or GPLv3. GPLvx makes it clear that you are 
subject to GPLvx if you include portions of the code from the project under 
license. However, an external DLL that is loaded by GNU Make via dlopen does 
not have to use any code from the code base. Using a published API, which would 
be the function interface has precedent for being excluded from license 
enforcement - the UNIX kernel API is an example that is purely public domain 
itself, while the individual header files are subject to licenses.

So, my question is why the GPL enforcement outside of what would be a usual 
interpretation for GPLv3, for external integrations that may have nothing 
specifically to do with the Make code? Sure, if you include function.h then yes 
you are subject to it, but you do not have to. This seems overly aggressive and 
not really necessary. Is there an answer back in history that might explain it?

Thanks,
Randall