GNU binutils import libraries aren't the same kind of short import libraries as link.exe and LLD produce, but are a plain static library containing .idata section chunks. MSVC link.exe can successfully link to them.
In order for imports from GNU import libraries to mix properly with the normal import chunks, the chunks from the existing mechanism needs to be added into named sections like .idata$2.
These GNU import libraries consist of one header object, a number of object files, one for each imported function/variable, and one trailer. Within the import libraries, the object files are ordered alphabetically in this order. The chunks stemming from these libraries have to be grouped by what library they originate from and sorted, to make sure the section chunks for headers and trailers for the lists are ordered as intended. This is done on all sections named .idata$*, before adding the synthesized chunks to them.