dub windows unrecognised file extension a

[Nicholas Wilson]

On Sunday, 9 September 2018 at 04:01:30 UTC, Nicholas Wilson 
wrote:
> On windows with dub it seems to be creating libfoo.a instead of 
> foo.lib, I don't think I changed any settings. Old build based 
> on 2.078 DMDFE seem to have built .lib but LDC based on 2.082 
> seems to be building .a

This definitely seems to be dubs fault: it passes 
-of/path/to/output/libFoo.a to LDC which compiles. `dub describe` 
also has

{
...
"packages" : [
...
{
...
"targetFileName" : "libFoo.a",