Assignment vs comparison operator error?

[dokipen3d]

I'm attempting to compile this on windows and get an error here when it gets to the '==' operator. Was assignment meant here? I think its between a Featuremappybind11::size_T and a double.

pixel-perfect-sfm/pixsfm/features/src/featuremap.h

Line 146 in 40f7c13

shape[1] == -1;