Installing libff (via libsnark) results in awkward header structure

[copumpkin]

For example, libsnark depends on libff, and using a header from libsnark gives me the following error:

In file included from /nix/store/glnz76ald47lz78al77wq98my1qn6dmi-libsnark-pre9e6b19ff/include/libsnark/common/default_types/r1cs_ppzksnark_pp.hpp:16:
In file included from /nix/store/glnz76ald47lz78al77wq98my1qn6dmi-libsnark-pre9e6b19ff/include/libff/common/default_types/ec_pp.hpp:28:
In file included from /nix/store/glnz76ald47lz78al77wq98my1qn6dmi-libsnark-pre9e6b19ff/include/libff/algebra/curves/bn128/bn128_pp.hpp:10:
/nix/store/glnz76ald47lz78al77wq98my1qn6dmi-libsnark-pre9e6b19ff/include/libff/algebra/curves/bn128/bn128_g1.hpp:12:10: fatal error: 'depends/ate-pairing/include/bn.h' file not found
#include "depends/ate-pairing/include/bn.h"
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1 error generated.

As far as I can tell, this is because the "public" header bn128_g1.hpp includes a header from the depends folder, which doesn't get installed with any of the standard scripts, so downstream packages can't use it easily without messing with their include directories.

[howardwu]

You will need to fetch the dependencies:

git submodule init && git submodule update

This is the same from libsnark. All content from the libsnark/depends folder are installed as part of the parent's compilation process. The parent's dependency CMakeLists.txt calls into all child dependencies and compiles the requisite libraries natively. See https://github.com/scipr-lab/libsnark/blob/master/depends/CMakeLists.txt