zstd adds a zbuff.h header file to /usr/local/include and within this file, there are two lines that look like:
on lines 31 and 189. This doesn't seem correct and when I was building mongodb42-tools with portinstall, I was getting a file not found for zstd.h. Changing the lines to remove the ../ fixed the compile issue.
I think this is an issue with zstd port but I'm not certain, my C header includes knowledge is really rusty.
In file included from vendor/github.com/DataDog/zstd/zstd_stream.go:7:
/usr/local/include/zbuff.h:31:10: error: '../zstd.h' file not found, did you mean 'zstd.h'?
#include "../zstd.h" /* ZSTD_CStream, ZSTD_DStream, ZSTDLIB_API */
1 error generated.
The problem is still here...