Cygwin pkg-config/protobuf filepath issues

Question

I'm trying to compile & install a C++ library using Cygwin. I've properly installed the library's dependencies. However, ./configure is throwing an error:

checking for protobuf... no configure: error: Package requirements (protobuf >= 3.3) were not met:

No package 'protobuf' found

Consider adjusting the PKG_CONFIG_PATH environment variable if you installed software in a non-standard prefix.

I then checked config.log, and found a suggestion to point PKG_CONFIG_PATH at the lib/pkgconfig directory. I promptly set PKG_CONFIG_PATH to /usr/local/lib/pkgconfig, the directory where protobuf.pc is located on my system. The error persisted. Some checking of similar questions here showed that some people had to use the Windows filepath, so I switched PKG_CONFIG_PATH to c:\\cygwin64\\usr\\local\\lib\\pkgconfig. The error persisted. I even tried setting PKG_CONFIG_PATH to /cygdrive/c/cygwin64/usr/local/lib/pkgconfig. Which didn't work.

What am I doing wrong here?

Answer 1

(Since I can't comment yet, I guess I need to leave this as an answer?)

After installing the libprotobuf-devel package from the cygwin setup.exe, I could run pkg-config --list-all and see protobuf listed in the output. Also, pkg-config --print-provides protobuf returns protobuf = 3.3.1. Are you getting the same output?

I would also look at the configure script to see what it's trying to check. Opening up configure and searching for protobuf or checking for protobuf should get you close to the actual check. Maybe configure is trying to do something weird.

Lastly, at least on my cygwin install, I do not have a /usr/local/lib/pkgconfig directory. If you installed protobuf from source, maybe you could try the cygwin devel package (libprotobuf-devel) and see if that helps.