MesonBuild: How to define dependency to a library that cannot be found by `pkg-config`?

Question

My project (in C) has a third party dependency at build time. But the third party library is, by default, installed to /opt/ instead of /lib, and I can

Answer 1

Refer to meson object here : current_source_dir() method returns a string to the current source directory.

Use it for the case libhello.so and libhello.h are located in /hello directory

/main.c
/meson.build

/hello/libhello.so
/hello/libhello.h
/hello/meson.build

In /hello/meson.build:

lib_hello = cc.find_library('hello', dirs : meson.current_source_dir())

In /meson.build:

project('myproj', 'c')
subdir('hello')

inc_hello = include_directories('./')
exec = executable('app',
                  'main.c',
                  dependencies : [lib_hello],
                  include_directories : inc_hello)