Include header file of external library in another header file

Question

Currently I have the following project structure, where the libs directory purpose is to store external C libraries that I download from github because they are not available on my OS's repos:

├── cli
│   └── cli.c
├── libs
│   ├── meson.build
│   └── pqueue
│       ├── pqueue.c
│       └── pqueue.h
├── modules
│   ├── algorithms
│   │   ├── a_star.c
│   │   └── a_star.h
│   ├── meson.build
├── meson.build

Where libs/meson.build is:

libpqueue_sources = [
  'pqueue/pqueue.c',
]

pqueue_lib = shared_library('pqueue', libpqueue_sources)
pqueue_dep = declare_dependency(link_with: pqueue_lib)

modules/meson.build is:

algs_sources = [
  'algorithms/a_star.c',
]
algs_lib = static_library('algorithms',
  sources: algs_sources,
  include_directories: libs_include_dirs,
  dependencies: pqueue_dep)

and meson.build is:

project('graph-search', 'c')
graph_search_include_dirs = include_directories('modules')
libs_include_dirs = include_directories('libs')   
subdir('libs')
subdir('modules')
cli_sources = [
    'cli/cli.c'
]
executable('cli', 
           sources: cli_sources,
           include_directories : graph_search_include_dirs,
           link_with: [algs_lib])

My problem arises when I try to make an #include "pqueue/pqueue.h" inside a_star.h, it says /modules/algorithms/a_star.h:5:10: fatal error: pqueue/pqueue.h: No such file or directory, but when I move the include to a_star.c the error disappears. Sadly I need to include it on the header file because I need to export a struct that uses a type of pqueue.h

Is there a way to include pqueue.h inside a_star.h without using paths like ../../libs/pqueue/pqueue.h?

You need to add the include search path for the header in your make file or build environment. — Rishikesh Raje, Feb 18 '19 at 04:26
@RishikeshRaje I already added it with `include_directories('libs')` no? — Chromz, Feb 18 '19 at 04:49

score 1 · Accepted Answer · answered Feb 18 '19 at 05:33

Because you don't specify libs_include_dirs for cli.c to build, compiler don't know how to search pqueue/pqueue.h.

Change your meson.build to include libs_include_dirs.

diff --git a/meson.build b/meson.build
index 4087a00..3347466 100644
--- a/meson.build
+++ b/meson.build
@@ -8,5 +8,5 @@ cli_sources = [
 ]
 executable('cli',
            sources: cli_sources,
-           include_directories : graph_search_include_dirs,
+           include_directories : [graph_search_include_dirs, libs_include_dirs],
            link_with: [algs_lib])

Include header file of external library in another header file

1 Answers1