header file isn't found by cmake
<p>I have a folder with only headers.</p>

<p>In my <strong>config</strong> project I need some interfaces of the <strong>param</strong> project</p>

<pre><code>src
  CMakeList.txt
  - config
    - CMakeList.txt
  - param
    - CMakeList.txt
    - parameter.h
</code></pre>

<p>This is inside my <strong>config</strong> CMakeList.txt</p>

<pre><code>project(config)
file(GLOB_RECURSE SOURCES "${config_SOURCE_DIR}/*.cpp")

add_library(config ${SOURCES})

target_include_directories(config PUBLIC "${param_SOURCE_DIR}")
target_include_directories(config PUBLIC "${Utils_SOURCE_DIR}/include")

qt5_use_modules(config Core)
target_link_libraries(config)
</code></pre>

<p>My <strong>param</strong> library CMakeList.txt is (it needs Utils too)</p>

<pre><code>project(param)
file(GLOB_RECURSE HEADERS "${param_SOURCE_DIR}/*.h")

add_library(param INTERFACE)
</code></pre>

<p>Then in my config project I have a class that include one of the interface and when building it doesn't find it. "parameter.h" file not found.</p>

<pre><code>/usr/local/bin/clang++   -DQT_CORE_LIB -DQT_NO_DEBUG -I/builds/modules/project/src/config -I~/modules/project/src/config -I/usr/include/eigen3 -I~/modules/libs/utils/include -isystem ~/devel/qt5/qtbase/include -isystem ~/devel/qt5/qtbase/include/QtCore -isystem ~/devel/qt5/qtbase/./mkspecs/linux-g++  -fPIC -std=gnu++11 -o CMakeFiles/config.dir/configuration.cpp.o -c ~/modules/project/src/config/configuration.cpp
</code></pre>

<p>One of the source file in config cannot compile because of :</p>

<pre><code>fatal error: 'parameter.h' file not found
#include "parameter.h"
</code></pre>