Setup
I have a project that builds and runs fine with CMake. My project setup is like this:
├── CMakeLists.txt
|
├── include/
│ └── standalone/
│ └── x.hpp
|
├── src/
└── standalone/
└── main.cpp
The contents of my headers is like this:
// ------x.hpp--------
#pragma once
#include <iostream>
class X
{
public:
void hello()
{
std::cout << "Hello World!\n"; // needs <iostream>
}
};
// -------main.cpp-------
#include <standalone/x.hpp>
int main()
{
X x;
x.hello();
}
I use the following CMakeLists.txt
cmake_minimum_required(VERSION 2.8)
project(standalone)
###############################################################
# Compiler settings
###############################################################
# use C++11 features
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11")
# set warning level
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Werror -pedantic -pedantic-errors -Wall -Wextra")
###############################################################
# header dependencies
###############################################################
# compile against project headers
include_directories(${PROJECT_SOURCE_DIR}/include)
# the header files
file(GLOB_RECURSE header_files FOLLOW_SYMLINKS "include/*.hpp")
# the source files
file(GLOB_RECURSE source_files FOLLOW_SYMLINKS "src/*.cpp")
###############################################################
# build target
###############################################################
# the program depends on the header files and the source files
add_executable(main ${header_files} ${source_files})
The sequence of commands mkdir build, cd build, cmake .., make, and ./main correctly prints "Hello World!" without warnings.
Problem
The above setup is correct. But suppose <iostream> was not included in x.hpp but in main.cpp instead. Then the program would still have built correctly, but the x.hpp would not be a standalone header. So I would like to test for self-sufficiency of my headers, i.e. for every header I would like to compile a small test program
#include "some_header.hpp"
int main() {}
However, if I add the following section to the CMakeList.txt
###############################################################
# header self-sufficiency
###############################################################
set(CMAKE_REQUIRED_FLAGS ${CMAKE_CXX_FLAGS})
message("REQUIRED_FLAGS=${CMAKE_REQUIRED_FLAGS}")
set(CMAKE_REQUIRED_INCLUDES ${CMAKE_SOURCE_DIR}/include)
message("REQUIRED_INCLUDES=${CMAKE_REQUIRED_INCLUDES}")
include(CheckIncludeFiles)
check_include_files("${header_files}" IS_STANDALONE)
The macro ${header_files} correctly expands to the header x.hpp, but the check_include_files() command does not correctly compile it
REQUIRED_FLAGS= -std=c++11 -Werror -pedantic -pedantic-errors -Wall -Wextra
REQUIRED_INCLUDES=/home/rein/projects/standalone/include
-- Looking for include file /home/rein/projects/standalone/include/standalone/x.hpp
-- Looking for include file /home/rein/projects/standalone/include/standalone/x.hpp - not found.
Question
Apparantly I am missing some configuration variable that lets CMake search in the right place. Even for correct headers, check_include_files() does not work. What do I need to do to make this work? Only when correct headers are deemed correct, can I go on and test incorrect headers.
NOTE Unless it's
absolutey necessary, I am not interested in shell scripts or elaborate CMake for loops that directly call TRY_COMPILE or something like that. AFAICS, that's what the CheckIncludeFiles module is for, and I'd like to know how to correctly configure that, if at all possible.
chkhdr, that can be used for testing headers self-containedness. – Yasmineyasu