CMake can't find header file

Question

I have a project that looks like this.

.
├──include
|  └──utilities.hpp
├──source
|  ├──main.cpp
|  └──utilities.cpp
└──CMakeLists.txt

Where both source/main.cpp and source/utilities.cpp have an #include "include/utilities.hpp directive, and the contents of CMakeLists.txtare:

cmake_minimum_required(VERSION 3.16.3)
set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED ON)
project(search VERSION 1.0.0)


add_executable(
    search
    source/utilities.cpp
    source/main.cpp
    include/utilities.hpp
)
include_directories(search PUBLIC include)

When I run make VERBOSE+1, I get the following output:

[ 33%] Building CXX object CMakeFiles/search.dir/source/utilities.cpp.o
/home/mohammed/Work/Projects/search/source/utilities.cpp:1:10: fatal error: include/utilities.hpp: No such file or directory
    1 | #include "include/utilities.hpp"
      |          ^~~~~~~~~~~~~~~~~~~~~~~
compilation terminated.
make[2]: *** [CMakeFiles/search.dir/build.make:63 : CMakeFiles/search.dir/source/utilities.cpp.o] Error 1
make[1]: *** [CMakeFiles/Makefile2:76 : CMakeFiles/search.dir/all] Error 2
make: *** [Makefile:84 : all] Error 2

I tried all the answers to this question. But none of them worked.

Can anyone tell me what am I doing wrong?

p.s If it is not yet clear, I am new to CMake.

In CMake, `add_executable` only needs the `.cpp` files. You've added `include/utilities.hpp`. This causes confusion between the compiler and CMake where to find that file. (Not an answer, since the quoted error message is caused by an earlier problem compiling utilities.cpp) — MSalters, Aug 03 '21 at 14:15

0x5453 · Answer 1 · 2021-08-03T14:25:55.870

3

include_directories != target_include_directories. Looks like you meant to use the latter.

Additionally, as RoQuOTriX pointed out: When you add a directory to the include path, includes should be relative to that directory. So if include is on your include path, you would want to #include "utilities.hpp" instead of #include "include/utilities.hpp".

edited Aug 03 '21 at 14:25

answered Aug 03 '21 at 14:02

0x5453

12,753
1
32
61

I tried both `include_directories(include)` and `target_include_directories(searchPUBLIC include)` with similar results. – 0sharp Aug 03 '21 at 14:22

score 2 · Answer 2 · answered Aug 03 '21 at 14:01

2

If you specify include_directories() directly you don't need to use the relative paths in your source files:

#include "include/utilities.hpp"

Instead use:

#include "utilities.hpp"

If you instead want to keep the relative paths then you need to remove the include_directories() from the CMakeLists.txt.

The include_directories() tells the compiler where it should search for includes.

answered Aug 03 '21 at 14:01

RoQuOTriX

2,871
14
25

That actually worked. I don't know how I managed to miss the fact that the verbose message was saying `-I ./include` rather than `-I .` Thanks a lot. – 0sharp Aug 03 '21 at 14:25

score 1 · Answer 3 · answered Aug 03 '21 at 14:28

1

I solved the problem by changing the contents of CMakeLists.txt to:

cmake_minimum_required(VERSION 3.16.3)
set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED ON)
project(search VERSION 1.0.0)
set(WORKING_DIRECTORY /home/mohammed/Work/Projects/search)

add_executable(
    search
    ${WORKING_DIRECTORY}/source/utilities.cpp
    ${WORKING_DIRECTORY}/source/main.cpp
    ${WORKING_DIRECTORY}/include/utilities.hpp
)

include_directories(${WORKING_DIRECTORY})

A huge thanks to RoQuOTrix.

answered Aug 03 '21 at 14:28

0sharp

43
6

1

It is not necessary to add .hpp files to your `add_executable` statement, and you should _really_ use `target_include_directories` over `include_directories` (in addition to removing `include/` from your `#include` statement. – Botje Aug 03 '21 at 14:47

CMake can't find header file

3 Answers3