cmake include header only library

Question

I want to include spdlog into one of my project. It is a header only library. The project that i am building is using cmake. Currently i am using

include_directories('src/logger/spdlog/')

in cmake and including the library as

#include <spdlog/spdlog.h>

in logs.h inside logger folder. I am getting fatal error no such file or directory. What is the correct way to include the same library in my application.

@JoseLinares working with <> now. Was adding inverted commas extra :p — xander cage, Jul 02 '16 at 11:17
@xandercage What are _"inverted-commas"_ please? Did you mean replacing `'` with `""` in the `CMakeLists.txt` code? — πάντα ῥεῖ, Jul 02 '16 at 11:43

score 8 · Answer 1 · answered Jan 03 '21 at 23:35

Cmake provides interface library specifically for "header-only library". I would suggest to do the following:

Create a file structure like the following

third-party\spdlog\include

Git clone the spdlog repository into the include directory with the name spdlog
Create third-party\spdlog\CMakeLists.txt with the following content

find_package(Threads REQUIRED)
add_library(${TARGET_LOGGER} INTERFACE)
# add_library(spdlog::spdlog_header_only ALIAS ${TARGET_LOGGER})
target_include_directories(${TARGET_LOGGER} INTERFACE "$<BUILD_INTERFACE:${CMAKE_CURRENT_LIST_DIR}/include>"
                                                        "$<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}>")
target_link_libraries(${TARGET_LOGGER} INTERFACE Threads::Threads)

Define TARGET_LOGGER in the CMakeLists.txt of your project. Link this target to your project with target_link_libraries(${TARGET_PROJECT} LINK_PUBLIC ${TARGET_LOGGER}). Also don't forget to

add_subdirectory(
    third-party\spdlog
  )

Then, in your project, you can use #include "spdlog/spdlog.h" to include the library

this is the best answer, and uses modern cmake practices – simplename Feb 05 '21 at 03:46 — simplename, Feb 05 '21 at 03:46

πάντα ῥεῖ · Answer 2 · 2016-07-02T11:18:10.883

5

You are probably off one directory. Try either

 include_directories("src/logger")

in the CMakeLists.txt, or

 #include <spdlog.h>

in the source code.

edited Jul 02 '16 at 11:18

answered Jul 02 '16 at 11:12

πάντα ῥεῖ

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Thanks that was one of them, but the major issue that i forgot was `inverted-commas` while adding path in include_directories working fine now :) – xander cage Jul 02 '16 at 11:16

score 0 · Accepted Answer · answered Jul 03 '16 at 08:39

First, don't use single quotes ' but double quotes " or just plain strings if they don't contain spaces.

I would advice you to use find_path instead of adding includes directly. There you can add PATH_SUFFIXES. You get a message during configuration if the header is not found, which makes it easier to spot errors.
Documentation: https://cmake.org/cmake/help/v3.6/command/find_path.html

cmake include header only library

3 Answers3