Friday, September 2, 2022

[SOLVED] CMake include errors (file not found, undefined reference)

Issue

I'm creating a project that makes use of CMake.

I have an include folder for headers and an src folder for source code. When attempting to build the project with cmake --build ., I get an "undefined reference" error:

/sdcard/dev/cpp/Bedrock++/src/main.cpp:(.text+0x70): undefined 
reference to `ChatFormat::Blue'

Additional detail below:

$ cmake --build .
-- Configuring done
-- Generating done
-- Build files have been written to: /sdcard/dev/cpp/Bedrock++
Scanning dependencies of target Bedrock++
[ 33%] Building CXX object src/CMakeFiles/Bedrock++.dir/Server.cpp.o
[ 66%] Building CXX object src/CMakeFiles/Bedrock++.dir/main.cpp.o
[100%] Linking CXX executable Bedrock++
CMakeFiles/Bedrock++.dir/main.cpp.o: In function `main':
/sdcard/dev/cpp/Bedrock++/src/main.cpp:(.text+0x70): undefined 
reference to `ChatFormat::Blue'
clang-5.0: error: linker command failed with exit code 1 (use -v to see 
invocation)
make[2]: *** [src/CMakeFiles/Bedrock++.dir/build.make:121: 
src/Bedrock++] Error 1
make[1]: *** [CMakeFiles/Makefile2:86: 
src/CMakeFiles/Bedrock++.dir/all] Error 2
make: *** [Makefile:130: all] Error 2

Project root CMakeLists.txt

cmake_minimum_required(VERSION 2.8.7)

# Build all dependent libraries as static

project(Bedrock++)

#add_subdirectory(lib/json)

add_subdirectory(src)
add_subdirectory(include)

src/CMakeLists.txt

project(bedrock++)

set(CMAKE_INCLUDE_CURRENT_DIR ON)

include_directories("${PROJECT_SOURCE_DIR}/include")

file(GLOB SOURCES "*.cpp")

add_executable(${PROJECT_NAME} ${SOURCES})

include/CMakeLists.txt

install(DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}/ DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}" FILES_MATCHING PATTERN "*.h")

main.cpp

#include <iostream>
#include <string>
#include "util/ChatFormat.h"

int main()
{
    std::cout << "Hello World! " << ChatFormat::Blue << "hey" << std::endl;
}

The ChatFormat.h header is found in include/util/ChatFormat.h and contains the following for every different colour:

static const std::string Black;

I've attempted to solve the problem myself to no avail with hours of research on the internet proving to be a dead end. I hope I didn't miss something obvious.

Any help would be greatly appreciated.


Solution

The CMake output suggests that 'ChatFormat.cpp', which contains the definition of 'ChatFormat::Black', is not being compiled. Only 'Server.cpp' and 'main.cpp' are being compiled.

I'm guessing that 'ChatFormat.cpp', like it's corresponding header, is under a 'utils' directory? But the GLOB command you are using to find your source files will only be finding files name *.cpp in the root folder. You might want to try changing 'GLOB' to 'GLOB_RECURSE' so it will pick up files in subfolders, though it is generally recommended that you avoid using globbing entirely and list each source file explicitly...



Answered By - Sean Burton
Answer Checked By - Timothy Miller (WPSolving Admin)
at