My software that compiled fine on linux a few months ago stopped compiling on my new ubuntu:
Linking CXX executable myApp
/usr/bin/ld: ../libMyLib/libMyLib.a(MyFile.cpp.o): undefined reference to symbol '_ZN2cv6resizeERKNS_11_InputArrayERKNS_12_OutputArrayENS_5Size_IiEEddi'
/usr/bin/ld: note: '_ZN2cv6resizeERKNS_11_InputArrayERKNS_12_OutputArrayENS_5Size_IiEEddi' is defined in DSO /usr/lib/gcc/x86_64-linux-gnu/4.7/../../../../lib/libopencv_imgproc.so so try adding it to the linker command line
/usr/lib/gcc/x86_64-linux-gnu/4.7/../../../../lib/libopencv_imgproc.so: could not read symbols: Invalid operation
collect2: error: ld returned 1 exit status
make[2]: *** [myApp/myApp] Error 1
make[1]: *** [myApp/CMakeFiles/myApp.dir/all] Error 2
make: *** [all] Error 2
I guess it's related to https://fedoraproject.org/wiki/UnderstandingDSOLinkChange.
My project (all cmake) contains several libraries and an application, both the libraries and the application depend on opencv and/or boost (each on some different ones). My own libraries are built as .a files, ocv/boost are pulled in as shared libraries, and the linking of the application then fails with above error.
I also tried to build my own libraries as SHARED but that resulted in even more errors. The CMakeLists of my libraries look like
FIND_PACKAGE(Boost REQUIRED)
FIND_PACKAGE(OpenCV REQUIRED core)
...stuff...
include_directories( ${OpenCV_INCLUDE_DIRS} )
include_directories( ${Boost_INCLUDE_DIRS} )
add_library( ${SUBPROJECT_NAME} ${SOURCE} ${HEADERS} )
The application CMakeLists looks like
FIND_PACKAGE( OpenCV REQUIRED core imgproc highgui)
include_directories( ${OpenCV_INCLUDE_DIRS} )
TARGET_LINK_LIBRARIES( ${SUBPROJECT_NAME} ${OpenCV_LIBS} MyLib )
That was all correct and I always thought that's the way to do it but now with this DSO stuff I just cannot get it to work anymore.
If relevant, I tried with CMake 2.8.7 and 2.8.10, and g++ 4.7.2 and 4.8, all produce the same errors.
GCC is very sensible to the order in which you specify libraries during the linking stage. For example, if libA.a depends on libB.a and an executable App depends on both, then you'd have to invoke linker in the following way:
gcc main.o object1.o ... object2.o -lA -lB -o App
NOTE: Pay attention to the fact that although A depends on B, still A goes before B. As a conclusion, the most independent artifact should be linked the last one. Sure that's counterintuitive in some sense, but try to treat it in the same way as the const qualifier is applied in C++. :)
Does OpenCV_LIBS contains -lopencv_imgproc?
If not, try to add manually -lopencv_imgproc the link command line (run make V=1)
If it works added it to TARGET_LINK
Related
I want to build a statically, because I need to distribute the application on multiple platforms (Linux and Windows). OpenCV has been built and installed on a linux machine statically.
Here you can see the relevant parts that are included in my CMakeLists.txt that were supposed to make OpenCV link statically
#windows
message("Compiling for windows")
set(CMAKE_CXX_COMPILER x86_64-w64-mingw32-g++)
set(BUILD_SHARED_LIBS OFF) #this has no effect
set(CMAKE_LINK_LIBRARY_SUFFIX ".a") #this has no effect
#openCV
set(OpenCV_STATIC ON) #this has no effect
find_package(OpenCV REQUIRED )
include_directories(${OpenCV_INCLUDE_DIRS} )
During linking I get this error, as it apparently is a library required by opencv:
/usr/lib/x86_64-linux-gnu/libpng.so: error adding symbols: File in wrong format
collect2: error: ld returned 1 exit status
As you can see libpng.so is being used. Even though in that Folder a libpng.a file is also available.
This only happens with mingw, but using the "-static" flag inside
target_link_libraries( Tracking ${OpenCV_LIBS} "-static")
results in
/usr/bin/x86_64-w64-mingw32-ld: attempted static link of dynamic object `/usr/lib/x86_64-linux-gnu/libpng.so'
collect2: error: ld returned 1 exit status
So It still uses the .so file instead of .a That is why I suspect I need to change the OpenCV configuration
I have spent hours on this, so help is appreciated.
This should force to link libpng statically:
set_target_properties(libpng PROPERTIES LINK_SEARCH_START_STATIC 1)
set_target_properties(libpng PROPERTIES LINK_SEARCH_END_STATIC 1)
set(CMAKE_FIND_LIBRARY_SUFFIXES ".a")
set(CMAKE_EXE_LINKER_FLAGS "-static-libgcc -static-libstdc++")
As mentioned above i have problems with compiling my c++ project (using CMake) which uses some dynamic libraries (.so).
There are 3 libs in my directory (i.e. home/sources/lib/). When i only tell the compiler (in the CMake file) to use the first lib (foo1.so) it works (only this file, the order does not matter). But it does not work with any of the other libs (foo2.so and foo2.so). All 3 files have the .so extension.
Note: The directory and file names were changed but the structure is the same.
The libraries i am using were not compiled / created by me and are from a 3rd party. (it would not matter when they were broken, would it?)
And this is how my CMake file looks like:
cmake_minimum_required(VERSION 3.3)
project(MyProj)
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11 -pthread -m64")
INCLUDE_DIRECTORIES("/home/sources/include")
LINK_DIRECTORIES("/home/sources/lib")
set(SOURCE_FILES main.cpp)
add_executable(MyProj ${SOURCE_FILES})
TARGET_LINK_LIBRARIES(MyProj foo1.so)
Changing the above line to this does not work anymore:
TARGET_LINK_LIBRARIES(MyProj foo1.so foo2.so foo3.so)
Just another way to write it (does not help)
TARGET_LINK_LIBRARIES(MyProj foo1.so)
TARGET_LINK_LIBRARIES(MyProj foo2.so)
TARGET_LINK_LIBRARIES(MyProj foo3.so)
And as mentioned above: ALL 3 libraries are in the SAME directory (which i refer to with LINK_DIRECTORIES)
And this is the error i get when trying to compile with the other libs (as said only foo1.so works):
[ 50%] Linking CXX executable MyProj
/usr/bin/ld: cannot find -lfoo2
/usr/bin/ld: cannot find -lfoo3
collect2: error: ld returned 1 exit status
make[3]: *** [MyProj] Error 1
make[2]: *** [CMakeFiles/MyProj.dir/all] Error 2
make[1]: *** [CMakeFiles/MyProj.dir/rule] Error 2
make: *** [MyProj] Error 2
P.S.: I did some research before posting here but did not find any otherone with this "strange" problem. And for sure i wouldn't have come so far with my CMake file without some googling skills ^^
Not sure, but it seems to me that CMake is looking for libfoo1.so whereas the file is actually foo1.so (the same applies for foo2 and foo3)
Try "importing" the libs:
add_library(foo1 SHARED IMPORTED)
set_property(TARGET foo1 PROPERTY IMPORTED_LOCATION "/home/sources/lib/libfoo1.so")
# same thing for foo2 and foo3 ...
target_link_libraries(MyProj foo1 foo2 foo3)
EDIT
There's also the possibility to provide the full path to the library:
target_link_libraries(MyProj "/home/sources/lib/libfoo1.so"
"/home/sources/lib/libfoo2.so"
"/home/sources/lib/libfoo3.so")
I want to compile an example code from this site (at the bottom). I downloaded GLFW 3.0.4 source code and I built it in a custom location. I used a default settings and GLFW was built as a static library. My CMakeLists.txt looks like this:
cmake_minimum_required(VERSION 2.8)
project(glfw_test_project)
SET(CMAKE_CXX_FLAGS "-Wall -Werror -g -std=c++11")
find_package(OpenGL REQUIRED)
include_directories(/home/user/MyLibs/OpenGL/glfw-3.0.4/include)
link_directories(/home/user/MyLibs/OpenGL/glfw-3.0.4/build/src)
add_executable(glfw_test main.cpp)
target_link_libraries(glfw_test ${OPENGL_gl_LIBRARY})
target_link_libraries(glfw_test glfw3)
When I run make I get following info:
Linking CXX executable glfw_test
/usr/bin/ld: /home/user/MyLibs/OpenGL/glfw-3.0.4/build/src/libglfw3.a(x11_clipboard.c.o): undefined reference to symbol 'XConvertSelection'
//usr/lib/x86_64-linux-gnu/libX11.so.6: error adding symbols: DSO missing from command line
collect2: error: ld returned 1 exit status
make[2]: *** [glfw_test] Error 1
make[1]: *** [CMakeFiles/glfw_test.dir/all] Error 2
make: *** [all] Error 2
What is wrong ?
Edit1
When I build GLFW as a dynamic library everything works fine. Then the last line in my CMakeLists.txt have to be replaced with:
target_link_libraries(glfw_test glfw)
What is wrong when using a static library ?
I experienced the same problems on Ubuntu 14.04 LTS.
First: error adding symbols: DSO missing from command line shows a wrong order of linker command line parameters. This post made me realise that. You need to call $ make VERBOSE=1 to see the linker call and check it with your own eyes. Remember: TARGET_LINK_LIBRARIES() should be the last command in your CMakeLists.txt And have a look at this order explanation.
Second: if you build against static GLFW3 libraries all the X11 libraries are not automatically added to your linker call, as atsui already showed above. In the GLFW-Documentation you can find a cmake variable which should fit your needs: ${GLFW_STATIC_LIBRARIES}. To make use of it and enable a more automatic build process, let pkg-config find all dependencies for X11 libs:
CMAKE_MINIMUM_REQUIRED(VERSION 2.8)
PROJECT(myProject)
FIND_PACKAGE( PkgConfig REQUIRED )
pkg_search_module( GLFW3 REQUIRED glfw3 ) # sets GLFW3 as prefix for glfw vars
# now ${GLFW3_INCLUDE_DIR}, ${GLFW3_LIBRARIES} and ${GLFW3_STATIC_LIBRARIES}
# are set
INCLUDE_DIRECTORIES( ${GLFW3_INCLUDE_DIR} )
ADD_EXECUTABLE( myProject mySource.cpp )
TARGET_LINK_LIBRARIES( myProject ${GLFW_STATIC_LIBRARIES} )
# they include X11 libs
Now check the linker lib parameters again with $ make VERBOSE=1 and you should find many more X11 libs like:
-lXrandr -lXi -lXrender -ldrm -lXdamage -lXxf86vm -lXext -lX11 and -lpthread.
Third: when linking against the shared library, the dependencies to X11 etc. are resolved dynamically. That is why you don't need to explicitly add X11 lib flags to the linker. In that case you only need:
TARGET_LINK_LIBRARIES( myProject ${GLFW_LIBRARIES} )
Fourth: it happened to me, that some glfwCommands had undefined reference to - linker errors. I found out, that I installed GLFW3 in /usr/local/lib but the linker was given only the LD_LIBRARY_PATH environment variable which was only set to /usr/lib32. Adding the parameter -L/usr/local/lib solved the reference problem. To avoid it in future I've set LD_LIBRARY_PATH=/usr/lib32;/usr/local/lib;.
Hint: to check what values are in your GLFW cmake variables, print them during build:
FOREACH(item ${GLFW3_STATIC_LIBRARIES})
MESSAGE(STATUS " using lib: " ${item})
ENDFOREACH()
It seems that you resolved your own issue by rebuilding GLFW as a shared library and linking the example code with that. Instead, I'll try to answer your followup question about why it doesn't work when you try to link the static library.
Basically, if you want to link against the static library libglfw3.a, you need to link all of the dependent X11 libraries. You get an error linking the static library because you didn't specify any additional libraries to link, and CMake doesn't know what these dependencies are. You don't get an error when you link the shared library libglfw.so because the X11 libraries are linked to the shared library, and CMake knows to pull those in for you automatically.
If you want to use the static library, you can determine the necessary libraries to link as follows. According to the .pc file in GLFW, you can type this in the command-line to find out what these are:
pkg-config --static --libs x11 xrandr xi xxf86vm gl
If you translate this into a CMake command, it would look like this:
target_link_libraries( glfw_test glfw3 Xrandr Xrender Xi GL m dl drm Xdamage X11-xcb xcb-glx xcb-dri2 xcb-dri3 xcb-present xcb-sync xshmfence Xxf86vm Xfixes Xext X11 pthread xcb Xau Xdmcp)
So if you add this to the CMakeLists.txt, the example code should build without an issue.
By the way, you can automatically find the X11 libraries using CMake in the following way:
find_package(X11 REQUIRED)
target_link_libraries( my_program ${X11_LIBRARIES} )
However, the set of libraries stored in the X11_LIBRARIES variable will only contain a subset of the libraries needed for statically linking GLFW.
I'm not really sure how to properly handle static/dynamic linking in CMake, but I hope this helps.
I have a cmake project where I want to add a class containing the matlab engine. For compiling it I need to include two libraries eng and mx, which I do by adding
target_link_libraries( ${TARGET} /usr/local/MATLAB/R2013b/bin/glnxa64/libeng.so)
target_link_libraries( ${TARGET} /usr/local/MATLAB/R2013b/bin/glnxa64/libmx.so)
to my CMakeLists.txt file.
However there are also lots of other old versions of libraries in /usr/local/MATLAB/R2013b/bin/glnxa64/, which seem
to be automatically added to the path as well when calling the above command. I think this causes the compiler to not find my
normal libraries anymore and produces an error.
How can I include only the two above libraries, and not all the others in the glnxa64 folder?
The warning shown after running cmake . :
CMake Warning at CMakeLists.txt:23 (add_executable):
Cannot generate a safe runtime search path for target CCDWidget because
files in some directories may conflict with libraries in implicit
directories:
runtime library [libboost_program_options.so.1.49.0] in /usr/lib may be hidden by files in:
/usr/local/MATLAB/R2013b/bin/glnxa64
runtime library [libboost_system.so.1.49.0] in /usr/lib may be hidden by files in:
/usr/local/MATLAB/R2013b/bin/glnxa64
runtime library [libboost_filesystem.so.1.49.0] in /usr/lib may be hidden by files in:
/usr/local/MATLAB/R2013b/bin/glnxa64
runtime library [libboost_regex.so.1.49.0] in /usr/lib may be hidden by files in:
/usr/local/MATLAB/R2013b/bin/glnxa64
Some of these libraries may not be found correctly.
And the error message during linking:
Linking CXX executable CCDWidget
/usr/lib/x86_64-linux-gnu/libharfbuzz.so.0: undefined reference to `FT_Face_GetCharVariantIndex'
/usr/lib/x86_64-linux-gnu/libharfbuzz.so.0: undefined reference to `FT_Get_Advance'
collect2: error: ld returned 1 exit status
make[2]: *** [CCDWidget] Error 1
make[1]: *** [CMakeFiles/CCDWidget.dir/all] Error 2
make: *** [all] Error 2
Below is my full CMakeLists.txt file. Lines commented out with two ## are alternatives that I tried before and didn't solve my problem.
I also added LINK_PRIVATE to the target_link_libraries command as shown in the code below, which didn't make a difference.
The option PRIVATE alone seems to be not accepted by my cmake version, as it changed the error meassage to
/usr/bin/ld: cannot find -lPRIVATE
collect2: error: ld returned 1 exit status
When the #eng line is commented out, the compilation and linking works without errors
(when calling the matlab engine is also commented out in Readout.cpp), so the error must be produced by that line.
#Specify the version being used as well as the language
cmake_minimum_required(VERSION 2.6)
##cmake_policy(SET CMP0003 NEW)
#Name your project here
project(CCDWidget)
set(TARGET CCDWidget)
set(MAIN_SOURCES CCDWidget.cpp main.cc CCDControl.cpp VideoWindow.cpp ImageWindow.cpp ThisMeasurement.cpp KineticSeries.cpp FastKinetics.cpp Readout.cpp)
##SET(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
#set_source_files_properties(Readout.cpp PROPERTIES COMPILE_FLAGS "-I/usr/local/MATLAB/R2013b/extern/include -I/usr/local/MATLAB/R2013b/simulink/include -DMATLAB_MEX_FILE -ansi -D_GNU_SOURCE -I/usr/local/MATLAB/R2013b/extern/include/cpp -I/usr/local/MATLAB/R2013b/extern/include -DGLNXA64 -DGCC -DMX_COMPAT_32 -DNDEBUG -Wno-effc++")
find_package(Boost COMPONENTS program_options system filesystem regex REQUIRED)
find_package(PkgConfig REQUIRED)
pkg_check_modules(GTKMM gtkmm-3.0)
include_directories( ${GTKMM_INCLUDE_DIRS} )
include_directories( ${Boost_INCLUDE_DIR} )
include_directories( ${PROJECT_SOURCE_DIR} )
##link_directories(/usr/local/MATLAB/R2013b/bin/glnxa64)
##target_link_libraries( ${TARGET} eng)
##target_link_libraries( ${TARGET} mx)
set(CMAKE_CXX_FLAGS "--std=c++11")
add_executable( ${TARGET} ${MAIN_SOURCES} )
target_link_libraries( ${TARGET} ${GTKMM_LIBRARIES} )
target_link_libraries( ${TARGET} ${Boost_LIBRARIES} )
target_link_libraries( ${TARGET} LINK_PRIVATE /usr/local/MATLAB/R2013b/bin/glnxa64/libeng.so) # eng
#target_link_libraries( ${TARGET} LINK_PRIVATE /usr/local/MATLAB/R2013b/bin/glnxa64/libmx.so ) # mx
target_link_libraries( ${TARGET} andor )
You could try using an imported target:
add_library(eng SHARED IMPORTED)
set_property(TARGET eng PROPERTY IMPORTED_LOCATION /usr/local/MATLAB/R2013b/bin/glnxa64/libeng.so)
...
add_executable( ${TARGET} ${MAIN_SOURCES} )
...
target_link_libraries(${TARGET} eng)
For debugging you could try to build with "make VERBOSE=1".
This will show you the used gcc command line.
CMake probably transforms your target_link_libraries command to something like:
g++ ... -L/usr/local/MATLAB/R2013b/bin/glnxa64 -leng ...
gcc then finds some boost libraries in this folder.
I'll begin stating that I'm almost complete dumb in Cmake matter.
I have the following CMakeLists.txt for a Kdevelop 4.1 project:
project(uart)
find_package(KDE4 REQUIRED)
include (KDE4Defaults)
include_directories( ${KDE4_INCLUDES} ${QT_INCLUDES} src/include src/include/QSerialDevce )
add_subdirectory(doc)
add_subdirectory(src)
add_subdirectory(icons)
link_directories(/usr/lib)
find_library(SERIALDEVICE_LIB qserialdeviced)
add_executable(uart ${uart_SRCS})
target_link_libraries(uart ${SERIALDEVICE_LIB})
When I try to build my project I see:
uart/build> make -j2
-- Found Qt-Version 4.6.3 (using /usr/bin/qmake-qt4)
-- Found X11: /usr/lib64/libX11.so
-- Found KDE 4.5 include dir: /usr/include/kde4
-- Found KDE 4.5 library dir: /usr/lib64/kde4/devel
-- Found the KDE4 kconfig_compiler4 preprocessor: /usr/bin/kconfig_compiler4
-- Found automoc4: /usr/bin/automoc4
CMake Error at CMakeLists.txt:16 (add_executable):
add_executable called with incorrect number of arguments
CMake Error: Attempt to add link library "/usr/lib/libqserialdeviced.so" to target "uart" which is not built by this project.
-- Configuring incomplete, errors occurred!
make: *** [cmake_check_build_system] Error 1
*** Failed ***
Everything I read says that add_executable and target_link_libraries should look like the last two lines of my file:
add_executable(uart ${uart_SRCS})
target_link_libraries(uart ${SERIALDEVICE_LIB})
If I change those two lines of CMakeLists.txt leaving it as:
project(uart)
find_package(KDE4 REQUIRED)
include (KDE4Defaults)
include_directories( ${KDE4_INCLUDES} ${QT_INCLUDES} src/include src/include/QSerialDevce )
add_subdirectory(doc)
add_subdirectory(src)
add_subdirectory(icons)
link_directories(/usr/lib)
find_library(SERIALDEVICE_LIB qserialdeviced)
target_link_libraries(${SERIALDEVICE_LIB})
I see:
uart/build> make -j2
-- Found Qt-Version 4.6.3 (using /usr/bin/qmake-qt4)
-- Found X11: /usr/lib64/libX11.so
-- Found KDE 4.5 include dir: /usr/include/kde4
-- Found KDE 4.5 library dir: /usr/lib64/kde4/devel
-- Found the KDE4 kconfig_compiler4 preprocessor: /usr/bin/kconfig_compiler4
-- Found automoc4: /usr/bin/automoc4
-- Configuring done
-- Generating done
-- Build files have been written to: uart/build
[ 11%] Built target doc-handbook
[ 11%] Built target uart_automoc
Linking CXX executable uart
CMakeFiles/uart.dir/uart.o: In function `uart::setupSerial()':
uart/src/uart.cpp:126: undefined reference to `AbstractSerial::AbstractSerial(QObject*)'
CMakeFiles/uart.dir/uart.o: In function `uart::setupEnumerator()':
uart/src/uart.cpp:108: undefined reference to `SerialDeviceEnumerator::SerialDeviceEnumerator(QObject*)'
CMakeFiles/uart.dir/uart.o: In function `uart::setupSerial()':
uart_/uart/src/uart.cpp:136: undefined reference to `AbstractSerial::enableEmitStatus(bool)'
CMakeFiles/uart.dir/uart.o: In function `uart::setupEnumerator()':
uart_/uart/src/uart.cpp:112: undefined reference to `SerialDeviceEnumerator::setEnabled(bool)'
collect2: ld returned 1 exit status
make[2]: *** [src/uart] Error 1
make[1]: *** [src/CMakeFiles/uart.dir/all] Error 2
make: *** [all] Error 2
*** Failed ***
That clearly shows that target_link_libraries is not linking my qserialdeviced.
qserialdeviced is at /usr/lib/libqserialdeviced.so.1.0.0, correctly simlinked to /usr/lib/libqserialdeviced.so and easily found if I manually add it in the Makefile.
I obviously tried:
target_link_libraries(-lqserialdeviced)
with no change.
I also tried:
if ("${SERIALDEVICE_LIB}" STREQUAL "SERIALDEVICE_LIB-NOTFOUND")
message(FATAL_ERROR "'qserialdeviced' wasn't found!")
else()
message("'qserialdeviced' found: " ${SERIALDEVICE_LIB})
endif ()
But this test succeeds. The library is found:
'qserialdeviced' found: /usr/lib/libqserialdeviced.so
Can anybody please help me to understand what happens here?
I am using Linux Fedora 13, cmake version 2.8.0, gcc (GCC) 4.4.5 20101112 (Red Hat 4.4.5-2) and kdevelop-4.1.0-1.fc13.x86_64.
Thanks i advance.
EDIT:
As suggested by #DatChu, I split my CMakeLists.txt across my subdirectories and everything makes sense to me now.
Thanks everbody!
For the original CMakeLists.txt file, the problem is not with target_link_libraries but with add_executable
add_executable(uart ${uart_SRCS})
where did you set your uart_SRCS variable? Do you have
set(uart_SRCS src/blahblah.cpp src/somethingblahblah.cpp)
I think you might misunderstand what add_subdirectory does. It does not add the source files inside. It tells CMake to descend into that folder and look for another CMakeLists.txt. You typically use it when you have a sub-project inside of your project folder.
If you have many source files which you don't want to manually set, you can also do
file(GLOB uart_SRCS src/*.cpp src/*.c)
The downside is you need to manually re-run CMake in order for it to detect new files. See Jack's comment on why this might not be what you want to use.
Your CMakeLists.txt will most likely be
project(uart)
find_package(Qt4 REQUIRED)
include (${QT_USE_FILE})
find_package(KDE4 REQUIRED)
include (KDE4Defaults)
include_directories( ${KDE4_INCLUDES} ${QT_INCLUDES} src/include src/include/QSerialDevice )
link_directories(/usr/lib)
file(GLOB uart_SRCS src/*.cpp src/*.h)
file(GLOB uart_HDRS include/*.h include/QSerialDevice/*.h)
find_library(SERIALDEVICE_LIB qserialdeviced)
add_executable(uart ${uart_SRCS} ${uart_HDRS})
target_link_libraries(uart ${SERIALDEVICE_LIB} ${QT_LIBRARIES})
This isn't really a direct solution, but I was having such difficulty with "undefined reference" errors (solved previously by linking the appropriate libraries, but not in this case), until I just discovered something - an incompatibility with c vs cpp somehow. The files that defined these reference functions were in .c files (which would default cmake to compile with a C compiler.) and my file referencing these functions is a .cpp file (using g++ compiler or whatever your environment c++ compiler is). Once I changed the .c file to .cpp the "undefined reference" errors disappeared. Above it looks like your uart file is .cpp, but maybe check what the other files are and try this method. It's probably not the appropriate solution or even one at all, but this might get you through the day and moving forward.