Setting path to Clang library in CMake - cmake

I build llvm from git and want to use the libraries in a project, especially the libclang.
The "makefiles" are generated by means of CMake and for the LLVM part I found the setting LLVM_DIR to reroute the path for the llvm libraries, but for Clang I cannot find such a variable and I still see in my link line (it is a Cygwin system):
/usr/lib/libclang.dll.a /usr/lib/libclangTooling.dll.a.
Question: which environment variable do I set to get the right build Clang libraries?

The variable is Clang_DIR.
Just in case, I attach a minimalistic example of CMakeLists.txt file as well.
cmake_minimum_required(VERSION 3.12)
# Find CMake file for Clang
find_package(Clang REQUIRED)
# Add path to LLVM modules
set(CMAKE_MODULE_PATH
${CMAKE_MODULE_PATH}
"${LLVM_CMAKE_DIR}"
)
# import LLVM CMake functions
include(AddLLVM)
include_directories(${LLVM_INCLUDE_DIRS})
include_directories(${CLANG_INCLUDE_DIRS})
add_definitions(${LLVM_DEFINITIONS})
add_definitions(${CLANG_DEFINITIONS})
add_llvm_executable(myTool main.cpp)
set_property(TARGET myTool PROPERTY CXX_STANDARD 11)
target_link_libraries(myTool PRIVATE clangTooling)

Related

About Specifying EIGEN3_DIR variable not use

My computer has multiple versions of the eigen library. I have an eigen3 in the /usr/include/ and another eigen3 in the /usr/local/. I use the set() command in cmakelists, but the compiler only uses the eigen library in the/usr/include directory. Here are my cmakelists.txt settings
`
cmake_minimum_required(VERSION 2.8.3)
project(cmake_test)
set(EIGEN3_DIR "/usr/local/eigen-3.3.9/share/eigen3/cmake/")
find_package(Eigen3)
include_directories(
# "/usr/local/eigen-3.3.9/include/eigen3/"
${PROJECT_SOURCE_DIR}/include
${EIGEN3_INCLUDE_DIR}
)
message("EIGEN3_INCLUDE_DIR =======" ${EIGEN3_DIR})
message("EIGEN3_INCLUDE_DIR =======" ${EIGEN3_INCLUDE_DIR})
add_executable(cmake_test src/main.cpp)
`
Does anyone know where I went wrong
I hope someone can tell me how cmake searches for header files, library files, and Search order of the find_ package() command

Cmakelist working outside of Clion

I've wanted to use Clion for awhile but I've always had trouble with Cmake. Armed with Cygwin, I've almost gotten this stupid thing to work.
The issue is while I can compile a cmake file from within a cygwin terminal, in Clion I am told it cannot find the library I want.
Error:A required package was not found
The cmakelist.txt file
cmake_minimum_required(VERSION 3.3)
project(Test)
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11")
set(PKG_CONFIG_PATH /usr/lib/pkgconfig)
set(PKG_CONFIG_EXECUTABLE /usr/bin/pkg-config.exe)
set(SOURCE_FILES main.cpp)
add_executable(Test ${SOURCE_FILES})
INCLUDE(FindPkgConfig)
pkg_check_modules(SDL2 REQUIRED "sdl2")
MESSAGE(STATUS "SDL library: " ${SDL2_LDFLAGS})
TARGET_LINK_LIBRARIES(Test ${SDL2_LDFLAGS})
I have no idea if setting the variables PKG_CONFIG_PATH and others work, but they successfully build a makefile for my use in cygwin that builds correctly.
I've deleted the cache, remade the project and everything. It just refuses to work in Clion
If I understood correctly, your cmake config is unable to find SDL library. I found it better to use find_package command instead of pkg_check_modules.
In order to find_package(SDL2) to work, there must be FindSDL2.cmake module in directory, specified by CMAKE_MODULE_PATH variable (usually, it is cmake/Modules directory inside your source tree).
FindSDL2.cmake is not a part of CMake, but you can find one online easily (check my own modules, for example: https://github.com/dragn/cmake-modules).
Refer to this doc for details: https://cmake.org/Wiki/CMake:How_To_Find_Libraries.
Put FindSDL2.cmake to cmake/Modules directory and add this to your CMakeLists.txt:
set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} ${CMAKE_SOURCE_DIR}/cmake/Modules)
find_package(SDL2 REQUIRED)
include_directories(${SDL2_INCLUDE_DIR})
...
target_link_libraries(${PROJECT_NAME} ${SDL2_LIBRARY})
NOTE: Sadly, it appears that Leonardo has not succeeded in finding volunteers for maintaining FindSDL2.cmake in SDL community: https://cmake.org/Bug/view.php?id=14826.

Ogre Error In Cmake

While implementing CMake in my code I am getting an ogre error:
/usr/bin/ld: cannot find -lOGRE
My CMakeLists.txt file looks like:
#Specify the version being used aswell as the language
cmake_minimum_required(VERSION 2.6)
#Name your project here
project(eCAD)
#sets cmake to run moc when needed
set(CMAKE_AUTOMOC ON)
#find requirements of this projects
find_package(Qt5Widgets)
find_package(Qt5Core)
find_package(OGRE)
find_package(OIS)
# Find includes in corresponding build directories
set(CMAKE_INCLUDE_CURRENT_DIR ON)
#Sends the -std=c++11 flag to the gcc compiler
add_definitions(-std=c++11)
qt5_wrap_ui(Cmake_form_hdr resources/ui/mainwindow.ui)
#This tells CMake to main.cpp and name it eCAD
add_executable(eCAD main.cpp ${Cmake_form_hdr})
#include the subdirectory containing our libs
add_subdirectory (gui)
include_directories(gui)
#link_libraries
target_link_libraries(eCAD Qt5::Widgets Qt5::Core OGRE OIS)
I am new to this. Please help me out to solve the problem
The command find_package(OGRE) runs file FindOGRE.cmake and sets variables OGRE_INCLUDE_DIRS and OGRE_LIBRARIES. To link with the OGRE library, you should use these variables, e.g.
target_include_directories(eCAD PRIVATE ${OGRE_INCLUDE_DIRS})
target_link_libraries(eCAD ${OGRE_LIBRARIES})
This is same for all of the external libraries you use.

Getting a CMake Error: Cannot specify link libraries for target which is not built by the project

I am implementing CMake in my code but I'm getting the error
"Cannot specify link libraries for target "Qt5::Widgets" which is not built by the project".
Below are the contents of the CMakeLists.txt:
#Specify the version being used aswell as the language
cmake_minimum_required(VERSION 2.6)
#Name your project here
project(eCAD)
#Sends the -std=c++11 flag to the gcc compiler
ADD_DEFINITIONS(-std=c++11)
#This tells CMake to main.cpp and name it eCAD
add_executable(eCAD main.cpp)
#include the subdirectory containing our libs
add_subdirectory (gui)
include_directories(gui)
#include Qt directories
find_package(Qt5Widgets)
find_package(Qt5Core)
find_package(Qt5Designer)
SET(QT_USE_QTDESIGNER ON)
#link_libraries
target_link_libraries(Qt5::Widgets Qt5::Core)
In addition to the accepted answer: An important detail is to place target_link_libraries after the add_executable and find_package lines, so all linked components are known.
The first argument of target_link_libraries is the target name:
target_link_libraries(eCAD Qt5::Widgets Qt5::Core)
Also, do not confuse target name with the project name:
a command project specifies a project name, but
a target is the one created with add_executable, add_library or add_custom_target.
The error message is about the target.
Set you_lib_name before setting target_link_libraries
set(you_lib_name libname)
target_link_libraries(you_lib_name Qt5::Widgets Qt5::Core)

Using CMake with ifort compiler

I am using CMake 2.8.7 on a Linux machine with Intel 11.0 compilers. I am trying to use CMake for the first time as I would like to build this project on both Windows and Linux machines.
I though of using a simple approach first and used a standard Hello World example:
My src/HelloWorld.f90:
!Test helloworld in Fortran using Cmake
program hello
print *, "Hello World!"
end program hello
My main CMakeLists.txt:
# States that CMake required version must be greater than 2.8.7
cmake_minimum_required(VERSION 2.8.7)
enable_language (Fortran)
project(helloworld Fortran)
add_subdirectory(src)
SET_TARGET_PROPERTIES(helloworld PROPERTIES LINKER_LANGUAGE FORTRAN)
My src/CMakeLists.txt:
cmake_minimum_required(VERSION 2.8.7)
# Include the directory itself as a path to include directories
set(CMAKE_INCLUDE_CURRENT_DIR ON)
# For a large number of source files you can create it in a simpler way
# using file() function:
file(GLOB helloworld_SOURCES *.f90)
I still get an error which says CMAKE_FORTRAN_LINK_EXECUTABLE variable missing. I looked at Abinader's CMake tutorial#1, but haven't had success so far.
any suggestions?? Thanks in advance !
Not a direct answer, as I've never used fortran with cmake, but I can see a few issues here.
First of all: where is your target helloworld defined? project is not a target.
Secondly: where do you use helloworld_SOURCES variable?
Try a more regular way. In your src/CMakeLists.txt add line at the end of file with:
add_executable(helloworld ${helloworld_SOURCES})
Also remove SET_TARGET_PROPERTIES(helloworld PROPERTIES LINKER_LANGUAGE FORTRAN) from main one as it should not be necessary.
Last advice: try not to use file(GLOB ). It is better to define list of all files manualy.
Probably the upper-case "FORTRAN", when setting the linker language is the problem. Try writing it as "Fortran" as in the enable_language statement. CMake derives the variables it uses from the language and this causes CMake to look for CMAKE_FORTRAN_LINK_EXECUTABLE instead of CMAKE_Fortran_LINK_EXECUTABLE.
As also mentioned by Michal, the add_executable has to be added to your CMakeLists.txt.
I tested your issue with the following CMake configurations files
main CMakeLists.txt:
# States that CMake required version must be greater than 2.8.7
cmake_minimum_required(VERSION 2.8.7)
enable_language (Fortran)
project(helloworld Fortran)
add_subdirectory(src)
src/CMakeLists.txt:
cmake_minimum_required(VERSION 2.8.7)
add_executable(helloworld HelloWorld.f90)
under Linux for following versions:
ifort (IFORT) 16.0.0.20150815
cmake version 2.8.12.2
I prefer to use cmake-gui. There you can define the ifort compiler as follows:
After definition of source code and binary folder, e.g. build, press "Configure" and select
Click "Next" and define the following compilers
Click "Finish" and "Generate".
Go to build/src folder and execute make. The helloworld executable is generated with ifort successfully and could be called here.
Hint: If ifort is already the default native compiler on your Linux computer then you don't have to specify it in cmake-gui and can go ahead with the first option "Use default native compilers".
Hope it helps.
Let's try this step-by-step:
1) Your Fortran Hello, world is OK!
src/hello.f90
!Test helloworld in Fortran using Cmake
program hello
print *, "Hello World!"
end program hello
2) Now let's write the "inner" CMakeLists.txt
src/CMakeLists.txt
add_executable(helloworld hello.f90)
set_target_properties(
helloworld
PROPERTIES
LINKER_LANGUAGE Fortran
RUNTIME_OUTPUT_DIRECTORY ${PROJECT_SOURCE_DIR}/build)
Here we've created an executable file, which you haven't in your question. Also, we've set its linker language to Fortran (it's case-sensitive parameter!) and the output directory for the compiled file.
3) Now we'll create the "main" CMakeLists.txt
CMakeLists.txt
# States that CMake required version must be greater than 2.8.7
cmake_minimum_required(VERSION 2.8.7)
project(helloworld Fortran)
add_subdirectory(src)
Here we've specified the src subdirectory with inner CMakeLists.txt and the compiler language - it's enough to use project() function, there's not need to use it together with enable_language().
4) Finally, let's build our code in out-of-source manner and run it!
cmake -S . -B build
cmake --build build
./build/helloworld