g++ compiling CLang standalone app but CMake isn't

Question

I am trying to compile my CLang standalone app using cmake on my Ubuntu machine, but no luck yet. Here is my CMakeLists.txt :-

cmake_minimum_required(VERSION 2.8)

project(Demo)

execute_process(
    COMMAND llvm-config --cxxflags
    OUTPUT_VARIABLE LLVM_CXX_FLAGS
)

execute_process(
    COMMAND llvm-config --ldflags
    OUTPUT_VARIABLE LLVM_LD_FLAGS
)

execute_process(
    COMMAND llvm-config --libs
    OUTPUT_VARIABLE LLVM_LIB_FLAGS
)

SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${LLVM_CXX_FLAGS}")
SET(CMAKE_CXX_LINK_FLAGS "${CMAKE_CXX_LINK_FLAGS} ${LLVM_LD_FLAGS}")

add_executable(clangTestApp TestCLang.cpp)

target_link_libraries(clangTestApp ${LLVM_LIB_FLAGS})

Here is the output when I am running cmake .. from build directory inside project directory:-

-- Configuring done
CMake Error at CMakeLists.txt:23 (add_executable):
  Target "clangTestApp" links to item "-lLLVMAsmParser -lLLVMInstrumentation
  -lLLVMLinker -lLLVMArchive -lLLVMBitReader -lLLVMDebugInfo -lLLVMJIT
  -lLLVMipo -lLLVMVectorize -lLLVMBitWriter -lLLVMTableGen
  -lLLVMHexagonCodeGen -lLLVMHexagonDesc -lLLVMHexagonInfo
  -lLLVMHexagonAsmPrinter -lLLVMNVPTXCodeGen -lLLVMNVPTXDesc -lLLVMNVPTXInfo
  -lLLVMNVPTXAsmPrinter -lLLVMMBlazeAsmParser -lLLVMMBlazeDisassembler
  -lLLVMMBlazeCodeGen -lLLVMMBlazeDesc -lLLVMMBlazeInfo
  -lLLVMMBlazeAsmPrinter -lLLVMCppBackendCodeGen -lLLVMCppBackendInfo
  -lLLVMMSP430CodeGen -lLLVMMSP430Desc -lLLVMMSP430Info
  -lLLVMMSP430AsmPrinter -lLLVMXCoreCodeGen -lLLVMXCoreDesc -lLLVMXCoreInfo
  -lLLVMCellSPUCodeGen -lLLVMCellSPUDesc -lLLVMCellSPUInfo
  -lLLVMMipsDisassembler -lLLVMMipsCodeGen -lLLVMMipsAsmParser -lLLVMMipsDesc
  -lLLVMMipsInfo -lLLVMMipsAsmPrinter -lLLVMARMDisassembler
  -lLLVMARMAsmParser -lLLVMARMCodeGen -lLLVMARMDesc -lLLVMARMInfo
  -lLLVMARMAsmPrinter -lLLVMPowerPCCodeGen -lLLVMPowerPCDesc
  -lLLVMPowerPCInfo -lLLVMPowerPCAsmPrinter -lLLVMSparcCodeGen
  -lLLVMSparcDesc -lLLVMSparcInfo -lLLVMX86Disassembler -lLLVMX86AsmParser
  -lLLVMX86CodeGen -lLLVMX86Desc -lLLVMX86Info -lLLVMX86AsmPrinter
  -lLLVMX86Utils -lLLVMR600CodeGen -lLLVMSelectionDAG -lLLVMAsmPrinter
  -lLLVMR600Desc -lLLVMR600Info -lLLVMR600AsmPrinter -lLLVMMCDisassembler
  -lLLVMMCParser -lLLVMInterpreter -lLLVMCodeGen -lLLVMScalarOpts
  -lLLVMInstCombine -lLLVMTransformUtils -lLLVMipa -lLLVMAnalysis -lLLVMMCJIT
  -lLLVMRuntimeDyld -lLLVMExecutionEngine -lLLVMTarget -lLLVMMC -lLLVMObject
  -lLLVMCore -lLLVMSupport

  " which has leading or trailing whitespace.  This is now an error according
  to policy CMP0004.


-- Generating done
-- Build files have been written to: /home/prakhar/Desktop/CLang/Demo/build

Now when I am running make inside build directory, its giving me:-

Scanning dependencies of target clangTestApp
[100%] Building CXX object CMakeFiles/clangTestApp.dir/TestCLang.o
Linking CXX executable clangTestApp
c++: fatal error: no input files
compilation terminated.
make[2]: *** [clangTestApp] Error 4
make[1]: *** [CMakeFiles/clangTestApp.dir/all] Error 2
make: *** [all] Error 2

I don't know why c++ is saying no input files . If anybody have a clue whats going on?

Thanks

Answer 1

I suggest you use a FindClang.cmake which you can find eg here: https://github.com/woboq/woboq_codebrowser/blob/master/cmake/modules/FindClang.cmake (Or just google for FindClang.cmake). You'll also need the corresponding FindLLVM.cmake ( https://github.com/woboq/woboq_codebrowser/blob/master/cmake/modules/FindLLVM.cmake )