[cmake-developers] check_cxx_source_compiles and include directories

[Roman Wüger]

So, here is the piece of code which works

 

Main CMakeLists.txt:

 

project(MyProject)

 

list(APPEND CMAKE_MODULE_PATH ${CMAKE_SOURCE_DIR}/cmake)

 

if (APPLE)

    set(CMAKE_CXX_EXTENSIONS OFF) # Use -std=c++11 instead of -std=gnu++11

endif()

set(CMAKE_CXX_STANDARD 11)

include(CheckCXXCompilerFlag)

 

# Required for check_cxx_source_cmopiles

check_cxx_compiler_flag("-std=c++11" CXX11_FLAG)

if (CXX11_FLAG)

    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11")

endif()

 

include(CheckMyCXX11Features.cmake)

.

.

.

add_subdirectory(SubProj1)

add_subdirectory(SubProj2)

.

.

.

 

 

CheckMyCXX11Features.cmake:

 

include(CheckCXXSourceCompiles)

 

# C++11 Unique Lock and Mutex

set(CMAKE_REQUIRED_FLAGS "${CMAKE_CXX_FLAGS}")

check_cxx_source_compiles(

   "#include <mutex>          // std::mutex, std::unique_lock

 

    std::mutex mtx;           // mutex for critical section

 

    void print_block (int n, char c) {

      // critical section (exclusive access to std::cout signaled by
lifetime of lck):

      std::unique_lock<std::mutex> lck (mtx);

      for (int i=0; i<n; ++i) { /* Do Something */ }

    }

 

    int main ()

    {

      print_block(50,'$');

 

      return 0;

    }"

  MY_HAVE_CXX11_MUTEX_AND_UNIQUE_LOCK

)

set(CMAKE_REQUIRED_FLAGS "")

 

configure_file(${CMAKE_SOURCE_DIR}/cmake/MyCXX11Features.h.in
${CMAKE_BINARY_DIR}/cmake/MyCXX11Features.h)

 

 

SubProj1 and SubProj2 does not find <mutex>, but check_cxx_source_compiles
succeeds.

Did I miss configure something here?

 

Best Regards

Roman

 

 

> -----Ursprüngliche Nachricht-----

> Von: cmake-developers [mailto:cmake-developers-bounces at cmake.org] Im

> Auftrag von Roman Wüger

> Gesendet: Montag, 27. Juli 2015 07:35

> An: CMake MailingList <cmake at cmake.org>; CMake Developer MailingList

> <cmake-developers at cmake.org>

> Betreff: [cmake-developers] check_cxx_source_compiles and include

> directories

> 

> Hello,

> 

> I've a small code example to test if the <mutex> header file exists (with

> check_cxx_source_compiles), which sets my variable successfully to TRUE.

> 

> When I compile the real code then I got an error message saying 'mutex'
file

> not found.

> 

> I checked the compile flags for both situations and these are equal. So I

> thought that the include directories could be the problem.

> 

> Any hints?

> 

> Best Regards

> Roman

> --

> 

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