[cmake-developers] [CMake 0015355]: cmake 3.1 doesn't know how to select CMAKE_CXX_STANDARD 11 on Mac OS

[Mantis Bug Tracker]

The following issue has been SUBMITTED. 
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http://public.kitware.com/Bug/view.php?id=15355 
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Reported By:                Laurent Demailly
Assigned To:                
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Project:                    CMake
Issue ID:                   15355
Category:                   CMake
Reproducibility:            always
Severity:                   major
Priority:                   normal
Status:                     new
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Date Submitted:             2015-01-15 15:25 EST
Last Modified:              2015-01-15 15:25 EST
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Summary:                    cmake 3.1 doesn't know how to select
CMAKE_CXX_STANDARD 11 on Mac OS
Description: 
I have a very simple CMakeLists.txt – am using cmake 3.1 to be able to easily
request C++ 11 – it works fine on ubuntu but not on MacOS with Xcode 6 and
command line tools installed:

$ cat CMakeLists.txt
cmake_minimum_required(VERSION 3.1)

project("Test1" C CXX)

# We need C++ 11
set(CMAKE_CXX_STANDARD 11)
set(CMAKE_CXX_STANDARD_REQUIRED on)

file(WRITE test1.cpp "int main(int argc, char** argv) {auto x=argc; return x;}")

add_executable(test1 test1.cpp)

$ cmake31 .
-- The C compiler identification is AppleClang 6.0.0.6000056
-- The CXX compiler identification is AppleClang 6.0.0.6000056
-- Check for working C compiler:
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang
-- Check for working C compiler:
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang
-- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working CXX compiler:
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang++
-- Check for working CXX compiler:
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang++
-- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Configuring done
CMake Error in CMakeLists.txt:
  Target "test1" requires the language dialect "CXX11" (with compiler
  extensions), but CMake does not know the compile flags to use to enable it.


This is with 
CXX=/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang++
CXXFLAGS="-std=c++11"
But same without that


Steps to Reproduce: 
cmake_minimum_required(VERSION 3.1)

project("Test1" C CXX)

# We need C++ 11
set(CMAKE_CXX_STANDARD 11)
set(CMAKE_CXX_STANDARD_REQUIRED on)

file(WRITE test1.cpp "int main(int argc, char** argv) {auto x=argc; return x;}")

add_executable(test1 test1.cpp)


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Issue History 
Date Modified    Username       Field                    Change               
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2015-01-15 15:25 Laurent DemaillyNew Issue                                    
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