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IDProjectCategoryView StatusDate SubmittedLast Update
0014962CMakeCMakepublic2014-06-08 14:232016-06-10 14:31
ReporterMichael Kahane 
Assigned ToAlex Neundorf 
PrioritynormalSeverityminorReproducibilityalways
StatusclosedResolutionmoved 
Platformx86_64OSLinuxOS Version14.04
Product VersionCMake 2.8.12 
Target VersionFixed in Version 
Summary0014962: Eclipse generator does not cause -std= and -stdlib= flags to affect include path
DescriptionI'm trying to setup a C++ project in eclipse. The project is using the clang++ compiler and I'm using it in C++11 mode with libc++. To make the Eclipse generator detect the proper include paths and language I'm setting CMAKE_CXX_COMPILER_ARG1="-std=c++11 -stdlib=libc+11" on the command line but the the include paths do not appear in the generated eclipse project. I've also tried CMAKE_CXX_COMPILER_ARG1=-std=c++11\;-stdlib=libc+11 but the generator fails with an error in this case.

If I use only one argument to CMAKE_CXX_COMPILER_ARG1 it works. However if I use CMAKE_CXX_COMPILER_ARG1=-std=c11 it will set the __GXX_EXPERIMENTAL_CXX0X__ flag but not the include path to libc++ (instead it will set the include paths to stdlibc++). If I use CMAKE_CXX_COMPILER_ARG1=-stblib=libc+11 it will add /usr/include/c++/v1 to the include path but not set the __GXX_EXPERIMENTAL_CXX0X__ flags.
Steps To ReproduceYou need a setup with clang++ and libc++.
Assuming you have a c++ project in proj_dir make an adjacent build_dir. cd to the build_dir and:
CC=clang CXX=clang++ cmake -G"Eclipse CDT4 - Unix Makefiles" -DCMAKE_BUILD_TYPE=Debug -DCMAKE_CXX_COMPILER_ARG1=-std=c++11\;-stdlib=libc++ -DCMAKE_ECLIPSE_VERSION=4.3 ../proj_dir

or

CC=clang CXX=clang++ cmake -G"Eclipse CDT4 - Unix Makefiles" -DCMAKE_BUILD_TYPE=Debug -DCMAKE_CXX_COMPILER_ARG1="-std=c++11-stdlib=libc++" -DCMAKE_ECLIPSE_VERSION=4.3 ../proj_dir
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Issue History
Date ModifiedUsernameFieldChange
2014-06-08 14:23Michael KahaneNew Issue
2014-06-09 09:52Brad KingNote Added: 0036132
2014-06-09 10:17Michael KahaneNote Added: 0036133
2014-06-09 10:19Michael KahaneNote Edited: 0036133bug_revision_view_page.php?bugnote_id=36133#r1474
2014-06-09 10:20Brad KingSummaryEclipse generator fails with several params to CMAKE_CXX_COMPILER_ARG1 => Eclipse generator does not cause -std= and -stdlib= flags to affect include path
2014-06-09 10:22Brad KingNote Added: 0036134
2014-06-09 10:44Alex NeundorfAssigned To => Alex Neundorf
2014-06-09 10:44Alex NeundorfStatusnew => assigned
2014-06-09 11:35Ben BoeckelNote Added: 0036137
2014-06-09 16:40Michael KahaneNote Added: 0036145
2014-06-09 17:00Michael KahaneNote Added: 0036146
2016-06-10 14:29Kitware RobotNote Added: 0042561
2016-06-10 14:29Kitware RobotStatusassigned => resolved
2016-06-10 14:29Kitware RobotResolutionopen => moved
2016-06-10 14:31Kitware RobotStatusresolved => closed

Notes
(0036132)
Brad King   
2014-06-09 09:52   
CMAKE_CXX_COMPILER_ARG1 is an internal implementation detail. The proper way to specify C++ flags is with the CXXFLAGS environment variable, or in the CMAKE_CXX_FLAGS cache entry. If the Eclipse generator does not pick things up from that then that is the real issue.
(0036133)
Michael Kahane   
2014-06-09 10:17   
(edited on: 2014-06-09 10:19)
Actually I have:
add_compile_options(-std=c++11 -stdlib=libc++)

in CMakeLists.txt in the project source dir and I expected the Eclipse generator to pick the options from there (shouldn't it?). Googling around I got to this page about using CMAKE_CXX_COMPILER_ARG1:
http://stackoverflow.com/questions/18358389/eclipse-indexer-proper-c11-syntax-highlighting-when-generating-projects-with-c [^]

So now I tried:
CC=clang CXX=clang++ CXXFLAGS="-std=c++11 -stdlib=libc++" cmake -G"Eclipse CDT4 - Unix Makefiles" -DCMAKE_BUILD_TYPE=Debug -DCMAKE_ECLIPSE_VERSION=4.3 ../proj_dir
It also doesn't detect C++11 (no __GXX_EXPERIMENTAL_CXX0X__) and doesn't set the include path to /usr/include/c++/v1.

So both add_compile_options(-std=c++11 -stdlib=libc++) and CXXFLAGS="-std=c++11 -stdlib=libc++" don't seem to work with the Eclipse generator.
(0036134)
Brad King   
2014-06-09 10:22   
Side note: you may be interested in some recent development in the CMake 'master' branch that adds first-class support for requesting C and C++ language-standard levels (but not yet standard library selection). Look for the CXX_STANDARD target property and the CMAKE_CXX_STANDARD variable.
(0036137)
Ben Boeckel   
2014-06-09 11:35   
> add_compile_options(-std=c++11 -stdlib=libc++)

The flags given here are only used during compilation, not linking. Use the CMAKE_CXX_FLAGS for this. I imagine add_compile_options will eventually get a global-flag variant, but it doesn't exist yet.
(0036145)
Michael Kahane   
2014-06-09 16:40   
Ben,
I didn't understand your comment. For linking I have in CMakeLists.txt:
target_link_libraries(proj -std=c++1y -stdlib=libc++)

But I assume that the detection of c++ standard and include paths is done via the preprocessor so the compilation options should be enough.

In any case I've tried to run:
CC=clang CXX=clang++ cmake -G"Eclipse CDT4 - Unix Makefiles" -DCMAKE_CXX_FLAGS="-std=c++11 -stdlib=libc++" -DCMAKE_BUILD_TYPE=Debug -DCMAKE_ECLIPSE_VERSION=4.3 ../proj_dir

but it also fails to correctly detect c++11 and include paths.
(0036146)
Michael Kahane   
2014-06-09 17:00   
I've checked the development version (cmake version 3.0.20140606-g7ef8d). Using:
CC=clang CXX=clang++ cmake -G"Eclipse CDT4 - Unix Makefiles" -DCMAKE_CXX_STANDARD=11 -DCMAKE_BUILD_TYPE=Debug -DCMAKE_ECLIPSE_VERSION=4.3 ../proj_dir

The generated Eclipse project is still for C++98 (no __GXX_EXPERIMENTAL_CXX0X__ flag and also __cplusplus is 199711L).
(0042561)
Kitware Robot   
2016-06-10 14:29   
Resolving issue as `moved`.

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