307 lines
8.8 KiB
ReStructuredText
307 lines
8.8 KiB
ReStructuredText
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===============
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Building libc++
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===============
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.. contents::
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:local:
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Getting Started
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===============
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On Mac OS 10.7 (Lion) and later, the easiest way to get this library is to install
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Xcode 4.2 or later. However if you want to install tip-of-trunk from here
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(getting the bleeding edge), read on.
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The basic steps needed to build libc++ are:
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#. Checkout LLVM:
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* ``cd where-you-want-llvm-to-live``
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* ``svn co http://llvm.org/svn/llvm-project/llvm/trunk llvm``
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#. Checkout libc++:
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* ``cd where-you-want-llvm-to-live``
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* ``cd llvm/projects``
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* ``svn co http://llvm.org/svn/llvm-project/libcxx/trunk libcxx``
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#. Checkout libc++abi:
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* ``cd where-you-want-llvm-to-live``
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* ``cd llvm/projects``
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* ``svn co http://llvm.org/svn/llvm-project/libcxxabi/trunk libcxxabi``
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#. Configure and build libc++ with libc++abi:
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CMake is the only supported configuration system. Unlike other LLVM
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projects autotools is not supported for either libc++ or libc++abi.
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Clang is the preferred compiler when building and using libc++.
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* ``cd where you want to build llvm``
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* ``mkdir build``
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* ``cd build``
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* ``cmake -G <generator> [options] <path to llvm sources>``
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For more information about configuring libc++ see :ref:`CMake Options`.
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* ``make cxx`` --- will build libc++ and libc++abi.
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* ``make check-libcxx check-libcxxabi`` --- will run the test suites.
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Shared libraries for libc++ and libc++ abi should now be present in llvm/build/lib.
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See :ref:`using an alternate libc++ installation <alternate libcxx>`
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#. **Optional**: Install libc++ and libc++abi
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If your system already provides a libc++ installation it is important to be
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careful not to replace it. Remember Use the CMake option ``CMAKE_INSTALL_PREFIX`` to
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select a safe place to install libc++.
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* ``make install-libcxx install-libcxxabi`` --- Will install the libraries and the headers
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.. warning::
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* Replacing your systems libc++ installation could render the system non-functional.
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* Mac OS X will not boot without a valid copy of ``libc++.1.dylib`` in ``/usr/lib``.
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The instructions are for building libc++ on
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FreeBSD, Linux, or Mac using `libc++abi`_ as the C++ ABI library.
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On Linux, it is also possible to use :ref:`libsupc++ <libsupcxx>` or libcxxrt.
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It is sometimes beneficial to build outside of the LLVM tree. An out-of-tree
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build would look like this:
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.. code-block:: bash
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$ cd where-you-want-libcxx-to-live
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$ # Check out llvm, libc++ and libc++abi.
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$ ``svn co http://llvm.org/svn/llvm-project/llvm/trunk llvm``
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$ ``svn co http://llvm.org/svn/llvm-project/libcxx/trunk libcxx``
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$ ``svn co http://llvm.org/svn/llvm-project/libcxxabi/trunk libcxxabi``
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$ cd where-you-want-to-build
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$ mkdir build && cd build
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$ export CC=clang CXX=clang++
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$ cmake -DLLVM_PATH=path/to/llvm \
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-DLIBCXX_CXX_ABI=libcxxabi \
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-DLIBCXX_CXX_ABI_INCLUDE_PATHS=path/to/libcxxabi/include \
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path/to/libcxx
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$ make
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$ make check-libcxx # optional
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.. _`libc++abi`: http://libcxxabi.llvm.org/
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.. _CMake Options:
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CMake Options
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=============
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Here are some of the CMake variables that are used often, along with a
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brief explanation and LLVM-specific notes. For full documentation, check the
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CMake docs or execute ``cmake --help-variable VARIABLE_NAME``.
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**CMAKE_BUILD_TYPE**:STRING
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Sets the build type for ``make`` based generators. Possible values are
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Release, Debug, RelWithDebInfo and MinSizeRel. On systems like Visual Studio
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the user sets the build type with the IDE settings.
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**CMAKE_INSTALL_PREFIX**:PATH
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Path where LLVM will be installed if "make install" is invoked or the
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"INSTALL" target is built.
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**CMAKE_CXX_COMPILER**:STRING
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The C++ compiler to use when building and testing libc++.
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.. _libcxx-specific options:
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libc++ specific options
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-----------------------
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.. option:: LIBCXX_ENABLE_ASSERTIONS:BOOL
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**Default**: ``ON``
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Build libc++ with assertions enabled.
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.. option:: LIBCXX_BUILD_32_BITS:BOOL
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**Default**: ``OFF``
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Build libc++ as a 32 bit library. Also see :option:`LLVM_BUILD_32_BITS`.
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.. option:: LIBCXX_ENABLE_SHARED:BOOL
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**Default**: ``ON``
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Build libc++ as a shared library. If ``OFF`` is specified then libc++ is
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built as a static library.
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.. option:: LIBCXX_LIBDIR_SUFFIX:STRING
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Extra suffix to append to the directory where libraries are to be installed.
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This option overrides :option:`LLVM_LIBDIR_SUFFIX`.
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.. _ABI Library Specific Options:
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ABI Library Specific Options
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----------------------------
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.. option:: LIBCXX_CXX_ABI:STRING
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**Values**: ``none``, ``libcxxabi``, ``libcxxrt``, ``libstdc++``, ``libsupc++``.
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Select the ABI library to build libc++ against.
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.. option:: LIBCXX_CXX_ABI_INCLUDE_PATHS:PATHS
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Provide additional search paths for the ABI library headers.
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.. option:: LIBCXX_CXX_ABI_LIBRARY_PATH:PATH
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Provide the path to the ABI library that libc++ should link against.
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.. option:: LIBCXX_ENABLE_STATIC_ABI_LIBRARY:BOOL
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**Default**: ``OFF``
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If this option is enabled, libc++ will try and link the selected ABI library
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statically.
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.. option:: LIBCXX_ENABLE_ABI_LINKER_SCRIPT:BOOL
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**Default**: ``ON`` by default on UNIX platforms other than Apple unless
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'LIBCXX_ENABLE_STATIC_ABI_LIBRARY' is ON. Otherwise the default value is ``OFF``.
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This option generate and installs a linker script as ``libc++.so`` which
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links the correct ABI library.
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.. option:: LIBCXXABI_USE_LLVM_UNWINDER:BOOL
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**Default**: ``OFF``
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Build and use the LLVM unwinder. Note: This option can only be used when
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libc++abi is the C++ ABI library used.
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libc++ Feature options
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----------------------
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.. option:: LIBCXX_ENABLE_EXCEPTIONS:BOOL
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**Default**: ``ON``
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Build libc++ with exception support.
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.. option:: LIBCXX_ENABLE_RTTI:BOOL
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**Default**: ``ON``
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Build libc++ with run time type information.
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libc++ Feature options
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----------------------
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The following options allow building libc++ for a different ABI version.
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.. option:: LIBCXX_ABI_VERSION:STRING
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**Default**: ``1``
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Defines the target ABI version of libc++.
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.. option:: LIBCXX_ABI_UNSTABLE:BOOL
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**Default**: ``OFF``
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Build the "unstable" ABI version of libc++. Includes all ABI changing features
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on top of the current stable version.
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.. _LLVM-specific variables:
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LLVM-specific options
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---------------------
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.. option:: LLVM_LIBDIR_SUFFIX:STRING
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Extra suffix to append to the directory where libraries are to be
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installed. On a 64-bit architecture, one could use ``-DLLVM_LIBDIR_SUFFIX=64``
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to install libraries to ``/usr/lib64``.
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.. option:: LLVM_BUILD_32_BITS:BOOL
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Build 32-bits executables and libraries on 64-bits systems. This option is
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available only on some 64-bits unix systems. Defaults to OFF.
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.. option:: LLVM_LIT_ARGS:STRING
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Arguments given to lit. ``make check`` and ``make clang-test`` are affected.
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By default, ``'-sv --no-progress-bar'`` on Visual C++ and Xcode, ``'-sv'`` on
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others.
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Using Alternate ABI libraries
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=============================
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.. _libsupcxx:
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Using libsupc++ on Linux
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------------------------
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You will need libstdc++ in order to provide libsupc++.
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Figure out where the libsupc++ headers are on your system. On Ubuntu this
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is ``/usr/include/c++/<version>`` and ``/usr/include/c++/<version>/<target-triple>``
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You can also figure this out by running
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.. code-block:: bash
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$ echo | g++ -Wp,-v -x c++ - -fsyntax-only
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ignoring nonexistent directory "/usr/local/include/x86_64-linux-gnu"
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ignoring nonexistent directory "/usr/lib/gcc/x86_64-linux-gnu/4.7/../../../../x86_64-linux-gnu/include"
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#include "..." search starts here:
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#include <...> search starts here:
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/usr/include/c++/4.7
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/usr/include/c++/4.7/x86_64-linux-gnu
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/usr/include/c++/4.7/backward
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/usr/lib/gcc/x86_64-linux-gnu/4.7/include
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/usr/local/include
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/usr/lib/gcc/x86_64-linux-gnu/4.7/include-fixed
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/usr/include/x86_64-linux-gnu
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/usr/include
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End of search list.
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Note that the first two entries happen to be what we are looking for. This
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may not be correct on other platforms.
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We can now run CMake:
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.. code-block:: bash
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$ CC=clang CXX=clang++ cmake -G "Unix Makefiles" \
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-DLIBCXX_CXX_ABI=libstdc++ \
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-DLIBCXX_CXX_ABI_INCLUDE_PATHS="/usr/include/c++/4.7/;/usr/include/c++/4.7/x86_64-linux-gnu/" \
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-DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=/usr \
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<libc++-source-dir>
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You can also substitute ``-DLIBCXX_CXX_ABI=libsupc++``
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above, which will cause the library to be linked to libsupc++ instead
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of libstdc++, but this is only recommended if you know that you will
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never need to link against libstdc++ in the same executable as libc++.
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GCC ships libsupc++ separately but only as a static library. If a
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program also needs to link against libstdc++, it will provide its
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own copy of libsupc++ and this can lead to subtle problems.
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.. code-block:: bash
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$ make cxx
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$ make install
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You can now run clang with -stdlib=libc++.
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