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Using libc++
.. contents::
Getting Started
If you already have libc++ installed you can use it with clang.
.. code-block:: bash
$ clang++ -stdlib=libc++ test.cpp
$ clang++ -std=c++11 -stdlib=libc++ test.cpp
On OS X and FreeBSD libc++ is the default standard library
and the ``-stdlib=libc++`` is not required.
.. _alternate libcxx:
If you want to select an alternate installation of libc++ you
can use the following options.
.. code-block:: bash
$ clang++ -std=c++11 -stdlib=libc++ -nostdinc++ \
-I<libcxx-install-prefix>/include/c++/v1 \
-L<libcxx-install-prefix>/lib \
-Wl,-rpath,<libcxx-install-prefix>/lib \
The option ``-Wl,-rpath,<libcxx-install-prefix>/lib`` adds a runtime library
search path. Meaning that the systems dynamic linker will look for libc++ in
``<libcxx-install-prefix>/lib`` whenever the program is run. Alternatively the
environment variable ``LD_LIBRARY_PATH`` (``DYLD_LIBRARY_PATH`` on OS X) can
be used to change the dynamic linkers search paths after a program is compiled.
An example of using ``LD_LIBRARY_PATH``:
.. code-block:: bash
$ clang++ -stdlib=libc++ -nostdinc++ \
-L<libcxx-install-prefix>/lib \
test.cpp -o
$ ./a.out # Searches for libc++ in the systems library paths.
$ export LD_LIBRARY_PATH=<libcxx-install-prefix>/lib
$ ./a.out # Searches for libc++ along LD_LIBRARY_PATH
Using libc++ on Linux
On Linux libc++ typically links to a shared version of libc++abi. Unfortunately
you can't simply run clang with "-stdlib=libc++" as clang is not set up to
link for this configuration. To get around this you'll have to manually
link libc++abi yourself. For example:
.. code-block:: bash
$ clang++ -stdlib=libc++ test.cpp -lc++ -lc++abi -lm -lc -lgcc_s -lgcc
Alternately, you could just add libc++abi to your libraries list, which in
most situations will give the same result:
.. code-block:: bash
$ clang++ -stdlib=libc++ test.cpp -lc++abi
Using libc++ with GCC
GCC does not provide a way to switch from libstdc++ to libc++. You must manually
configure the compile and link commands.
In particular you must tell GCC to remove the libstdc++ include directories
using ``-nostdinc++`` and to not link using ``-nodefaultlibs``.
Note that ``-nodefaultlibs`` removes all of the standard system libraries and
not just libstdc++ so they must be manually linked. For example:
.. code-block:: bash
$ g++ -nostdinc++ -I<libcxx-install-prefix>/include/c++/v1 \
test.cpp -nodefaultlibs -lc++ -lc++abi -lm -lc -lgcc_s -lgcc