Keywords: ISO C++, library

Chapter 2. Setup
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## Chapter 2. Setup

Transforming libstdc++ sources into installed include files and properly built binaries useful for linking to other software is done as part of building GCC. Building libstdc++ separately from the rest of GCC is not supported.

The general outline of commands to build GCC is something like:

       get gcc sources
       extract into gccsrcdir
       mkdir gccbuilddir
       cd gccbuilddir
       gccsrcdir/configure --prefix=destdir --other-opts...
       make
       make check
       make install

Each step is described in more detail in the following sections.

## Prerequisites

Because libstdc++ is part of GCC, the primary source for installation instructions is the GCC install page. In particular, list of prerequisite software needed to build the library starts with those requirements. The same pages also list the tools you will need if you wish to modify the source.

Additional data is given here only where it applies to libstdc++.

To take full advantage of useful space-saving features and bug-fixes you should use a recent binutils whenever possible. The configure process will automatically detect and use these features if the underlying support is present.

To generate the API documentation from the sources you will need Doxygen, see Documentation Hacking in the appendix for full details.

Finally, a few system-specific requirements:

linux

  The 'gnu' locale model makes use of `iconv` for character set conversions. The relevant functions are provided by Glibc and so are always available, however they can also be provided by the separate GNU libiconv library. If GNU libiconv is found when GCC is built (e.g., because its headers are installed in `/usr/local/include`) then the `libstdc++.so.6` library will have a run-time dependency on `libiconv.so.2`. If you do not want that run-time dependency then you should do one of the following:

  - Uninstall the libiconv headers before building GCC. Glibc already provides `iconv` so you should not need libiconv anyway.

  - Download the libiconv sources and extract them into the top level of the GCC source tree, e.g.,

        wget https://ftp.gnu.org/pub/gnu/libiconv/libiconv-1.16.tar.gz
        tar xf libiconv-1.16.tar.gz
        ln -s libiconv-1.16 libiconv

    This will build libiconv as part of building GCC and link to it statically, so there is no `libiconv.so.2` dependency.

  - Configure GCC with `--with-libiconv-type=static`. This requires the static `libiconv.a` library, which is not installed by default. You might need to reinstall libiconv using the `--enable-static` configure option to get the static library.

  If GCC 3.1.0 or later on is being used on GNU/Linux, an attempt will be made to use "C" library functionality necessary for C++ named locale support, e.g. the `newlocale` and `uselocale` functions. For GCC 4.6.0 and later, this means that glibc 2.3 or later is required.

  If the 'gnu' locale model is being used, the following locales are used and tested in the libstdc++ testsuites. The first column is the name of the locale, the second is the character set it is expected to use.

      de_DE               ISO-8859-1
      de_DE@euro          ISO-8859-15
      en_GB               ISO-8859-1
      en_HK               ISO-8859-1
      en_PH               ISO-8859-1
      en_US               ISO-8859-1
      en_US.ISO-8859-1    ISO-8859-1
      en_US.ISO-8859-15   ISO-8859-15
      en_US.UTF-8         UTF-8
      es_ES               ISO-8859-1
      es_MX               ISO-8859-1
      fr_FR               ISO-8859-1
      fr_FR@euro          ISO-8859-15
      is_IS               UTF-8
      it_IT               ISO-8859-1
      ja_JP.eucjp         EUC-JP
      ru_RU.ISO-8859-5    ISO-8859-5
      ru_RU.UTF-8         UTF-8
      se_NO.UTF-8         UTF-8
      ta_IN               UTF-8
      zh_TW               BIG5

  Failure to have installed the underlying "C" library locale information for any of the above regions means that the corresponding C++ named locale will not work: because of this, the libstdc++ testsuite will skip named locale tests which need missing information. If this isn't an issue, don't worry about it. If a named locale is needed, the underlying locale information must be installed. Note that rebuilding libstdc++ after "C" locales are installed is not necessary.

  To install support for locales, do only one of the following:

  - install all locales, e.g., run `dnf install glibc-all-langpacks` for Fedora and related distributions.

  - install just the necessary locales

    - with Debian GNU/Linux:

      Add the above list, as shown, to the file `/etc/locale.gen`

      run `/usr/sbin/locale-gen`

    - on most Unix-like operating systems:

      `localedef -i de_DE -f ISO-8859-1 de_DE`

      (repeat for each entry in the above list)

    - Instructions for other operating systems solicited.

  Some tests for the `std::messages` facet require a message catalog created by the msgfmt utility. That is usually installed as part of the GNU gettext library. If msgfmt is not available, some tests under the `22_locale/messages` directory will fail.

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