# Prerequisites for GCC

GCC requires that various tools and packages be available for use in the build procedure. Modifying GCC sources requires additional tools described below.

### Tools/packages necessary for building GCC

ISO C90 compiler
  Necessary to bootstrap GCC, although versions of GCC prior to 3.4 also allow bootstrapping with a traditional (K&R) C compiler.

  To build all languages in a cross-compiler or other configuration where 3-stage bootstrap is not performed, you need to start with an existing GCC binary (version 2.95 or later) because source code for language frontends other than C might use GCC extensions.

GNAT
  In order to build the Ada compiler (GNAT) you must already have GNAT installed because portions of the Ada frontend are written in Ada (with GNAT extensions.) Refer to the Ada installation instructions for more specific information.
A “working” POSIX compatible shell, or GNU bash
  Necessary when running `configure` because some `/bin/sh` shells have bugs and may crash when configuring the target libraries. In other cases, `/bin/sh` or `ksh` have disastrous corner-case performance problems. This can cause target `configure` runs to literally take days to complete in some cases.

  So on some platforms `/bin/ksh` is sufficient, on others it isn't. See the host/target specific instructions for your platform, or use `bash` to be sure. Then set `CONFIG_SHELL` in your environment to your “good” shell prior to running `configure`/`make`.

  `zsh` is not a fully compliant POSIX shell and will not work when configuring GCC.

GNU binutils
  Necessary in some circumstances, optional in others. See the host/target specific instructions for your platform for the exact requirements.
gzip version 1.2.4 (or later) or
bzip2 version 1.0.2 (or later)
  Necessary to uncompress GCC `tar` files when source code is obtained via FTP mirror sites.
GNU make version 3.79.1 (or later)
  You must have GNU make installed to build GCC.
GNU tar version 1.14 (or later)
  Necessary (only on some platforms) to untar the source code. Many systems' `tar` programs will also work, only try GNU `tar` if you have problems.
GNU Multiple Precision Library (GMP) version 4.1 (or later)
  Necessary to build the Fortran frontend. If you do not have it installed in your library search path, you will have to configure with the `--with-gmp` configure option. See also `--with-gmp-lib` and `--with-gmp-include`.
MPFR Library version 2.2.1 (or later)
  Necessary to build the Fortran frontend. It can be downloaded from http://www.mpfr.org/. The version of MPFR that is bundled with GMP 4.1.x contains numerous bugs. Although GNU Fortran will appear to function with the buggy versions of MPFR, there are a few GNU Fortran bugs that will not be fixed when using this version. It is strongly recommended to upgrade to the recommended version of MPFR.

  The `--with-mpfr` configure option should be used if your MPFR Library is not installed in your default library search path. See also `--with-mpfr-lib` and `--with-mpfr-include`.

`jar`, or InfoZIP (`zip` and `unzip`)
  Necessary to build libgcj, the GCJ runtime.

### Tools/packages necessary for modifying GCC

autoconf versions 2.13 and 2.59
GNU m4 version 1.4 (or later)
  Necessary when modifying `configure.ac`, `aclocal.m4`, etc. to regenerate `configure` and `config.in` files. Most directories require autoconf 2.59 (exactly), but the toplevel still requires autoconf 2.13 (exactly).
automake version 1.9.6
  Necessary when modifying a `Makefile.am` file to regenerate its associated `Makefile.in`.

  Much of GCC does not use automake, so directly edit the `Makefile.in` file. Specifically this applies to the `gcc`, `intl`, `libcpp`, `libiberty`, `libobjc` directories as well as any of their subdirectories.

  For directories that use automake, GCC requires the latest release in the 1.9.x series, which is currently 1.9.6. When regenerating a directory to a newer version, please update all the directories using an older 1.9.x to the latest released version.

gettext version 0.14.5 (or later)
  Needed to regenerate `gcc.pot`.
gperf version 2.7.2 (or later)
  Necessary when modifying `gperf` input files, e.g. `gcc/cp/cfns.gperf` to regenerate its associated header file, e.g. `gcc/cp/cfns.h`.
DejaGnu 1.4.4
Expect
Tcl
  Necessary to run the GCC testsuite; see the section on testing for details.
autogen version 5.5.4 (or later) and
guile version 1.4.1 (or later)
  Necessary to regenerate `fixinc/fixincl.x` from `fixinc/inclhack.def` and `fixinc/*.tpl`.

  Necessary to run ``make check`' for `fixinc`.

  Necessary to regenerate the top level `Makefile.in` file from `Makefile.tpl` and `Makefile.def`.

GNU Bison version 1.28 (or later)
  Berkeley `yacc` (`byacc`) is also reported to work other than for GCJ.

  Necessary when modifying `*.y` files.

  Necessary to build GCC during development because the generated output files are not included in the SVN repository. They are included in releases.

Flex version 2.5.4 (or later)
  Necessary when modifying `*.l` files.

  Necessary to build GCC during development because the generated output files are not included in the SVN repository. They are included in releases.

Texinfo version 4.4 (or later)
  Necessary for running `makeinfo` when modifying `*.texi` files to test your changes.

  Necessary for running `make dvi` or `make pdf` to create printable documentation in DVI or PDF format. Texinfo version 4.8 or later is required for `make pdf`.

  Necessary to build GCC documentation during development because the generated output files are not included in the SVN repository. They are included in releases.

TeX (any working version)
  Necessary for running `texi2dvi` and `texi2pdf`, which are used when running `make dvi` or `make pdf` to create DVI or PDF files, respectively.
SVN (any version)
SSH (any version)
  Necessary to access the SVN repository. Public releases and weekly snapshots of the development sources are also available via FTP.
Perl version 5.6.1 (or later)
  Necessary when regenerating `Makefile` dependencies in libiberty. Necessary when regenerating `libiberty/functions.texi`. Necessary when generating manpages from Texinfo manuals. Necessary when targetting Darwin, building libstdc++, and not using `--disable-symvers`. Used by various scripts to generate some files included in SVN (mainly Unicode-related and rarely changing) from source tables.
GNU diffutils version 2.7 (or later)
  Useful when submitting patches for the GCC source code.
patch version 2.5.4 (or later)
  Necessary when applying patches, created with `diff`, to one's own sources.

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