Installing From Sources
=======================

To install and use Coq, we recommend relying on [the Coq
platform](https://github.com/coq/platform/) or on a package manager
(e.g. opam or Nix).

See https://coq.inria.fr/download and
https://github.com/coq/coq/wiki#coq-installation to learn more.

If you need to build Coq from sources manually (e.g. to
contribute to Coq or to write a Coq package), the remainder of this
file explains how to do so.

Build Requirements
------------------

To compile Coq yourself, you need:

- [OCaml](https://ocaml.org/) (version >= 4.09.0)
  (This version of Coq has been tested up to OCaml 4.14.0)

- The [Dune OCaml build system](https://github.com/ocaml/dune/) >= 2.9.1

- The [ZArith library](https://github.com/ocaml/Zarith) >= 1.11

- The [findlib](http://projects.camlcity.org/projects/findlib.html) library (version >= 1.8.1)

- a C compiler

- an IEEE-754 compliant architecture with rounding to nearest
  ties to even as default rounding mode (most architectures
  should work nowadays)

- for CoqIDE, the
  [lablgtk3-sourceview3](https://github.com/garrigue/lablgtk) library
  (version >= 3.1.2), and the corresponding GTK 3.x libraries, as
  of today (gtk+3 >= 3.18 and gtksourceview3 >= 3.18)

- [optional] GNU Make (version >= 3.81)

See [below](#Known-Problems) for a discussion of platform-specific
issues with dependencies.

Primitive floating-point numbers require IEEE-754 compliance
(`Require Import Floats`). Common sources of incompatibility
are checked at configure time, preventing compilation. In the
unlikely event an incompatibility remains undetected, using `Floats`
would enable proving `False` on this architecture.

Note that OCaml dependencies (`zarith` and `lablgtk3-sourceview3` at
this moment) must be properly registered with `findlib/ocamlfind`
since Coq's build system uses `findlib` to locate them.

Debian / Ubuntu users can get the necessary system packages for
CoqIDE with:

    $ sudo apt-get install libgtksourceview-3.0-dev

Opam (https://opam.ocaml.org/) is recommended to install OCaml and
the corresponding packages.

    $ opam switch create coq --packages="ocaml-variants.4.12.0+options,ocaml-option-flambda"
    $ eval $(opam env)
    $ opam install dune ocamlfind zarith lablgtk3-sourceview3

should get you a reasonable OCaml environment to compile Coq. See the
OPAM documentation for more help.

Nix users can also get all the required dependencies by running:

    $ nix-shell

Run-time dependencies of native compilation
-------------------------------------------

The OCaml compiler and findlib are build-time dependencies, but also
run-time dependencies if you wish to use the native compiler.

Build and install procedure
---------------------------

Note that Coq supports a faster, but less optimized developer build,
but final users must always use the release build. See
[dev/doc/build-system.dune.md](dev/doc/build-system.dune.md)
for more details.

To build and install Coq (and CoqIDE if desired) do:

    $ ./configure -prefix <install_prefix> $options
    $ make dunestrap
    $ dune build -p coq-core,coq-stdlib,coq,coqide-server,coqide
    $ dune install --prefix=<install_prefix> coq-core coq-stdlib coq coqide-server coqide

You can drop the `coqide` packages if not needed.

Packagers may want to play with `dune install` options as to tweak
installation path, the `-prefix` argument in `./configure` tells Coq
where to find its standard library, but doesn't control any other
installation path these days.

OCaml toolchain advisory
------------------------

When loading plugins or `vo` files, you should make sure that these
were compiled with the same OCaml setup (version, flags,
dependencies...) as Coq.  Distribution of pre-compiled plugins and
`.vo` files is only possible if users are guaranteed to have the same
Coq version compiled with the same OCaml toolchain.  An OCaml setup
mismatch is the most probable cause for an `Error while loading ...:
implementation mismatch on ...`.

coq_environment.txt
-------------------
Coq binaries which honor environment variables, such as `COQLIB`, can
be seeded values for these variables by placing a text file named
`coq_environment.txt` next to them. The file can contain assignments
like `COQLIB="some path"`, that is a variable name followed by `=` and
a string that follows OCaml's escaping conventions. This feature can be
used by installers of binary package to make Coq aware of its installation
path.

Known problems
--------------

- On OSX, when using Opam with sandboxing and Dune < 3.0 with caching
  enabled, Coq may fail to install, due to Opam's sandboxing
  restricting the permissions needed for the Dune 2.x caching
  daemon. See https://github.com/coq/coq/issues/15138 more details.
