Remove Cygwin from installation guide and README

README.md

@@ -36,7 +36,7 @@ Supported Platforms
 -------------------
 
 Sage attempts to support all major Linux distributions, recent versions of
-macOS, and Windows (using Windows Subsystem for Linux, Cygwin, or
+macOS, and Windows (using Windows Subsystem for Linux or
 virtualization).
 
 Detailed information on supported platforms for a specific version of Sage
@@ -67,57 +67,6 @@ your Windows.  Then all instructions for installation in Linux apply.
 As an alternative, you can also run Linux on Windows using Docker (see
 above) or other virtualization solutions.
 
-Finally, Sage also works on the 64-bit version of `Cygwin
-<https://cygwin.com/>`_. If you wish to use Cygwin, use the following
-instructions to get started.
-
-1.  Download [cygwin64](https://cygwin.com/install.html) (do not get
-    the 32-bit version; it is not supported by Sage).
-
-2.  Run the `setup-x86_64.exe` graphical installer.  Pick the default
-    options in most cases.  At the package selection screen, use the
-    search bar to find and select at least the following packages:
-    `bzip2`, `coreutils`, `curl`, `gawk`, `gzip`, `tar`, `wget`, `git`.
-
-3.  Start the Cygwin terminal and ensure you get a working bash prompt.
-
-4.  Make sure the path of your Cygwin home directory does not contain
-    space characters.
-
-    By default, your username in Cygwin is the same as your username in
-    Windows.  This might contain spaces and other traditionally
-    non-UNIX-friendly characters, e.g., if it is your full name.  You
-    can check this as follows:
-
-        $ whoami
-        Erik M. Bray
-
-    This means your default home directory on Cygwin contains this
-    username verbatim; in the above example, `/home/Erik M. Bray`.
-    It will save some potential trouble if you change your Cygwin home
-    directory to contain only alphanumeric characters, for example,
-    `/home/embray`.  The easiest way to do this is to first create
-    the home directory you want to use instead, then create an
-    `/etc/passwd` file specifying that directory as your home, as follows:
-
-        $ whocanibe=embray
-        $ mkdir /home/$whocanibe
-        $ mkpasswd.exe -l -u "$(whoami)" | sed -r 's,/home/[^:]+,/home/'$whocanibe, > /etc/passwd
-
-    After this, close all Cygwin terminals (ensure nothing in
-    `C:\cygwin64` is running), then start a new Cygwin terminal and
-    your home directory should have moved.
-
-    There are [other ways to do
-    this](https://stackoverflow.com/questions/1494658/how-can-i-change-my-cygwin-home-folder-after-installation),
-    but the above seems to be the simplest that's still supported.
-
-5.  Install the package manager `apt-cyg`:
-
-        $ curl -OL https://rawgit.com/transcode-open/apt-cyg/master/apt-cyg
-        $ install apt-cyg /usr/local/bin
-        $ rm -f apt-cyg
-
 [macOS] Preparing the Platform
 ------------------------------
 
@@ -162,7 +111,7 @@ Like many other software packages, Sage is built from source using
 `./configure`, followed by `make`.  However, we strongly recommend to
 read the following step-by-step instructions for building Sage.
 
-The instructions cover all of Linux, macOS, and Cygwin.
+The instructions cover all of Linux, macOS, and WSL.
 
 More details, providing a background for these instructions, can be found
 in the [section "Install from Source Code"](https://doc.sagemath.org/html/en/installation/source.html).
@@ -193,9 +142,6 @@ in the Installation Guide.
       capitalization when changing into :envvar:`SAGE_ROOT` can lead to build
       errors for dependencies requiring exact capitalization in path names.
 
-    - [Cygwin] Avoid building in home directories of Windows domain
-      users or in paths with capital letters.
-
 2.  Download/unpack or clone the sources.
 
     - Go to https://www.sagemath.org/download-source.html, select a mirror,
@@ -236,12 +182,12 @@ in the Installation Guide.
       line endings are used.
 
       Therefore it is crucial that you unpack the source tree from the
-      Cygwin (or WSL) `bash` using the Cygwin (or WSL) `tar` utility
-      and not using other Windows tools (including mingw). Likewise,
-      when using `git`, it is recommended (but not necessary) to use
-      the Cygwin (or WSL) version of `git`.
+      WSL `bash` using the WSL `tar` utility and not using other
+      Windows tools (including mingw). Likewise, when using `git`, it
+      is recommended (but not necessary) to use the WSL version of
+      `git`.
 
-3.  [Linux, Cygwin] Install the required minimal build prerequisites.
+3.  [Linux, WSL] Install the required minimal build prerequisites.
 
     - Compilers: `gcc`, `gfortran`, `g++` (GCC 6.3 to 12.x and recent
       versions of Clang (LLVM) are supported).
@@ -259,7 +205,6 @@ in the Installation Guide.
     [build/pkgs/_prereq/distros](build/pkgs/_prereq/distros),
     the files
     [arch.txt](build/pkgs/_prereq/distros/arch.txt),
-    [cygwin.txt](build/pkgs/_prereq/distros/cygwin.txt),
     [debian.txt](build/pkgs/_prereq/distros/debian.txt)
     (also for Ubuntu, Linux Mint, etc.),
     [fedora.txt](build/pkgs/_prereq/distros/fedora.txt)

src/doc/en/installation/binary.rst

@@ -25,12 +25,9 @@ This has been discontinued, and the old binaries that are still available
 there are no longer supported.
 
 
-Microsoft Windows (Cygwin)
---------------------------
+Microsoft Windows
+-----------------
 
-SageMath on Windows requires a 64-bit Windows (which is likely to be the case
-on a modern computer). If you happen to have a 32-bit Windows, you can consider
-the alternatives mentioned at the end of :ref:`installation-guide`.
-
-To install SageMath on Windows, just download the installer (see the above
-"Download Guide" section) and run it.
+SageMath used to provide pre-built binaries for Windows based on Cygwin.
+This has been discontinued, and the old binaries that can be found
+are no longer supported. Use Windows Subsystem for Linux instead.

src/doc/en/installation/index.rst

@@ -80,10 +80,6 @@ Windows
       can use any of the installation methods described below for
       Linux.
 
-    - Alternatively, in particular if you cannot use WSL, install
-      `Cygwin <https://cygwin.com/>`_ and then build SageMath from source
-      as described in section :ref:`sec-installation-from-sources`.
-
 Linux
 =====
 

src/doc/en/installation/source.rst

@@ -167,8 +167,6 @@ On Redhat-derived systems not all perl components are installed by
 default and you might have to install the ``perl-ExtUtils-MakeMaker``
 package.
 
-On Cygwin, the ``lapack`` and ``liblapack-devel`` packages are required.
-
 Installing prerequisites
 ~~~~~~~~~~~~~~~~~~~~~~~~
 
@@ -306,43 +304,6 @@ Some additional optional packages are taken care of by:
 .. literalinclude:: homebrew-optional.txt
 
 
-.. _section_cygwinprereqs:
-
-Cygwin prerequisite installation
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-Sage can be built only on the 64-bit version of Cygwin.  See
-the file `README.md <https://github.com/sagemath/sage/#readme>`_
-in ``SAGE_ROOT`` for the most up-to-date instructions for building Sage
-on Cygwin.
-
-Although it is possible to install Sage's dependencies using the Cygwin
-graphical installer, it is recommended to install the `apt-cyg
-<https://github.com/transcode-open/apt-cyg>`_ command-line package
-installer, which is used for the remainder of these instructions.  To
-run ``apt-cyg``, you must have already installed (using the graphical
-installer) the following packages at a minimum::
-
-    bzip2 coreutils gawk gzip tar wget
-
-With the exception of ``wget`` most of these are included in the default
-package selection when you install Cygwin.  Then, to install ``apt-cyg``
-run::
-
-    $ curl -OL https://rawgit.com/transcode-open/apt-cyg/master/apt-cyg
-    $ install apt-cyg /usr/local/bin
-    $ rm -f apt-cyg
-
-To install the current set of system packages known to work for building
-Sage, run:
-
-.. literalinclude:: cygwin.txt
-
-Optional packages that are also known to be installable via system packages
-include:
-
-.. literalinclude:: cygwin-optional.txt
-
 Ubuntu on Windows Subsystem for Linux (WSL) prerequisite installation
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
@@ -734,46 +695,6 @@ General procedure
 
 #. Have fun! Discover some amazing conjectures!
 
-Rebasing issues on Cygwin
-~~~~~~~~~~~~~~~~~~~~~~~~~
-
-Building on Cygwin will occasionally require "rebasing" ``dll`` files.
-Sage provides some scripts, located in :file:`$SAGE_LOCAL/bin`, to do so:
-
-- ``sage-rebaseall.sh``, a shell script which calls Cygwin's ``rebaseall``
-  program.
-  It must be run within a ``dash`` shell from the :envvar:`SAGE_ROOT` directory
-  after all other Cygwin processes have been shut down and needs write-access
-  to the system-wide rebase database located at :file:`/etc/rebase.db.i386`,
-  which usually means administrator privileges.
-  It updates the system-wide database and adds Sage dlls to it, so that
-  subsequent calls to ``rebaseall`` will take them into account.
-- ``sage-rebase.sh``, a shell script which calls Cygwin's ``rebase`` program
-  together with the ``-O/--oblivious`` option.
-  It must be run within a shell from :envvar:`SAGE_ROOT` directory.
-  Contrary to the ``sage-rebaseall.sh`` script, it neither updates the
-  system-wide database, nor adds Sage dlls to it.
-  Therefore, subsequent calls to ``rebaseall`` will not take them into account.
-- ``sage-rebaseall.bat`` (respectively ``sage-rebase.bat``), an MS-DOS batch
-  file which calls the ``sage-rebaseall.sh`` (respectively ``sage-rebase.sh``)
-  script.
-  It must be run from a Windows command prompt, after adjusting
-  :envvar:`SAGE_ROOT` to the Windows location of Sage's home directory, and, if
-  Cygwin is installed in a non-standard location, adjusting
-  :envvar:`CYGWIN_ROOT` as well.
-
-Some systems may encounter this problem frequently enough to make building or
-testing difficult.
-If executing the above scripts or directly calling ``rebaseall`` does not solve
-rebasing issues, deleting the system-wide database and then regenerating it
-from scratch, e.g., by executing ``sage-rebaseall.sh``, might help.
-
-Finally, on Cygwin, one should also avoid the following:
-
-- building in home directories of Windows domain users;
-- building in paths with capital letters
-  (see :trac:`13343`, although there has been some success doing so).
-
 
 .. _section_make: