diff -r c68a1df5c79a -r 4371f543efda contrib/packaging/wix/readme.rst
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+++ b/contrib/packaging/wix/readme.rst	Fri Mar 08 10:48:22 2019 -0800
@@ -0,0 +1,71 @@
+WiX Installer
+=============
+
+The files in this directory are used to produce an MSI installer using
+the WiX Toolset (http://wixtoolset.org/).
+
+The MSI installers require elevated (admin) privileges due to the
+installation of MSVC CRT libraries into the Windows system store. See
+the Inno Setup installers in the ``inno`` sibling directory for installers
+that do not have this requirement.
+
+Requirements
+============
+
+Building the WiX installers requires a Windows machine. The following
+dependencies must be installed:
+
+* Python 2.7 (download from https://www.python.org/downloads/)
+* Microsoft Visual C++ Compiler for Python 2.7
+  (https://www.microsoft.com/en-us/download/details.aspx?id=44266)
+* Python 3.5+ (to run the ``build.py`` script)
+
+Building
+========
+
+The ``build.py`` script automates the process of producing an MSI
+installer. It manages fetching and configuring non-system dependencies
+(such as py2exe, gettext, and various Python packages).
+
+The script requires an activated ``Visual C++ 2008`` command prompt.
+A shortcut to such a prompt was installed with ``Microsoft Visual
+C++ Compiler for Python 2.7``. From your Start Menu, look for
+``Microsoft Visual C++ Compiler Package for Python 2.7`` then
+launch either ``Visual C++ 2008 32-bit Command Prompt`` or
+``Visual C++ 2008 64-bit Command Prompt``.
+
+From the prompt, change to the Mercurial source directory. e.g.
+``cd c:\src\hg``.
+
+Next, invoke ``build.py`` to produce an MSI installer. You will need
+to supply the path to the Python interpreter to use.::
+
+   $ python3 contrib\packaging\wix\build.py \
+      --python c:\python27\python.exe
+
+.. note::
+
+   The script validates that the Visual C++ environment is active and
+   that the architecture of the specified Python interpreter matches the
+   Visual C++ environment. An error is raised otherwise.
+
+If everything runs as intended, dependencies will be fetched and
+configured into the ``build`` sub-directory, Mercurial will be built,
+and an installer placed in the ``dist`` sub-directory. The final line
+of output should print the name of the generated installer.
+
+Additional options may be configured. Run ``build.py --help`` to see
+a list of program flags.
+
+Relationship to TortoiseHG
+==========================
+
+TortoiseHG uses the WiX files in this directory.
+
+The code for building TortoiseHG installers lives at
+https://bitbucket.org/tortoisehg/thg-winbuild and is maintained by
+Steve Borho (steve@borho.org).
+
+When changing behavior of the WiX installer, be sure to notify
+the TortoiseHG Project of the changes so they have ample time
+provide feedback and react to those changes.