The website page /manual/en/install.windows.php and locale "it" version
(perhaps others?) are missing key information compared to other locale
versions of this page. Versions for "he", "de" and "fr" contain
additional information, such as
http://ca.php.net/manual/he/install.windows.php:
[Begin quote]
Preparations
Before you get started, you have a lot to download... 

For starters, get the Cygwin toolkit from the closest cygwin mirror
site. This will provide you most of the popular GNU utilities used by
the build process. 

Download the rest of the build tools you will need from the PHP site at
http://www.php.net/extra/win32build.zip. 
[End quote]

Compared to:
[Begin quote]
Requirements
To compile and build PHP you need a Microsoft Development Environment.
Microsoft Visuaul C++ 6.0 is recommended. To extract the downloaded
files you need a extraction utilitiy (e.g.: Winzip). If you don't
already have an unzip utility, you can get a free version from InfoZip.

Before you get started, you have to download... 

..the win32 buildtools from the PHP site at
http://www.php.net/extra/win32build.zip. 
[End quote]

The "en" and "it" version of this page makes passing mention of cygwin
as if it is incidental, whereas in fact it (or equivalent UNIX tools) is
a prerequisite to building under MS-Windows.

Ooops, my original posting got this around backwards due to a mistake
following the instructions to configure MS Visual Studio. The "en"
instructions are correct (bison and flex are supplied in
/extra/win32build.zip so cygwin is not needed) and the "he", "de" and
"fr" instructions are perhaps out of date in their requiring cygwin.

I'd rather kill the original description and start over to avoid
confusion, but I don't see how to do this. Does bugs.php.net allow the
author of a bug report to delete it?

this is documentation issue..

Locale version are sometimes outdated. Goba already added a note to the
website to warn about this.

When the translators have time they will check this.