wlad, you suggested that it is OK to simplify code and use the forward slash on Microsoft Windows. So, as part of this simplification, we would remove os_normalize_path() and instead add some Windows-specific code that will treat some occurrences of the backslash in the same way as we would treat a forward slash.

This change will break compatibility on Microsoft Windows in two ways:

1. A crash-upgrade from 10.5 to 10.6 might not work. But we do not really recommend to do it anyway.
2. If someone specified a Microsoft Windows UNC (Universal Naming Convention) path for a DATA DIRECTORY or any of the InnoDB directory parameters, then things will likely fail.

Here is an example of what would start to fail (with double escaping, as needed in a .test file):

CREATE TABLE t(a INT) ENGINE=InnoDB

DATA DIRECTORY '\\\\\\\\?\\\\Volume{ae26d559-276d-11e6-80c1-000d3a3019c7}\\\\share\\\\';

Apparently, forward slashes are not allowed in path names that start with the characters that precede the string Volume. (Jira does not allow me to write the backslashes outside a code block.)

File names like E:/share/test/t.ibd or \\server\share/test/t.ibd will work just fine.

Looks fine