Invalid XML is produced by write_xml when there is a special character in the key

[martongabesz@…]

I have the following property tree, dumped in INFO format:

CudbAppServiceId=1
{
    userLabel ""
    sqlAppSrvPlSchema identities-pl.sql
    CudbAppServiceId CudbAppServiceId=1
}

When I dump it in XML format, I got the following:

<?xml version="1.0" encoding="utf-8"?>
<CudbAppServiceId=1>
<userLabel/>
<sqlAppSrvPlSchema>identities-pl.sql</sqlAppSrvPlSchema>
<CudbAppServiceId>CudbAppServiceId=1</CudbAppServiceId>
</CudbAppServiceId=1>

This is not a valid XML, because we have a tag "CudbAppServiceId=1". Of course, any other xml parser like xmllint will fail to parse it, because of the equality sign in the tag.

Is there any solution to this problem? Like somehow emitting = instead of the raw '=' inside the tag and in the text?

This is a possible problem in 1.53 as well, since property tree was not updated.

[Sebastian Redl]

There is no solution that will turn your data into valid XML. Element names must follow the Name production, which cannot contain entity references.

The best I can do is fail validation when writing the XML, so that you don't end up with invalid documents.

[Gray Wolf <wolf+"https://svn.boost.org"@…>]

I've hit another edge case today when converting bunch of .info to .xml. In my case the issue was empty key (since this is valid in info format):

"" value

but produces

<>value</>

in xml.

I think failing the generation with an exception would be best (and only) solution. Sure, I can (and do now) re-read the xml after pt::write_xml() and validate it but feels like unnecessary, since I can't imagine when the invalid xml would be actually useful (since not even property_tree can read it back, correct?).