Description:
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One of the options to simplexml_load_string is LIBXML_NOENT. This option cannot be turned off.

Reproduce code:
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The prototype for the simplexml_load_string function is:

object simplexml_load_string ( string $data [, string $class_name="SimpleXMLElement" [, int $options=0 [, string $ns [, bool $is_prefix=false ]]]] )

Note the "$options=0". However, it actually behaves like "$options=LIBXML_NOENT". There is no way to disable this behavior. Explicitly specifying 0 does not turn off LIBXML_NOENT.

Code to reproduce:
echo simplexml_load_string("<data>&amp;</data>", "SimpleXMLElement", 0);

Expected result:
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This should return "&amp;", because I have explicity turned off the LIBXML_NOENT option. However, "&amp;" is converted to "&" by libxml regardless of the specified options.

It's as if the underlying C code is calling:

libxml->load_string(data, classname, options | LIBXML_NOENT);

(Note: not the real function names...)

Actual result:
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Resolution:

There would seem to be two resolutions. Either:
a) Change the prototype so that the default value of $options is LIBXML_NOENT, allowing this to be overridden by specifying the options.

OR

b) Create a special LIBXML flag especially for PHP, such as LIBXML_KEEPENT that negates the LIBXML_NOENT flag.


Note: This is not an important bug for me, because I will just ditch using SimpleXML and find another way, but I think it should still be on the books as a bug.