Here are a couple of 'xml' and a 'dtd' files

--- begin "a.xml" ---
<?xml version="1.0"?>
<!DOCTYPE root SYSTEM "a.dtd">
<root ns:attr="1"/>
--- end "a.xml" ---

--- begin "b.xml" ---
<?xml version="1.0"?>
<root ns:attr="1"/>
--- end "b.xml" ---

--- begin "a.dtd" ---
<!ELEMENT root EMPTY>
<!ATTLIST root
          xmlns:ns CDATA #FIXED "http://foo-dtd.org"
          ns:attr CDATA #IMPLIED>
--- end "a.dtd" ---

When i use 'xmllint' to verify the validity of "a.xml" against "a.dtd" implicitly ("--valid") or explicitly ("--dtdvalid a.dtd"), all goes well: "a.xml" result valid.

But when i verify the validity of "b.xml" explicitly against "a.dtd" ("--dtdvalid a.dtd"), i obtain the following error:

--- begin output ---
<root ns:attr="1"/>
                 ^
b.xml:2: element root: validity error : No declaration for attribute attr of element root
Document b.xml does not validate against a.dtd
--- end output ---

I suppose that this bug (i suppose this is a bug) is caused by the fact that the attributes default values are write down in the parser context ("xmlHashTablePtr    attsDefault"); i suppose they must be write down in the internal or in the external subset.
When xmlParseDTD() (xmlSAXParseDTD()) return the dtd pointer, the 'attsDefault' are missed.

When 'xmllint' validate "a.xml" explicitly ("--dtdvalid") against "a.dtd", it use the dtd explicitly loaded *and* the 'attsDefault' implicitly loaded; so "a.xml" result valid.
When 'xmllint' validate "b.xml" explicitly against "a.dtd", the 'attsDefault' are missed; so "b.xml" result invalid.

If i'm not wrong, obvioulsy

massimo morara