Distribution/Version: 4.3

On AIX V4.3 using cc_r (AIX Compilers V3.1, level 4.4.0.0 - though I don't think
the version's important), configure and compile libxml2 and run the regressions
tests.

I used the configure options "--enable-shared=no --without-ftp --without-http
--without-python --without-modules" but I think the only important one is
"--with-schemas", which is on by default.

The problem is demonstrated in the Schemas regression tests (by date_0.xsd). The
individual test can be run with:
./testSchemas ./test/schemas/date_0.xsd ./test/schemas/date_0.xml
I've attached the error messages.

The cause of the problem is the use of an 'int' data type for the tzo member (a
bitfield) of the _xmlSchemaValDate struct in xmlschemastypes.c.

The C standard does not specify whether 'int' data types for bitfields are
signed or unsigned - the implementation is free to choose (section 6.7.2.1 of
the C standard, according to gcc's documentation). IBM's C compiler makes them
unsigned and (it seems that) just about everything else makes them signed.

Since tzo is unsigned on AIX the VALID_TZO macro nearly always evaluates to false.

The tzo member must be signed (since a time zone can be both positive and
negative) so it needs to be marked as signed. The comment in the code indicates
that the range of tzo is -1440 to +1440, for which 12 bits is required (not the
current 11). I've attached a patch to make both these changes.

Note that the same problem occurs in libxslt, in the _exsltDateValDate struct in
libexslt/date.c.

Also, is there any real reason to use bitfields in these structs? It doesn't
save any data space (because of alignment) but adds to the size of the generated
code. Wouldn't it be better to use unsigned chars and a short?