can 'make', can 'make dist', but can't 'make distcheck'

[Joao Miguel Ferreira]

Hello all,

I have the following problem:

I configure my package like this:

./configure \
--prefix=$HOME/jmf/testes/localroot/usr/ \
CPPFLAGS="-DHPUX -DSUN -DLINUX -I/usr/include/libxml2/ \
-I/home/jmf/tibcu/tibrv/include/"

all goes well. make is successfull and builds my libs correctly !

make dist also creates the tar.gz

but make distcheck complains. this is my distcheck command:
-----------------------------------------
make distcheck \
CPPFLAGS="-DHPUX -DSUN -DLINUX -I/usr/include/libxml2/ \
 -I/home/jmf/tibcu/tibrv/include/"
---------------------------------------

this is how it complaints
---------------------------------------
../../../c/src/IFXDoc.c: In function 'IFXDoc_addNullU64Array':
../../../c/src/IFXDoc.c:10258: warning: this decimal constant is
unsigned only in ISO C90
../../../c/src/IFXDoc.c:10258: warning: integer constant is too large
for 'long' type

../../../c/src/IFXDoc.c: In function
'IFXINTERNAL_IFXDoc_xml_addArrayField2XML':
../../../c/src/IFXDoc.c:18747: warning: assignment makes pointer from
integer without a cast

make[3]: *** [IFXDoc.lo] Error 1
make[3]: Leaving directory 
`/home/jmf/ifxlib/libifxlib-7.8.9/_build/c/src'

make[2]: *** [all-recursive] Error 1
---------------------------------------

just guessing ? could make distcheck be using something like a very
demanding, 'no cast warnings allowed' or some '-Werror' compiler flag ?

Thanks
Joao