Hi,

on Fedora Rawhide (==22) i686 using --with-python=/usr/bin/python3 one gets:

gcc -g   -I. -I. -I./common -I./config -DLOCALEDIR="\"/usr/local/share/locale\"" -DHAVE_CONFIG_H -I./../include/opcode -I./../opcodes/.. -I./../readline/.. -I../bfd -I./../bfd -I./../include -I../libdecnumber -I./../libdecnumber  -I./gnulib/import -Ibuild-gnulib/import   -DTUI=1   -pthread -I/usr/include/guile/2.0  -I/usr/include/python3.4m -I/usr/include/python3.4m -Wall -Wdeclaration-after-statement -Wpointer-arith -Wpointer-sign -Wno-unused -Wunused-value -Wunused-function -Wno-switch -Wno-char-subscripts -Wmissing-prototypes -Wdeclaration-after-statement -Wempty-body -Wmissing-parameter-type -Wold-style-declaration -Wold-style-definition -Wformat-nonliteral -Werror -c -o py-value.o -MT py-value.o -MMD -MP -MF .deps/py-value.Tpo -fno-strict-aliasing -DNDEBUG -fwrapv ./python/py-value.c
./python/py-value.c:1696:3: error: initialization from incompatible pointer type [-Werror]
   valpy_hash,            /*tp_hash*/
   ^
./python/py-value.c:1696:3: error: (near initialization for ‘value_object_type.tp_hash’) [-Werror]
cc1: all warnings being treated as errors
Makefile:2628: recipe for target 'py-value.o' failed

This is because in Python 2 tp_hash was:
	typedef long (*hashfunc)(PyObject *);
while in Python 3 tp_hash is:
	typedef Py_hash_t (*hashfunc)(PyObject *);

Py_hash_t is int for 32-bit hosts and long for 64-bit hosts.  While on 32-bit
hosts sizeof(long)==sizeof(int) still the hashfunc type is formally
incompatible.  As this patch should have no compiled code change it is not
really necessary for gdb-7.9, it would fix there just this non-fatal
compilation warning:
	./python/py-value.c:1696:3: warning: initialization from incompatible pointer type
	   valpy_hash,            /*tp_hash*/
	   ^
	./python/py-value.c:1696:3: warning: (near initialization for ‘value_object_type.tp_hash’)

A question is whether the autoconf test isn't an overkill.  One could use
instead just:
	#if PYTHON_ABI_VERSION >= 3
Also one could use that #if either just at the valpy_hash() definition or one
could provide Py_hash_t in gdb/defs.h or one could provide some GDB_Py_hash_t
in gdb/defs.h.

Tested compilation with:
	python-devel-2.7.9-4.fc22.x86_64
	python-devel-2.7.9-4.fc22.i686
	python3-devel-3.4.2-4.fc22.x86_64
	python3-devel-3.4.2-4.fc22.i686


Jan