Eric N. Vander Weele added the comment: I came across this issue while researching where to post my patch (having come across this while building Python 2.7 & 3.x on AIX via xlc).
> In general in C, if a bit-field has type “int” without a signed or unsigned > qualifier, it is up to the implementation which mode is chosen. Unfortunately, the ISO C standard leaves it up to the compiler to decide whether to default to 'signed' or 'unsigned' for non-qualified bit-field declarations. gcc defaults to signed (https://gcc.gnu.org/onlinedocs/gcc-3.3.6/gcc/Non_002dbugs.html); however, xlc defaults to unsigned (https://www.ibm.com/support/knowledgecenter/SSGH2K_13.1.3/com.ibm.xlc1313.aix.doc/compiler_ref/opt_bitfields.html). > [...] having bitfields working regardless of the compiler should be preferred. However, ctypes_test assumes an unqualified bit-field will be signed. To achieve bit-fields working regardless of the compiler, declarations must explicitly qualifying the sign for bit-fields. This makes the intent of what is expected explicit and avoids implementation-defined behavior that will differ from one compiler to the next. With patch ctypes_test_sign_bitfields.diff provided, I have verified ctypes_test passes on Python 2.7, Python 3.4, and Python 3.5 (on AIX & Solaris). If need be, I'm happy to provide before-&-after output of ctypes_test with & without the patch applied (or verification from others would be greatly appreciated). ---------- Added file: http://bugs.python.org/file44189/ctypes_test_sign_bitfields.diff _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue27643> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
