bpo-27643 - fix test_ctypes test_bitfields with XLC compiler.

[aixtools]

This PR skips the "signed short" bitfield test when the compiler is XLC
It also removes the failing code (signed short declaration) in test_bitfields.py and _ctypes_test.c)

https://bugs.python.org/issue27643

[trudeaun]

@aixtools I noticed this line in your code:
+#ifdef __GCC_HAVE_SYNC_COMPARE_AND_SWAP_1 /* Something to distinguish GCC and XLC */
Another way to distinguish GCC and XL would be to check if __xlc__ is defined. See Knowledge Center for more details.

[trudeaun]

@aixtools I believe the latest C standard does not state that signed short is a valid data type in a bitfield, so XLC does not support it. When compiling your code with XLC, you may have seen an error such as: 1506-159 (E) Bit field type specified for xyz is not valid. Type signed assumed., which converts your signed short into the closest valid type identified by the standard, signed.

[aixtools]

On 15-Jan-18 18:09, trudeaun wrote: @aixtools <https://github.com/aixtools> I noticed this line in your code: |+#ifdef __GCC_HAVE_SYNC_COMPARE_AND_SWAP_1 /* Something to distinguish GCC and XLC */| Another way to distinguish GCC and XL would be to check if |__xlc__| is defined.

Yes, I think that is a much better choice!

…

See Knowledge Center <https://www.ibm.com/support/knowledgecenter/SSGH3R_13.1.3/com.ibm.xlcpp1313.aix.doc/compiler_ref/xlmacros.html> for more details. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#5164 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AKWY9a78XJZbD7fF1xN3Qwci0rbKxzl7ks5tK4YsgaJpZM4RcBwq>.