Project: datamanagement
Issue DM-4946: afw Wcs object copying does not copy exactly
A probable bug in WCSLIB is causing {{wcscopy}} to create copies of {{Wcs}} objects which are not the same as the object that was copied. In some cases when this object is passed to {{wcsset}} it fails, as the {{Wcs}} object contains impossible values. This has behaviour is non-deterministic (failure is only seen occasionally). The error has only been observed on OSX, but we do not believe it to be operating system dependent (except insofar as different systems and compilers produce different memory layouts and hence different failure modes). This reliably causes {{ci_hsc}} to fail when running on a Mac. Relevant lines in {{afw}} are {{image/Wcs.cc:140}} and the {{Wcs}} copy constructor in {{image/Wcs.cc:468}} Additionally a bug has been found in {{image/Wcs.cc}} on line 485 where the flag property should be set on an element, and not on the object itself, ie {{_wcsInfo[i]->flag = -1;}}.
Story points: 6