Bug 39545 is an x86_64 ABI issue relating to the handling of structures with flexible array members in function call and return. It seems likely this corner case has bugs (and incompatibilities with other implementations) for other targets as well. There should be gcc.dg/compat tests specifically testing the ABI when structures with flexible array members, and unions containing such structures, are passed to or returned from functions (including passing through ... and va_arg), covering various cases for the types of the initial elements and the flexible array members.
If we believe that [0] arrays (the old GNU extension) at the ends of structures should be passed identically to [] arrays (C99 flexible array members), which is probably a good idea, then there should be tests of this as well. -- Summary: compat tests for flexible array members Product: gcc Version: 4.4.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: testsuite AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: jsm28 at gcc dot gnu dot org http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39550