The vxworks kernel-mode linking is partial linking, so it cannot
detect missing symbols.
for gcc/testsuite/ChangeLog
* g++.dg/other/anon5.C: Skip on vxworks kernel.
// PR c++/34094
// { dg-do link { target { ! { *-*-darwin* *-*-hpux* *-*-solaris2.* } } } }
// { dg-require-effective-target nonpic }
+// Skip on vxworks kernel: The link being partial, the linker doesn't see
+// the undefined reference
+// { dg-skip-if "partial link" { vxworks_kernel } }
// { dg-options "-gdwarf-2" }
// Ignore additional message on powerpc-ibm-aix
// { dg-prune-output "obtain more information" } */