With the current garbage collector implementation, most issues should show up as GCC compilation errors. Some of the most commonly encountered issues are described below.
GTY-marked type.
Gengtype checks if there is at least one possible path from GC roots to
at least one instance of each type before outputting allocators. If
there is no such path, the GTY markers will be ignored and no
allocators will be output. Solve this by making sure that there exists
at least one such path. If creating it is unfeasible or raises a “code
smell”, consider if you really must use GC for allocating such type.
gt_ggc_r_foo_bar and
similarly-named symbols. Check if your foo_bar source file has
#include "gt-foo_bar.h" as its very last line.