[Bug libbacktrace/87529] New: libbacktrace API forces users to have memory leaks

[antoshkka at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87529

            Bug ID: 87529
           Summary: libbacktrace API forces users to have memory leaks
           Product: gcc
           Version: 9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libbacktrace
          Assignee: unassigned at gcc dot gnu.org
          Reporter: antoshkka at gmail dot com
                CC: ian at gcc dot gnu.org
  Target Milestone: ---

Function for creating state `backtrace_create_state` returns a pointer to
`struct backtrace_state`.

There's no function to free the state so the users assume that the pointer
returned from `backtrace_create_state` is a pointer to some static variable
that should not be freed... Which is not true. `struct backtrace_state` is
dynamically allocated.

Multiple usages of `backtrace_create_state` consume all the available memory
and lead to segfaults.

Please add `backtrace_free_state` function that frees the resources allocated
by `backtrace_create_state` and document that state returned by
`backtrace_create_state` should be freed.


Another way to solve the problem is to 
* always return the same state `backtrace_create_state` and override the
`threaded` argument with 1
* free that state on exit