[Bug jit/64206] New: fake.so is unlinked too early for some users

[drepper.fsp+rhbz at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64206

            Bug ID: 64206
           Summary: fake.so is unlinked too early for some users
           Product: gcc
           Version: 5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: jit
          Assignee: dmalcolm at gcc dot gnu.org
          Reporter: drepper.fsp+rhbz at gmail dot com

Some users of the DSO created by the JIT (probably mostly debuggers) might have
a hard time getting to the file before it gets unlinked.  For some gdb
versions, for instance, this is fatal.  Try gdb 7.8.1, for instance, see

https://bugzilla.redhat.com/show_bug.cgi?id=1170861

That is certainly gdb's fault but it's an example about the type of problems
that can appear.

It certainly is useful to unlink the file as quickly as possible so that in
case of a problem crash nothing is left behind.  But there at least should be
the possibility to prevent the early unlink.  Dave suggested to tie this to the
enabling of debuginfo generation in libgccjit.  I'm actually not entirely sure
that's the best possibility since even without debuginfo the debugger can use
the ELF symbols to place breakpoints etc.  Maybe a boolean option?

As a solution it should be quite easy to transfer ownership of the file and
directory from playback::context to result.