[Bug lto/88185] New: LTO merges -fPIC/fpie and -fPIE/-fpie options to nothing - fails to warn when both are specified

[danglin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88185

            Bug ID: 88185
           Summary: LTO merges -fPIC/fpie and -fPIE/-fpie options to
                    nothing - fails to warn when both are specified
           Product: gcc
           Version: 8.2.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: lto
          Assignee: unassigned at gcc dot gnu.org
          Reporter: danglin at gcc dot gnu.org
                CC: marxin at gcc dot gnu.org
  Target Milestone: ---
              Host: hppa-unknown-linux-gnu
            Target: hppa-unknown-linux-gnu
             Build: hppa-unknown-linux-gnu

The systemd package fails to build on hppa-linux with gcc-8.  See:
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=909396

The build fails when it tries to link a pie executable.  It's main object
was compiled with -fPIE.  Several archive libraries are linked against the
main object.  These contain objects compiled with both the -fPIE and -fPIC
options.  Only the -fPIC option is recorded for LTO.

In gcc-8, -fPIE + -fPIC are merged to nothing.  So, the link fails when
non position-independent object is generated for an LTO object.

There is no warning about using -fPIE and -fPIC together.  The documentation
implies these options are not compatible.  In the systemd build, the addition
of these options is done by meson and it's not clear why both are added.