[Bug c/77464] New: gcc -no-pie breaks -shared

[balint at balintreczey dot hu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77464

            Bug ID: 77464
           Summary: gcc -no-pie breaks -shared
           Product: gcc
           Version: 6.2.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: balint at balintreczey dot hu
  Target Milestone: ---

Compiling shared libraries is broken with -no-pie, which should be a noop in
this case.

Test:
# echo "int bar(void) {return 0;}" > foo.c
# gcc -shared foo.c
# gcc -shared -no-pie foo.c
/usr/lib/gcc/x86_64-linux-gnu/6/../../../x86_64-linux-gnu/crt1.o: In function
`_start':
(.text+0x20): undefined reference to `main'
collect2: error: ld returned 1 exit status

This prevents enabling --enable-default-pie in Debian because when PIE is
disabled for a package -no-pie is added to LDFLAGS. 

One failure due to this bug:
https://people.debian.org/~lucas/logs/2016/08/30/pie-bindnow-20160830/with-pie-bindnow/afterstep_2.2.12-8_unstable_pie-bindnow.log.gz

Some background on enabling PIE by default on Debian:
https://lists.debian.org/debian-devel/2016/08/msg00620.html