[Bug go/65616] New: libgobegin.a not compiled with -fPIC

[nyh at math dot technion.ac.il]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65616

            Bug ID: 65616
           Summary: libgobegin.a not compiled with -fPIC
           Product: gcc
           Version: 4.9.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: go
          Assignee: ian at airs dot com
          Reporter: nyh at math dot technion.ac.il
                CC: cmang at google dot com

When one tries to build a position-independent executable (PIE or shared
object) with gccgo, the final linking stage fails. For example:

$ gccgo -pie -fpie hello.go
/usr/bin/ld: /usr/lib/gcc/x86_64-redhat-linux/4.9.2/libgobegin.a(go-main.o):
relocation R_X86_64_32 against `runtime_main' can not be used when making a
shared object; recompile with -fPIC

The problem is that libgobegin.a was not compiled with -fPIC, so the main() it
contains is not usable to produce a shared object or PIE. That could easily be
rectified - go-main.c should be compiled with -fPIC. The main() function is
obviously not performance sensitive, so there is no downside in compiling it
with -fPIC.

When I compile go-main.o myself with -fPIC, and do "gccgo -pie -fpic hello.go
go-main.o", things work correctly.

There are many reasons why someone might want to produce a PIE or shared
object. My personal interest is for the OSv operating system (http://osv.io),
which can run Linux executables, but only position-independent ones (because
OSv is a single-address-space operating system).