Since common symbols that are turned into definitions don't have the
DEF_REGULAR flag set, we need to check ELF_COMMON_DEF_P for common
symbols.
bfd/
PR ld/19579
PR ld/21306
* elf32-s390.c (elf_s390_finish_dynamic_symbol): Check
ELF_COMMON_DEF_P for common symbols.
* elf64-s390.c (elf_s390_finish_dynamic_symbol): Likewise.
* elf64-x86-64.c (elf_x86_64_relocate_section): Likewise.
* elflink.c (_bfd_elf_merge_symbol): Revert commits
202ac193bb and
07492f668d.
ld/
PR ld/19579
PR ld/21306
* testsuite/ld-elf/pr19579a.c (main): Updated.
Common symbol in executable is a definition, which overrides definition
from shared objects. When linker sees a new definition from a shared
object, the new dynamic definition should be overridden by the previous
common symbol in executable.
bfd/
PR ld/19579
* elflink.c (_bfd_elf_merge_symbol): Treat common symbol in
executable as definition if the new definition comes from a
shared library.
ld/
PR ld/19579
* testsuite/ld-elf/pr19579a.c: New file.
* testsuite/ld-elf/pr19579b.c: Likewise.
* testsuite/ld-elf/shared.exp: Run PR ld/19579 test.
