Treat common symbol in executable as definition

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.

1 files changed, 24 insertions, 0 deletions

diff --git a/ld/testsuite/ld-elf/shared.exp b/ld/testsuite/ld-elf/shared.exp
index 678ab1b..ef0747d 100644
--- a/ld/testsuite/ld-elf/shared.exp
+++ b/ld/testsuite/ld-elf/shared.exp
@@ -524,6 +524,21 @@ if { [istarget *-*-linux*]
 	    {} \
 	    "libpr2404b.a" \
 	] \
+	[list \
+	    "Build pr19579a.o" \
+	    "" "-fPIE" \
+	    {pr19579a.c} \
+	    {} \
+	    "libpr19579a.a" \
+	] \
+	[list \
+	    "Build libpr19579.so" \
+	    "-shared" \
+	    "-fPIC" \
+	    {pr19579b.c} \
+	    {} \
+	    "libpr19579.so" \
+	] \
     ]
     run_ld_link_exec_tests [] [list \
 	[list \
@@ -580,6 +595,15 @@ if { [istarget *-*-linux*]
 	    "pass.out" \
 	    "-O2 -fPIC -I../bfd" \
 	] \
+	[list \
+	    "Run pr19579" \
+	    "-pie -z text tmpdir/pr19579a.o tmpdir/libpr19579.so" \
+	    "" \
+	    {dummy.c} \
+	    "pr19579" \
+	    "pass.out" \
+	    "-fPIE" \
+	] \
     ]
 }