gold: Properly remove the versioned symbol

When the versioned symbol foo is removed from the shared library,  the
".symver foo,foo@VER" directive provides binary compatibility for foo@VER.
In this case, the unversioned symbol foo should be hidden and shouldn't
generate a multiple definition error.

	PR gold/31830
	* resolve.cc (Symbol_table::resolve): Move symbol version handling
	to ...
	* symtab.cc (Symbol_table::add_from_object): Here. If the hidden
	version from .symver is the same as the default version from the
	unversioned symbol, don't make the unversioned symbol the default
	versioned
	symbol.
	* testsuite/Makefile.am (check_SCRIPTS): Add ver_test_pr31830.sh.
	(check_DATA): ver_test_pr31830_a.syms and ver_test_pr31830_b.syms.
	(ver_test_pr31830_a.syms): New.
	(ver_test_pr31830_b.syms): Likewise.
	(ver_test_pr31830_a.so): Likewise.
	(ver_test_pr31830_b.so): Likewise.
	* testsuite/Makefile.in: Regenerated.
	* testsuite/ver_test_pr31830.script: New file.
	* testsuite/ver_test_pr31830.sh: Likewise.
	* testsuite/ver_test_pr31830_a.c: Likewise.
	* testsuite/ver_test_pr31830_b.c: Likewise.
	* testsuite/ver_test_pr31830_lto.c: Likewise.
	* testsuite/ver_test_pr31830_lto.sh: Likewise.

Signed-off-by: H.J. Lu <hjl.tools@gmail.com>

1 files changed, 65 insertions, 11 deletions

diff --git a/gold/symtab.cc b/gold/symtab.cc
index 9a55e6e..5857dd7 100644
--- a/gold/symtab.cc
+++ b/gold/symtab.cc
@@ -998,12 +998,64 @@ Symbol_table::add_from_object(Object* object,
       ret = this->get_sized_symbol<size>(ins.first->second);
       gold_assert(ret != NULL);
 
+      bool ret_is_ordinary;
+      const unsigned int ret_shndx = ret->shndx(&ret_is_ordinary);
+
       was_undefined_in_reg = ret->is_undefined() && ret->in_reg();
       // Commons from plugins are just placeholders.
       was_common = ret->is_common() && ret->object()->pluginobj() == NULL;
 
-      this->resolve(ret, sym, st_shndx, is_ordinary, orig_st_shndx, object,
-		    version, is_default_version);
+      // It's possible for a symbol to be defined in an object file
+      // using .symver to give it a version, and for there to also be
+      // a linker script giving that symbol the same version.  We
+      // don't want to give a multiple-definition error for this
+      // harmless redefinition.
+      bool check_version = false;
+      bool erase_default_version = false;
+      bool no_default_version = false;
+      if (ret->source() == Symbol::FROM_OBJECT
+	  && is_ordinary
+	  && ret_shndx == st_shndx)
+	{
+	  if (ret->object() == object)
+	    check_version = true;
+
+	  if (version != NULL && version == ret->version())
+	    {
+	      // Don't give a multiple-definition error if the hidden
+	      // version from .symver is the same as the default version
+	      // from the unversioned symbol.
+	      if (is_default_version && !ret->is_default ())
+		{
+		  no_default_version = true;
+		  if (insdefault.second)
+		    {
+		      // Don't make the unversioned symbol the default
+		      // version.
+		      is_default_version = false;
+		      erase_default_version = true;
+		      check_version = true;
+		    }
+		}
+	      else if (!is_default_version && ret->is_default ())
+		{
+		  // Don't make the unversioned symbol the default
+		  // version.
+		  ret->set_is_not_default();
+		  no_default_version = true;
+		  check_version = true;
+		}
+	    }
+	}
+
+      if (!(check_version
+	    && ret->is_defined()
+	    && ret_is_ordinary
+	    && (no_default_version
+		|| ret->value() == sym.get_st_value())))
+	this->resolve(ret, sym, st_shndx, is_ordinary, orig_st_shndx,
+		      object, version, is_default_version);
+
       if (parameters->options().gc_sections())
         this->gc_mark_dyn_syms(ret);
 
@@ -1012,13 +1064,7 @@ Symbol_table::add_from_object(Object* object,
 						       insdefault.first);
       else
 	{
-	  bool dummy;
-	  if (version != NULL
-	      && ret->source() == Symbol::FROM_OBJECT
-	      && ret->object() == object
-	      && is_ordinary
-	      && ret->shndx(&dummy) == st_shndx
-	      && ret->is_default())
+	  if (version != NULL && check_version)
 	    {
 	      // We have seen NAME/VERSION already, and marked it as the
 	      // default version, but now we see a definition for
@@ -1032,9 +1078,17 @@ Symbol_table::add_from_object(Object* object,
 	      // In any other case, the two symbols should have generated
 	      // a multiple definition error.
 	      // (See PR gold/18703.)
-	      ret->set_is_not_default();
+	      // If the hidden version from .symver is the same as the
+	      // default version from the unversioned symbol, don't make
+	      // the unversioned symbol the default versioned symbol.
 	      const Stringpool::Key vnull_key = 0;
-	      this->table_.erase(std::make_pair(name_key, vnull_key));
+	      if (erase_default_version)
+		this->table_.erase(std::make_pair(name_key, vnull_key));
+	      else if (ret->object() == object)
+		{
+		  ret->set_is_not_default();
+		  this->table_.erase(std::make_pair(name_key, vnull_key));
+		}
 	    }
 	}
     }