Fix issues with gold undefined symbol diagnostics.

PR binutils/15435 complains that gold issues a visibility error for an
weak undefined symbol with hidden visibility. The message should be
suppressed if the symbol is a weak undef.

An earlier patch to add an extra note about key functions when a class's
vtable symbol is undefined missed a case where the reference to the
vtable came from a shared library. This patch moves the check to a
lower-level routine that catches both cases.

gold/

2014-02-05  Cary Coutant  <[email protected]>

	* errors.cc (Errors::undefined_symbol): Move undef vtable symbol
	check to here.
	* target-reloc.h (is_strong_undefined): New function.
	(relocate_section): Move undef vtable symbol check from here.
	Check for is_strong_undefined.

Author: Cary Coutant

Diff for: gold/ChangeLog

@@ -1,3 +1,14 @@
+2014-02-05  Cary Coutant  <[email protected]>
+
+	Fix issues with gold undefined symbol diagnostics.
+
+	PR binutils/15435
+	* errors.cc (Errors::undefined_symbol): Move undef vtable symbol
+	check to here.
+	* target-reloc.h (is_strong_undefined): New function.
+	(relocate_section): Move undef vtable symbol check from here.
+	Check for is_strong_undefined.
+
 2014-02-05  Cary Coutant  <[email protected]>
 
 	Fix problems with the --dynamic-list option.

Diff for: gold/errors.cc

@@ -193,6 +193,11 @@ Errors::undefined_symbol(const Symbol* sym, const std::string& location)
     fprintf(stderr,
             _("%s: %s: undefined reference to '%s', version '%s'\n"),
 	    location.c_str(), zmsg, sym->demangled_name().c_str(), version);
+
+  if (sym->is_cxx_vtable())
+    gold_info(_("%s: the vtable symbol may be undefined because "
+		"the class is missing its key function"),
+	      program_name);
 }
 
 // Issue a debugging message.

Diff for: gold/target-reloc.h

@@ -144,6 +144,12 @@ class Default_comdat_behavior
   }
 };
 
+inline bool
+is_strong_undefined(const Symbol* sym)
+{
+  return sym->is_undefined() && sym->binding() != elfcpp::STB_WEAK;
+}
+
 // Give an error for a symbol with non-default visibility which is not
 // defined locally.
 
@@ -411,16 +417,10 @@ relocate_section(
 	}
 
       if (issue_undefined_symbol_error(sym))
-	{
-	  gold_undefined_symbol_at_location(sym, relinfo, i, offset);
-	  if (sym->is_cxx_vtable())
-	    gold_info(_("%s: the vtable symbol may be undefined because "
-			"the class is missing its key function"),
-		      program_name);
-	}
+	gold_undefined_symbol_at_location(sym, relinfo, i, offset);
       else if (sym != NULL
 	       && sym->visibility() != elfcpp::STV_DEFAULT
-	       && (sym->is_undefined() || sym->is_from_dynobj()))
+	       && (is_strong_undefined(sym) || sym->is_from_dynobj()))
 	visibility_error(sym);
 
       if (sym != NULL && sym->has_warning())