gold patch committed: Implement --unresolved-symbols

[Ian Lance Taylor <iant at google dot com>]

This gold patch implements --unresolved-symbols more or less as it
exists in GNU ld.  Gold generally acts as like GNU ld using
--unresolved-symbols=ignore-in-shared-libs, and this patch does not
change that behaviour.  Committed to mainline.

Ian


2011-07-08  Ian Lance Taylor  <iant@google.com>

	PR gold/12386
	* options.h (class General_options): Add --unresolved-symbols.
	* target-reloc.h (issue_undefined_symbol_error): Check
	--unresolved-symbols.  Add comments.


Index: options.h
===================================================================
RCS file: /cvs/src/src/gold/options.h,v
retrieving revision 1.166
diff -u -p -r1.166 options.h
--- options.h	6 Jul 2011 22:15:12 -0000	1.166
+++ options.h	9 Jul 2011 06:09:34 -0000
@@ -1069,6 +1069,13 @@ class General_options
   DEFINE_set(undefined, options::TWO_DASHES, 'u',
 	     N_("Create undefined reference to SYMBOL"), N_("SYMBOL"));
 
+  DEFINE_enum(unresolved_symbols, options::TWO_DASHES, '\0', NULL,
+	      N_("How to handle unresolved symbols"),
+	      ("ignore-all,report-all,ignore-in-object-files,"
+	       "ignore-in-shared-libs"),
+	      {"ignore-all", "report-all", "ignore-in-object-files",
+		  "ignore-in-shared-libs"});
+
   DEFINE_bool(verbose, options::TWO_DASHES, '\0', false,
               N_("Synonym for --debug=files"), NULL);
 
Index: target-reloc.h
===================================================================
RCS file: /cvs/src/src/gold/target-reloc.h,v
retrieving revision 1.48
diff -u -p -r1.48 target-reloc.h
--- target-reloc.h	9 Jul 2011 00:47:11 -0000	1.48
+++ target-reloc.h	9 Jul 2011 06:09:34 -0000
@@ -176,13 +176,46 @@ visibility_error(const Symbol* sym)
 inline bool
 issue_undefined_symbol_error(const Symbol* sym)
 {
-  return (sym != NULL
-	  && (sym->is_undefined() || sym->is_placeholder())
-	  && sym->binding() != elfcpp::STB_WEAK
-	  && !sym->is_defined_in_discarded_section()
-	  && !parameters->target().is_defined_by_abi(sym)
-	  && (!parameters->options().shared()
-	      || parameters->options().defs()));
+  // We only report global symbols.
+  if (sym == NULL)
+    return false;
+
+  // We only report undefined symbols.
+  if (!sym->is_undefined() && !sym->is_placeholder())
+    return false;
+
+  // We don't report weak symbols.
+  if (sym->binding() == elfcpp::STB_WEAK)
+    return false;
+
+  // We don't report symbols defined in discarded sections.
+  if (sym->is_defined_in_discarded_section())
+    return false;
+
+  // If the target defines this symbol, don't report it here.
+  if (parameters->target().is_defined_by_abi(sym))
+    return false;
+
+  // See if we've been told to ignore whether this symbol is
+  // undefined.
+  const char* const u = parameters->options().unresolved_symbols();
+  if (u != NULL)
+    {
+      if (strcmp(u, "ignore-all") == 0)
+	return false;
+      if (strcmp(u, "ignore-in-object-files") == 0 && !sym->in_dyn())
+	return false;
+      if (strcmp(u, "ignore-in-shared-libs") == 0 && !sym->in_reg())
+	return false;
+    }
+
+  // When creating a shared library, only report unresolved symbols if
+  // -z defs was used.
+  if (parameters->options().shared() && !parameters->options().defs())
+    return false;
+
+  // Otherwise issue a warning.
+  return true;
 }
 
 // This function implements the generic part of relocation processing.