Test for weak undefined symbols in linknamespace.pl.

This patch makes linknamespace.pl require weak undefined symbols to be
within the standard namespace.  (It remains the case that
linknamespace.pl does not look for definitions of such symbols or
require symbols used in those definitions to be within the standard
namespace.)

Tested for x86_64 and x86.

	* conform/linknamespace.pl: Require weak undefined symbols to be
	in the standard namespace.
	(%strong_syms): Rename to %seen_syms.
	(%strong_seen): Rename to %seen_where.

ChangeLog

@@ -1,3 +1,10 @@
+2015-09-17  Joseph Myers  <joseph@codesourcery.com>
+
+	* conform/linknamespace.pl: Require weak undefined symbols to be
+	in the standard namespace.
+	(%strong_syms): Rename to %seen_syms.
+	(%strong_seen): Rename to %seen_where.
+
 2015-09-17  H.J. Lu  <hongjiu.lu@intel.com>
 
 	[BZ #18970]

conform/linknamespace.pl

@@ -97,8 +97,8 @@ sub list_syms {
 
 # Load information about GLOBAL and WEAK symbols defined or used in
 # the standard libraries.
-# Strong symbols (defined or undefined) from a given object.
-%strong_syms = ();
+# Symbols from a given object, except for weak defined symbols.
+%seen_syms = ();
 # Strong undefined symbols from a given object.
 %strong_undef_syms = ();
 # Objects defining a given symbol (strongly or weakly).
@@ -112,17 +112,17 @@ sub list_syms {
     }
     push (@{$sym_objs{$name}}, $file);
   }
-  if ($bind eq "GLOBAL") {
-    if (!defined ($strong_syms{$file})) {
-      $strong_syms{$file} = [];
+  if ($bind eq "GLOBAL" || !$defined) {
+    if (!defined ($seen_syms{$file})) {
+      $seen_syms{$file} = [];
     }
-    push (@{$strong_syms{$file}}, $name);
-    if (!$defined) {
-      if (!defined ($strong_undef_syms{$file})) {
-	$strong_undef_syms{$file} = [];
-      }
-      push (@{$strong_undef_syms{$file}}, $name);
+    push (@{$seen_syms{$file}}, $name);
+  }
+  if ($bind eq "GLOBAL" && !$defined) {
+    if (!defined ($strong_undef_syms{$file})) {
+      $strong_undef_syms{$file} = [];
     }
+    push (@{$strong_undef_syms{$file}}, $name);
   }
 }
 
@@ -132,12 +132,7 @@ sub list_syms {
 # The rules followed are heuristic and so may produce false positives
 # and false negatives.
 #
-# * Weak undefined symbols are ignored; however, if a code path that
-# references one (even just to check if its address is 0) is executed,
-# that may conflict with a definition of that symbol in the user's
-# program.
-#
-# * Strong undefined symbols are considered of signficance, but it is
+# * All undefined symbols are considered of signficance, but it is
 # possible that (a) any standard library definition is weak, so can be
 # overridden by the user's definition, and (b) the symbol is only used
 # conditionally and not if the program is limited to standard
@@ -192,14 +187,14 @@ sub list_syms {
 unlink ($cincfile_o) || die ("unlink $cincfile_o: $!\n");
 unlink ($cincfile_sym) || die ("unlink $cincfile_sym: $!\n");
 
-%strong_seen = ();
+%seen_where = ();
 %files_seen = ();
 %all_undef = ();
 %current_undef = ();
 foreach my $sym (@elf_syms) {
   my ($file, $name, $bind, $defined) = @$sym;
   if ($bind eq "GLOBAL" && !$defined) {
-    $strong_seen{$name} = "[initial] $name";
+    $seen_where{$name} = "[initial] $name";
     $all_undef{$name} = "[initial] $name";
     $current_undef{$name} = "[initial] $name";
   }
@@ -213,9 +208,9 @@ sub list_syms {
 	next;
       }
       $files_seen{$file} = 1;
-      foreach my $ssym (@{$strong_syms{$file}}) {
-	if (!defined ($strong_seen{$ssym})) {
-	  $strong_seen{$ssym} = "$current_undef{$sym} -> [$file] $ssym";
+      foreach my $ssym (@{$seen_syms{$file}}) {
+	if (!defined ($seen_where{$ssym})) {
+	  $seen_where{$ssym} = "$current_undef{$sym} -> [$file] $ssym";
 	}
       }
       foreach my $usym (@{$strong_undef_syms{$file}}) {
@@ -230,14 +225,14 @@ sub list_syms {
 }
 
 $ret = 0;
-foreach my $sym (sort keys %strong_seen) {
+foreach my $sym (sort keys %seen_where) {
   if ($sym =~ /^_/) {
     next;
   }
   if (defined ($stdsyms{$sym})) {
     next;
   }
-  print "$strong_seen{$sym}\n";
+  print "$seen_where{$sym}\n";
   $ret = 1;
 }