Error messages emitted during bfd_check_format_matches

Error messages emitted during bfd_check_format_matches

[Alan Modra]

Error/warning messages are only printed for the target that
successfully matched, which makes sense for warnings, but not so much
for errors where the errors cause no target to match.  I noticed this
when looking at the pr20520 testcase again with objdump, which just
reports "file format not recognized" omitting the five "SHT_GROUP
section [index n] has no SHF_GROUP sections" messages.  They are
omitted because multiple ELF targets match the object file.  This is
going to be true for all ELF objects due to at least the proper ELF
target and the generic ELF target matching.

	* format.c (print_and_clear_messages): Print messages if all
	targets with messages have exactly the same set of messages.

diff --git a/bfd/format.c b/bfd/format.c
index 443fc6dbde0..d0af388ab45 100644
--- a/bfd/format.c
+++ b/bfd/format.c
@@ -282,20 +282,40 @@ clear_warnmsg (struct per_xvec_message **list)
 /* Free all the storage in LIST.  Note that the first element of LIST
    is special and is assumed to be stack-allocated.  TARG is used for
    re-issuing warning messages.  If TARG is PER_XVEC_NO_TARGET, then
-   it acts like a sort of wildcard -- messages are only reissued if
-   they are all associated with a single BFD target, regardless of
-   which one it is.  If TARG is anything else, then only messages
-   associated with TARG are emitted.  */
+   it acts like a sort of wildcard -- messages are reissued if all
+   targets with messages have identical messages.  One copy of the
+   messages are then reissued.  If TARG is anything else, then only
+   messages associated with TARG are emitted.  */
 
 static void
 print_and_clear_messages (struct per_xvec_messages *list,
 			  const bfd_target *targ)
 {
-  struct per_xvec_messages *iter = list;
+  struct per_xvec_messages *iter;
 
-  if (targ == PER_XVEC_NO_TARGET && list->next == NULL)
-    print_warnmsg (&list->messages);
+  if (targ == PER_XVEC_NO_TARGET)
+    {
+      iter = list->next;
+      while (iter != NULL)
+	{
+	  struct per_xvec_message *msg1 = list->messages;
+	  struct per_xvec_message *msg2 = iter->messages;
+	  do
+	    {
+	      if (strcmp (msg1->message, msg2->message))
+		break;
+	      msg1 = msg1->next;
+	      msg2 = msg2->next;
+	    } while (msg1 && msg2);
+	  if (msg1 || msg2)
+	    break;
+	  iter = iter->next;
+	}
+      if (iter == NULL)
+	targ = list->targ;
+    }
 
+  iter = list;
   while (iter != NULL)
     {
       struct per_xvec_messages *next = iter->next;

-- 
Alan Modra