From e9194a1a0e49f0646d5ac415836cc5d133f14bbe Mon Sep 17 00:00:00 2001
From: Tankut Baris Aktemur <tankut.baris.aktemur@intel.com>
Date: Fri, 29 Nov 2019 12:17:36 +0100
Subject: [PATCH] gdb: fix segfault in overload resolution debug output

A segfault occurs if overload resolution debug mode is turned on via
the 'set debug overload' command.  E.g.:

~~~
$ gdb ./a.out
...
(gdb) start
...
(gdb) set debug overload 1
(gdb) print foo(5)
-- Arg is int [8], parm is double [9]
Overloaded function instance (null) # of parms 1
Segmentation fault
$
~~~

The problem is, GDB tries to print the badness vector after it has
been std::move'd.  Fix the problem by printing the vector before it is
moved.

gdb/ChangeLog:
2019-11-29  Tankut Baris Aktemur  <tankut.baris.aktemur@intel.com>

	* valops.c (find_oload_champ): Print part of debug messages
	before the badness vector is std::move'd.

Change-Id: Ia623f9637e82ec332bfeac23eb6b0f2ffdcdde27
---
 gdb/ChangeLog |  5 +++++
 gdb/valops.c  | 48 +++++++++++++++++++++++++-----------------------
 2 files changed, 30 insertions(+), 23 deletions(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index bc61c35064e..a3c06705d97 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,8 @@
+2019-11-29  Tankut Baris Aktemur  <tankut.baris.aktemur@intel.com>
+
+	* valops.c (find_oload_champ): Print part of debug messages
+	before the badness vector is std::move'd.
+
 2019-11-28  Tom Tromey  <tom@tromey.com>
 
 	* value.c (creal_internal_fn): Fix comment.
diff --git a/gdb/valops.c b/gdb/valops.c
index cbb1f30e71b..8af53deaa6f 100644
--- a/gdb/valops.c
+++ b/gdb/valops.c
@@ -3023,6 +3023,28 @@ find_oload_champ (gdb::array_view<value *> args,
       bv = rank_function (parm_types,
 			  args.slice (static_offset));
 
+      if (overload_debug)
+	{
+	  if (methods != NULL)
+	    fprintf_filtered (gdb_stderr,
+			      "Overloaded method instance %s, # of parms %d\n",
+			      methods[ix].physname, (int) parm_types.size ());
+	  else if (xmethods != NULL)
+	    fprintf_filtered (gdb_stderr,
+			      "Xmethod worker, # of parms %d\n",
+			      (int) parm_types.size ());
+	  else
+	    fprintf_filtered (gdb_stderr,
+			      "Overloaded function instance "
+			      "%s # of parms %d\n",
+			      functions[ix]->demangled_name (),
+			      (int) parm_types.size ());
+	  for (jj = 0; jj < args.size () - static_offset; jj++)
+	    fprintf_filtered (gdb_stderr,
+			      "...Badness @ %d : %d\n",
+			      jj, bv[jj].rank);
+	}
+
       if (oload_champ_bv->empty ())
 	{
 	  *oload_champ_bv = std::move (bv);
@@ -3048,29 +3070,9 @@ find_oload_champ (gdb::array_view<value *> args,
 	    break;
 	  }
       if (overload_debug)
-	{
-	  if (methods != NULL)
-	    fprintf_filtered (gdb_stderr,
-			      "Overloaded method instance %s, # of parms %d\n",
-			      methods[ix].physname, (int) parm_types.size ());
-	  else if (xmethods != NULL)
-	    fprintf_filtered (gdb_stderr,
-			      "Xmethod worker, # of parms %d\n",
-			      (int) parm_types.size ());
-	  else
-	    fprintf_filtered (gdb_stderr,
-			      "Overloaded function instance "
-			      "%s # of parms %d\n",
-			      functions[ix]->demangled_name (),
-			      (int) parm_types.size ());
-	  for (jj = 0; jj < args.size () - static_offset; jj++)
-	    fprintf_filtered (gdb_stderr,
-			      "...Badness @ %d : %d\n", 
-			      jj, bv[jj].rank);
-	  fprintf_filtered (gdb_stderr, "Overload resolution "
-			    "champion is %d, ambiguous? %d\n", 
-			    oload_champ, oload_ambiguous);
-	}
+	fprintf_filtered (gdb_stderr, "Overload resolution "
+			  "champion is %d, ambiguous? %d\n",
+			  oload_champ, oload_ambiguous);
     }
 
   return oload_champ;
-- 
2.30.2