[binutils-gdb] gdb: fix segfault in overload resolution debug output

[binutils-gdb] gdb: fix segfault in overload resolution debug output

[Tankut Baris Aktemur]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=e9194a1a0e49f0646d5ac415836cc5d133f14bbe

commit e9194a1a0e49f0646d5ac415836cc5d133f14bbe
Author: Tankut Baris Aktemur <tankut.baris.aktemur@intel.com>
Date:   Fri Nov 29 12:17:36 2019 +0100

    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

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

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index bc61c35..a3c0670 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 cbb1f30..8af53de 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;