Allow hiding of some filtered frames

When a frame filter elides some frames, they are still printed by
"bt", indented a few spaces.  PR backtrace/15582 notes that it would
be nice for users if elided frames could simply be dropped.  This
patch adds this capability.

gdb/ChangeLog
2018-03-26  Tom Tromey  <tom@tromey.com>

	PR backtrace/15582:
	* stack.c (backtrace_command): Parse "hide" argument.
	* python/py-framefilter.c (py_print_frame): Handle PRINT_HIDE.
	* extension.h (enum frame_filter_flags) <PRINT_HIDE>: New
	constant.

gdb/doc/ChangeLog
2018-03-26  Tom Tromey  <tom@tromey.com>

	PR backtrace/15582:
	* gdb.texinfo (Backtrace): Mention "hide" argument.

gdb/testsuite/ChangeLog
2018-03-26  Tom Tromey  <tom@tromey.com>

	PR backtrace/15582:
	* gdb.python/py-framefilter.exp: Add "bt hide" test.

8 files changed, 57 insertions, 25 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index ed1d9dd..8f80593 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,13 @@
 2018-03-26  Tom Tromey  <tom@tromey.com>
 
+	PR backtrace/15582:
+	* stack.c (backtrace_command): Parse "hide" argument.
+	* python/py-framefilter.c (py_print_frame): Handle PRINT_HIDE.
+	* extension.h (enum frame_filter_flags) <PRINT_HIDE>: New
+	constant.
+
+2018-03-26  Tom Tromey  <tom@tromey.com>
+
 	* stack.c (backtrace_command_1): Remove "show_locals" parameter,
 	add "flags".
 	(backtrace_command): Remove "fulltrace", add "flags".
diff --git a/gdb/doc/ChangeLog b/gdb/doc/ChangeLog
index 413e456..4da77de 100644
--- a/gdb/doc/ChangeLog
+++ b/gdb/doc/ChangeLog
@@ -1,5 +1,10 @@
 2018-03-26  Tom Tromey  <tom@tromey.com>
 
+	PR backtrace/15582:
+	* gdb.texinfo (Backtrace): Mention "hide" argument.
+
+2018-03-26  Tom Tromey  <tom@tromey.com>
+
 	* gdb.texinfo (Backtrace): Describe options individually.
 
 2018-03-19  Tom Tromey  <tom@tromey.com>
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 28254c9..d37b107 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -7342,6 +7342,12 @@ Filter API}, for more information.  Additionally use @ref{disable
 frame-filter all} to turn off all frame filters.  This is only
 relevant when @value{GDBN} has been configured with @code{Python}
 support.
+
+@item hide
+A Python frame filter might decide to ``elide'' some frames.  Normally
+such elided frames are still printed, but they are indented relative
+to the filtered frames that cause them to be elided.  The @code{hide}
+option causes elided frames to not be printed at all.
 @end table
 @end table
 
diff --git a/gdb/extension.h b/gdb/extension.h
index 943792d..a972928 100644
--- a/gdb/extension.h
+++ b/gdb/extension.h
@@ -103,6 +103,9 @@ enum frame_filter_flag
 
     /* Set this flag if a "More frames" message is to be printed.  */
     PRINT_MORE_FRAMES = 1 << 4,
+
+    /* Set this flag if elided frames should not be printed.  */
+    PRINT_HIDE = 1 << 5,
   };
 
 DEF_ENUM_FLAGS_TYPE (enum frame_filter_flag, frame_filter_flags);
diff --git a/gdb/python/py-framefilter.c b/gdb/python/py-framefilter.c
index 99d47f2..aae8d5d 100644
--- a/gdb/python/py-framefilter.c
+++ b/gdb/python/py-framefilter.c
@@ -1238,37 +1238,37 @@ py_print_frame (PyObject *filter, frame_filter_flags flags,
 	return EXT_LANG_BT_ERROR;
     }
 
-  {
-    /* Finally recursively print elided frames, if any.  */
-    gdbpy_ref<> elided (get_py_iter_from_func (filter, "elided"));
-    if (elided == NULL)
-      return EXT_LANG_BT_ERROR;
+  if ((flags & PRINT_HIDE) == 0)
+    {
+      /* Finally recursively print elided frames, if any.  */
+      gdbpy_ref<> elided (get_py_iter_from_func (filter, "elided"));
+      if (elided == NULL)
+	return EXT_LANG_BT_ERROR;
 
-    if (elided != Py_None)
-      {
-	PyObject *item;
+      if (elided != Py_None)
+	{
+	  PyObject *item;
 
-	ui_out_emit_list inner_list_emiter (out, "children");
+	  ui_out_emit_list inner_list_emiter (out, "children");
 
-	if (! out->is_mi_like_p ())
-	  indent++;
+	  if (! out->is_mi_like_p ())
+	    indent++;
 
-	while ((item = PyIter_Next (elided.get ())))
-	  {
-	    gdbpy_ref<> item_ref (item);
+	  while ((item = PyIter_Next (elided.get ())))
+	    {
+	      gdbpy_ref<> item_ref (item);
 
-	    enum ext_lang_bt_status success = py_print_frame (item, flags,
-							      args_type, out,
-							      indent,
-							      levels_printed);
+	      enum ext_lang_bt_status success
+		= py_print_frame (item, flags, args_type, out, indent,
+				  levels_printed);
 
-	    if (success == EXT_LANG_BT_ERROR)
-	      return EXT_LANG_BT_ERROR;
-	  }
-	if (item == NULL && PyErr_Occurred ())
-	  return EXT_LANG_BT_ERROR;
-      }
-  }
+	      if (success == EXT_LANG_BT_ERROR)
+		return EXT_LANG_BT_ERROR;
+	    }
+	  if (item == NULL && PyErr_Occurred ())
+	    return EXT_LANG_BT_ERROR;
+	}
+    }
 
   return EXT_LANG_BT_COMPLETED;
 }
diff --git a/gdb/stack.c b/gdb/stack.c
index 76695ff..8e8fe12 100644
--- a/gdb/stack.c
+++ b/gdb/stack.c
@@ -1867,6 +1867,8 @@ backtrace_command (const char *arg, int from_tty)
 	    filters = false;
 	  else if (subset_compare (this_arg.c_str (), "full"))
 	    flags |= PRINT_LOCALS;
+	  else if (subset_compare (this_arg.c_str (), "hide"))
+	    flags |= PRINT_HIDE;
 	  else
 	    {
 	      /* Not a recognized argument, so stop.  */
diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index a359571..5537a91 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2018-03-26  Tom Tromey  <tom@tromey.com>
+
+	PR backtrace/15582:
+	* gdb.python/py-framefilter.exp: Add "bt hide" test.
+
 2018-03-23  Keith Seitz  <keiths@redhat.com>
 
 	PR c++/22968
diff --git a/gdb/testsuite/gdb.python/py-framefilter.exp b/gdb/testsuite/gdb.python/py-framefilter.exp
index 7e02e9d..cc31dd5 100644
--- a/gdb/testsuite/gdb.python/py-framefilter.exp
+++ b/gdb/testsuite/gdb.python/py-framefilter.exp
@@ -157,6 +157,9 @@ gdb_test "bt no-filter full" \
 gdb_test "bt full" \
     ".*#0.*end_func.*str = $hex \"The End\".*st2 = $hex \"Is Near\".*b = 12.*c = 5.*#1.*in funca \\(\\).*#2.*in funcb \\(j=10\\).*bar = \{a = 42, b = 84\}.*#22.*in func1 \\(\\).*#23.*in func2 \\(f=3\\).*elided = $hex \"Elided frame\".*fb = \{nothing = $hex \"Elided Foo Bar\", f = 84, s = 38\}.*bf = $hex.*" \
     "bt full with Reverse disabled"
+gdb_test "bt full hide" \
+    ".*#0.*end_func.*str = $hex \"The End\".*st2 = $hex \"Is Near\".*b = 12.*c = 5.*#1.*in funca \\(\\).*#2.*in funcb \\(j=10\\).*bar = \{a = 42, b = 84\}.*#22.*in func1 \\(\\)\[^#\]*#24.*in func3 \\(i=3\\).*" \
+    "bt full hide with Reverse disabled"
 
 # Test set print frame-arguments
 # none