PR gdb/16483 - simplify "info frame-filters" output

PR gdb/16483 notes that the output of "info frame-filters" is quite
voluminous.  In particular it prints an entry for each objfile, even if
only to say that the objfile does not have any associated frame filters.

I think it's better to only print output when there is a frame filter.
There's nothing worth doing with the no-frame-filter information, and
limiting the output makes it much more readable.

Built and regtested on x86-64 Fedora 23.

2016-06-23  Tom Tromey  <tom@tromey.com>

	PR gdb/16483:
	* python/lib/gdb/command/frame_filters.py
	(InfoFrameFilter.list_frame_filters): Rename to print_list.  Print
	nothing if no filters found.  Return value indicating whether
	filters were printed.
	(InfoFrameFilter.print_list): Remove.
	(InfoFrameFilter.invoke): Print message if no frame filters
	found.

2016-06-23  Tom Tromey  <tom@tromey.com>

	PR gdb/16483:
	* gdb.python/py-framefilter.exp: Add "info frame-filter" test
	before any filters are loaded.

gdb/ChangeLog

@@ -1,3 +1,14 @@
+2016-06-23  Tom Tromey  <tom@tromey.com>
+
+	PR gdb/16483:
+	* python/lib/gdb/command/frame_filters.py
+	(InfoFrameFilter.list_frame_filters): Rename to print_list.  Print
+	nothing if no filters found.  Return value indicating whether
+	filters were printed.
+	(InfoFrameFilter.print_list): Remove.
+	(InfoFrameFilter.invoke): Print message if no frame filters
+	found.
+
 2016-06-21  Walfred Tedeschi  <walfred.tedeschi@intel.com>
 
 	* f-valprint.c (f_val_print): Add field names for printing

gdb/python/lib/gdb/command/frame_filters.py

@@ -56,22 +56,15 @@ class InfoFrameFilter(gdb.Command):
         else:
             return "No"
 
-    def list_frame_filters(self, frame_filters):
-        """ Internal worker function to list and print frame filters
-        in a dictionary.
-
-        Arguments:
-           frame_filters: The name of the dictionary, as
-           specified by GDB user commands.
-        """
-
+    def print_list(self, title, frame_filters, blank_line):
         sorted_frame_filters = sorted(frame_filters.items(),
                                       key=lambda i: gdb.frames.get_priority(i[1]),
                                       reverse=True)
 
         if len(sorted_frame_filters) == 0:
-            print("  No frame filters registered.")
-        else:
+            return 0
+
+        print(title)
         print("  Priority  Enabled  Name")
         for frame_filter in sorted_frame_filters:
             name = frame_filter[0]
@@ -80,29 +73,28 @@ class InfoFrameFilter(gdb.Command):
                     str(gdb.frames.get_priority(frame_filter[1])))
                 enabled = '{:<7}'.format(
                     self.enabled_string(gdb.frames.get_enabled(frame_filter[1])))
+                print("  %s  %s  %s" % (priority, enabled, name))
             except Exception:
                 e = sys.exc_info()[1]
                 print("  Error printing filter '"+name+"': "+str(e))
-                else:
-                    print("  %s  %s  %s" % (priority, enabled, name))
-
-    def print_list(self, title, filter_list, blank_line):
-        print(title)
-        self.list_frame_filters(filter_list)
         if blank_line:
             print("")
+        return 1
 
     def invoke(self, arg, from_tty):
-        self.print_list("global frame-filters:", gdb.frame_filters, True)
+        any_printed = self.print_list("global frame-filters:", gdb.frame_filters, True)
 
         cp = gdb.current_progspace()
-        self.print_list("progspace %s frame-filters:" % cp.filename,
+        any_printed += self.print_list("progspace %s frame-filters:" % cp.filename,
                                        cp.frame_filters, True)
 
         for objfile in gdb.objfiles():
-            self.print_list("objfile %s frame-filters:" % objfile.filename,
+            any_printed += self.print_list("objfile %s frame-filters:" % objfile.filename,
                                            objfile.frame_filters, False)
 
+        if any_printed == 0:
+            print ("No frame filters.")
+
 # Internal enable/disable functions.
 
 def _enable_parse_arg(cmd_name, arg):

gdb/testsuite/ChangeLog

@@ -1,3 +1,9 @@
+2016-06-23  Tom Tromey  <tom@tromey.com>
+
+	PR gdb/16483:
+	* gdb.python/py-framefilter.exp: Add "info frame-filter" test
+	before any filters are loaded.
+
 2016-06-21  Walfred Tedeschi  <walfred.tedeschi@intel.com>
 
 	* gdb.fortran/derived-type.exp (print q): Add fields to the output.

gdb/testsuite/gdb.python/py-framefilter.exp

@@ -33,6 +33,10 @@ gdb_start
 # Skip all tests if Python scripting is not enabled.
 if { [skip_python_tests] } { continue }
 
+gdb_test "info frame-filter" \
+    "No frame filters\\." \
+    "info frame filter before loading filters"
+
 # Make the -gdb.py script available to gdb, it is automagically loaded by gdb.
 # Care is taken to put it in the same directory as the binary so that
 # gdb will find it.