PR gdb/15911: "info threads" changes the default source and line (for "break", "list")

"info threads" changes the default source for "break" and "list", to
whatever the location of the first/bottom thread in the thread list
is...

 (gdb) b start
 (gdb) c
 ...
 (gdb) list
 *lists "start"*
 (gdb) b 23
 Breakpoint 3 at 0x400614: file test.c, line 23.
 (gdb) info threads
   Id   Target Id         Frame
 * 2    Thread 0x7ffff7fcb700 (LWP 1760) "test" start (arg=0x0) at test.c:23
   1    Thread 0x7ffff7fcc740 (LWP 1748) "test" 0x000000323dc08e60 in pthread_join (threadid=140737353922304, thread_return=0x0) at pthread_join.c:93
 (gdb) b 23
 Breakpoint 4 at 0x323dc08d90: file pthread_join.c, line 23.
                                    ^^^^^^^^^^^^^^^
 (gdb) list
 93          lll_wait_tid (pd->tid);
 94
 95
 96        /* Restore cancellation mode.  */
 97        CANCEL_RESET (oldtype);
 98
 99        /* Remove the handler.  */
 100       pthread_cleanup_pop (0);
 101
 102

The issue is that print_stack_frame always sets the current sal to the
frame's sal.  print_frame_info (which print_stack_frame calls to do
most of the work) also sets the last displayed sal, but only if
print_what isn't LOCATION.  Now the call in question, from within
thread.c:print_thread_info, does pass in LOCATION as print_what, but
print_stack_frame doesn't have the same check print_frame_info has.
We could consider adding it, but setting these globals depending on
print_what isn't very clean, IMO.  What we have is two logically
distinct operations mixed in the same function(s):

  #1 - print frame, in the format specified by {print_what,
    print_level and print_args}.

  #2 - We're displaying a frame to the user, and I want the default
    sal to point here, because the program stopped here, or the user
    did some context-changing command (up, down, etc.).

So I added a new parameter to print_stack_frame & friends for point
#2, and went through all calls in the tree adjusting as necessary.

Tested on x86_64 Fedora 17.

gdb/
2013-09-17  Pedro Alves  <palves@redhat.com>

	PR gdb/15911
	* ada-tasks.c (task_command_1): Adjust call to print_stack_frame.
	* bsd-kvm.c (bsd_kvm_open, bsd_kvm_proc_cmd, bsd_kvm_pcb_cmd):
	* corelow.c (core_open):
	* frame.h (print_stack_frame, print_frame_info): New
	'set_current_sal' parameter.
	* infcmd.c (finish_command, kill_command): Adjust call to
	print_stack_frame.
	* inferior.c (inferior_command): Likewise.
	* infrun.c (normal_stop): Likewise.
	* linux-fork.c (linux_fork_context): Likewise.
	* record-full.c (record_full_goto_entry, record_full_restore):
	Likewise.
	* remote-mips.c (common_open): Likewise.
	* stack.c (print_stack_frame): New 'set_current_sal' parameter.
	Use it.
	(print_frame_info): New 'set_current_sal' parameter.  Set the last
	displayed sal depending on the new paremeter instead of looking at
	print_what.
	(backtrace_command_1, select_and_print_frame, frame_command)
	(current_frame_command, up_command, down_command): Adjust call to
	print_stack_frame.
	* thread.c (print_thread_info, restore_selected_frame)
	(do_captured_thread_select): Adjust call to print_stack_frame.
	* tracepoint.c (tfind_1): Likewise.
	* mi/mi-cmd-stack.c (mi_cmd_stack_list_frames)
	(mi_cmd_stack_info_frame): Likewise.
	* mi/mi-interp.c (mi_on_normal_stop): Likewise.
	* mi/mi-main.c (mi_cmd_exec_return, mi_cmd_trace_find): Likewise.

	gdb/testsuite/
	* gdb.threads/info-threads-cur-sal-2.c: New file.
	* gdb.threads/info-threads-cur-sal.c: New file.
	* gdb.threads/info-threads-cur-sal.exp: New file.

1 files changed, 57 insertions, 0 deletions

diff --git a/gdb/testsuite/gdb.threads/info-threads-cur-sal.exp b/gdb/testsuite/gdb.threads/info-threads-cur-sal.exp
new file mode 100644
index 0000000..f18ae0c
--- /dev/null
+++ b/gdb/testsuite/gdb.threads/info-threads-cur-sal.exp
@@ -0,0 +1,57 @@
+# Copyright (C) 2013 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+standard_testfile info-threads-cur-sal.c info-threads-cur-sal-2.c
+
+set executable ${testfile}
+
+if {[gdb_compile_pthreads \
+	 "${srcdir}/${subdir}/${srcfile} ${srcdir}/${subdir}/${srcfile2}" \
+	 "${binfile}" executable {debug}] != "" } {
+    return -1
+}
+
+clean_restart ${executable}
+
+if ![runto_main] {
+    return -1
+}
+
+gdb_breakpoint "start"
+gdb_continue_to_breakpoint "start"
+
+set line [gdb_get_line_number "should show this line" "${srcfile2}"]
+
+gdb_test "list $line" \
+    "\"list\" should show this line.*" \
+    "list before info threads"
+
+# There used to be a bug where "info threads" would set the current
+# SAL to the location of the last thread displayed.
+gdb_test "info threads" \
+    "\r\n\[ \t\]*Id\[ \t\]+Target\[ \t\]+Id\[ \t\]+Frame\[ \t\]*\r\n\\* 2 *Thread \[^\r\n\]* at \[^\r\n\]*\r\n  1 *Thread \[^\r\n\]* .* \[^\r\n\]*" \
+    "info threads before break"
+
+# Check that "break" is still operating on the same file by default.
+gdb_test "break $line" ".*${srcfile2}.*" "break on line"
+
+gdb_test "info threads" \
+    "\r\n\[ \t\]*Id\[ \t\]+Target\[ \t\]+Id\[ \t\]+Frame\[ \t\]*\r\n\\* 2 *Thread \[^\r\n\]* at \[^\r\n\]*\r\n  1 *Thread \[^\r\n\]* .* \[^\r\n\]*" \
+    "info threads before list"
+
+# And that so is "list".
+gdb_test "list $line" \
+    "\"list\" should show this line.*" \
+    "list after info threads"