Add testing infrastruture bits for running with MI on a separate UI

With this, a specific test may can start GDB with MI on a separate UI
by using:

  mi_gdb_start separate-mi-tty

In addition, it's also possible to run the whole testsuite with MI on
a separate tty, with:

 make check RUNTESTFLAGS="FORCE_SEPARATE_MI_TTY=1"

gdb_main_spawn_id and mi_spawn_id are added so that tests may expect
output from either channel.

While at it, inferior_spawn_id was not being cleared when gdb exits,
unlike the other spawn ids, thus a test that starts gdb more than once
would end up using a stale spawn id.

gdb/testsuite/ChangeLog:
2016-06-21  Pedro Alves  <palves@redhat.com>

	* README (Testsuite Parameters): Document FORCE_SEPARATE_MI_TTY.
	* lib/gdb.exp (default_gdb_exit): Clear inferior_spawn_id.
	* lib/mi-support.exp (mi_uncatched_gdb_exit): Unset
	gdb_main_spawn_id, mi_spawn_id, unset inferior_spawn_id.
	(gdb_main_spawn_id, mi_spawn_id): Declare and
	comment.
	(mi_create_inferior_pty): New procedure,
	factored out from default_mi_gdb_start.
	(switch_gdb_spawn_id, mi_gdb_start_separate_mi_tty): New
	procedures.
	(default_mi_gdb_start): Call mi_gdb_start_separate_mi_tty if the
	separate-mi-tty option is specified, or SEPARATE_MI_TTY is set.
	Use mi_create_inferior_pty.
	(mi_gdb_start): Use eval to pass down args list.

4 files changed, 156 insertions, 29 deletions

diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index 9ad93eb..888d6cd 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,5 +1,22 @@
 2016-06-21  Pedro Alves  <palves@redhat.com>
 
+	* README (Testsuite Parameters): Document FORCE_SEPARATE_MI_TTY.
+	* lib/gdb.exp (default_gdb_exit): Clear inferior_spawn_id.
+	* lib/mi-support.exp (mi_uncatched_gdb_exit): Unset
+	gdb_main_spawn_id, mi_spawn_id, unset inferior_spawn_id.
+	(gdb_main_spawn_id, mi_spawn_id): Declare and
+	comment.
+	(mi_create_inferior_pty): New procedure,
+	factored out from default_mi_gdb_start.
+	(switch_gdb_spawn_id, mi_gdb_start_separate_mi_tty): New
+	procedures.
+	(default_mi_gdb_start): Call mi_gdb_start_separate_mi_tty if the
+	separate-mi-tty option is specified, or SEPARATE_MI_TTY is set.
+	Use mi_create_inferior_pty.
+	(mi_gdb_start): Use eval to pass down args list.
+
+2016-06-21  Pedro Alves  <palves@redhat.com>
+
 	* gdb.opt/inline-cmds.c: Add "set mi break here" marker.
 	* gdb.opt/inline-cmds.exp: Add MI tests.
 
diff --git a/gdb/testsuite/README b/gdb/testsuite/README
index 043a8bd..152318a 100644
--- a/gdb/testsuite/README
+++ b/gdb/testsuite/README
@@ -208,6 +208,12 @@ FORCE_PARALLEL
 Setting FORCE_PARALLEL to any non-empty value forces parallel testing
 mode even if RUNTESTFLAGS is not empty.
 
+FORCE_SEPARATE_MI_TTY
+
+Setting FORCE_MI_SEPARATE_UI to 1 forces all MI testing to start GDB
+in console mode, with MI running on a separate TTY, on a secondary UI
+started with "new-ui".
+
 GDB_INOTIFY
 
 For debugging parallel mode, it is handy to be able to see when a test
diff --git a/gdb/testsuite/lib/gdb.exp b/gdb/testsuite/lib/gdb.exp
index 436f708..878da16 100644
--- a/gdb/testsuite/lib/gdb.exp
+++ b/gdb/testsuite/lib/gdb.exp
@@ -1359,7 +1359,7 @@ proc default_gdb_exit {} {
     global GDB
     global INTERNAL_GDBFLAGS GDBFLAGS
     global verbose
-    global gdb_spawn_id
+    global gdb_spawn_id inferior_spawn_id
     global inotify_log_file
 
     gdb_stop_suppressing_tests
@@ -1400,6 +1400,7 @@ proc default_gdb_exit {} {
 	remote_close host
     }
     unset gdb_spawn_id
+    unset inferior_spawn_id
 }
 
 # Load a file into the debugger.
diff --git a/gdb/testsuite/lib/mi-support.exp b/gdb/testsuite/lib/mi-support.exp
index 87ce634..edfc07d 100644
--- a/gdb/testsuite/lib/mi-support.exp
+++ b/gdb/testsuite/lib/mi-support.exp
@@ -28,6 +28,16 @@ if ![info exists mi_gdb_prompt] then {
 
 global mi_inferior_tty_name
 
+# Always points to GDB's main UI spawn ID, even when testing with MI
+# running on a secondary UI.
+global gdb_main_spawn_id
+
+# Points to the spawn id of the MI channel.  When testing with MI
+# running as the primary/main UI, this is the same as
+# gdb_main_spawn_id, but will be different when testing with MI
+# running on a secondary UI.
+global mi_spawn_id
+
 set MIFLAGS "-i=mi"
 
 set thread_selected_re "=thread-selected,id=\"\[0-9\]+\"\r\n"
@@ -46,7 +56,8 @@ proc mi_uncatched_gdb_exit {} {
     global GDB
     global INTERNAL_GDBFLAGS GDBFLAGS
     global verbose
-    global gdb_spawn_id
+    global gdb_spawn_id gdb_main_spawn_id
+    global mi_spawn_id inferior_spawn_id
     global gdb_prompt
     global mi_gdb_prompt
     global MIFLAGS
@@ -83,14 +94,103 @@ proc mi_uncatched_gdb_exit {} {
 	remote_close host
     }
     unset gdb_spawn_id
+    unset gdb_main_spawn_id
+    unset mi_spawn_id
+    unset inferior_spawn_id
+}
+
+# Create the PTY for the inferior process and tell GDB about it.
+
+proc mi_create_inferior_pty {} {
+    global mi_gdb_prompt
+    global inferior_spawn_id
+    global mi_inferior_tty_name
+
+    spawn -pty
+    set inferior_spawn_id $spawn_id
+    set tty_name $spawn_out(slave,name)
+    set mi_inferior_tty_name $tty_name
+
+    send_gdb "102-inferior-tty-set $tty_name\n"
+    gdb_expect 10 {
+	-re ".*102\\\^done\r\n$mi_gdb_prompt$" {
+	    verbose "redirect inferior output to new terminal device."
+	}
+	timeout {
+	    warning "Couldn't redirect inferior output." 2
+	}
+    }
+}
+
+# Switch the default spawn id to SPAWN_ID, so that mi_gdb_test
+# etc. default to using it.
+
+proc switch_gdb_spawn_id {spawn_id} {
+    global gdb_spawn_id
+    global board board_info
+
+    set gdb_spawn_id $spawn_id
+    set board [host_info name]
+    set board_info($board,fileid) $spawn_id
+}
+
+proc mi_gdb_start_separate_mi_tty { args } {
+    global gdb_prompt mi_gdb_prompt
+    global timeout
+    global gdb_spawn_id gdb_main_spawn_id mi_spawn_id
+    global inferior_spawn_id
+
+    set separate_inferior_pty 0
+
+    foreach arg $args {
+	if {$arg == "separate-inferior-tty"} {
+	    set separate_inferior_pty 1
+	}
+    }
+
+    gdb_start
+
+    # Create the new PTY for the MI UI.
+    spawn -pty
+    set mi_spawn_id $spawn_id
+    set mi_tty_name $spawn_out(slave,name)
+    gdb_test_multiple "new-ui mi $mi_tty_name" "new-ui" {
+	-re "New UI allocated\r\n$gdb_prompt $" {
+	}
+    }
+
+    # Switch to the MI channel.
+    set gdb_main_spawn_id $gdb_spawn_id
+    switch_gdb_spawn_id $mi_spawn_id
+
+    # Consume pending output and MI prompt.
+    gdb_expect {
+	-re "$mi_gdb_prompt$" {
+	}
+	default {
+	    perror "MI channel failed"
+	    remote_close host
+	    return -1
+	}
+    }
+
+    if {$separate_inferior_pty} {
+	mi_create_inferior_pty
+    }
+
+    mi_detect_async
+
+    return 0
 }
 
 #
-# default_mi_gdb_start [INFERIOR_PTY] -- start gdb running, default procedure
+# default_mi_gdb_start [FLAGS] -- start gdb running, default procedure
 #
-# INFERIOR_PTY should be set to separate-inferior-tty to have the inferior work 
-# with it's own PTY. If set to same-inferior-tty, the inferior shares GDB's PTY. 
-# The default value is same-inferior-tty.
+# If "separate-inferior-tty" is specified, the inferior works with
+# it's own PTY.
+#
+# If "separate-mi-tty" is specified, the gdb starts in CLI mode, with
+# MI running on a secondary UI, on its own tty.
 #
 # When running over NFS, particularly if running many simultaneous
 # tests on different hosts all using the same server, things can
@@ -103,8 +203,29 @@ proc default_mi_gdb_start { args } {
     global gdb_prompt
     global mi_gdb_prompt
     global timeout
-    global gdb_spawn_id inferior_spawn_id
+    global gdb_spawn_id gdb_main_spawn_id inferior_spawn_id mi_spawn_id
     global MIFLAGS
+    global SEPARATE_MI_TTY
+
+    if {[info exists FORCE_SEPARATE_MI_TTY]} {
+	set separate_mi_pty $FORCE_SEPARATE_MI_TTY
+    } else {
+	set separate_mi_pty 0
+    }
+
+    set separate_inferior_pty 0
+
+    foreach arg $args {
+	if {$arg == "separate-mi-tty"} {
+	    set separate_mi_pty 1
+	} elseif {$arg == "separate-inferior-tty"} {
+	    set separate_inferior_pty 1
+	}
+    }
+
+    if {$separate_mi_pty} {
+	return [eval mi_gdb_start_separate_mi_tty $args]
+    }
 
     gdb_stop_suppressing_tests
     set inferior_pty no-tty
@@ -112,12 +233,6 @@ proc default_mi_gdb_start { args } {
     # Set the default value, it may be overriden later by specific testfile.
     set use_gdb_stub [target_info exists use_gdb_stub]
 
-    if { [llength $args] == 1} {
-	set inferior_pty [lindex $args 0]
-    }
-
-    set separate_inferior_pty [string match $inferior_pty separate-inferior-tty]
-
     # Start SID.
     if { [info procs sid_start] != "" } {
 	verbose "Spawning SID"
@@ -182,6 +297,8 @@ proc default_mi_gdb_start { args } {
 	}
     }
     set gdb_spawn_id $res
+    set gdb_main_spawn_id $res
+    set mi_spawn_id $res
 
     # FIXME: mi output does not go through pagers, so these can be removed.
     # force the height to "unlimited", so no pagers get used
@@ -205,22 +322,8 @@ proc default_mi_gdb_start { args } {
 	}
     }
 
-    # Create the new PTY for the inferior process.
     if { $separate_inferior_pty } {
-	spawn -pty
-	global mi_inferior_tty_name
-	set inferior_spawn_id $spawn_id
-	set mi_inferior_tty_name $spawn_out(slave,name)
-
-	send_gdb "102-inferior-tty-set $mi_inferior_tty_name\n"
-	gdb_expect 10 {
-	    -re ".*102\\\^done\r\n$mi_gdb_prompt$" {
-		verbose "redirect inferior output to new terminal device."
-	    }
-	    timeout {
-		warning "Couldn't redirect inferior output." 2
-	    }
-	}
+	mi_create_inferior_pty
     }
 
     if {![info exists inferior_spawn_id]} {
@@ -237,7 +340,7 @@ proc default_mi_gdb_start { args } {
 # baseboard file.
 #
 proc mi_gdb_start { args } {
-  return [default_mi_gdb_start $args]
+  return [eval default_mi_gdb_start $args]
 }
 
 # Many of the tests depend on setting breakpoints at various places and