Testcase for previous handle_no_resumed fixes

This adds a testcase that covers the scenarios described in the
previous two commits.

gdb/testsuite/ChangeLog:

	PR gdb/26199
	* gdb.multi/multi-target.c (exit_thread): New.
	(thread_start): Break loop if EXIT_THREAD.
	* gdb.multi/multi-target.exp (test_no_unwaited_for): New proc.
	(top level) Call test_no_resumed.

gdb/testsuite/ChangeLog

@@ -1,3 +1,11 @@
+2020-07-10  Pedro Alves  <pedro@palves.net>
+
+	PR gdb/26199
+	* gdb.multi/multi-target.c (exit_thread): New.
+	(thread_start): Break loop if EXIT_THREAD.
+	* gdb.multi/multi-target.exp (test_no_unwaited_for): New proc.
+	(top level) Call test_no_resumed.
+
 2020-07-08  Tom Tromey  <tromey@adacore.com>
 
 	* gdb.ada/catch_ex/foo.adb: Pass string to raise.

gdb/testsuite/gdb.multi/multi-target.c

@@ -26,12 +26,14 @@
 
 static pthread_barrier_t barrier;
 
+volatile int exit_thread;
+
 static void *
 thread_start (void *arg)
 {
   pthread_barrier_wait (&barrier);
 
-  while (1)
+  while (!exit_thread)
     sleep (1);
   return NULL;
 }

gdb/testsuite/gdb.multi/multi-target.exp

@@ -439,6 +439,77 @@ proc test_info_inferiors {multi_process} {
     }
 }
 
+# Test that when there's a foreground execution command in progress, a
+# TARGET_WAITKIND_NO_RESUMED for a particular target is ignored when
+# other targets are still resumed.
+
+proc test_no_resumed {} {
+    proc test_no_resumed_infs {inf_A inf_B} {
+	global gdb_prompt
+
+	if {![setup "off"]} {
+	    untested "setup failed"
+	    return
+	}
+
+	gdb_test "thread $inf_A.2" "Switching to thread $inf_A\.2 .*" \
+	    "select thread of target A"
+
+	gdb_test_no_output "set scheduler-locking on"
+
+	gdb_test_multiple "continue &" "" {
+	    -re "Continuing.*$gdb_prompt " {
+		pass $gdb_test_name
+	    }
+	}
+
+	gdb_test "thread $inf_B.2" "Switching to thread $inf_B\.2 .*" \
+	    "select thread of target B"
+	gdb_test "p exit_thread = 1" " = 1" \
+	    "set the thread to exit on resumption"
+
+	# Wait 3 seconds.  If we see any response from GDB, such as
+	# "No unwaited-for children left." it's a bug.
+	gdb_test_multiple "continue" "continue" {
+	    -timeout 3
+	    timeout {
+		pass $gdb_test_name
+	    }
+	}
+
+	# Now stop the program (all targets).
+	send_gdb "\003"
+	gdb_test_multiple "" "send_gdb control C" {
+	    -re "received signal SIGINT.*$gdb_prompt $" {
+		pass $gdb_test_name
+	    }
+	}
+
+	gdb_test_multiple "info threads" "all threads stopped" {
+	    -re "\\\(running\\\).*$gdb_prompt $" {
+		fail $gdb_test_name
+	    }
+	    -re "$gdb_prompt $" {
+		pass $gdb_test_name
+	    }
+	}
+    }
+
+    # inferior 1 -> native
+    # inferior 2 -> extended-remote 1
+    # inferior 5 -> extended-remote 2
+    set inferiors {1 2 5}
+    foreach_with_prefix inf_A $inferiors {
+	foreach_with_prefix inf_B $inferiors {
+	    if {$inf_A == $inf_B} {
+		continue
+	    }
+	    test_no_resumed_infs $inf_A $inf_B
+	}
+    }
+}
+
+
 # Make a core file with two threads upfront.  Several tests load the
 # same core file.
 prepare_core
@@ -467,4 +538,9 @@ with_test_prefix "info-inferiors" {
     }
 }
 
+# Test TARGET_WAITKIND_NO_RESUMED handling with multiple targets.
+with_test_prefix "no-resumed" {
+    test_no_resumed
+}
+
 cleanup_gdbservers