[Ada] Raise exception on call to Expect for a dead process

Call to Expect for a dead process results in SIGBUS signal on Linux
systems. Process_Died exception is raised in this case now.

2019-09-18  Vadim Godunko  <godunko@adacore.com>

gcc/ada/

	* libgnat/g-expect.adb (Expect_Internal): Don't include invalid
	file descriptors into the set of file descriptors for Poll.
	Raise Process_Died exception when computed set of file
	descriptors to monitor is empty.

gcc/testsuite/

	* gnat.dg/expect4.adb: New testcase.

From-SVN: r275847

1 files changed, 35 insertions, 0 deletions

diff --git a/gcc/testsuite/gnat.dg/expect4.adb b/gcc/testsuite/gnat.dg/expect4.adb
new file mode 100644
index 0000000..7a974cc
--- /dev/null
+++ b/gcc/testsuite/gnat.dg/expect4.adb
@@ -0,0 +1,35 @@
+--  { dg-do run }
+
+with GNAT.Expect.TTY;
+with GNAT.OS_Lib;
+
+procedure Expect4 is
+   Pid    : GNAT.Expect.TTY.TTY_Process_Descriptor;
+   Args   : GNAT.OS_Lib.Argument_List (1 .. 0);
+   Result : GNAT.Expect.Expect_Match;
+
+begin
+   Pid.Non_Blocking_Spawn ("true", Args);
+
+   begin
+      Pid.Expect (Result, ".*");
+
+      raise Program_Error;
+
+   exception
+      when GNAT.Expect.Process_Died =>
+         null;
+   end;
+
+   begin
+      Pid.Expect (Result, ".*");
+
+      raise Program_Error;
+
+   exception
+      when GNAT.Expect.Process_Died =>
+         null;
+   end;
+
+   Pid.Close;
+end Expect4;
\ No newline at end of file