gdb: make set/show inferior-tty work with $_gdb_setting_str

Like the previous two commits, this commit fixes set/show inferior-tty
to work with $_gdb_setting_str.

Instead of using a scratch variable which is then pushed into the
current inferior from a set callback, move to the API that allows for
getters and setters, and store the value directly within the current
inferior.

Update an existing test to check the inferior-tty setting.

Reviewed-By: Tom Tromey <tom@tromey.com>

gdb/infcmd.c

@@ -66,11 +66,6 @@ static void step_1 (int, int, const char *);
 #define ERROR_NO_INFERIOR \
    if (!target_has_execution ()) error (_("The program is not being run."));
 
-/* Scratch area where 'set inferior-tty' will store user-provided value.
-   We'll immediate copy it into per-inferior storage.  */
-
-static std::string inferior_io_terminal_scratch;
-
 /* Pid of our debugged inferior, or 0 if no inferior now.
    Since various parts of infrun.c test this to see whether there is a program
    being debugged it should be nonzero (currently 3 is used) for remote
@@ -94,15 +89,24 @@ static bool finish_print = true;
 
 
 
+/* Store the new value passed to 'set inferior-tty'.  */
+
 static void
-set_inferior_tty_command (const char *args, int from_tty,
-			  struct cmd_list_element *c)
+set_tty_value (const std::string &tty)
 {
-  /* CLI has assigned the user-provided value to inferior_io_terminal_scratch.
-     Now route it to current inferior.  */
-  current_inferior ()->set_tty (inferior_io_terminal_scratch);
+  current_inferior ()->set_tty (tty);
 }
 
+/* Get the current 'inferior-tty' value.  */
+
+static const std::string &
+get_tty_value ()
+{
+  return current_inferior ()->tty ();
+}
+
+/* Implement 'show inferior-tty' command.  */
+
 static void
 show_inferior_tty_command (struct ui_file *file, int from_tty,
 			   struct cmd_list_element *c, const char *value)
@@ -3136,14 +3140,14 @@ _initialize_infcmd ()
 
   /* Add the filename of the terminal connected to inferior I/O.  */
   auto tty_set_show
-    = add_setshow_optional_filename_cmd ("inferior-tty", class_run,
-					 &inferior_io_terminal_scratch, _("\
+    = add_setshow_optional_filename_cmd ("inferior-tty", class_run, _("\
 Set terminal for future runs of program being debugged."), _("		\
 Show terminal for future runs of program being debugged."), _("		\
 Usage: set inferior-tty [TTY]\n\n					\
 If TTY is omitted, the default behavior of using the same terminal as GDB\n \
 is restored."),
-					 set_inferior_tty_command,
+					 set_tty_value,
+					 get_tty_value,
 					 show_inferior_tty_command,
 					 &setlist, &showlist);
   add_alias_cmd ("tty", tty_set_show.set, class_run, 0, &cmdlist);

gdb/testsuite/gdb.base/inferior-clone.exp

@@ -30,6 +30,8 @@ with_test_prefix "setup inferior 1" {
     gdb_test_no_output "set environment FOO foo"
     gdb_test_no_output "set environment BAR bar"
     gdb_test_no_output "set inferior-tty some_tty"
+    gdb_test {print $_gdb_setting_str("inferior-tty")} \
+	" = \"some_tty\""
 }
 
 # Check that properties of inferior 1 have been copied
@@ -45,6 +47,8 @@ with_test_prefix "inferior 2" {
     gdb_test "show environment ENVVAR" "ENVVAR = var"
     gdb_test "show inferior-tty" \
 	"Terminal for future runs of program being debugged is \"some_tty\"\."
+    gdb_test {print $_gdb_setting_str("inferior-tty")} \
+	" = \"some_tty\""
 }
 
 # Change this second inferior, to check that the next clone-inferior
@@ -54,6 +58,9 @@ with_test_prefix "update inferior 2" {
     gdb_test_no_output "set args foo"
     gdb_test_no_output "set cwd /somewhere/else"
     gdb_test_no_output "set environment FOO oof"
+    gdb_test_no_output "set inferior-tty another_tty"
+    gdb_test {print $_gdb_setting_str("inferior-tty")} \
+	" = \"another_tty\""
 }
 
 with_test_prefix "inferior 1" {
@@ -67,6 +74,8 @@ with_test_prefix "inferior 1" {
     gdb_test "show environment ENVVAR" "ENVVAR = var"
     gdb_test "show inferior-tty" \
 	"Terminal for future runs of program being debugged is \"some_tty\"\."
+    gdb_test {print $_gdb_setting_str("inferior-tty")} \
+	" = \"some_tty\""
 }
 
 # Tweak inferior 1 a bit more.

gdb/testsuite/gdb.multi/gdb-settings.exp

@@ -70,6 +70,7 @@ foreach_with_prefix inf $inferiors {
 	"switch to inferior ${inf} before set"
     gdb_test_no_output "set args inf${inf}-args"
     gdb_test_no_output "set cwd /inf${inf}-cwd"
+    gdb_test_no_output "set inferior-tty /inf${inf}-tty"
 }
 
 # Check settings are still correct for each inferior.
@@ -84,19 +85,30 @@ foreach_with_prefix inf $inferiors {
     gdb_test "with cwd tmp-value -- print 1" " = 1"
     gdb_test "show cwd" "/inf${inf}-cwd.*"
 
+    gdb_test "with inferior-tty tmp-value -- print 1" " = 1"
+    gdb_test "show inferior-tty" "/inf${inf}-tty.*"
+
     # If the inferiors are running check $_gdb_setting_str and
     # $_gdb_setting return the correct values.
     if { $run } {
 	gdb_test {print $_gdb_setting_str("args")} "\"inf${inf}-args\""
 	gdb_test {print $_gdb_setting("args")} "\"inf${inf}-args\""
+
 	gdb_test {print $_gdb_setting_str("cwd")} "\"/inf${inf}-cwd\""
 	gdb_test {print $_gdb_setting("cwd")} "\"/inf${inf}-cwd\""
+
+	gdb_test {print $_gdb_setting_str("inferior-tty")} \
+	    "\"/inf${inf}-tty\""
+	gdb_test {print $_gdb_setting("inferior-tty")} \
+	    "\"/inf${inf}-tty\""
     }
 
     # Check the settings can be read from Python.
     if { $run_python_tests } {
 	gdb_test "python print(gdb.parameter('args'))" "inf${inf}-args"
 	gdb_test "python print(gdb.parameter('cwd'))" "/inf${inf}-cwd"
+	gdb_test "python print(gdb.parameter('inferior-tty'))" \
+	    "/inf${inf}-tty"
     }
 
     # Check the settings can be read from Guile.
@@ -105,5 +117,7 @@ foreach_with_prefix inf $inferiors {
 	    "inf${inf}-args"
 	gdb_test "guile (print (parameter-value \"cwd\"))" \
 	    "/inf${inf}-cwd"
+	gdb_test "guile (print (parameter-value \"inferior-tty\"))" \
+	    "/inf${inf}-tty"
     }
 }