Test case for Bug 28308

The purpose of this test is described in the comments in
dprintf-execution-x-script.exp.

Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=28308

The name of this new test was based on that of an existing test,
bp-cmds-execution-x-script.exp.  I started off by copying that test,
adding to it, and then rewriting almost all of it.  It's different
enough that I decided that listing the copyright year as 2021
was sufficient.

gdb/testsuite/gdb.base/dprintf-execution-x-script.c

@@ -0,0 +1,53 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2021 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/>.  */
+
+#include <stdlib.h>
+#include <stdio.h>
+
+volatile int vi = 0;
+
+void
+inc_vi ()
+{
+  vi++;
+}
+
+void
+print_vi ()
+{
+  printf ("vi=%d\n", vi);
+}
+
+void
+increment ()
+{
+  inc_vi ();
+}
+
+int
+main (int argc, char **argv)
+{
+  print_vi ();
+  increment ();
+  print_vi ();
+  increment ();
+  print_vi ();
+  increment ();
+  print_vi ();
+
+  exit (0);
+}

gdb/testsuite/gdb.base/dprintf-execution-x-script.exp

@@ -0,0 +1,85 @@
+# Copyright 2021 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/>.  */
+
+# Test that commands in a GDB script file run via GDB's -x flag work
+# as expected.  Specifically, the script creates a dprintf breakpoint
+# as well as a normal breakpoint that has "continue" in its command
+# list, and then does "run".  Correct output from GDB is checked as
+# part of this test.
+
+# Bail out if the target can't use the 'run' command.
+if ![target_can_use_run_cmd] {
+    return 0
+}
+
+standard_testfile
+
+if {[build_executable "failed to prepare" $testfile $srcfile debug]} {
+    return -1
+}
+
+# This is the name of the GDB script to load.
+set x_file ${srcdir}/${subdir}/$testfile.gdb
+
+# Create context in which the global, GDBFLAGS, will be restored at
+# the end of the block.  All commands run within the block are
+# actually run in the outer context.  (This is why 'res' is available
+# outside of the save_vars block.)
+save_vars { GDBFLAGS } {
+    # Set flags with which to start GDB.
+    append GDBFLAGS " -ex \"set height unlimited\""
+    append GDBFLAGS " -x \"$x_file\""
+    append GDBFLAGS " --args \"$binfile\""
+
+    # Start GDB with above flags.
+    set res [gdb_spawn]
+}
+
+set test "load and run script with -x"
+if { $res != 0} {
+    fail $test
+    return -1
+}
+
+# The script loaded via -x contains a run command; while running, GDB
+# is expected to print three messages from dprintf breakpoints along
+# with three interspersed messages from an ordinary breakpoint (which
+# was set up with a continue command).  Set up pattern D to match
+# output from hitting the dprintf breakpoint and B for the ordinary
+# breakpoint.  Then set PAT to contain the entire pattern of expected
+# output from the interspersed dprintf and ordinary breakpoints along
+# with some (additional) expected output from the dprintf breakpoints,
+# i.e. 0, 1, and 2.
+set d "dprintf in increment.., vi="
+set b "Breakpoint ., inc_vi"
+set pat "${d}0.*?$b.*?${d}1.*?$b.*?${d}2.*?$b.*?"
+
+proc do_test {cmd test} {
+    gdb_test $cmd "$::pat$::inferior_exited_re normally.*" $test
+}
+
+# Check output from running script with -x
+do_test "" $test
+
+# Restart GDB and 'source' the script; this will (still) run the program
+# due to the 'run' command in the script.
+clean_restart $binfile
+do_test "source $x_file" "load and run script using source command"
+
+# This should leave us at the gdb prompt; Run program again using
+# already established breakpoints, i.e. those loaded from the
+# script.  Prior to fixing PR 28308, this was the only test that
+# would pass.
+do_test "run" "run again"

gdb/testsuite/gdb.base/dprintf-execution-x-script.gdb

@@ -0,0 +1,21 @@
+# Copyright 2021 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/>.  */
+
+dprintf increment, "dprintf in increment(), vi=%d\n", vi
+break inc_vi
+commands
+  continue
+end
+run