warn if "source" fails to open the file when from_tty == 0

Consider the following example:

    % gdb -q -batch -ex 'source nonexistant-file'
    [nothing]

One would have at least expected the debugger to warn about
not finding the file, similar to the error shown when using
a more interactive mode. Eg:

    (gdb) source nonexistant-file
    nonexistant-file: No such file or directory.

Not raising an error appears to be intentional, presumably in order
to prevent this situation from stoping the execution of a GDB script.
But the lack of at least a warning makes it harder for a user to
diagnose any issue, if the file was expected to be there and readable.

This patch adds a warning in that case:

    % gdb -q -batch -ex 'source nonexistant-file'
    warning: nonexistant-file: No such file or directory.

gdb/ChangeLog:

        * utils.h (perror_warning_with_name): Add declaration.
        * utils.c (perror_warning_with_name): New function.
        * cli/cli-cmds.c (source_script_with_search): Add call to
        perror_warning_with_name if from_tty is nul.

gdb/testsuite/ChangeLog:

        * gdb.base/source-nofile.gdb: New file.
        * gdb.base/source.exp: Add two tests verifying the behavior when
        the "source" command is given a non-existant filename.

gdb/ChangeLog

@@ -1,3 +1,10 @@
+2013-11-11  Joel Brobecker  <brobecker@adacore.com>
+
+	* utils.h (perror_warning_with_name): Add declaration.
+	* utils.c (perror_warning_with_name): New function.
+	* cli/cli-cmds.c (source_script_with_search): Add call to
+	perror_warning_with_name if from_tty is nul.
+
 2013-11-11  Joel Brobecker  <brobecker@adacore.com>
 
 	* utils.c (perror_string): New function, extracted out of

gdb/cli/cli-cmds.c

@@ -571,12 +571,15 @@ source_script_with_search (const char *file, int from_tty, int search_path)
       /* The script wasn't found, or was otherwise inaccessible.
          If the source command was invoked interactively, throw an
 	 error.  Otherwise (e.g. if it was invoked by a script),
-	 silently ignore the error.  */
+	 just emit a warning, rather than cause an error.  */
       if (from_tty)
 	perror_with_name (file);
       else
+	{
+	  perror_warning_with_name (file);
 	  return;
 	}
+    }
 
   old_cleanups = make_cleanup (xfree, full_path);
   make_cleanup_fclose (stream);

gdb/testsuite/ChangeLog

@@ -1,3 +1,9 @@
+2013-10-11  Joel Brobecker  <brobecker@adacore.com>
+
+	* gdb.base/source-nofile.gdb: New file.
+	* gdb.base/source.exp: Add two tests verifying the behavior when
+	the "source" command is given a non-existant filename.
+
 2013-10-11  Yao Qi  <yao@codesourcery.com>
 
 	* gdb.mi/mi-catch-load.c: Remove the include of "dlfcn.h".

gdb/testsuite/gdb.base/source-nofile.gdb

@@ -0,0 +1,22 @@
+# This testcase is part of GDB, the GNU debugger.
+#
+# Copyright 2013 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/>.
+
+source for-sure-nonexistant-file
+
+# Just print an message to confirm that failing to source the file
+# did not cause this script to abort.
+echo source error not fatal\n

gdb/testsuite/gdb.base/source.exp

@@ -57,4 +57,13 @@ gdb_test "source -v -s ./source-test.gdb" \
     "echo test source options.*" \
     "source -v -s"
 
+# Test sourcing a non-existant file, both when the source command
+# comes from the a command entered at the GDB prompt, and when
+# it comes from a script being sourced.
+gdb_test "source for-sure-nonexistant-file" \
+         "for-sure-nonexistant-file: No such file or directory\."
+
+gdb_test "source source-nofile.gdb" \
+         "warning: for-sure-nonexistant-file: No such file or directory\.\[\r\n\]*source error not fatal"
+
 gdb_exit

gdb/utils.c

@@ -1006,6 +1006,19 @@ perror_with_name (const char *string)
   throw_perror_with_name (GENERIC_ERROR, string);
 }
 
+/* Same as perror_with_name except that it prints a warning instead
+   of throwing an error.  */
+
+void
+perror_warning_with_name (const char *string)
+{
+  char *combined;
+
+  combined = perror_string (string);
+  warning (_("%s"), combined);
+  xfree (combined);
+}
+
 /* Print the system error message for ERRCODE, and also mention STRING
    as the file name for which the error was encountered.  */
 

gdb/utils.h

@@ -285,6 +285,8 @@ extern void throw_perror_with_name (enum errors errcode, const char *string)
   ATTRIBUTE_NORETURN;
 extern void perror_with_name (const char *) ATTRIBUTE_NORETURN;
 
+extern void perror_warning_with_name (const char *string);
+
 extern void print_sys_errmsg (const char *, int);
 
 /* Warnings and error messages.  */