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.

1 files changed, 5 insertions, 2 deletions

diff --git a/gdb/cli/cli-cmds.c b/gdb/cli/cli-cmds.c
index 460b719..0ef325d 100644
--- a/gdb/cli/cli-cmds.c
+++ b/gdb/cli/cli-cmds.c
@@ -571,11 +571,14 @@ 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
-	return;
+	{
+	  perror_warning_with_name (file);
+	  return;
+	}
     }
 
   old_cleanups = make_cleanup (xfree, full_path);