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, 13 insertions, 0 deletions

diff --git a/gdb/utils.c b/gdb/utils.c
index 402fe8ee240..89c248cc46d 100644
--- a/gdb/utils.c
+++ b/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.  */