sendemail: teach git-send-email to dump alias names

Add an option "--dump-aliases" which changes the default behavior of
git-send-email. This mode will simply read the alias files configured by
sendemail.aliasesfile and sendemail.aliasfiletype and dump a list of all
configured aliases, one per line. The intended use case for this option
is the bash-completion script which will use it to autocomplete aliases
on the options which take addresses.

Add some tests for the new option using various alias file formats.

A possible future extension to the alias dump format could be done by
extending the --dump-aliases to take an optional argument defining the
format to display. This has not been done in this patch as no user of
this information has been identified.

Signed-off-by: Jacob Keller <jacob.keller@gmail.com>
Signed-off-by: Jeff King <peff@peff.net>

1 files changed, 15 insertions, 0 deletions

diff --git a/git-send-email.perl b/git-send-email.perl
index e907e0eac..a475b0d75 100755
--- a/git-send-email.perl
+++ b/git-send-email.perl
@@ -46,6 +46,7 @@ package main;
 sub usage {
 	print <<EOT;
 git send-email [options] <file | directory | rev-list options >
+git send-email --dump-aliases
 
   Composing:
     --from                  <str>  * Email From:
@@ -101,6 +102,9 @@ git send-email [options] <file | directory | rev-list options >
                                      `git format-patch` ones.
     --force                        * Send even if safety checks would prevent it.
 
+  Information:
+    --dump-aliases                 * Dump configured aliases and exit.
+
 EOT
 	exit(1);
 }
@@ -180,6 +184,7 @@ my ($quiet, $dry_run) = (0, 0);
 my $format_patch;
 my $compose_filename;
 my $force = 0;
+my $dump_aliases = 0;
 
 # Handle interactive edition of files.
 my $multiedit;
@@ -291,6 +296,11 @@ $SIG{INT}  = \&signal_handler;
 
 my $help;
 my $rc = GetOptions("h" => \$help,
+                    "dump-aliases" => \$dump_aliases);
+usage() unless $rc;
+die "--dump-aliases incompatible with other options\n"
+    if !$help and $dump_aliases and @ARGV;
+$rc = GetOptions(
 		    "sender|from=s" => \$sender,
                     "in-reply-to=s" => \$initial_reply_to,
 		    "subject=s" => \$initial_subject,
@@ -551,6 +561,11 @@ if (@alias_files and $aliasfiletype and defined $parse_alias{$aliasfiletype}) {
 	}
 }
 
+if ($dump_aliases) {
+    print "$_\n" for (sort keys %aliases);
+    exit(0);
+}
+
 # is_format_patch_arg($f) returns 0 if $f names a patch, or 1 if
 # $f is a revision list specification to be passed to format-patch.
 sub is_format_patch_arg {