send-email: refactor address list process

Simplify code by creating a function which transform a list of strings
containing email addresses (separated by commas, comporting aliases)
into a clean list of valid email addresses.

Signed-off-by: Remi Lespinet <remi.lespinet@ensimag.grenoble-inp.fr>
Signed-off-by: Matthieu Moy <Matthieu.Moy@imag.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

git-send-email.perl

@@ -808,12 +808,9 @@ sub expand_one_alias {
 	return $aliases{$alias} ? expand_aliases(@{$aliases{$alias}}) : $alias;
 }
 
-@initial_to = expand_aliases(@initial_to);
+@initial_to = process_address_list(@initial_to);
-@initial_to = validate_address_list(sanitize_address_list(@initial_to));
+@initial_cc = process_address_list(@initial_cc);
-@initial_cc = expand_aliases(@initial_cc);
+@bcclist = process_address_list(@bcclist);
-@initial_cc = validate_address_list(sanitize_address_list(@initial_cc));
-@bcclist = expand_aliases(@bcclist);
-@bcclist = validate_address_list(sanitize_address_list(@bcclist));
 
 if ($thread && !defined $initial_reply_to && $prompting) {
 	$initial_reply_to = ask(
@@ -1026,6 +1023,13 @@ sub sanitize_address_list {
 	return (map { sanitize_address($_) } @_);
 }
 
+sub process_address_list {
+	my @addr_list = expand_aliases(@_);
+	@addr_list = sanitize_address_list(@addr_list);
+	@addr_list = validate_address_list(@addr_list);
+	return @addr_list;
+}
+
 # Returns the local Fully Qualified Domain Name (FQDN) if available.
 #
 # Tightly configured MTAa require that a caller sends a real DNS
@@ -1535,10 +1539,8 @@ foreach my $t (@files) {
 		($confirm =~ /^(?:auto|compose)$/ && $compose && $message_num == 1));
 	$needs_confirm = "inform" if ($needs_confirm && $confirm_unconfigured && @cc);
 
-	@to = expand_aliases(@to);
+	@to = process_address_list(@to);
-	@to = validate_address_list(sanitize_address_list(@to));
+	@cc = process_address_list(@cc);
-	@cc = expand_aliases(@cc);
-	@cc = validate_address_list(sanitize_address_list(@cc));
 
 	@to = (@initial_to, @to);
 	@cc = (@initial_cc, @cc);