Merge branch 'jk/maint-send-email-alias-loop'

* jk/maint-send-email-alias-loop:
  send-email: detect cycles in alias expansion

git-send-email.perl

@@ -654,13 +654,17 @@ sub ask {
 }
 
 sub expand_aliases {
-	my @cur = @_;
-	my @last;
-	do {
-		@last = @cur;
-		@cur = map { $aliases{$_} ? @{$aliases{$_}} : $_ } @last;
-	} while (join(',',@cur) ne join(',',@last));
-	return @cur;
+	return map { expand_one_alias($_) } @_;
+}
+
+my %EXPANDED_ALIASES;
+sub expand_one_alias {
+	my $alias = shift;
+	if ($EXPANDED_ALIASES{$alias}) {
+		die "fatal: alias '$alias' expands to itself\n";
+	}
+	local $EXPANDED_ALIASES{$alias} = 1;
+	return $aliases{$alias} ? expand_aliases(@{$aliases{$alias}}) : $alias;
 }
 
 @to = expand_aliases(@to);