altid: warn about non-word prefixes

We only support searching on prefixes matching /\A\w+\z/ because
Xapian requires ':' to delimit the prefix and splits on spaces
without quotes.

I've also verified Xapian supports multibyte UTF-8 characters,
underscores, and bare numbers as search prefixes, so there's
no need to restrict it beyond what Perl's UTF-8 aware \w
character class offers.

1 files changed, 2 insertions, 0 deletions

diff --git a/lib/PublicInbox/Search.pm b/lib/PublicInbox/Search.pm
index fabf5301..86a6ad67 100644
--- a/lib/PublicInbox/Search.pm
+++ b/lib/PublicInbox/Search.pm
@@ -316,6 +316,8 @@ sub qp {
                 my $user_pfx = $self->{-user_pfx} = [];
                 for (@$altid) {
                         # $_ = 'serial:gmane:/path/to/gmane.msgmap.sqlite3'
+                        # note: Xapian supports multibyte UTF-8, /^[0-9]+$/,
+                        # and '_' with prefixes matching \w+
                         /\Aserial:(\w+):/ or next;
                         my $pfx = $1;
                         push @$user_pfx, "$pfx:", <<EOF;