index: warn with info about the message as context

This can help users track down the source of warnings
when presented with imperfect emails.

While we're at it, make the __WARN__ callback in t/v2writable.t
a no-op since we don't check for warnings, there.

1 files changed, 7 insertions, 0 deletions

diff --git a/lib/PublicInbox/SearchIdxPart.pm b/lib/PublicInbox/SearchIdxPart.pm
index 7fe2120a..51d81a0a 100644
--- a/lib/PublicInbox/SearchIdxPart.pm
+++ b/lib/PublicInbox/SearchIdxPart.pm
@@ -48,8 +48,15 @@ sub spawn_worker {
 sub partition_worker_loop ($$$$) {
         my ($self, $r, $part, $bnote) = @_;
         $0 = "pi-v2-partition[$part]";
+        my $current_info = '';
+        my $warn_cb = $SIG{__WARN__} || sub { print STDERR @_ };
+        local $SIG{__WARN__} = sub {
+                chomp $current_info;
+                $warn_cb->("[$part] $current_info: ", @_);
+        };
         $self->begin_txn_lazy;
         while (my $line = $r->getline) {
+                $current_info = $line;
                 if ($line eq "commit\n") {
                         $self->commit_txn_lazy;
                 } elsif ($line eq "close\n") {