Issue with enable-log option failing while building

[Gaurav Arora]

Pastebin of error: ​https://pastebin.com/Zk4hqU7R

:
./common/pretty.h:59:11:   required from ‘PrettyOStream<S>& operator<<(PrettyOStream<S>&, const T&) [with S = std::__cxx11::basic_ostringstream<char>; T = Xapian::KeyMaker]’
./common/pretty.h:87:15:   required from ‘PrettyOStream<S>& operator<<(PrettyOStream<S>&, const T*) [with S = std::__cxx11::basic_ostringstream<char>; T = Xapian::KeyMaker]’
api/registry.cc:448:5:   required from here
/usr/include/c++/8/ostream:682:5: error: no type named ‘type’ in ‘struct std::enable_if<false, std::basic_ostream<char>&>’
make[2]: *** [Makefile:3259: api/registry.lo] Error 1

When build is configured with --enable-log option, building xapian fails. It fails because KeyMaker class doesn't have get_description method which is probably used for logging.

I was get away with an error while adding a dummy get_description method. It will be good to fix this issue. I can try fixing this but I was not sure what to return in description for KeyMaker.

I can give it a go with guidance on what to return.

[Olly Betts]

Classes which don't have a get_description() method are handled in common/pretty.h. Something like this (untested) should show them in the debug log as their class name:

diff --git a/xapian-core/common/pretty.h b/xapian-core/common/pretty.h
index 1e0393399fa3..c459d3836893 100644
--- a/xapian-core/common/pretty.h
+++ b/xapian-core/common/pretty.h
@@ -280,6 +280,7 @@ operator<<(PrettyOStream<S> &ps, const Xapian::VecCOW<T>& v)
 {
 
 namespace Xapian {
     class ExpandDecider;
+    class KeyMaker;
     class LatLongMetric;
     class MatchDecider;
     class Registry;
@@ -316,6 +317,7 @@ XAPIAN_PRETTY_AS_CLASSNAME(Xapian::Centroid)
 XAPIAN_PRETTY_AS_CLASSNAME(Xapian::Cluster)
 XAPIAN_PRETTY_AS_CLASSNAME(Xapian::ClusterSet)
 XAPIAN_PRETTY_AS_CLASSNAME(Xapian::ExpandDecider)
+XAPIAN_PRETTY_AS_CLASSNAME(Xapian::KeyMaker)
 XAPIAN_PRETTY_AS_CLASSNAME(Xapian::LatLongMetric)
 XAPIAN_PRETTY_AS_CLASSNAME(Xapian::MatchDecider)
 XAPIAN_PRETTY_AS_CLASSNAME(Xapian::Point)

XAPIAN_PRETTY_AS_CLASSNAME(C) is a macro which expands to an operator<< overload for const C&.

Classes with get_description() are handled automatically via the template in common/output.h.

[Gaurav Arora]

Thanks, olly This change seems to work. Do you want me to make a PR or would it be better if you directly apply the change?

[Olly Betts]

It's simplest for me just to apply the fix - will push as 99ee5809c4d21a4c2d284cbabff2b9d1293e3be9 shortly once my test build completes. This problem shouldn't affect 1.4.x as it's caused by the changes to support remote KeyMaker objects, so nothing to backport.

[Olly Betts]

I pushed a fix back on Jan 6th: 99ee5809c4d21a4c2d284cbabff2b9d1293e3be9