Hi!

I have two C++ projects (using name A and B afterwards). Project B depends on A; Ie. doxygen-generation of B depends on ../A/A.tag, which is created in a previous build-step.

There was no error or warning in doxygen-pass A, but the second doxygen-generation of B results in following warnings:
../A/A.tag:16087: warning: Unknown compound attribute `singleton' found!
../A/A.tag:16088: warning: Unexpected tag `name' found
../A/A.tag:16089: warning: Unexpected tag `filename' found
../A/A.tag:16090: warning: Unexpected tag `templarg' found
../A/A.tag:16091: warning: tag `compound' was not expected!

After some investigations, Ie. comparing the output of doxygen 1.8.8 to the previous release 1.8.7, I've determined following issue:

A C++ header-file of project A does contain a forward-declaration of a template-class, like:
template <typename TFnc> class Delegate; /*FORWARD-DECLARATION*/

Doxygen 1.8.7 has generated a documentation (snippet) like:

  Delegate< TFnc > Class Template Reference
and in 'Detailed Description':
  template<typename TFnc>
  class Gmc::util::Delegate< TFnc >

, but the HTML-result of Doxygen 1.8.8 was:

  Delegate< TFnc > Singleton Reference
and in 'Detailed Description':
  template<typename TFnc>
  singleton Gmc::util::Delegate< TFnc >

At least, it seems, that doxygen 1.8.8 has changes the (principal) type/classification from 'class template' to 'singleton' for this templated class-declaration. The warnings afterwards (Unknown compound attribute) for "doxygen" project B are subsequent issues.

I've also searched for some information a similar Singleton-issue or whether this is a special kind of (doxygen-) region/type; but w/o success :-(

Best regards from Salzburg,
Markus