problems with conversion function

[Oliver Kullmann <O dot Kullmann at Swansea dot ac dot uk>]

Hi,

nearly every time I'm using a conversion function it does not work, so I basically
stopped using conversion functions, but this evening I'm pretty determined --- I have
to know what's going on!

Unfortunately, I have never been able to reproduce the error with a small example, so
here's the error message I get (I'm using gcc version 3.0.4 (SuSE)):


submission.cpp: In function `CgiHandling::Transfer_codes transfer(const
   CgiHandling::ValueMap&, const std::string&)':
submission.cpp:257: no matching function for call to
   `SystemHandling::PidType::PidType(AutomatedCompilation::Compilation<AutomatedCompilation::gpc_delphi_transfer,
   AutomatedCompilation::Environment_wwwrun,
   AutomatedCompilation::both_outputs,
   AutomatedCompilation::unchanged_source_file,
   AutomatedCompilation::transfer_source_name> (&)(std::basic_string<char,
   std::char_traits<char>, std::allocator<char> >, std::basic_string<char,
   std::char_traits<char>, std::allocator<char> >))'
SystemHandling.hpp:317: candidates
   are: SystemHandling::PidType::PidType(const SystemHandling::PidType&)
SystemHandling.hpp:319:
                  SystemHandling::PidType::PidType()


the offending line 257 (in submission.cpp) is:

Pid = (PidType) C;

(where I get the same error for other forms:
Pid = C; Pid = PidType(C);),

where we have the declaration

PidType Pid;

and

Compilation
  <gpc_delphi_transfer, Environment_wwwrun, both_outputs, unchanged_source_file, transfer_source_name>
  C (unchanged_source_file::Source_file_data(program_full_name), transfer_source_name::Executable_file_data(base_compilation));

(sorry for the mess, but I don't know what's wrong here, so I included everything)

while in the class template Compilation a conversion function is declared:

 template
  < class Compiler, class Environment, class Compiler_Output, class Source, class Executable >
  class Compilation : public Compiler, public Environment, public Compiler_Output, public Source, public Executable {
  public :
    operator SystemHandling::PidType() const { return Pid; }

  private :

    SystemHandling::PidType Pid;
  };

One sees, that the compiler, when seeing
Pid = (PidType) C;
only looks out for a constructor for class PidType (there is an explicitely defined default constructor,
while the copy assignment operator is defined implicitly), but ignores the conversion function 
defined in class Compilation. WHY???

I would be glad for any help!

Oliver