[Bug c++/28631] New: no candidate even when it exists, depends on position of the function

[dan at danny dot cz]

I have a code (usage of C++ binding for the Squirrel language in the
Code::Blocks IDE) that cannot be compiled with g++ from 4.1.1 (from FC devel)
and 4.2.0 (20060729), but can be compiled with 3.2, 3.4 and 4.0 (all on
Redhat/Fedora).

The output from the compiler is
--
scriptbindings.cc: In static member function ‘static void
SqPlus::ReturnSpecialization<RT>::Call(Callee&, RT (Callee::*)(P1)const) [with
Callee = Base, P1 = const String&, RT = const String&]’:
scriptbindings.cc:55:   instantiated from ‘void SqPlus::Call(Callee&, RT
(Callee::*)(P1)const) [with Callee = Base, RT = const String&, P1 = const
String&]’
scriptbindings.cc:60:   instantiated from ‘void
SqPlus::RegisterInstance(Callee&, Func) [with Callee = Base, Func = const
String& (Base::*)(const String&)const]’
scriptbindings.cc:69:   instantiated from ‘SqPlus::SQClassDef<TClassType>&
SqPlus::SQClassDef<TClassType>::func(Func) [with Func = const String&
(Base::*)(const String&)const, TClassType = Base]’
scriptbindings.cc:84:   instantiated from here
scriptbindings.cc:44: error: no matching function for call to ‘Push(const
String&)’
scriptbindings.cc:27: note: candidates are: void SqPlus::Push(bool)
scriptbindings.cc:30: note:                 void SqPlus::Push(int)
--


It compiles when
 - I remove the SqPlus namespace
 - move the Push(bool) and Push(int) down to the definition of Push(String)
 - move the Push(String) up to the Push(bool) and Push(int)

The code is here (downsized from 80K+ lines and 2+ MB :-) )

class String
{
public:
        String();
};

class Base
{
public:
        Base();

        const String& GetString(const String& key) const;
        bool GetBool() const;
};

namespace SqPlus {

        template<class T>
        struct TypeWrapper {
        };

        template<typename T>
        T * GetInstance() {
                return (T *)0;
        }

        inline void Push(bool value) { }
        inline bool Get(TypeWrapper<bool>) { return *GetInstance<bool>(); }

        inline void Push(int value) { }

        template<class RT>
        struct ReturnSpecialization {

                template <typename Callee>
                static void Call(Callee & callee,RT (Callee::*func)() const) {
                        RT ret = (callee.*func)();
                        Push(ret);
                }

                template <typename Callee,typename P1>
                static void Call(Callee & callee,RT (Callee::*func)(P1) const)
{
                        RT ret = (callee.*func)(Get(TypeWrapper<P1>()));
                        Push(ret);
                }
        };

        template<typename Callee,typename RT>
        void Call(Callee & callee, RT (Callee::*func)() const) {
                ReturnSpecialization<RT>::Call(callee,func);
        }

        template<typename Callee,typename RT,typename P1>
        void Call(Callee & callee,RT (Callee::*func)(P1) const) {
                ReturnSpecialization<RT>::Call(callee,func);
        }

        template<typename Callee,typename Func>
        inline void RegisterInstance(Callee & callee,Func func) {
                Call(*(Callee *)0,*(Func *)0);
        }

        template<typename TClassType>
        struct SQClassDef {
                SQClassDef();

                template<typename Func>
                SQClassDef & func(Func pfunc) {
                        RegisterInstance(*(TClassType *)0,pfunc);
                        return *this;
                }
        };

        inline void Push(const String & value) { }
        inline const String & Get(TypeWrapper<const String &>) { return
*GetInstance<String>(); }

        inline void Push(Base * value) { }
        inline Base & Get(TypeWrapper<Base &>) { return *GetInstance<Base>(); }
};

void RegisterBindings()
{
        SqPlus::SQClassDef<Base>().
                func(&Base::GetString).
                func(&Base::GetBool);
}


References:
http://forums.codeblocks.org/index.php?topic=3766.0
http://forums.codeblocks.org/index.php?topic=3481.0
http://squirrel-lang.org/forums/thread/1015.aspx


-- 
           Summary: no candidate even when it exists, depends on position of
                    the function
           Product: gcc
           Version: 4.1.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: dan at danny dot cz


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28631