template<class T>
class Param {
public:
  Param(const T _value) : value_(_value), ref_count_(1) { };

  T v() { return value_; } const

  int add_ref() { return ++ref_count_; }
  int release() { if( --ref_count_ == 0 ) { delete this; return 0; } return ref_count_;}

private:
  T value_;
  int ref_count_;
};

template<class T>
static Param<T> * Param_Factory(const double) {
  return new Param<T>(double);
}

void myFunction(const double d) {
}

engine->RegisterObjectType("Pdouble", 0, asOBJ_REF);
engine->RegisterObjectBehaviour("Pdouble", asBEHAVE_FACTORY, "Pdouble @f(double)", asFUNCTIONPR(Param_Factory<double>, (), Param<double> *), asCALL_CDECL);
engine->RegisterObjectBehaviour("Pdouble", asBEHAVE_ADDREF,  "void f()", asMETHOD(Param<double>, add_ref), asCALL_THISCALL);
engine->RegisterObjectBehaviour("Pdouble", asBEHAVE_RELEASE, "void f()", asMETHOD(Param<double>, release), asCALL_THISCALL);

engine->RegisterObjectBehaviour("Pdouble", asBEHAVE_IMPLICIT_VALUE_CAST, "double f() const", asMETHOD(Param<double>, v), asCALL_THISCALL);

engine->RegisterGlobalFunction("void myFunction(const double)", asFUNCTIONPR(myFunction, (const double), void), asCALL_CDECL);

Pdouble myValue( 0.3 );
double temp = myValue;   // <-- Implicit cast
myFunction( temp );

Pdouble myValue( 0.3 );
myFunction( myValue );   // <-- Implicit cast

My full script is like that :

Pdouble myValue(0.3);

void setup()
{
// double temp = myValue;
myFunction(myValue);
}

void update()
{
}

My C++ code is much bigger than the code snippet I provided in my post.

I will test the script in a simpler program to see if I still reproduce the problem.

FYI, I reproduced the problem with this program :

 
#include <Windows.h>
#include "angelscript.h"
#include <stdio.h>
 
using namespace std;
 
void cb(const asSMessageInfo *msg, void *param) {
 
    const char *type = "ERR ";
    if (msg->type == asMSGTYPE_WARNING)
        type = "WARN ";
    else if (msg->type == asMSGTYPE_INFORMATION)
        type = "INFO ";
 
    printf("%s (%d, %d) : %s : %s\n", msg->section, msg->row, msg->col, type,
        msg->message);
}
 
 
 
const char mscript[] = "Pdouble myValue(0.3);\n"
"\n"
"void setup()\n"
"{\n"
"// double temp = myValue;\n"
"  myFunction(myValue);\n"
"}\n"
"\n"
"void update()\n"
"{\n"
"}\n"
"\n";
 
template<class T>
class Param {
public:
  Param(const T _value) : value_(_value), ref_count_(1) { };
 
  T v() { return value_; } const
 
  int add_ref() { return ++ref_count_; }
  int release() { if( --ref_count_ == 0 ) { delete this; return 0; } return ref_count_;}
 
private:
  T value_;
  int ref_count_;
};
 
template<class T>
static Param<T> * Param_Factory(const T _value) {
  return new Param<T>(_value);
}
 
void myFunction(const double d) {
}
 
 
int main() {
 
    asIScriptEngine *ng = asCreateScriptEngine(ANGELSCRIPT_VERSION);
 
    int r;
 
    r = ng->SetMessageCallback(asFUNCTION(cb), 0, asCALL_CDECL);
    if (r < 0) printf("error %d\n", r);
 
 
  r = ng->RegisterObjectType("Pdouble", 0, asOBJ_REF);
    if (r < 0) printf("error %d\n", r);
  r = ng->RegisterObjectBehaviour("Pdouble", asBEHAVE_FACTORY, "Pdouble @f(const double)", asFUNCTIONPR(Param_Factory<double>, (const double), Param<double> *), asCALL_CDECL);
    if (r < 0) printf("error %d\n", r);
  r = ng->RegisterObjectBehaviour("Pdouble", asBEHAVE_ADDREF,  "void f()", asMETHOD(Param<double>, add_ref), asCALL_THISCALL);
    if (r < 0) printf("error %d\n", r);
  r = ng->RegisterObjectBehaviour("Pdouble", asBEHAVE_RELEASE, "void f()", asMETHOD(Param<double>, release), asCALL_THISCALL);
    if (r < 0) printf("error %d\n", r);
  r = ng->RegisterObjectBehaviour("Pdouble", asBEHAVE_IMPLICIT_VALUE_CAST, "double f() const", asMETHOD(Param<double>, v), asCALL_THISCALL);
    if (r < 0) printf("error %d\n", r);
  r = ng->RegisterGlobalFunction("void myFunction(const double)", asFUNCTIONPR(myFunction, (const double), void), asCALL_CDECL);
    if (r < 0) printf("error %d\n", r);
 
    // build
    asIScriptModule *mod = ng->GetModule("moi", asGM_ALWAYS_CREATE);
    mod->AddScriptSection("joo", mscript);
 
    r = mod->Build();
    if (r < 0) printf("error %d\n", r);
 
    // execute
    asIScriptFunction *f = mod->GetFunctionByDecl("void setup()");
    if (!f)
        return 1;
 
    asIScriptContext *ctx = ng->CreateContext();
    ctx->Prepare(f);
    r = ctx->Execute();
    if (r < 0) printf("error %d\n", r);
 
    ng->Release();
 
    return 0;
}

I tried the fix. My script is running ok now.

Thank you very much.