Question

My code (not yet released, in file iaca.hh) is on pastebin: Basile Iaca C++ new conflict I m using GCC 4.6 on Debian/Linux/Sid AMD64 with the C++11 dialect.

g++  -std=c++0x -Wall -Wextra -g -O -flto -I/usr/local/include -o iaca.hh.gch iaca.hh 
iaca.hh:631:2: warning: #warning should implement the methods [-Wcpp]
iaca.hh: In static member function  static IaDictionnaryItem* IaDictionnaryItem::make() :
iaca.hh:964:46: error: request for member  operator new  is ambiguous
/usr/local/include/gc/gc_cpp.h:304:14: error: c以及idates are: static void* gc::operator new(size_t, void*)
/usr/local/include/gc/gc_cpp.h:296:14: error:                 static void* gc::operator new(size_t, GCPlacement)
/usr/local/include/gc/gc_cpp.h:293:14: error:                 static void* gc::operator new(size_t)
iaca.hh:675:7: error:                 static void* IaAnyValue::operator new(size_t, IaAnyValue::allocate_new_value_st)
iaca.hh:667:7: error:                 static void* IaAnyValue::operator new(size_t, size_t, IaAnyValue::allocate_new_value_st)

我可以列举强迫<条码>使用新IaAnyValue将刊登在我的职衔<代码>上。 IaDictionnaryItem:make at the end of my iaca.h 档案

我先介绍了空洞的<代码>alloate_new_ Value/code>,以解决含糊不清之处,而没有成功。

我没有成功

IaDictionnaryItem* IaDictionnaryItem::make() {
  return new(IaAnyValue::allocate_new_value) IaDictionnaryItem;
}

以及

IaDictionnaryItem* IaDictionnaryItem::make() {
  return IaAnyValue::operator new(IaAnyValue::allocate_new_value) IaDictionnaryItem;
}

根据我所知,新运营商总是被称之为“规模(*)”作为隐含的第一论点。

Some motivations about my question is in this question about Boehm s GC & C++. Please, don t tell me I should not use Boehm s GC. I need to use it (otherwise I won t use C++).

究竟是哪一个右派把好经营者称作新经营者?

I want the Boehm s GC allocator to be used. It is available thru the gc_cleanup class, which is in class IaItemValue : public IaAnyValue, gc_cleanup 以及 also as the new in my class IaAnyValue (the only super-class of IaDictionnaryItem) I agree there is ambiguity, I just don t guess the syntax to force it.

因此,我如何制定我三边的<代码>。 IaDictionnaryItem:make, at the end of the file to have it prepared better?

For readability, I would prefer calling IaAnyValue::operator new with sz=sizeof(*this) i.e. sizeof(IaDictionnaryItem), gap=0 以及 al=allocate_new_value. I just can t figure out the syntax to force this particular one to be called (of course, I still want the constructor of IaDictionnaryItem to be called inside IaDictionnaryItem::make).

I vetries to force the gc:operator new (size_tume, GCPlacement gcp) (gc 由<代码>gc_cleanup从<gc/gc_cpp.h>继承。

IaDictionnaryItem* IaDictionnaryItem::make() {
  return new (UseGC) IaDictionnaryItem;
}

My make function is a static function returning a new instance of my object. Remember that I m using Beohm s GC, 以及 it will eventually release the memory used (以及 delete the object) when no pointers point to it.

But I m still getting

iaca.hh: In static member function  static IaDictionnaryItem* IaDictionnaryItem::make() :
iaca.hh:962:22: error: request for member  operator new  is ambiguous
/usr/local/include/gc/gc_cpp.h:304:14: error: c以及idates are: static void* gc::operator new(size_t, void*)
/usr/local/include/gc/gc_cpp.h:296:14: error:                 static void* gc::operator new(size_t, GCPlacement)
/usr/local/include/gc/gc_cpp.h:293:14: error:                 static void* gc::operator new(size_t)
iaca.hh:675:7: error:                 static void* IaAnyValue::operator new(size_t, IaAnyValue::allocate_new_value_st)
iaca.hh:667:7: error:                 static void* IaAnyValue::operator new(size_t, size_t, IaAnyValue::allocate_new_value_st)

在这方面。

http://www.un.org。问题的例子很简单:

#include <cstddef>
struct A {};
struct B { void* operator new(std::size_t, A); };

struct C {};
struct D { void* operator new(std::size_t, C); };

struct E : B, D {};

int main()
{
    //I want to use `void* D::operator new(std::size_t, C);` to allocate memory
    //but it will not compile because the call to operator new is ambiguous.
    new(C()) E;
}

Answer 1

Your problem is a multiple inheritance issue. Notice that the class IaItemValue inherits from both IaAnyValue and gc_cleanup (and IaDictionnaryItem inherits from IaItemValue), both of which provide overloads for operator new. In order to resolve this, you can add the following line to the class definition for IaDictionnaryItem:

<编码>使用IaAnyValue:operator new;

Answer 2

In order to understand your problem, I ve dug through your code and can make the following assertions:

IaAnyValue::allocate_new_value is a struct allocate_new_value_st {}
GCPlacement is an enum { NoGC, PointerFreeGC }

You have three defined new operators:

void* operator new(size_t);               
void* operator new(size_t, GCPlacement);  
void* operator new(size_t, void*);

你需要具体了解你所说的话。

电话:new(size_t):

new X;

电话:new(size_t, GCPlacement):

new(NoGC) X;

电话:new(size_t, void*:

allocate_new_value_st Y;
new(&Y) X;

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