 |
C++Talk.NET
C++ language newsgroups
|
| View previous topic :: View next topic |
| Author |
Message |
Mark P
Guest
|
 Posted: Fri Apr 29, 2005 8:28 pm Post subject: help with STL compiler error |
 |
|
In my code I use something like:
typedef std::list<Edge*,g_mm_Alloc EdgeList;
and then instantiate some EdgeList objects. Here Edge is a previously
defined class and g_mm_Alloc<T> is a previously defined custom STL
allocator template.
Trying to compile on a Sun system I get the following error:
"/opt/SUNWspro/prod/include/CC/Cstd/./memory", line 488: Error: Using
static_cast to convert from newScan::Edge** to std::list<newScan::Edge*,
g_mm_Alloc::__list_node_buffer* not allowed.
"/opt/SUNWspro/prod/include/CC/Cstd/./list", line 132: Where: While
instantiating "std::allocator_interface<g_mm_Alloc
std::list<newScan::Edge*,
g_mm_Alloc::__list_node_buffer>::allocate(unsigned,
std::list<newScan::Edge*,
g_mm_Alloc::__list_node_buffer*)".
"/opt/SUNWspro/prod/include/CC/Cstd/./list", line 132: Where:
Instantiated from non-template code.
Looking for line 488 of ".../memory" I see:
//
// allocator_interface provides all types and typed functions. Memory
// allocated as raw bytes using the class provided by the Allocator
// template parameter. allocator_interface casts appropriately.
//
// Multiple allocator_interface objects can attach to a single
// allocator, thus allowing one allocator to allocate all storage
// for a container, regardless of how many types are involved.
//
// The only real restriction is that pointer and reference are
// hard coded as T* and T&. Partial specialization would
// get around this.
//
template <class Allocator,class T>
class allocator_interface
{
public:
typedef Allocator allocator_type;
typedef T* pointer;
typedef const T* const_pointer;
typedef T& reference;
typedef const T& const_reference;
typedef T value_type;
typedef _TYPENAME _RWSTD_ALLOC_SIZE_TYPE size_type;
typedef _TYPENAME _RWSTD_ALLOC_DIFF_TYPE difference_type;
typedef void* void_pointer;
typedef const void* const_void_pointer;
protected:
allocator_type alloc_;
public:
allocator_interface() _RWSTD_THROW_SPEC_NULL { ; }
allocator_interface(const Allocator& a) _RWSTD_THROW_SPEC_NULL
: alloc_(a) { ; }
pointer address (T& x)
{
return _RWSTD_STATIC_CAST(pointer,&x);
}
size_type max_size () const
{
return alloc_.max_size(sizeof(T));
}
pointer allocate(size_type n, pointer p = 0)
{
return _RWSTD_STATIC_CAST(pointer,alloc_.allocate(n*sizeof(T),p));
// LINE 488 IS IMMEDIATELY ABOVE
}
void deallocate(pointer p, size_type n)
{
alloc_.deallocate(p,n*sizeof(T));
}
inline void construct(pointer p, const T& val);
inline void destroy(T* p);
};
I have no idea what to make of this. It looks like it's trying to cast
a list node to a T*, where it ought to be using some sort of rebind
mechanism. Any help or guidance would be greatly appreciated.
Thanks,
Mark
|
|
| Back to top |
|
 |
abecedarian@spambob.com
Guest
|
| Posted: Fri Apr 29, 2005 9:16 pm Post subject: Re: help with STL compiler error |
|
|
Mark P wrote:
| Quote: | In my code I use something like:
typedef std::list<Edge*,g_mm_Alloc EdgeList;
|
This is a list of _pointers_ to newScan::Edge objects. Does it really
make sense in your case to use an allocator to allocate pointers (not
pointed-to objects)?
| Quote: | and then instantiate some EdgeList objects. Here Edge is a
previously
defined class and g_mm_Alloc<T> is a previously defined custom STL
allocator template.
Trying to compile on a Sun system I get the following error:
"/opt/SUNWspro/prod/include/CC/Cstd/./memory", line 488: Error: Using
static_cast to convert from newScan::Edge** to
std::list<newScan::Edge*,
g_mm_Alloc::__list_node_buffer* not allowed.
|
Your RogueWave allocator seemingly doesn't like pointers as objects.
| Quote: | Looking for line 488 of ".../memory" I see:
template <class Allocator,class T
class allocator_interface
{
[...]
pointer allocate(size_type n, pointer p = 0)
{
return
_RWSTD_STATIC_CAST(pointer,alloc_.allocate(n*sizeof(T),p));
// LINE 488 IS IMMEDIATELY ABOVE
}
|
_RWSTD_STATIC_CAST expands to static_cast (see above) which doesn't
work for pointers. They probably should have used a reinterpret_cast or
a C-style cast here. I'm not entirely sure though ...
[...]
| Quote: | };
I have no idea what to make of this. It looks like it's trying to
cast
a list node to a T*, where it ought to be using some sort of rebind
mechanism.
|
They try to cast a newScan::Edge** to a ...__list_node_buffer*
(probably a void*). The static_cast only works for g_mm_Alloc
not for g_mm_Alloc<Edge*>. In the former case you would static_cast a
newScan::Edge* to a ...__list_node_buffer*.
| Quote: | Any help or guidance would be greatly appreciated.
|
Most probably you don't need the g_mm_Alloc<Edge*> thing, just
std::list<Edge*>.
Abe
|
|
| Back to top |
|
|
Victor Bazarov
Guest
|
| Posted: Fri Apr 29, 2005 9:33 pm Post subject: Re: help with STL compiler error |
|
|
[email]abecedarian (AT) spambob (DOT) com[/email] wrote:
| Quote: | Mark P wrote:
In my code I use something like:
typedef std::list<Edge*,g_mm_Alloc EdgeList;
This is a list of _pointers_ to newScan::Edge objects. Does it really
make sense in your case to use an allocator to allocate pointers (not
pointed-to objects)?
|
Why not? He stores pointers to Edge, so he allocates them...
Just a thought.
|
|
| Back to top |
|
|
Mark P
Guest
|
| Posted: Fri Apr 29, 2005 9:52 pm Post subject: Re: help with STL compiler error |
|
|
[email]abecedarian (AT) spambob (DOT) com[/email] wrote:
| Quote: | Mark P wrote:
In my code I use something like:
typedef std::list<Edge*,g_mm_Alloc EdgeList;
This is a list of _pointers_ to newScan::Edge objects. Does it really
make sense in your case to use an allocator to allocate pointers (not
pointed-to objects)?
|
Well my understanding is that a list of Edge* is unlikely to ever
actually allocate space for an Edge* but instead would allocate space
for a list node type, each instance of which would include an Edge* and
other information (prev, next node*, etc.) too. In any case, I don't
see anything non-compliant about this usage.
| Quote: |
Most probably you don't need the g_mm_Alloc<Edge*> thing, just
std::list<Edge*>.
|
But I really do. The memory needs to come from g_mm_Alloc.
|
|
| Back to top |
|
|
Mark P
Guest
|
| Posted: Sat Apr 30, 2005 12:19 am Post subject: Re: help with STL compiler error |
|
|
Mark P wrote:
| Quote: | In my code I use something like:
typedef std::list<Edge*,g_mm_Alloc EdgeList;
and then instantiate some EdgeList objects. Here Edge is a previously
defined class and g_mm_Alloc<T> is a previously defined custom STL
allocator template.
Trying to compile on a Sun system I get the following error:
|
I think I've got this sorted out. This allocator interface wraps an
allocator which has no knowledge of the type for which it allocates, it
just returns void* to allocated memory. To make this work, I simply
modified max_size, allocate, and deallocate within my custom allocator,
such that all of these work in terms of void* and numbers of allocated
words rather than T* and numbers of allocated T objects.
Mark
| Quote: |
//
// allocator_interface provides all types and typed functions. Memory
// allocated as raw bytes using the class provided by the Allocator
// template parameter. allocator_interface casts appropriately.
//
// Multiple allocator_interface objects can attach to a single
// allocator, thus allowing one allocator to allocate all storage
// for a container, regardless of how many types are involved.
//
// The only real restriction is that pointer and reference are
// hard coded as T* and T&. Partial specialization would
// get around this.
//
template
class allocator_interface
{
public:
typedef Allocator allocator_type;
typedef T* pointer;
typedef const T* const_pointer;
typedef T& reference;
typedef const T& const_reference;
typedef T value_type;
typedef _TYPENAME _RWSTD_ALLOC_SIZE_TYPE size_type;
typedef _TYPENAME _RWSTD_ALLOC_DIFF_TYPE difference_type;
typedef void* void_pointer;
typedef const void* const_void_pointer;
protected:
allocator_type alloc_;
public:
allocator_interface() _RWSTD_THROW_SPEC_NULL { ; }
allocator_interface(const Allocator& a) _RWSTD_THROW_SPEC_NULL
: alloc_(a) { ; }
pointer address (T& x)
{
return _RWSTD_STATIC_CAST(pointer,&x);
}
size_type max_size () const
{
return alloc_.max_size(sizeof(T));
}
pointer allocate(size_type n, pointer p = 0)
{
return _RWSTD_STATIC_CAST(pointer,alloc_.allocate(n*sizeof(T),p));
// LINE 488 IS IMMEDIATELY ABOVE
}
void deallocate(pointer p, size_type n)
{
alloc_.deallocate(p,n*sizeof(T));
}
inline void construct(pointer p, const T& val);
inline void destroy(T* p);
};
I have no idea what to make of this. It looks like it's trying to cast
a list node to a T*, where it ought to be using some sort of rebind
mechanism. Any help or guidance would be greatly appreciated.
Thanks,
Mark
|
|
|
| Back to top |
|
|
|
|
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
|
|
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
