=?windows-1252?Q?Re=3A_g++4.3.2_w/_c++0x=3A_error=3A?= =?windows-1252?Q?_no_type_named_=91iterator'_in_=91class_?= =?windows-1252?Q?std=3A=3Aunordered=5Fmap=3C...=27?=

Alan Johnson <awjcs@yahoo.com>
Sun, 23 Nov 2008 01:29:57 -0800
Samuel.Hornus@gmail.com wrote:

I have a problem with g++ 4.3.2 in -std=c++0x mode.
Here is some code which works fine:

struct My_data
 typedef std::map<Key, My_data, Compare> My_Map; (***)
 typedef typename My_map::iterator My_iterator;
 // data members
 My_iterator cousin_;
typedef std::map<Key, My_data, Compare> My_Map;
My_map Family;

Note, that it uses My_data as the data_value for the std::map type
defined in the My_data struct *itself*.
This works fine. But now I want to change std::map by
So do I, with appropriate hash function and Equality comparator.
But then, g++ 4.3.2 gives me the following error:

error: no type named ?iterator? in ?class std::unordered_map<...'
at line (***). I know this does come from the fact that I'm using
My_data as a template parameter inside the definition of the struct
My_data itself.
But... it did work for std::map... so why shouldn't it work for
unordered_map ?
Is there a workaround ? is this a bug of libstd++ ?
Thank you very much !

This may have changed in C++0X (I haven't checked), but in the 2003
standard what you are doing is undefined behavior. You cannot
instantiate a template component for any of the standard library
templates with an incomplete type. Within the definition of My_data,
My_data is an incomplete type.

Reference in the 2003 standard.


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