Hi,

I'm a happy user of boost::extension library.  Thanks Jeremy Pack et al. for this great work, and hope it'll be accepted by Boost soon.   My extension library is dowloaded from http://boost-extension.blogspot.com/  (August 14, 2008 Link), which works great for me when compiled with "-O0" optimization flag in g++  (my version: i686-apple-darwin9-g++-4.0.1).

But, when I compile with -O2 and access type_map object through member template function, g++ seems to optimize away the initialization logic for 'type_map', and I'd get signal assertion of  EXC_BAD_ACCESS.  Here's my test program: 

 65     struct MyDict {

 66         boost::extensions::type_map     mTypeDict;

 67         template< typename T >

 68         T &         refInstance()               { mTypeDict.get<T>(); }

 69     };

 70 

 71     typedef std::set<int>   IntSetType;

 72     

 73     void test_MyDict_1_mem_data_access() {

 74         MyDict  testObj; 

 75         std::cout << "------ 1 " << std:: endl;

 76         IntSetType  &rIntSet = testObj.mTypeDict.get<IntSetType>();

 77         std::cout << "------ 2 " << std:: endl;

 78         std::cout << "rIntSet.size() is " << rIntSet.size() << std::endl;

 79         std::cout << "------ 3 " << std:: endl;

 80         rIntSet.insert (123);

 81         std::cout << "------ 4 " << std:: endl;

 82         std::cout << "rIntSet.size() is now " << rIntSet.size() << std::endl    ;

 83         std::cout << "------ 5 " << std:: endl;

 84     }

 85     

 86     void test_MyDict_2_mem_func_access() {

 87         MyDict  testObj;

 88         std::cout << "====== 1 " << std:: endl;

 89         IntSetType  &rIntSet = testObj.refInstance<IntSetType>();

 90         std::cout << "====== 2 " << std:: endl;

 91         std::cout << "rIntSet.size() is " << rIntSet.size() << std::endl;

 92         std::cout << "====== 3 " << std:: endl;

 93         rIntSet.insert (123);

 94         std::cout << "====== 4 " << std:: endl;

 95         std::cout << "rIntSet.size() is now " << rIntSet.size() << std::endl    ;

 96         std::cout << "====== 5 " << std:: endl;

 97     }

This test program runs without any problem when compiled with "-O0"; but with "-O2" compiler flag, "test_MyDIct_1_mem_data_access()" is still run ok as expect, but "test_MyDict_2_mem_func_access()" halts at line 93.  Here's the output when run under gdb:

------ 1 

------ 2 

rIntSet.size() is 0

------ 3 

------ 4 

rIntSet.size() is now 1

------ 5 

====== 1 

====== 2 

rIntSet.size() is 86

====== 3 

Program received signal EXC_BAD_ACCESS, Could not access memory.

Reason: KERN_PROTECTION_FAILURE at address: 0x0000005e

std::_Rb_tree<int, int, std::_Identity<int>, std::less<int>, std::allocator<int> >::insert_unique (this=0x56, __v=@0xbffff24c) at testHpcDictByType.c:871

871      _Link_type __x = _M_begin();

(gdb) 

So my question is, what's wrong with accessing boost::extension::type_map through "MyDict::refInstance<T>()" here?  In g++ "-O2" mode, why does the direct access to "MyDict::mTypeDict" is ok, while "MyDict::refInstance<T>()" is not ?

I'm not sure if this is a generic g++ optimization problem, or specific to boost::extension library.  But, for me, it seems to happen only for type_map data structure, but not others.

Thanks for shedding any light on this.

--- Jeffrey