[boost] [thread] 1.41.0 regression

Subject: [boost] [thread] 1.41.0 regression
From: Dmitry Goncharov (dgoncharov_at_[hidden])
Date: 2009-12-15 13:17:07

Hi,

The thread_data_base constructor is defined in a header file. Function 
make_external_thread_data() is defined in a .cpp file. This can lead to 
a situation when different libraries contain the definitions of these 
functions. The example below explains how this can happen and why this 
causes problems.

The new version of struct thread_data_base contains an std::map member.
The size of an std::map object depends on if libboost_thread.so was 
build with or w/o _GLIBCXX_DEBUG.
libboost_thread.so contains make_external_thread_data(). This function 
allocates an instance of thread_data_base. Due to an std::map member the 
size of the allocated object depends on _GLIBCXX_DEBUG.

There is a library (e.g. libuser.so) which uses the Boost.Thread 
library. Since the thread_data_base constructor is defined in a header 
file libuser.so can contain its definition.
Again, the size of thread_data_base object, that the thread_data_base 
constructor from libuser.so expects, depends on if libuser.so was built 
with _GLIBCXX_DEBUG defined or not.

An application cannot link agains both libboost_thread.so and libuser.so 
if these libraries were built with different _GLIBCXX_DEBUG definitions 
(or different alignment, etc).
While loading the application the dynamic linker will use the definition 
of thread_data_base constructor either from libuser.so be or from 
libboost_thread.so. Whichever it finds first.

Can both the thread_data_base constructor and 
make_external_thread_data() reside either in a .cpp file or in a header?

BR, Dmitry