Re: [boost] regex and g++ 3.4.2 problem

From: John Maddock (john_at_[hidden])
Date: 2004-11-29 08:46:19

> When compiling a very simple example for the regex library, I've got the 
> following error:

> A short investigation points to the following code in the instances.hpp 
> file:

> As a temporary solution, I have just uncommented the following line in 
> boost/regex/user.hpp:
>
> #define BOOST_REGEX_NO_EXTERNAL_TEMPLATES
>
> Now the simple program compiles and works fine. What influence will the 
> above change in user.hpp have on bigger programs?

They'll take longer to compile, have bigger object files, and if you're 
linking to the shared library, be a larger program as well.

> Is this a known problem?

It is now :-)

I can only reproduce this when compiling with -pedantic, the following fix 
will be going into cvs shortly:

Index: instances.hpp
===================================================================
RCS file: /cvsroot/boost/boost/boost/regex/v4/instances.hpp,v
retrieving revision 1.10
diff -u -r1.10 instances.hpp
--- instances.hpp       12 Mar 2004 13:12:25 -0000      1.10
+++ instances.hpp       29 Nov 2004 13:42:52 -0000
@@ -60,7 +60,11 @@
 #elif (defined(BOOST_MSVC) && defined(_MSC_EXTENSIONS)) || 
defined(__GNUC__)

 #  ifndef BOOST_REGEX_INSTANTIATE
-#     define template extern template
+#     ifdef __GNUC__
+#        define template __extension__ extern template
+#     else
+#        define template extern template
+#     endif
 #  endif

 #  ifdef BOOST_MSVC

John.