template function inlining in g++ version < 4.0

[Stephan Tolksdorf <andorxor at gmx dot de>]

Hi,

I'm writing a numerical c++ library and would like to support GCC 
version >= 3.4.4. For performance reasons I absolutely require the 
inlining of certain templated helper functions, but this seems to be a 
problem with GCC prior to version 4.0 under certain circumstances 
because of http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14950

For example, the following code will not compile with "-g":
--
#include <iostream>

template <int size>
inline __attribute__((always_inline)) int shift(int val) {
    return val << size;
}

int main() {
    std::cout << shift<2>(1); // "sorry unimplemented: inlining failed"
}
--

It actually does compile with "-O1" but I've got more complicated code 
where the inlining fails in a similar situation even though I'm 
compiling with optimizations switched on.

Now I'm having difficulties understanding when exactly this bug is 
triggered. Could maybe someone explain to me under which circumstances 
GCC 3.4 fails to inline a templated function? Are there any general 
workarounds? Is there any chance that the compiler inlines code even 
though always_inline fails?

Thanks in advance for any hint.

Stephan