A possible bug

[Ivo Doko <ivo dot doko at gmail dot com>]

The OS I am using is Windows 7 64-bit. I am using Code::Blocks 13.12 
with MinGW-w64 (x86_64-4.9.1-posix-seh-rt_v3-rev1). (I already asked in 
mingw-w64-public and was told to ask here instead.)
For this particular instance I've used these compiler options:
-O2 -std=c++11 -Wextra -Wall -march=amdfam10 -pipe -lm -lstdc++

Now that that's out of the way, I have this:
https://sourceforge.net/projects/xorshift-cpp/files/

Compiling the "main.cpp" is fine, unless I remove the "-O2" flag (i.e. 
disable compiler optimisation). Then I get the following build log:
http://pastebin.com/LXRX4Pq4

The same thing happens if I remove "-march=amdfam10".

What the linker seems to specifically be complaining about:
undefined reference to `xorshift_engine<unsigned long long, 64ull, 
(signed char)-25, (signed char)3, (signed char)49, 
8372773778140471301ull>::shift_3'
undefined reference to `xorshift_engine<unsigned long long, 64ull, 
(signed char)-25, (signed char)3, (signed char)49, 
8372773778140471301ull>::shift_2'

Which makes absolutely no sense, not only because those linker errors 
don't come up when compiling even with just "-O", but because, in 
"xorshift.h", three constexprs in the xorshift_engine class are defined 
like so:

    static constexpr int_fast8_t  shift_1      = a >= 0 ? a : -a;
    static constexpr int_fast8_t  shift_2      = b >= 0 ? b : -b;
    static constexpr int_fast8_t  shift_3      = c >= 0 ? c : -c;

yet shift_1 is ok, but shift_2 and shift_3 somehow aren't...? (There is 
no function which does not use all three of these, in order.)

This smells like a bug in the compiler to me, but I am not sure. Can 
someone please help me?

--
Ivo Doko