Here's a very annoying regression that swamps my builds in warning
messages:
------------------------------
void g (int, int);

template <int> void f () {
  for (int i;; ++i, ++i)
    g(i,i);
}

template void f<1> ();
------------------------------
g/x> /home/bangerth/bin/gcc-3.4-pre/bin/c++ -W -Wall -c x.cc
x.cc: In function `void f()':
x.cc:4: warning: left-hand operand of comma expression has no effect

Clearly, the left hand side of the comma expression _does_ have
an effect. The warning disappears when the function is not a template.

W.