This would appear to be a recent regression:
----------------------------
template <int> struct X { static const int s = 2; };
template <typename T> int f() {
const unsigned int dim = 2;
return X<dim>::s;
}
template int f<int>();
-----------------------------
deal.II> c++ -c -W -Wunused x.cc
x.cc: In function 'int f() [with T = int]':
x.cc:8:21: instantiated from here
x.cc:4:22: warning: unused variable 'dim'
'dim' is used here, it just is never read from or written to.
W.
--
Summary: [4.5 regression] Wrong "unused variable" warning
Product: gcc
Version: 4.5.0
Status: UNCONFIRMED
Keywords: diagnostic
Severity: normal
Priority: P3
Component: c++
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: bangerth at gmail dot com
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41110
