gcc-4.1.2 would produce a warning when checking conversion from 'int' to 'double'

[[Imported from SVN: r5321]]

common/test/.gitignore

@@ -40,3 +40,4 @@ testfassign2
 testfassign3
 testfassign4
 smallobject
+conversiontest

common/test/Makefile.am

@@ -9,7 +9,8 @@ TESTPROGS = parsetest test-stack arraylisttest smartpointertest \
 	testfassign1 testfassign2 testfassign3 \
 	testfassign4 \
     testfassign_fail1 testfassign_fail2 testfassign_fail3 \
-    testfassign_fail4 testfassign_fail5 testfassign_fail6
+    testfassign_fail4 testfassign_fail5 testfassign_fail6 \
+    conversiontest
 
 # which tests to run
 COMPILE_XFAIL=$(DUNE_COMMON_ROOT)/bin/xfail-compile-tests
@@ -122,6 +123,8 @@ testfassign_fail5_CPPFLAGS = $(AM_CPPFLAGS) -D_N=2 -D_M=2 -D_VALUES="1, 2"
 testfassign_fail6_SOURCES = testfassign.cc
 testfassign_fail6_CPPFLAGS = $(AM_CPPFLAGS) -D_N=2 -D_M=2 -D_VALUES="1, 2, nextRow, 2, 3, nextRow, 4, 5"
 
+conversiontest_SOURCES = conversiontest.cc
+
 sourcescheck_NOSOURCES = exprtmpl.cc timing.cc
 
 include $(top_srcdir)/am/global-rules

common/test/conversiontest.cc

+// -*- tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+// vi: set et ts=4 sw=2 sts=2:
+#include <iostream>
+#include <dune/common/typetraits.hh>
+
+int main ()
+{
+  std :: cout << "Conversion from int to double exists? "
+              << Dune::Conversion< int, double > :: exists << std :: endl;
+
+  return 0;
+}

common/typetraits.hh

@@ -218,6 +218,17 @@ namespace Dune
     };
   };
 
+  template<>
+  class Conversion< int, double >
+  {
+  public:
+    enum {
+      exists = true,
+      isTwoWay = false,
+      sameType = false
+    };
+  };
+
   template<class T>
   class Conversion<T,T>{
   public: