Try preventing static casts when calling hash_value.

[SVN r63716]

test/Jamfile.v2

@@ -50,6 +50,8 @@ test-suite functional/hash
         [ run container_no_fwd_test.cpp ]
         [ compile-fail hash_no_ext_fail_test.cpp ]
         [ compile-fail namespace_fail_test.cpp ]
+        [ compile-fail implicit_fail_test.cpp ]
+        [ compile-fail shared_ptr_fail_test.cpp ]
         [ run hash_no_ext_macro_1.cpp ]
         [ run hash_no_ext_macro_2.cpp ]
     ;

test/implicit_fail_test.cpp

@@ -0,0 +1,16 @@
+#include <boost/functional/hash.hpp>
+
+namespace test
+{
+    struct base {};
+    std::size_t hash_value(base const&) { return 0; }
+    
+    struct converts { operator base() const { return base(); } };
+}
+
+int main() {
+    boost::hash<test::converts> hash;
+    test::converts x;
+    
+    hash(x);
+}

test/shared_ptr_fail_test.cpp

@@ -0,0 +1,11 @@
+#include <boost/functional/hash.hpp>
+#include <boost/shared_ptr.hpp>
+
+// This should obviously pass if shared_ptr ever supports Boost.Hash.
+
+int main() {
+    boost::hash<boost::shared_ptr<int> > hash;
+    boost::shared_ptr<int> x(new int(10));
+    
+    hash(x);
+}