Looks like const value types, once passed thru BOOST_IDENTITY_TYPE, "becomes" non-const. Like so:

// Attempt to implement a multi-argument utility macro, where arguments are

// types, parenthesized only when required (by the user, when type has commas)

#define ASSERT_EQUAL( t1, t2 ) \

static_assert( std::is_same< \

BOOST_IDENTITY_TYPE((t1)), BOOST_IDENTITY_TYPE((t2)) \

>::value, #t1 " not same as " #t2)

// sanity check: static_asserts as expected

ASSERT_EQUAL( int, double );

// sanity check: static_assert as expected for types with commas

ASSERT_EQUAL( (std::pair<int, double>), (std::pair<double, int>) );

// Here is the failure: this is expected to assert but it doesnt!

ASSERT_EQUAL( const int, int );

From the implementation of BOOST_IDENTITY_TYPE, it is clear why this is happening, as the function signature is independent of const-ness of value type.

Is this a bug? Or is this not the way BOOST_IDENTITY_TYPE is supposed to be used?

Nick