"Ralf W. Grosse-Kunstleve" <[EMAIL PROTECTED]> writes:
> Below is a stand-alone minimal test that still produces the same error message
> with MIPSpro:
>
> % CC -LANG:std zminmin.cpp
> cc-1108 CC: ERROR File = zminmin.cpp, Line = 13
> The indicated expression must have pointer-to-function type.
>
> static const unsigned long value = sizeof(bdhelper_t::check());
> ^
>
> 1 error detected in the compilation of "zminmin.cpp".
>
> The same code works correctly with gcc 2.96 and an EDG245-based compiler
> (Compaq cxx). However, here is an interesting observation:
>
> % cxx -std strict_ansi zminmin.cpp
> % a.out
> 4
>
> No problem with "strict_ansi." But:
>
> % cxx -std ansi -D__USE_STD_IOSTREAM zminmin.cpp
> cxx: Error: zminmin.cpp, line 13: operand of sizeof may not be a function
> static const unsigned long value = sizeof(bdhelper_t::check());
> ----------------------------------------------^
> cxx: Info: 1 error detected in the compilation of "zminmin.cpp".
>
> I am jumping to the conclusion that older EDG's don't support
> sizeof(some_function()). Does that sound plausible?
Not to me; this technique is used all over the Boost type traits.
Nothing would've ever worked with this compiler if that were true,
pretty much.
> What could be done to make the is_base_and_derived test work with
> MIPSpro? Is the test actually used in Boost.Python?
Yes.
> -- I noticed that MIPSpro chokes even if is_base_and_derived_impl2
> is not instantiated.
>
> Thanks!
> Ralf
There are any number of ways you could try reformulating this to make
the error go away. At worst you could try the __BORLANDC__ branch in
is_base_and_derived.hpp.
Another approach:
template <typename B, typename D, typename T>
static type_traits::yes_type bd_helper(D const volatile *, T);
template <typename B, typename D>
static type_traits::no_type bd_helper(B const volatile *, int);
template<typename B, typename D>
struct is_base_and_derived_impl2
{
struct Host
{
operator B const volatile *() const;
operator D const volatile *();
};
BOOST_STATIC_CONSTANT(bool, value =
sizeof(bd_helper<B,D>(Host(), 0)) == sizeof(type_traits::yes_type));
};
>
> #include <iostream>
>
> template <typename B, typename D>
> struct bd_helper
> {
> static int check();
> };
>
> template<typename B, typename D>
> struct is_base_and_derived_impl2
> {
> typedef bd_helper<B,D> bdhelper_t;
> static const unsigned long value = sizeof(bdhelper_t::check());
> };
>
> int main()
> {
> unsigned long n = is_base_and_derived_impl2<int, float>::value;
> std::cout << n << std::endl;
> }
>
>
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--
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