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Some fixes to is_convertible to get rid of the g++ warning.

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This included:
  - changes to is_convertible under g++ #ifdef
  - added parenthesis around body of BOOST_IS_CLASS macro
  - a specialization of is_array for const arrays


[SVN r8822]
This commit is contained in:
Jeremy Siek
2001-01-31 02:15:10 +00:00
parent de81a21597
commit a9d7c53394
1 changed files with 46 additions and 4 deletions
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50
include/boost/detail/type_traits.hpp
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@ -10,6 +10,8 @@
// see libs/utility/type_traits.htm
/* Release notes:
31 Jan 2001:
Fixes for is_convertible with g++. (Jeremy Siek)
21 Jan 2001:
Fixed tests for long long to detect its presence on GCC (David Abrahams)
03 Oct 2000:
@ -64,11 +66,11 @@
// BOOST_HAS_TRIVIAL_ASSIGN(T) should evaluate to true if t = u <==> memcpy
// BOOST_HAS_TRIVIAL_DESTRUCTOR(T) should evaluate to true if ~T() has no effect
#define BOOST_IS_CLASS(T) !is_union<T>::value && \
#define BOOST_IS_CLASS(T) (!is_union<T>::value && \
!is_scalar<T>::value && \
!is_array<T>::value && \
!is_reference<T>::value && \
!is_void<T>::value
!is_void<T>::value)
#define BOOST_IS_ENUM(T) false
#define BOOST_IS_UNION(T) false
#define BOOST_IS_POD(T) false
@ -330,6 +332,8 @@ template <typename T> struct is_array
{ static const bool value = false; };
template <typename T, std::size_t N> struct is_array<T[N]>
{ static const bool value = true; };
template <typename T, std::size_t N> struct is_array<const T[N]>
{ static const bool value = true; };
//* is a type T a pointer type (including function pointers) - is_pointer<T>
template <typename T> struct is_pointer { static const bool value = false; };
@ -466,13 +470,51 @@ template <typename T, std::size_t sz> struct is_POD<T[sz]>
//
// is one type convertable to another?
#if defined(__GNUC__)
template <bool isPOD_or_nonclass, class From, class To>
struct is_convertible_dispatch {
typedef char (&no)[1];
typedef char (&yes)[2];
template <class T>
struct checker {
static no check(...);
static yes check(T);
};
static From from;
static const bool value = sizeof( checker<To>::check(from) ) == sizeof(yes);
};
template <class From, class To>
struct is_convertible_dispatch<false, From, To> {
typedef char (&no)[1];
typedef char (&yes)[2];
template <class T>
struct checker {
static no check(void*);
static yes check(T*);
};
static From from;
static const bool value = sizeof( checker<To>::check(&from) ) == sizeof(yes);
};
template <class From, class To>
struct is_convertible
{
private:
typedef is_convertible_dispatch<is_POD<From>::value
|| !BOOST_IS_CLASS(From) || is_reference<From>::value, From, To> Dispatch;
public:
static const bool value = Dispatch::value;
};
#else // not __GNUC__
template <class From, class To>
struct is_convertible
{
private:
typedef char (&no)[1];
typedef char (&yes)[2];
# if defined(__BORLANDC__) || defined(__GNUC__)
# if defined(__BORLANDC__)
// This workaround for Borland breaks the EDG C++ frontend,
// so we only use it for Borland.
template <class T>
@ -484,7 +526,6 @@ private:
static From from;
public:
static const bool value = sizeof( checker<To>::check(from) ) == sizeof(yes);
# else // not __BORLANDC__
static no check(...);
static yes check(To);
@ -494,6 +535,7 @@ public:
# endif
void foo(); // avoid warning about all members being private
};
#endif // not __GNUC__
template <class From>
struct is_convertible<From, void>