[boost] type_traits changes break Boost.Python under IRIX

From: Ralf W. Grosse-Kunstleve (rwgk_at_[hidden])
Date: 2005-02-02 02:08:57

The recent changes to the type_traits library break our Boost.Python
builds under IRIX, using the old MIPSpro 7.3.1 compiler. This compiler
is based on EDG 238. The problem is illustrated by this simple piece
of code:

  template <class T>
  struct is_signed_helper
  {
    static const bool value = (static_cast<T>(-1) < 0);
  };

% CC -n32 -mips4 -LANG:std -c foo.cpp
cc-3314 CC: ERROR File = foo.cpp, Line = 4
  The expression must have arithmetic, enum, or pointer type.

    static const bool value = (static_cast<T>(-1) < 0);
                               ^

1 error detected in the compilation of "foo.cpp".

I tried several ideas for a workaround. The only one that worked
in the end is the patch attached to this message. I know it is
not pretty, but it has no effect on compilers other than EDG 238.

I'd be happy to try other ideas, but all of Boost.Python compiles and
runs with the patch. Unless someone else needs a more general fix (that
works for user-defined types) I doubt the old compiler is worth more
effort.

Is the attached patch acceptable as a workaround?

Cheers,
        Ralf

Index: is_signed.hpp
===================================================================
RCS file: /cvsroot/boost/boost/boost/type_traits/is_signed.hpp,v
retrieving revision 1.1
diff -u -r1.1 is_signed.hpp
--- is_signed.hpp       30 Jan 2005 15:47:45 -0000      1.1
+++ is_signed.hpp       2 Feb 2005 06:42:43 -0000
@@ -21,12 +21,35 @@
 
 namespace detail{
 
+#if !(defined(__EDG_VERSION__) && __EDG_VERSION__ == 238)
+
 template <class T>
 struct is_signed_helper
 {
    BOOST_STATIC_CONSTANT(bool, value = (static_cast<T>(-1) < 0));
 };
 
+#else
+
+template <class T>
+struct is_signed_helper;
+
+template <> struct is_signed_helper<char> { BOOST_STATIC_CONSTANT(bool, value
= false); };
+template <> struct is_signed_helper<signed char> { BOOST_STATIC_CONSTANT(bool,
value = true); };
+template <> struct is_signed_helper<unsigned char> {
BOOST_STATIC_CONSTANT(bool, value = false); };
+template <> struct is_signed_helper<short> { BOOST_STATIC_CONSTANT(bool, value
= true); };
+template <> struct is_signed_helper<unsigned short> {
BOOST_STATIC_CONSTANT(bool, value = false); };
+template <> struct is_signed_helper<int> { BOOST_STATIC_CONSTANT(bool, value =
true); };
+template <> struct is_signed_helper<unsigned int> {
BOOST_STATIC_CONSTANT(bool, value = false); };
+template <> struct is_signed_helper<long> { BOOST_STATIC_CONSTANT(bool, value
= true); };
+template <> struct is_signed_helper<unsigned long> {
BOOST_STATIC_CONSTANT(bool, value = false); };
+template <> struct is_signed_helper<long long> { BOOST_STATIC_CONSTANT(bool,
value = true); };
+template <> struct is_signed_helper<unsigned long long> {
BOOST_STATIC_CONSTANT(bool, value = false); };
+template <> struct is_signed_helper<float> { BOOST_STATIC_CONSTANT(bool, value
= true); };
+template <> struct is_signed_helper<double> { BOOST_STATIC_CONSTANT(bool,
value = true); };
+
+#endif
+
 template <bool integral_type>
 struct is_signed_select_helper
 {
Index: is_unsigned.hpp
===================================================================
RCS file: /cvsroot/boost/boost/boost/type_traits/is_unsigned.hpp,v
retrieving revision 1.1
diff -u -r1.1 is_unsigned.hpp
--- is_unsigned.hpp     30 Jan 2005 15:47:45 -0000      1.1
+++ is_unsigned.hpp     2 Feb 2005 06:42:43 -0000
@@ -21,12 +21,35 @@
 
 namespace detail{
 
+#if !(defined(__EDG_VERSION__) && __EDG_VERSION__ == 238)
+
 template <class T>
 struct is_unsigned_helper
 {
    BOOST_STATIC_CONSTANT(bool, value = (static_cast<T>(-1) > 0));
 };
 
+#else
+
+template <class T>
+struct is_unsigned_helper;
+
+template <> struct is_unsigned_helper<char> { BOOST_STATIC_CONSTANT(bool,
value = true); };
+template <> struct is_unsigned_helper<signed char> {
BOOST_STATIC_CONSTANT(bool, value = false); };
+template <> struct is_unsigned_helper<unsigned char> {
BOOST_STATIC_CONSTANT(bool, value = true); };
+template <> struct is_unsigned_helper<short> { BOOST_STATIC_CONSTANT(bool,
value = false); };
+template <> struct is_unsigned_helper<unsigned short> {
BOOST_STATIC_CONSTANT(bool, value = true); };
+template <> struct is_unsigned_helper<int> { BOOST_STATIC_CONSTANT(bool, value
= false); };
+template <> struct is_unsigned_helper<unsigned int> {
BOOST_STATIC_CONSTANT(bool, value = true); };
+template <> struct is_unsigned_helper<long> { BOOST_STATIC_CONSTANT(bool,
value = false); };
+template <> struct is_unsigned_helper<unsigned long> {
BOOST_STATIC_CONSTANT(bool, value = true); };
+template <> struct is_unsigned_helper<long long> { BOOST_STATIC_CONSTANT(bool,
value = false); };
+template <> struct is_unsigned_helper<unsigned long long> {
BOOST_STATIC_CONSTANT(bool, value = true); };
+template <> struct is_unsigned_helper<float> { BOOST_STATIC_CONSTANT(bool,
value = false); };
+template <> struct is_unsigned_helper<double> { BOOST_STATIC_CONSTANT(bool,
value = false); };
+
+#endif
+
 template <bool integral_type>
 struct is_unsigned_select_helper
 {

                
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