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MAINT-1175: Use workaround for comparing std::type_info* on gcc < 4.4. 

We now specialize std::less<const std::type_info*> to use
std::type_info::before(), and on Windows and Mac that Just Works. It even
works on Linux when using gcc 4.4+: more recent implementations of gcc's
std::type_info::before() apparently do name()-string comparisons internally.
It doesn't work so well on Linux with gcc 4.1, though, and that's the compiler
we still use on our Linux build-farm machines. But rather than give up,
perform explicit name()-string comparison in that case.
master
Nat Goodspeed 2012-07-19 08:35:11 -04:00
parent 2e83dfa217
commit 27cbfef026
1 changed files with 39 additions and 18 deletions
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57
indra/llcommon/llstl.h
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@ -471,6 +471,27 @@ llbind2nd(const _Operation& __oper, const _Tp& __x)
return llbinder2nd<_Operation>(__oper, _Arg2_type(__x));
}
/**
* Compare std::type_info* pointers a la std::less. We break this out as a
* separate function for use in two different std::less specializations.
*/
inline
bool before(const std::type_info* lhs, const std::type_info* rhs)
{
#if LL_LINUX && defined(__GNUC__) && ((__GNUC__ < 4) || (__GNUC__ == 4 && __GNUC_MINOR__ < 4))
// If we're building on Linux with gcc, and it's either gcc 3.x or
// 4.{0,1,2,3}, then we have to use a workaround. Note that we use gcc on
// Mac too, and some people build with gcc on Windows (cygwin or mingw).
// On Linux, different load modules may produce different type_info*
// pointers for the same type. Have to compare name strings to get good
// results.
return strcmp(lhs->name(), rhs->name()) < 0;
#else // not Linux, or gcc 4.4+
// Just use before(), as we normally would
return lhs->before(*rhs);
#endif
}
/**
* Specialize std::less<std::type_info*> to use std::type_info::before().
* See MAINT-1175. It is NEVER a good idea to directly compare std::type_info*
@ -479,25 +500,25 @@ llbind2nd(const _Operation& __oper, const _Tp& __x)
*/
namespace std
{
template <>
struct less<const std::type_info*>:
public std::binary_function<const std::type_info*, const std::type_info*, bool>
{
bool operator()(const std::type_info* lhs, const std::type_info* rhs) const
{
return lhs->before(*rhs);
}
};
template <>
struct less<const std::type_info*>:
public std::binary_function<const std::type_info*, const std::type_info*, bool>
{
bool operator()(const std::type_info* lhs, const std::type_info* rhs) const
{
return before(lhs, rhs);
}
};
template <>
struct less<std::type_info*>:
public std::binary_function<std::type_info*, std::type_info*, bool>
{
bool operator()(std::type_info* lhs, std::type_info* rhs) const
{
return lhs->before(*rhs);
}
};
template <>
struct less<std::type_info*>:
public std::binary_function<std::type_info*, std::type_info*, bool>
{
bool operator()(std::type_info* lhs, std::type_info* rhs) const
{
return before(lhs, rhs);
}
};
} // std
#endif // LL_LLSTL_H