Closes #58 ("Comparing strings does not compile in gcc 7+ in C++17 mode")

doc/container.qbk

@@ -1220,6 +1220,7 @@ use [*Boost.Container]? There are several reasons for that:
 
 * Fixed bugs:
    * [@https://github.com/boostorg/container/pull/54 GitHub #54: ['"no sbrk() in VxWorks, configure dlmalloc to use only mmap"]].
+   * [@https://github.com/boostorg/container/issues/58 GitHub #58: ['"Comparing strings does not compile in gcc 7+ in C++17 mode"]].
 
 [endsect]
 

include/boost/container/string.hpp

@@ -2953,6 +2953,20 @@ typedef basic_string
    ,new_allocator<wchar_t> >
 wstring;
 
+#else
+
+template<class S>
+struct is_string
+{
+   static const bool value = false;
+};
+
+template<class C, class T, class A>
+struct is_string< basic_string<C, T, A> >
+{
+   static const bool value = true;
+};
+
 #endif
 
 // ------------------------------------------------------------
@@ -3060,16 +3074,22 @@ operator==(const basic_string<CharT,Traits,Allocator>& x, const CharT* s)
 }
 
 template <class CharT, class Traits, class Allocator, template <class, class> class BasicStringView>
-inline bool
+inline 
-operator==( BasicStringView<CharT,Traits> x, const basic_string<CharT,Traits,Allocator>& y)
+   BOOST_CONTAINER_DOC1ST( bool, 
+                           typename container_detail::disable_if
+                              <is_string< BasicStringView<CharT BOOST_MOVE_I Traits> > BOOST_MOVE_I bool >::type)
+      operator==( BasicStringView<CharT,Traits> x, const basic_string<CharT,Traits,Allocator>& y)
 {
    return x.size() == y.size() &&
           Traits::compare(x.data(), y.data(), x.size()) == 0;
 }
 
 template <class CharT, class Traits, class Allocator, template <class, class> class BasicStringView>
-inline bool
+inline
-operator==( const basic_string<CharT,Traits,Allocator>& x, BasicStringView<CharT,Traits> y)
+   BOOST_CONTAINER_DOC1ST( bool, 
+                           typename container_detail::disable_if
+                              <is_string< BasicStringView<CharT BOOST_MOVE_I Traits> > BOOST_MOVE_I bool >::type)
+      operator==( const basic_string<CharT,Traits,Allocator>& x, BasicStringView<CharT,Traits> y)
 {
    return x.size() == y.size() &&
           Traits::compare(x.data(), y.data(), x.size()) == 0;
@@ -3092,12 +3112,18 @@ operator!=(const basic_string<CharT,Traits,Allocator>& x, const CharT* s)
 
 
 template <class CharT, class Traits, class Allocator, template <class, class> class BasicStringView>
-inline bool
+inline
+   BOOST_CONTAINER_DOC1ST( bool, 
+                           typename container_detail::disable_if
+                              <is_string< BasicStringView<CharT BOOST_MOVE_I Traits> > BOOST_MOVE_I bool >::type)
 operator!=( BasicStringView<CharT,Traits> x, const basic_string<CharT,Traits,Allocator>& y)
    {  return !(x == y);  }
 
 template <class CharT, class Traits, class Allocator, template <class, class> class BasicStringView>
-inline bool
+inline
+   BOOST_CONTAINER_DOC1ST( bool, 
+                           typename container_detail::disable_if
+                              <is_string< BasicStringView<CharT BOOST_MOVE_I Traits> > BOOST_MOVE_I bool >::type)
 operator!=( const basic_string<CharT,Traits,Allocator>& x, BasicStringView<CharT,Traits> y)
    {  return !(x == y);  }
 
@@ -3124,12 +3150,18 @@ operator<(const basic_string<CharT,Traits,Allocator>& x, const CharT* s)
 }
 
 template <class CharT, class Traits, class Allocator, template <class, class> class BasicStringView>
-inline bool
+inline
+   BOOST_CONTAINER_DOC1ST( bool, 
+                           typename container_detail::disable_if
+                              <is_string< BasicStringView<CharT BOOST_MOVE_I Traits> > BOOST_MOVE_I bool >::type)
 operator<( BasicStringView<CharT,Traits> x, const basic_string<CharT,Traits,Allocator>& y)
    {  return y.compare(x) > 0;  }
 
 template <class CharT, class Traits, class Allocator, template <class, class> class BasicStringView>
-inline bool
+inline
+   BOOST_CONTAINER_DOC1ST( bool, 
+                           typename container_detail::disable_if
+                              <is_string< BasicStringView<CharT BOOST_MOVE_I Traits> > BOOST_MOVE_I bool >::type)
 operator<(  const basic_string<CharT,Traits,Allocator>& x, BasicStringView<CharT,Traits> y)
    {  return x.compare(y) < 0;  }
 
@@ -3153,12 +3185,18 @@ operator>(const basic_string<CharT,Traits,Allocator>& x, const CharT* s)
 }
 
 template <class CharT, class Traits, class Allocator, template <class, class> class BasicStringView>
-inline bool
+inline
+   BOOST_CONTAINER_DOC1ST( bool, 
+                           typename container_detail::disable_if
+                              <is_string< BasicStringView<CharT BOOST_MOVE_I Traits> > BOOST_MOVE_I bool >::type)
 operator>( BasicStringView<CharT,Traits> x, const basic_string<CharT,Traits,Allocator>& y)
    {  return y < x;  }
 
 template <class CharT, class Traits, class Allocator, template <class, class> class BasicStringView>
-inline bool
+inline
+   BOOST_CONTAINER_DOC1ST( bool, 
+                           typename container_detail::disable_if
+                              <is_string< BasicStringView<CharT BOOST_MOVE_I Traits> > BOOST_MOVE_I bool >::type)
 operator>( const basic_string<CharT,Traits,Allocator>& x, BasicStringView<CharT,Traits> y)
    {  return y < x;  }
 
@@ -3181,12 +3219,18 @@ operator<=(const basic_string<CharT,Traits,Allocator>& x, const CharT* s)
 
 
 template <class CharT, class Traits, class Allocator, template <class, class> class BasicStringView>
-inline bool
+inline
+   BOOST_CONTAINER_DOC1ST( bool, 
+                           typename container_detail::disable_if
+                              <is_string< BasicStringView<CharT BOOST_MOVE_I Traits> > BOOST_MOVE_I bool >::type)
 operator<=( BasicStringView<CharT,Traits> x, const basic_string<CharT,Traits,Allocator>& y)
    {  return !(y < x);  }
 
 template <class CharT, class Traits, class Allocator, template <class, class> class BasicStringView>
-inline bool
+inline
+   BOOST_CONTAINER_DOC1ST( bool, 
+                           typename container_detail::disable_if
+                              <is_string< BasicStringView<CharT BOOST_MOVE_I Traits> > BOOST_MOVE_I bool >::type)
 operator<=( const basic_string<CharT,Traits,Allocator>& x, BasicStringView<CharT,Traits> y)
    {  return !(y < x);  }
 
@@ -3207,12 +3251,18 @@ operator>=(const basic_string<CharT,Traits,Allocator>& x, const CharT* s)
    {  return !(x < s);  }
 
 template <class CharT, class Traits, class Allocator, template <class, class> class BasicStringView>
-inline bool
+inline
+   BOOST_CONTAINER_DOC1ST( bool, 
+                           typename container_detail::disable_if
+                              <is_string< BasicStringView<CharT BOOST_MOVE_I Traits> > BOOST_MOVE_I bool >::type)
 operator>=( BasicStringView<CharT,Traits> x, const basic_string<CharT,Traits,Allocator>& y)
    {  return !(x < y);  }
 
 template <class CharT, class Traits, class Allocator, template <class, class> class BasicStringView>
-inline bool
+inline
+   BOOST_CONTAINER_DOC1ST( bool, 
+                           typename container_detail::disable_if
+                              <is_string< BasicStringView<CharT BOOST_MOVE_I Traits> > BOOST_MOVE_I bool >::type)
 operator>=( const basic_string<CharT,Traits,Allocator>& x, BasicStringView<CharT,Traits> y)
    {  return !(x < y);  }
 

test/comparison_test.hpp

@@ -0,0 +1,58 @@
+//////////////////////////////////////////////////////////////////////////////
+//
+// (C) Copyright Ion Gaztanaga 2017-2017. Distributed under the Boost
+// Software License, Version 1.0. (See accompanying file
+// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+// See http://www.boost.org/libs/container for documentation.
+//
+//////////////////////////////////////////////////////////////////////////////
+
+#ifndef BOOST_CONTAINER_TEST_COMPARISON_TEST_HPP
+#define BOOST_CONTAINER_TEST_COMPARISON_TEST_HPP
+
+#include <deque>
+#include <boost/core/lightweight_test.hpp>
+
+namespace boost {
+namespace container {
+namespace test {
+
+
+template<class Cont>
+bool test_container_comparisons()
+{
+   typedef typename Cont::value_type value_type;
+
+   Cont cont;
+   cont.push_back(value_type(1));
+   cont.push_back(value_type(2));
+   cont.push_back(value_type(3));
+
+   Cont cont_equal(cont);
+
+   Cont cont_less;
+   cont_less.push_back(value_type(1));
+   cont_less.push_back(value_type(2));
+   cont_less.push_back(value_type(2));
+
+   BOOST_TEST(cont == cont_equal);
+   BOOST_TEST(!(cont != cont_equal));
+   BOOST_TEST(cont != cont_less);
+   BOOST_TEST(cont_less < cont);
+   BOOST_TEST(cont_less <= cont);
+   BOOST_TEST(!(cont_less > cont));
+   BOOST_TEST(!(cont_less >= cont));
+   BOOST_TEST(!(cont < cont_less));
+   BOOST_TEST(!(cont <= cont_less));
+   BOOST_TEST(cont > cont_less);
+   BOOST_TEST(cont >= cont_less);
+
+   return ::boost::report_errors() == 0;
+}
+
+}  //namespace test {
+}  //namespace container {
+}  //namespace boost {
+
+#endif   //#ifndef BOOST_CONTAINER_TEST_COMPARISON_TEST_HPP

test/string_test.cpp

@@ -24,8 +24,10 @@
 #include "expand_bwd_test_template.hpp"
 #include "propagate_allocator_test.hpp"
 #include "default_init_test.hpp"
+#include "comparison_test.hpp"
 #include "../../intrusive/test/iterator_test.hpp"
 #include <boost/utility/string_view.hpp>
+#include <boost/core/lightweight_test.hpp>
 
 using namespace boost::container;
 
@@ -507,8 +509,10 @@ struct alloc_propagate_base<boost_container_string>
    };
 };
 
+
 }}}   //namespace boost::container::test
 
+
 int main()
 {
    if(string_test<char>()){
@@ -558,6 +562,16 @@ int main()
       boost::intrusive::test::test_iterator_random< cont_int >(a);
    }
 
+   ////////////////////////////////////
+   //    Comparison testing
+   ////////////////////////////////////
+   {
+      if(!boost::container::test::test_container_comparisons<string>())
+         return 1;
+      if(!boost::container::test::test_container_comparisons<wstring>())
+         return 1;
+   }
+
    return boost::report_errors();
 }