Add test for std::hash<>

Author: martinmoene

README.md

@@ -43,11 +43,12 @@ value_ptr: Allows to obtain engaged state via operator bool()
 value_ptr: Allows to reset content
 value_ptr: Allows to swap with other value_ptr (member)
 value_ptr: Allows to swap with other value_ptr (non-member)
-value_ptr: Provides relational operators (pointer comparison)
+value_ptr: Provides relational operators (pointer comparison, non-member)
 make_value: Allows to copy-construct value_ptr
 make_value: Allows to move-construct value_ptr (C++11)
 make_value: Allows to in-place copy-construct value_ptr from arguments (C++11)
 make_value: Allows to in-place move-construct value_ptr from arguments (C++11)
 make_value: Allows to in-place copy-construct value_ptr from initializer-list and arguments (C++11)
 make_value: Allows to in-place move-construct value_ptr from initializer-list and arguments (C++11)
+std::hash<>: Allows to obtain hash (C++11)
 ```

include/nonstd/value_ptr.hpp

@@ -940,7 +940,7 @@ struct hash< nonstd::value_ptr<T, D, C> >
 
     result_type operator()( argument_type const & p ) const nsvp_noexcept
     {
-        return hash<typename argument_type::pointer>()( p.get() );
+        return hash<typename argument_type::const_pointer>()( p.get() );
     }
 };
 

test/value-ptr.t.cpp

@@ -666,7 +666,7 @@ namespace {
     };
 }
 
-CASE( "value_ptr: Provides relational operators (pointer comparison)" )
+CASE( "value_ptr: Provides relational operators (pointer comparison, non-member)" )
 {
     SETUP( "" ) {
 
@@ -781,6 +781,20 @@ CASE( "make_value: Allows to in-place move-construct value_ptr from initializer-
 #endif
 }
 
+CASE( "std::hash<>: Allows to obtain hash (C++11)" )
+{
+#if nsvp_CPP11_OR_GREATER
+    value_ptr<int> a( 7 );
+    value_ptr<int> b( 7 );
+
+    EXPECT( std::hash<value_ptr<int> >()( a ) == std::hash<value_ptr<int> >()( a ) );
+    EXPECT( std::hash<value_ptr<int> >()( b ) == std::hash<value_ptr<int> >()( b ) );
+    EXPECT( std::hash<value_ptr<int> >()( a ) != std::hash<value_ptr<int> >()( b ) );
+#else
+    EXPECT( !!"std::hash<>: std::hash<> is not available (no C++11)" );
+#endif
+}
+
 //------------------------------------------------------------------------
 // Applets: