Disable warnings for compile-fail tests

doc/array/changes.adoc

@@ -18,3 +18,6 @@ http://www.boost.org/LICENSE_1_0.txt
 * Removed obsolete compiler workarounds.
 * Changed `array<T, 0>::begin()`, `cbegin()`, `end()`, `cend()` to return `nullptr`, enabling `constexpr`.
   This matches the behavior of `std::array`.
+* Removed local `hash_value` overload; `boost::hash` supports array-like types natively.
+* `array<T, 0>` can now be initialized with `= {{}}`.
+* Added `operator\<\=>`.

doc/array/reference.adoc

@@ -35,6 +35,9 @@ namespace boost {
   template<typename T, std::size_t N>
     constexpr bool operator>=(const array<T, N>&, const array<T, N>&);
 
+  template<typename T, std::size_t N>
+    constexpr auto operator<=>(const array<T, N>&, const array<T, N>&);
+
   template<std::size_t Idx, typename T, std::size_t N>
     constexpr T& get(array<T, N>&) noexcept;
   template<std::size_t Idx, typename T, std::size_t N>
@@ -136,7 +139,7 @@ public:
 template<typename U> array& operator=(const array<U, N>& other);
 ```
 [horizontal]
-Effects: :: `std::copy(rhs.begin(), rhs.end(), begin())`.
+Effects: :: For each `i` in `[0..N)`, performs `elems[i] = other.elems[i];`.
 
 ---
 
@@ -233,7 +236,7 @@ constexpr const_reference operator[](size_type i) const;
 [horizontal]
 Requires: :: `i < N`.
 Returns: ::  `elems[i]`.
-Throws: :: nothing.
+Throws: :: Nothing.
 
 ---
 
@@ -254,7 +257,7 @@ constexpr const_reference front() const;
 [horizontal]
 Requires: ::  `N > 0`.
 Returns: :: `elems[0]`.
-Throws: :: nothing.
+Throws: :: Nothing.
 
 ---
 
@@ -265,7 +268,7 @@ constexpr const_reference back() const;
 [horizontal]
 Requires: :: `N > 0`.
 Returns: :: `elems[N-1]`.
-Throws: :: nothing.
+Throws: :: Nothing.
 
 ---
 
@@ -302,7 +305,7 @@ Complexity: :: linear in `N`.
 void fill(const T& value);
 ```
 [horizontal]
-Effects: :: for each `i` in `[0..N)`, performs `elems[i] = value;`.
+Effects: :: For each `i` in `[0..N)`, performs `elems[i] = value;`.
 
 ---
 
@@ -382,6 +385,17 @@ Returns: :: `!(x < y)`.
 
 ---
 
+```
+template<typename T, std::size_t N>
+  constexpr auto operator<=>(const array<T, N>& x, const array<T, N>& y)
+  -> decltype(x[0] <=> y[0]);
+```
+[horizontal]
+Effects: :: For each `i` in `[0..N)`, if `(x[i] \<\=> y[i]) != 0`, returns `x[i] \<\=> y[i]`. Otherwise, returns `std::strong_ordering::equal`, converted to the return type.
+Remarks: :: When `N` is 0, the return type is `std::strong_ordering` and the return value is `std::strong_ordering::equal`.
+
+---
+
 ### Specializations
 
 ```

include/boost/array.hpp

@@ -37,9 +37,10 @@
 
 #if BOOST_WORKAROUND(BOOST_MSVC, >= 1400)
 # pragma warning(push)
-# pragma warning(disable:4510) // boost::array<T,N>' : default constructor could not be generated
-# pragma warning(disable:4512) // boost::array<T,N>' : assignment operator could not be generated
-# pragma warning(disable:4610) // class 'boost::array<T,N>' can never be instantiated - user defined constructor required
+# pragma warning(disable: 4510) // boost::array<T,N>' : default constructor could not be generated
+# pragma warning(disable: 4512) // boost::array<T,N>' : assignment operator could not be generated
+# pragma warning(disable: 4610) // class 'boost::array<T,N>' can never be instantiated - user defined constructor required
+# pragma warning(disable: 4702) // unreachable code
 #endif
 
 #include <boost/assert.hpp>
@@ -195,6 +196,8 @@ namespace boost {
 
     template< class T >
     class array< T, 0 > {
+      public:
+        struct {} elems; // enables initialization with = {{}}
 
       public:
         // type definitions
@@ -324,7 +327,7 @@ namespace boost {
 #if BOOST_WORKAROUND(BOOST_GCC, < 90000)
 
     template<class T>
-    BOOST_CXX14_CONSTEXPR bool operator== (const array<T, 0>& x, const array<T, 0>& y)
+    BOOST_CXX14_CONSTEXPR bool operator== (const array<T, 0>& /*x*/, const array<T, 0>& /*y*/)
     {
         return true;
     }
@@ -351,7 +354,7 @@ namespace boost {
 #if BOOST_WORKAROUND(BOOST_GCC, < 90000)
 
     template<class T>
-    BOOST_CXX14_CONSTEXPR bool operator< (const array<T, 0>& x, const array<T, 0>& y)
+    BOOST_CXX14_CONSTEXPR bool operator< (const array<T, 0>& /*x*/, const array<T, 0>& /*y*/)
     {
         return false;
     }
@@ -379,6 +382,30 @@ namespace boost {
         x.swap(y);
     }
 
+#if defined(__cpp_impl_three_way_comparison) && __cpp_impl_three_way_comparison >= 201907L
+
+    template<class T, std::size_t N>
+    constexpr auto operator<=> (const array<T,N>& x, const array<T,N>& y)
+        -> decltype( x.elems[ 0 ] <=> y.elems[ 0 ] )
+    {
+        for( std::size_t i = 0; i < N; ++i )
+        {
+            auto r = x.elems[ i ] <=> y.elems[ i ];
+            if( r != 0 ) return r;
+        }
+
+        return 0 <=> 0; // std::strong_ordering::equal
+    }
+
+    template<class T>
+    constexpr auto operator<=> (const array<T,0>& /*x*/, const array<T,0>& /*y*/)
+        -> decltype( 0 <=> 0 )
+    {
+        return 0 <=> 0; // std::strong_ordering::equal
+    }
+
+#endif
+
     // undocumented and obsolete
     template <typename T, std::size_t N>
     BOOST_DEPRECATED( "please use `elems` instead" )

test/Jamfile.v2

@@ -7,6 +7,38 @@ import testing ;
 import-search /boost/config/checks ;
 import config : requires ;
 
+project
+    : requirements
+
+        <warnings>extra
+
+        <toolset>msvc:<warnings-as-errors>on
+        <toolset>clang:<warnings-as-errors>on
+        <toolset>gcc:<warnings-as-errors>on
+
+        <toolset>gcc-4.6:<cxxflags>-Wno-missing-braces
+        <toolset>gcc-4.7:<cxxflags>-Wno-missing-braces
+
+        <toolset>gcc-4.6:<cxxflags>-Wno-missing-field-initializers
+        <toolset>gcc-4.7:<cxxflags>-Wno-missing-field-initializers
+        <toolset>gcc-4.8:<cxxflags>-Wno-missing-field-initializers
+        <toolset>gcc-4.9:<cxxflags>-Wno-missing-field-initializers
+
+        <toolset>gcc-4.6:<cxxflags>-Wno-type-limits
+        <toolset>gcc-4.7:<cxxflags>-Wno-type-limits
+        <toolset>gcc-10:<cxxflags>-Wno-type-limits
+
+        <toolset>clang:<cxxflags>-Wno-unnamed-type-template-args
+
+        <toolset>clang-3.5:<cxxflags>-Wno-missing-braces
+        <toolset>clang-3.6:<cxxflags>-Wno-missing-braces
+        <toolset>clang-3.7:<cxxflags>-Wno-missing-braces
+        <toolset>clang-3.8:<cxxflags>-Wno-missing-braces
+        <toolset>clang-3.9:<cxxflags>-Wno-missing-braces
+        <toolset>clang-4:<cxxflags>-Wno-missing-braces
+        <toolset>clang-5:<cxxflags>-Wno-missing-braces
+    ;
+
 #
 
 run array0.cpp ;
@@ -20,8 +52,10 @@ run array7.cpp ;
 
 compile array_constexpr.cpp ;
 
-compile-fail array_getfail1.cpp ;
-compile-fail array_getfail2.cpp ;
+compile-fail array_getfail1.cpp
+  : <warnings>off ;
+compile-fail array_getfail2.cpp
+  : <warnings>off ;
 
 run array_hash.cpp
   : : : [ requires cxx11_noexcept ] ;
@@ -45,6 +79,7 @@ run array_swap_test.cpp ;
 run array_swap_test2.cpp ;
 run array_eq_test.cpp ;
 run array_lt_test.cpp ;
+run array_thw_test.cpp ;
 run array_get_test.cpp ;
 
 # C++11 constexpr
@@ -64,6 +99,7 @@ compile array_access_test_cx2.cpp ;
 compile array_fill_test_cx.cpp ;
 compile array_eq_test_cx.cpp ;
 compile array_lt_test_cx.cpp ;
+compile array_thw_test_cx.cpp ;
 
 #
 

test/array5.cpp

@@ -5,6 +5,8 @@
  * http://www.boost.org/LICENSE_1_0.txt)
  */
 
+#define BOOST_ALLOW_DEPRECATED_SYMBOLS // assign
+
 #include <iostream>
 #include <boost/array.hpp>
 

test/array6.cpp

@@ -5,12 +5,20 @@
  * http://www.boost.org/LICENSE_1_0.txt)
  */
 
+#define BOOST_ALLOW_DEPRECATED_SYMBOLS // get_c_array
+
+#include <boost/array.hpp>
+#include <boost/core/lightweight_test.hpp>
+#include <boost/config.hpp>
 #include <string>
 #include <iostream>
-#include <boost/array.hpp>
 #include <algorithm>
 
-#include <boost/core/lightweight_test_trait.hpp>
+#if defined(BOOST_GCC) && BOOST_GCC / 10000 == 13
+// false -Warray-bounds positive when using -fsanitize=undefined
+// restricted to GCC 13 because that's what is tested on Drone
+# pragma GCC diagnostic ignored "-Warray-bounds"
+#endif
 
 namespace {
     template< class T >

test/array7.cpp

@@ -5,6 +5,8 @@
  * http://www.boost.org/LICENSE_1_0.txt)
  */
 
+#define BOOST_ALLOW_DEPRECATED_SYMBOLS // std::get
+
 #include <string>
 #include <iostream>
 #include <boost/array.hpp>

test/array_assign_test.cpp

@@ -2,12 +2,17 @@
 // Distributed under the Boost Software License, Version 1.0.
 // https://www.boost.org/LICENSE_1_0.txt)
 
+#define BOOST_ALLOW_DEPRECATED_SYMBOLS
+
+// assign is a deprecated nonstandard equivalent of fill
+
 #include <boost/array.hpp>
 #include <boost/core/lightweight_test.hpp>
 #include <cstddef>
 
-// assign is a nonstandard equivalent of fill
-// it probably needs to be deprecated and removed
+#if defined(_MSC_VER)
+# pragma warning(disable: 4702) // unreachable code
+#endif
 
 template<class T, std::size_t N> void test()
 {

test/array_c_array_test.cpp

@@ -2,14 +2,15 @@
 // Distributed under the Boost Software License, Version 1.0.
 // https://www.boost.org/LICENSE_1_0.txt)
 
+#define BOOST_ALLOW_DEPRECATED_SYMBOLS
+
 #include <boost/array.hpp>
 #include <boost/core/lightweight_test.hpp>
 #include <boost/config.hpp>
 #include <boost/config/workaround.hpp>
 #include <cstddef>
 
-// c_array and get_c_array are nonstandard extensions
-// probably need to be deprecated and removed
+// c_array and get_c_array are deprecated nonstandard extensions
 
 template<class T, std::size_t N> void test()
 {

test/array_copy_test.cpp

@@ -44,11 +44,11 @@ template<class T> void test4()
 
 int main()
 {
-    // test1<int, 0>();
+    test1<int, 0>();
     test1<int, 1>();
     test1<int, 7>();
 
-    // test1<int const, 0>();
+    test1<int const, 0>();
     test1<int const, 1>();
     test1<int const, 7>();
 

test/array_eq_test.cpp

@@ -6,6 +6,10 @@
 #include <boost/core/lightweight_test.hpp>
 #include <cstddef>
 
+#if defined(_MSC_VER)
+# pragma warning(disable: 4702) // unreachable code
+#endif
+
 template<class T, std::size_t N> void test()
 {
     {

test/array_fill_test.cpp

@@ -6,6 +6,10 @@
 #include <boost/core/lightweight_test.hpp>
 #include <cstddef>
 
+#if defined(_MSC_VER)
+# pragma warning(disable: 4702) // unreachable code
+#endif
+
 template<class T, std::size_t N> void test()
 {
     boost::array<T, N> a = {};

test/array_init_test.cpp

@@ -8,6 +8,10 @@
 #include <boost/config/workaround.hpp>
 #include <cstddef>
 
+#if defined(_MSC_VER)
+# pragma warning(disable: 4702) // unreachable code
+#endif
+
 template<class T, std::size_t N> void test1()
 {
     boost::array<T, N> a = {{}};
@@ -46,11 +50,11 @@ template<class T> void test4()
 
 int main()
 {
-    // test1<int, 0>();
+    test1<int, 0>();
     test1<int, 1>();
     test1<int, 7>();
 
-    // test1<int const, 0>();
+    test1<int const, 0>();
     test1<int const, 1>();
     test1<int const, 7>();
 

test/array_init_test_cx.cpp

@@ -56,7 +56,8 @@ template<class T> void test4()
 
 template<class T> void test5()
 {
-    // constexpr boost::array<T, 0> a = {{}};
+    constexpr boost::array<T, 0> a = {{}};
+    (void)a;
 }
 
 template<class T> void test6()

test/array_iterator_test.cpp

@@ -94,11 +94,11 @@ template<class T> void test2()
 
 int main()
 {
-    // test<int, 0>();
+    test<int, 0>();
     test<int, 1>();
     test<int, 7>();
 
-    // test<int const, 0>();
+    test<int const, 0>();
     test<int const, 1>();
     test<int const, 7>();
 

test/array_lt_test.cpp

@@ -6,6 +6,10 @@
 #include <boost/core/lightweight_test.hpp>
 #include <cstddef>
 
+#if defined(_MSC_VER)
+# pragma warning(disable: 4702) // unreachable code
+#endif
+
 template<class T, std::size_t N> void test()
 {
     {

test/array_reverse_test.cpp

@@ -76,11 +76,11 @@ template<class T, std::size_t N> void test()
 
 int main()
 {
-    // test<int, 0>();
+    test<int, 0>();
     test<int, 1>();
     test<int, 7>();
 
-    // test<int const, 0>();
+    test<int const, 0>();
     test<int const, 1>();
     test<int const, 7>();
 

test/array_size_test.cpp

@@ -15,6 +15,8 @@ template<class T, std::size_t N> void test1()
         BOOST_TEST_EQ( a.size(), N );
         BOOST_TEST_EQ( a.empty(), N == 0 );
         BOOST_TEST_EQ( a.max_size(), N );
+
+        (void)a; // msvc-12.0
     }
 
     {
@@ -23,6 +25,8 @@ template<class T, std::size_t N> void test1()
         BOOST_TEST_EQ( a.size(), N );
         BOOST_TEST_EQ( a.empty(), N == 0 );
         BOOST_TEST_EQ( a.max_size(), N );
+
+        (void)a; // msvc-12.0
     }
 }
 
@@ -49,11 +53,11 @@ template<class T, std::size_t N> void test3()
 
 int main()
 {
-    // test1<int, 0>();
+    test1<int, 0>();
     test1<int, 1>();
     test1<int, 7>();
 
-    // test1<int const, 0>();
+    test1<int const, 0>();
     test1<int const, 1>();
     test1<int const, 7>();
 

test/array_swap_test.cpp

@@ -6,6 +6,10 @@
 #include <boost/core/lightweight_test.hpp>
 #include <cstddef>
 
+#if defined(_MSC_VER)
+# pragma warning(disable: 4702) // unreachable code
+#endif
+
 template<class T, std::size_t N> void test()
 {
     boost::array<T, N> a1 = {};

test/array_swap_test2.cpp

@@ -6,6 +6,10 @@
 #include <boost/core/lightweight_test.hpp>
 #include <cstddef>
 
+#if defined(_MSC_VER)
+# pragma warning(disable: 4702) // unreachable code
+#endif
+
 template<class T, std::size_t N> void test()
 {
     boost::array<T, N> a1 = {};

test/array_thw_test.cpp

@@ -0,0 +1,91 @@
+// Copyright 2025 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt)
+
+#include <boost/array.hpp>
+#include <boost/core/lightweight_test.hpp>
+#include <boost/config.hpp>
+#include <boost/config/pragma_message.hpp>
+#include <cstddef>
+
+#if !defined(__cpp_impl_three_way_comparison)
+
+BOOST_PRAGMA_MESSAGE( "Test skipped because __cpp_impl_three_way_comparison is not defined" )
+int main() {}
+
+#elif !( __cpp_impl_three_way_comparison >= 201907L )
+
+BOOST_PRAGMA_MESSAGE( "Test skipped because __cpp_impl_three_way_comparison is defined to " BOOST_STRINGIZE(__cpp_impl_three_way_comparison) )
+int main() {}
+
+#else
+
+template<class T, std::size_t N> void test()
+{
+    constexpr auto eq = 0 <=> 0;
+    constexpr auto lt = 0 <=> 1;
+    constexpr auto gt = 1 <=> 0;
+
+    {
+        boost::array<T, N> const a1 = {};
+        boost::array<T, N> const a2 = {};
+
+        BOOST_TEST( ( a1 <=> a2 ) == eq );
+    }
+
+    {
+        boost::array<T, N> a1;
+        boost::array<T, N> a2;
+
+        a1.fill( 1 );
+        a2.fill( 1 );
+
+        BOOST_TEST( ( a1 <=> a2 ) == eq );
+    }
+
+    for( std::size_t i = 0; i < N; ++i )
+    {
+        boost::array<T, N> a1;
+        boost::array<T, N> a2;
+
+        a1.fill( 1 );
+        a2.fill( 1 );
+
+        a1[ i ] = 0;
+
+        BOOST_TEST( ( a1 <=> a2 ) == lt );
+
+        {
+            boost::array<T, N> const a3 = a1;
+            boost::array<T, N> const a4 = a2;
+
+            BOOST_TEST( ( a3 <=> a4 ) == lt );
+        }
+
+        a1[ i ] = 2;
+
+        BOOST_TEST( ( a1 <=> a2 ) == gt );
+
+        {
+            boost::array<T, N> const a3 = a1;
+            boost::array<T, N> const a4 = a2;
+
+            BOOST_TEST( ( a3 <=> a4 ) == gt );
+        }
+    }
+}
+
+int main()
+{
+    test<int, 0>();
+    test<int, 1>();
+    test<int, 7>();
+
+    test<float, 0>();
+    test<float, 1>();
+    test<float, 7>();
+
+    return boost::report_errors();
+}
+
+#endif

test/array_thw_test_cx.cpp

@@ -0,0 +1,70 @@
+// Copyright 2025 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt)
+
+#include <boost/array.hpp>
+#include <boost/config.hpp>
+#include <boost/config/pragma_message.hpp>
+#include <boost/config/workaround.hpp>
+#include <cstddef>
+
+#if !defined(__cpp_impl_three_way_comparison)
+
+BOOST_PRAGMA_MESSAGE( "Test skipped because __cpp_impl_three_way_comparison is not defined" )
+int main() {}
+
+#elif !( __cpp_impl_three_way_comparison >= 201907L )
+
+BOOST_PRAGMA_MESSAGE( "Test skipped because __cpp_impl_three_way_comparison is defined to " BOOST_STRINGIZE(__cpp_impl_three_way_comparison) )
+int main() {}
+
+#else
+
+#define STATIC_ASSERT(...) static_assert(__VA_ARGS__, #__VA_ARGS__)
+
+template<class T, std::size_t N> void test1()
+{
+    constexpr auto eq = 0 <=> 0;
+
+    constexpr boost::array<T, N> a1 = {};
+    constexpr boost::array<T, N> a2 = {};
+
+    STATIC_ASSERT( ( a1 <=> a2 ) == eq );
+}
+
+template<class T> void test2()
+{
+    constexpr auto eq = 0 <=> 0;
+    constexpr auto lt = 0 <=> 1;
+    constexpr auto gt = 1 <=> 0;
+
+    {
+        constexpr boost::array<T, 4> a1 = {{ 1, 2, 3, 4 }};
+        constexpr boost::array<T, 4> a2 = {{ 1, 2, 3, 4 }};
+
+        STATIC_ASSERT( ( a1 <=> a2 ) == eq );
+    }
+    {
+        constexpr boost::array<T, 4> a1 = {{ 1, 2, 3, 4 }};
+        constexpr boost::array<T, 4> a2 = {{ 1, 2, 3, 5 }};
+
+        STATIC_ASSERT( ( a1 <=> a2 ) == lt );
+    }
+    {
+        constexpr boost::array<T, 4> a1 = {{ 1, 2, 3, 4 }};
+        constexpr boost::array<T, 4> a2 = {{ 1, 2, 3, 2 }};
+
+        STATIC_ASSERT( ( a1 <=> a2 ) == gt );
+    }
+}
+
+int main()
+{
+    test1<int, 0>();
+    test1<int, 1>();
+    test1<int, 7>();
+
+    test2<int>();
+}
+
+#endif