From 14560070cab41ef6c76e94a85b80abb3a6bfdb82 Mon Sep 17 00:00:00 2001
From: Andrey Semashev <andrey.semashev@gmail.com>
Date: Sun, 21 May 2023 15:05:13 +0300
Subject: [PATCH] Make fallback is_complete implementation more robust.

When all else fails, at least indicate the types that we always know to
be incomplete: cv void and boundless arrays.

Also cleanup formatting a bit.
---
 include/boost/type_traits/is_complete.hpp | 41 +++++++++++++++++------
 test/is_complete_test.cpp                 | 16 +++++++--
 2 files changed, 45 insertions(+), 12 deletions(-)

diff --git a/include/boost/type_traits/is_complete.hpp b/include/boost/type_traits/is_complete.hpp
index 08f0e62..428edf1 100644
--- a/include/boost/type_traits/is_complete.hpp
+++ b/include/boost/type_traits/is_complete.hpp
@@ -27,11 +27,10 @@
  * DO NOT MAKE GENERAL USE OF THIS TRAIT, AS THE COMPLETENESS OF A TYPE
  * VARIES ACROSS TRANSLATION UNITS AS WELL AS WITHIN A SINGLE UNIT.
  *
-*/
+ */
 
 namespace boost {
 
-
 //
 // We will undef this if the trait isn't fully functional:
 //
@@ -39,7 +38,7 @@ namespace boost {
 
 #if !defined(BOOST_NO_SFINAE_EXPR) && !BOOST_WORKAROUND(BOOST_MSVC, <= 1900) && !BOOST_WORKAROUND(BOOST_GCC_VERSION, < 40600)
 
-   namespace detail{
+   namespace detail {
 
       template <std::size_t N>
       struct ok_tag { double d; char c[N]; };
@@ -48,15 +47,15 @@ namespace boost {
       ok_tag<sizeof(T)> check_is_complete(int);
       template <class T>
       char check_is_complete(...);
-   }
+
+   } // namespace detail
 
    template <class T> struct is_complete
       : public integral_constant<bool, ::boost::is_function<typename boost::remove_reference<T>::type>::value || (sizeof(boost::detail::check_is_complete<T>(0)) != sizeof(char))> {};
 
 #elif !defined(BOOST_NO_SFINAE) && !defined(BOOST_NO_CXX11_FUNCTION_TEMPLATE_DEFAULT_ARGS) && !BOOST_WORKAROUND(BOOST_GCC_VERSION, < 40500)
 
-   namespace detail
-   {
+   namespace detail {
 
       template <class T>
       struct is_complete_imp
@@ -70,7 +69,7 @@ namespace boost {
          static const bool value = sizeof(check<T>(0)) == sizeof(type_traits::yes_type);
       };
 
-} // namespace detail
+   } // namespace detail
 
 
    template <class T>
@@ -78,11 +77,33 @@ namespace boost {
    {};
    template <class T>
    struct is_complete<T&> : boost::is_complete<T> {};
-   
+
 #else
 
-      template <class T> struct is_complete
-         : public boost::integral_constant<bool, true> {};
+   namespace detail {
+
+      template <class T>
+      struct is_complete_impl : public boost::true_type {};
+
+      template < >
+      struct is_complete_impl<void> : public boost::false_type {};
+
+      template <class T>
+      struct is_complete_impl<T[]> : public boost::false_type {};
+
+      template <class T>
+      struct is_complete_impl<T&> : public is_complete_impl<T>::type {};
+
+   } // namespace detail
+
+   template <class T>
+   struct is_complete : public detail::is_complete_impl<T>::type {};
+   template <class T>
+   struct is_complete<const T> : public detail::is_complete_impl<T>::type {};
+   template <class T>
+   struct is_complete<volatile T> : public detail::is_complete_impl<T>::type {};
+   template <class T>
+   struct is_complete<const volatile T> : public detail::is_complete_impl<T>::type {};
 
 #undef BOOST_TT_HAS_WORKING_IS_COMPLETE
 
diff --git a/test/is_complete_test.cpp b/test/is_complete_test.cpp
index 075e70d..74d7a3d 100644
--- a/test/is_complete_test.cpp
+++ b/test/is_complete_test.cpp
@@ -14,6 +14,15 @@
 
 TT_TEST_BEGIN(is_complete)
 
+BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_complete<void>::value, false);
+BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_complete<void const>::value, false);
+BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_complete<void volatile>::value, false);
+BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_complete<void const volatile>::value, false);
+BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_complete<void*>::value, true);
+BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_complete<void const*>::value, true);
+BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_complete<void volatile*>::value, true);
+BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_complete<void const volatile*>::value, true);
+
 BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_complete<int>::value, true);
 BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_complete<int const>::value, true);
 BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_complete<int volatile>::value, true);
@@ -31,9 +40,11 @@ BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_complete<int[2]>::value, true);
 BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_complete<int const[3]>::value, true);
 BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_complete<int volatile[2][3]>::value, true);
 BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_complete<int const volatile[4][5][6]>::value, true);
-#ifdef BOOST_TT_HAS_WORKING_IS_COMPLETE
+
 BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_complete<int[]>::value, false);
-#endif
+BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_complete<int const[]>::value, false);
+BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_complete<int volatile[]>::value, false);
+BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_complete<int const volatile[]>::value, false);
 
 BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_complete<enum_UDT>::value, true);
 BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_complete<UDT>::value, true);
@@ -46,6 +57,7 @@ BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_complete<test_abc1>::value, true);
 #ifdef BOOST_TT_HAS_WORKING_IS_COMPLETE
 BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_complete<incomplete_type>::value, false);
 #endif
+BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_complete<incomplete_type*>::value, true);
 BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_complete<polymorphic_base>::value, true);
 BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_complete<virtual_inherit6>::value, true);
 BOOST_CHECK_INTEGRAL_CONSTANT(::tt::is_complete<foo0_t>::value, true);