Some cleanup in Thrust config headers (#1934)

* Drop THRUST_TRAILING_RETURN

* Remove obsolete comment

* Re-enable warning on obsolete memory fences

* Remove unused debug.h

docs/repo.toml

@@ -253,7 +253,6 @@ doxygen_predefined = [
   "THRUST_NAMESPACE_END=}",
   "THRUST_INLINE_CONSTANT",
   "THRUST_PREVENT_MACRO_SUBSTITUTION",
-  "THRUST_TRAILING_RETURN(x)= -> x",
   "THRUST_BINARY_FUNCTOR_VOID_SPECIALIZATION_OP(x,y)=",
   "THRUST_UNARY_FUNCTOR_VOID_SPECIALIZATION(x, y)=",
   "THRUST_BINARY_FUNCTOR_VOID_SPECIALIZATION(x, y)=",

thrust/thrust/detail/config/compiler.h

@@ -45,7 +45,6 @@
 #define THRUST_DEVICE_COMPILER_NVCC    4
 
 // figure out which host compiler we're using
-// XXX we should move the definition of THRUST_DEPRECATED out of this logic
 #if defined(_CCCL_COMPILER_MSVC)
 #  define THRUST_HOST_COMPILER     THRUST_HOST_COMPILER_MSVC
 #  define THRUST_MSVC_VERSION      _MSC_VER

thrust/thrust/detail/config/compiler_fence.h

@@ -28,14 +28,12 @@
 
 #include <thrust/detail/preprocessor.h>
 
-// TODO: Enable this or remove this file once nvGRAPH/CUSP migrates off of it.
-// #if defined(_CCCL_COMPILER_MSVC)
-//  #pragma message("warning: The functionality in this header is unsafe, deprecated, and will soon be removed. Use
-//  C++11 or C11 atomics instead.")
-// #else
-//  #warning The functionality in this header is unsafe, deprecated, and will soon be removed. Use C++11 or C11 atomics
-//  instead.
-// #endif
+#if defined(_CCCL_COMPILER_MSVC)
+#  pragma message( \
+    "warning: The functionality in this header is unsafe, deprecated, and will soon be removed. Use C++11 atomics instead.")
+#else
+#warning The functionality in this header is unsafe, deprecated, and will soon be removed. Use C++11 or C11 atomics instead.
+#endif
 
 // msvc case
 #if defined(_CCCL_COMPILER_MSVC)

thrust/thrust/detail/config/config.h

@@ -38,11 +38,9 @@
 #include <thrust/detail/config/cpp_dialect.h>
 #include <thrust/detail/config/deprecated.h>
 #include <thrust/detail/config/simple_defines.h>
-// host_system.h & device_system.h must be #included as early as possible
-// because other config headers depend on it
+// host_system.h & device_system.h must be #included as early as possible because other config headers depend on it
 #include <thrust/detail/config/host_system.h>
 
-#include <thrust/detail/config/debug.h>
 #include <thrust/detail/config/device_system.h>
 #include <thrust/detail/config/global_workarounds.h>
 #include <thrust/detail/config/namespace.h>

thrust/thrust/detail/config/cpp_compatibility.h

@@ -34,14 +34,6 @@
 #  define __has_cpp_attribute(X) 0
 #endif
 
-// Trailing return types seem to confuse Doxygen, and cause it to interpret
-// parts of the function's body as new function signatures.
-#if defined(THRUST_DOXYGEN)
-#  define THRUST_TRAILING_RETURN(...)
-#else
-#  define THRUST_TRAILING_RETURN(...) ->__VA_ARGS__
-#endif
-
 #define THRUST_NODISCARD _CCCL_NODISCARD
 
 // FIXME: Combine THRUST_INLINE_CONSTANT and

thrust/thrust/detail/functional/operators/arithmetic_operators.h

@@ -51,7 +51,7 @@ struct unary_plus
   _CCCL_EXEC_CHECK_DISABLE
   template <typename T1>
   _CCCL_HOST_DEVICE constexpr auto operator()(T1&& t1) const noexcept(noexcept(+THRUST_FWD(t1)))
-    THRUST_TRAILING_RETURN(decltype(+THRUST_FWD(t1)))
+    -> decltype(+THRUST_FWD(t1))
   {
     return +THRUST_FWD(t1);
   }
@@ -182,7 +182,7 @@ struct prefix_increment
   _CCCL_EXEC_CHECK_DISABLE
   template <typename T1>
   _CCCL_HOST_DEVICE constexpr auto operator()(T1&& t1) const noexcept(noexcept(++THRUST_FWD(t1)))
-    THRUST_TRAILING_RETURN(decltype(++THRUST_FWD(t1)))
+    -> decltype(++THRUST_FWD(t1))
   {
     return ++THRUST_FWD(t1);
   }
@@ -203,7 +203,7 @@ struct postfix_increment
   _CCCL_EXEC_CHECK_DISABLE
   template <typename T1>
   _CCCL_HOST_DEVICE constexpr auto operator()(T1&& t1) const noexcept(noexcept(THRUST_FWD(t1)++))
-    THRUST_TRAILING_RETURN(decltype(THRUST_FWD(t1)++))
+    -> decltype(THRUST_FWD(t1)++)
   {
     return THRUST_FWD(t1)++;
   }
@@ -224,7 +224,7 @@ struct prefix_decrement
   _CCCL_EXEC_CHECK_DISABLE
   template <typename T1>
   _CCCL_HOST_DEVICE constexpr auto operator()(T1&& t1) const noexcept(noexcept(--THRUST_FWD(t1)))
-    THRUST_TRAILING_RETURN(decltype(--THRUST_FWD(t1)))
+    -> decltype(--THRUST_FWD(t1))
   {
     return --THRUST_FWD(t1);
   }
@@ -245,7 +245,7 @@ struct postfix_decrement
   _CCCL_EXEC_CHECK_DISABLE
   template <typename T1>
   _CCCL_HOST_DEVICE constexpr auto operator()(T1&& t1) const noexcept(noexcept(THRUST_FWD(t1)--))
-    THRUST_TRAILING_RETURN(decltype(THRUST_FWD(t1)--))
+    -> decltype(THRUST_FWD(t1)--)
   {
     return THRUST_FWD(t1)--;
   }

thrust/thrust/detail/functional/operators/assignment_operator.h

@@ -53,8 +53,7 @@ struct assign
   _CCCL_EXEC_CHECK_DISABLE
   template <typename T1, typename T2>
   _CCCL_HOST_DEVICE constexpr auto operator()(T1&& t1, T2&& t2) const
-    noexcept(noexcept(THRUST_FWD(t1) = THRUST_FWD(t2)))
-      THRUST_TRAILING_RETURN(decltype(THRUST_FWD(t1) = THRUST_FWD(t2)))
+    noexcept(noexcept(THRUST_FWD(t1) = THRUST_FWD(t2))) -> decltype(THRUST_FWD(t1) = THRUST_FWD(t2))
   {
     return THRUST_FWD(t1) = THRUST_FWD(t2);
   }

thrust/thrust/detail/functional/operators/bitwise_operators.h

@@ -107,7 +107,7 @@ struct bit_not
   _CCCL_EXEC_CHECK_DISABLE
   template <typename T1>
   _CCCL_HOST_DEVICE constexpr auto operator()(T1&& t1) const noexcept(noexcept(~THRUST_FWD(t1)))
-    THRUST_TRAILING_RETURN(decltype(~THRUST_FWD(t1)))
+    -> decltype(~THRUST_FWD(t1))
   {
     return ~THRUST_FWD(t1);
   }
@@ -128,8 +128,7 @@ struct bit_lshift
   _CCCL_EXEC_CHECK_DISABLE
   template <typename T1, typename T2>
   _CCCL_HOST_DEVICE constexpr auto operator()(T1&& t1, T2&& t2) const
-    noexcept(noexcept(THRUST_FWD(t1) << THRUST_FWD(t2)))
-      THRUST_TRAILING_RETURN(decltype(THRUST_FWD(t1) << THRUST_FWD(t2)))
+    noexcept(noexcept(THRUST_FWD(t1) << THRUST_FWD(t2))) -> decltype(THRUST_FWD(t1) << THRUST_FWD(t2))
   {
     return THRUST_FWD(t1) << THRUST_FWD(t2);
   }
@@ -164,8 +163,7 @@ struct bit_rshift
   _CCCL_EXEC_CHECK_DISABLE
   template <typename T1, typename T2>
   _CCCL_HOST_DEVICE constexpr auto operator()(T1& t1, T2&& t2) const
-    noexcept(noexcept(THRUST_FWD(t1) >> THRUST_FWD(t2)))
-      THRUST_TRAILING_RETURN(decltype(THRUST_FWD(t1) >> THRUST_FWD(t2)))
+    noexcept(noexcept(THRUST_FWD(t1) >> THRUST_FWD(t2))) -> decltype(THRUST_FWD(t1) >> THRUST_FWD(t2))
   {
     return THRUST_FWD(t1) >> THRUST_FWD(t2);
   }

thrust/thrust/detail/functional/operators/compound_assignment_operators.h

@@ -43,8 +43,7 @@ struct plus_equal
   _CCCL_EXEC_CHECK_DISABLE
   template <typename T1, typename T2>
   _CCCL_HOST_DEVICE constexpr auto operator()(T1&& t1, T2&& t2) const
-    noexcept(noexcept(THRUST_FWD(t1) += THRUST_FWD(t2)))
-      THRUST_TRAILING_RETURN(decltype(THRUST_FWD(t1) += THRUST_FWD(t2)))
+    noexcept(noexcept(THRUST_FWD(t1) += THRUST_FWD(t2))) -> decltype(THRUST_FWD(t1) += THRUST_FWD(t2))
   {
     return THRUST_FWD(t1) += THRUST_FWD(t2);
   }
@@ -72,8 +71,7 @@ struct minus_equal
   _CCCL_EXEC_CHECK_DISABLE
   template <typename T1, typename T2>
   _CCCL_HOST_DEVICE constexpr auto operator()(T1&& t1, T2&& t2) const
-    noexcept(noexcept(THRUST_FWD(t1) -= THRUST_FWD(t2)))
-      THRUST_TRAILING_RETURN(decltype(THRUST_FWD(t1) -= THRUST_FWD(t2)))
+    noexcept(noexcept(THRUST_FWD(t1) -= THRUST_FWD(t2))) -> decltype(THRUST_FWD(t1) -= THRUST_FWD(t2))
   {
     return THRUST_FWD(t1) -= THRUST_FWD(t2);
   }
@@ -101,8 +99,7 @@ struct multiplies_equal
   _CCCL_EXEC_CHECK_DISABLE
   template <typename T1, typename T2>
   _CCCL_HOST_DEVICE constexpr auto operator()(T1&& t1, T2&& t2) const
-    noexcept(noexcept(THRUST_FWD(t1) *= THRUST_FWD(t2)))
-      THRUST_TRAILING_RETURN(decltype(THRUST_FWD(t1) *= THRUST_FWD(t2)))
+    noexcept(noexcept(THRUST_FWD(t1) *= THRUST_FWD(t2))) -> decltype(THRUST_FWD(t1) *= THRUST_FWD(t2))
   {
     return THRUST_FWD(t1) *= THRUST_FWD(t2);
   }
@@ -130,8 +127,7 @@ struct divides_equal
   _CCCL_EXEC_CHECK_DISABLE
   template <typename T1, typename T2>
   _CCCL_HOST_DEVICE constexpr auto operator()(T1&& t1, T2&& t2) const
-    noexcept(noexcept(THRUST_FWD(t1) /= THRUST_FWD(t2)))
-      THRUST_TRAILING_RETURN(decltype(THRUST_FWD(t1) /= THRUST_FWD(t2)))
+    noexcept(noexcept(THRUST_FWD(t1) /= THRUST_FWD(t2))) -> decltype(THRUST_FWD(t1) /= THRUST_FWD(t2))
   {
     return THRUST_FWD(t1) /= THRUST_FWD(t2);
   }
@@ -159,8 +155,7 @@ struct modulus_equal
   _CCCL_EXEC_CHECK_DISABLE
   template <typename T1, typename T2>
   _CCCL_HOST_DEVICE constexpr auto operator()(T1&& t1, T2&& t2) const
-    noexcept(noexcept(THRUST_FWD(t1) %= THRUST_FWD(t2)))
-      THRUST_TRAILING_RETURN(decltype(THRUST_FWD(t1) %= THRUST_FWD(t2)))
+    noexcept(noexcept(THRUST_FWD(t1) %= THRUST_FWD(t2))) -> decltype(THRUST_FWD(t1) %= THRUST_FWD(t2))
   {
     return THRUST_FWD(t1) %= THRUST_FWD(t2);
   }
@@ -188,8 +183,7 @@ struct bit_and_equal
   _CCCL_EXEC_CHECK_DISABLE
   template <typename T1, typename T2>
   _CCCL_HOST_DEVICE constexpr auto operator()(T1&& t1, T2&& t2) const
-    noexcept(noexcept(THRUST_FWD(t1) &= THRUST_FWD(t2)))
-      THRUST_TRAILING_RETURN(decltype(THRUST_FWD(t1) &= THRUST_FWD(t2)))
+    noexcept(noexcept(THRUST_FWD(t1) &= THRUST_FWD(t2))) -> decltype(THRUST_FWD(t1) &= THRUST_FWD(t2))
   {
     return THRUST_FWD(t1) &= THRUST_FWD(t2);
   }
@@ -217,8 +211,7 @@ struct bit_or_equal
   _CCCL_EXEC_CHECK_DISABLE
   template <typename T1, typename T2>
   _CCCL_HOST_DEVICE constexpr auto operator()(T1&& t1, T2&& t2) const
-    noexcept(noexcept(THRUST_FWD(t1) |= THRUST_FWD(t2)))
-      THRUST_TRAILING_RETURN(decltype(THRUST_FWD(t1) |= THRUST_FWD(t2)))
+    noexcept(noexcept(THRUST_FWD(t1) |= THRUST_FWD(t2))) -> decltype(THRUST_FWD(t1) |= THRUST_FWD(t2))
   {
     return THRUST_FWD(t1) |= THRUST_FWD(t2);
   }
@@ -246,8 +239,7 @@ struct bit_xor_equal
   _CCCL_EXEC_CHECK_DISABLE
   template <typename T1, typename T2>
   _CCCL_HOST_DEVICE constexpr auto operator()(T1&& t1, T2&& t2) const
-    noexcept(noexcept(THRUST_FWD(t1) ^= THRUST_FWD(t2)))
-      THRUST_TRAILING_RETURN(decltype(THRUST_FWD(t1) ^= THRUST_FWD(t2)))
+    noexcept(noexcept(THRUST_FWD(t1) ^= THRUST_FWD(t2))) -> decltype(THRUST_FWD(t1) ^= THRUST_FWD(t2))
   {
     return THRUST_FWD(t1) ^= THRUST_FWD(t2);
   }
@@ -275,8 +267,7 @@ struct bit_lshift_equal
   _CCCL_EXEC_CHECK_DISABLE
   template <typename T1, typename T2>
   _CCCL_HOST_DEVICE constexpr auto operator()(T1&& t1, T2&& t2) const
-    noexcept(noexcept(THRUST_FWD(t1) <<= THRUST_FWD(t2)))
-      THRUST_TRAILING_RETURN(decltype(THRUST_FWD(t1) <<= THRUST_FWD(t2)))
+    noexcept(noexcept(THRUST_FWD(t1) <<= THRUST_FWD(t2))) -> decltype(THRUST_FWD(t1) <<= THRUST_FWD(t2))
   {
     return THRUST_FWD(t1) <<= THRUST_FWD(t2);
   }
@@ -303,8 +294,7 @@ struct bit_rshift_equal
   _CCCL_EXEC_CHECK_DISABLE
   template <typename T1, typename T2>
   _CCCL_HOST_DEVICE constexpr auto operator()(T1&& t1, T2&& t2) const
-    noexcept(noexcept(THRUST_FWD(t1) >>= THRUST_FWD(t2)))
-      THRUST_TRAILING_RETURN(decltype(THRUST_FWD(t1) >>= THRUST_FWD(t2)))
+    noexcept(noexcept(THRUST_FWD(t1) >>= THRUST_FWD(t2))) -> decltype(THRUST_FWD(t1) >>= THRUST_FWD(t2))
   {
     return THRUST_FWD(t1) >>= THRUST_FWD(t2);
   }

thrust/thrust/device_make_unique.h

@@ -41,7 +41,7 @@ THRUST_NAMESPACE_BEGIN
 
 template <typename T, typename... Args>
 _CCCL_HOST auto device_make_unique(Args&&... args)
-  THRUST_TRAILING_RETURN(decltype(uninitialized_allocate_unique<T>(::cuda::std::declval<device_allocator<T>>())))
+  -> decltype(uninitialized_allocate_unique<T>(::cuda::std::declval<device_allocator<T>>()))
 {
   // FIXME: This is crude - we construct an unnecessary T on the host for
   // `device_new`. We need a proper dispatched `construct` algorithm to

thrust/thrust/functional.h

@@ -150,32 +150,30 @@ struct THRUST_DEPRECATED binary_function
  *  \{
  */
 
-#define THRUST_UNARY_FUNCTOR_VOID_SPECIALIZATION(func, impl)                          \
-  template <>                                                                         \
-  struct func<void>                                                                   \
-  {                                                                                   \
-    using is_transparent = void;                                                      \
-    _CCCL_EXEC_CHECK_DISABLE                                                          \
-    template <typename T>                                                             \
-    _CCCL_HOST_DEVICE constexpr auto operator()(T&& x) const noexcept(noexcept(impl)) \
-      THRUST_TRAILING_RETURN(decltype(impl))                                          \
-    {                                                                                 \
-      return impl;                                                                    \
-    }                                                                                 \
+#define THRUST_UNARY_FUNCTOR_VOID_SPECIALIZATION(func, impl)                                            \
+  template <>                                                                                           \
+  struct func<void>                                                                                     \
+  {                                                                                                     \
+    using is_transparent = void;                                                                        \
+    _CCCL_EXEC_CHECK_DISABLE                                                                            \
+    template <typename T>                                                                               \
+    _CCCL_HOST_DEVICE constexpr auto operator()(T&& x) const noexcept(noexcept(impl)) -> decltype(impl) \
+    {                                                                                                   \
+      return impl;                                                                                      \
+    }                                                                                                   \
   }
 
-#define THRUST_BINARY_FUNCTOR_VOID_SPECIALIZATION(func, impl)                                    \
-  template <>                                                                                    \
-  struct func<void>                                                                              \
-  {                                                                                              \
-    using is_transparent = void;                                                                 \
-    _CCCL_EXEC_CHECK_DISABLE                                                                     \
-    template <typename T1, typename T2>                                                          \
-    _CCCL_HOST_DEVICE constexpr auto operator()(T1&& t1, T2&& t2) const noexcept(noexcept(impl)) \
-      THRUST_TRAILING_RETURN(decltype(impl))                                                     \
-    {                                                                                            \
-      return impl;                                                                               \
-    }                                                                                            \
+#define THRUST_BINARY_FUNCTOR_VOID_SPECIALIZATION(func, impl)                                                      \
+  template <>                                                                                                      \
+  struct func<void>                                                                                                \
+  {                                                                                                                \
+    using is_transparent = void;                                                                                   \
+    _CCCL_EXEC_CHECK_DISABLE                                                                                       \
+    template <typename T1, typename T2>                                                                            \
+    _CCCL_HOST_DEVICE constexpr auto operator()(T1&& t1, T2&& t2) const noexcept(noexcept(impl)) -> decltype(impl) \
+    {                                                                                                              \
+      return impl;                                                                                                 \
+    }                                                                                                              \
   }
 
 #define THRUST_BINARY_FUNCTOR_VOID_SPECIALIZATION_OP(func, op) \
@@ -1415,7 +1413,7 @@ struct project1st<void, void>
   _CCCL_EXEC_CHECK_DISABLE
   template <typename T1, typename T2>
   _CCCL_HOST_DEVICE constexpr auto operator()(T1&& t1, T2&&) const noexcept(noexcept(THRUST_FWD(t1)))
-    THRUST_TRAILING_RETURN(decltype(THRUST_FWD(t1)))
+    -> decltype(THRUST_FWD(t1))
   {
     return THRUST_FWD(t1);
   }
@@ -1475,7 +1473,7 @@ struct project2nd<void, void>
   _CCCL_EXEC_CHECK_DISABLE
   template <typename T1, typename T2>
   _CCCL_HOST_DEVICE constexpr auto operator()(T1&&, T2&& t2) const noexcept(noexcept(THRUST_FWD(t2)))
-    THRUST_TRAILING_RETURN(decltype(THRUST_FWD(t2)))
+    -> decltype(THRUST_FWD(t2))
   {
     return THRUST_FWD(t2);
   }

thrust/thrust/optional.h

@@ -154,7 +154,7 @@ template <
   int      = 0>
 _CCCL_HOST_DEVICE constexpr auto
 invoke(Fn&& f, Args&&... args) noexcept(noexcept(std::mem_fn(f)(std::forward<Args>(args)...)))
-  THRUST_TRAILING_RETURN(decltype(std::mem_fn(f)(std::forward<Args>(args)...)))
+  -> decltype(std::mem_fn(f)(std::forward<Args>(args)...))
 {
   return std::mem_fn(f)(std::forward<Args>(args)...);
 }
@@ -163,7 +163,7 @@ _CCCL_EXEC_CHECK_DISABLE
 template <typename Fn, typename... Args, typename = enable_if_t<!std::is_member_pointer<decay_t<Fn>>::value>>
 _CCCL_HOST_DEVICE constexpr auto
 invoke(Fn&& f, Args&&... args) noexcept(noexcept(std::forward<Fn>(f)(std::forward<Args>(args)...)))
-  THRUST_TRAILING_RETURN(decltype(std::forward<Fn>(f)(std::forward<Args>(args)...)))
+  -> decltype(std::forward<Fn>(f)(std::forward<Args>(args)...))
 {
   return std::forward<Fn>(f)(std::forward<Args>(args)...);
 }

thrust/thrust/zip_function.h

@@ -162,7 +162,7 @@ class zip_function
   template <typename Tuple>
   _CCCL_HOST_DEVICE auto operator()(Tuple&& args) const
     noexcept(noexcept(detail::zip_detail::apply(std::declval<Function>(), THRUST_FWD(args))))
-      THRUST_TRAILING_RETURN(decltype(detail::zip_detail::apply(std::declval<Function>(), THRUST_FWD(args))))
+      -> decltype(detail::zip_detail::apply(std::declval<Function>(), THRUST_FWD(args)))
   {
     return detail::zip_detail::apply(func, THRUST_FWD(args));
   }