Check for name collisions with system header macros.

Fix places where using `I` for an identifier was causing conflicts
with complex.h.

Fixes #1244.

cmake/ThrustHeaderTesting.cmake

@@ -4,10 +4,14 @@
 # .inl files are not globbed for, because they are not supposed to be used as public
 # entrypoints.
 
+# Meta target for all configs' header builds:
+add_custom_target(thrust.all.headers)
+
 foreach(thrust_target IN LISTS THRUST_TARGETS)
   thrust_get_target_property(config_host ${thrust_target} HOST)
   thrust_get_target_property(config_device ${thrust_target} DEVICE)
   thrust_get_target_property(config_prefix ${thrust_target} PREFIX)
+  set(config_systems ${config_host} ${config_device})
 
   string(TOLOWER "${config_host}" host_lower)
   string(TOLOWER "${config_device}" device_lower)
@@ -115,5 +119,14 @@ foreach(thrust_target IN LISTS THRUST_TARGETS)
   target_link_libraries(${headertest_target} PUBLIC ${thrust_target})
   thrust_clone_target_properties(${headertest_target} ${thrust_target})
 
+  # Disable macro checks on TBB; the TBB atomic implementation uses `I` and
+  # our checks will issue false errors.
+  if ("TBB" IN_LIST config_systems)
+    target_compile_definitions(${headertest_target}
+      PRIVATE THRUST_IGNORE_MACRO_CHECKS
+    )
+  endif()
+
+  add_dependencies(thrust.all.headers ${headertest_target})
   add_dependencies(${config_prefix}.all ${headertest_target})
 endforeach()

cmake/header_test.in

@@ -1,4 +1,55 @@
+// This source file checks that:
+// 1) Header <thrust/${header}> compiles without error.
+// 2) Common macro collisions with platform/system headers are avoided.
+
+// Turn off failures for certain configurations:
 #define THRUST_CPP11_REQUIRED_NO_ERROR
 #define THRUST_CPP14_REQUIRED_NO_ERROR
 #define THRUST_MODERN_GCC_REQUIRED_NO_ERROR
+
+#ifndef THRUST_IGNORE_MACRO_CHECKS
+
+// Define THRUST_MACRO_CHECK(macro, header), which emits a diagnostic indicating
+// a potential macro collision and halts.
+//
+// Hacky way to build a string, but it works on all tested platforms.
+#define THRUST_MACRO_CHECK(MACRO, HEADER)                                      \
+  THRUST_MACRO_CHECK_IMPL(Identifier MACRO should not be used from Thrust      \
+                            headers due to conflicts with HEADER.)
+
+// Use raw platform checks instead of the THRUST_HOST_COMPILER macros since we
+// don't want to #include any headers other than the one being tested.
+//
+// This is only implemented for MSVC/GCC/Clang.
+#if defined(_MSC_VER) // MSVC
+
+// Fake up an error for MSVC
+#define THRUST_MACRO_CHECK_IMPL(msg)                                           \
+  /* Print message that looks like an error: */                                \
+  __pragma(message(__FILE__ ":" THRUST_MACRO_CHECK_IMPL0(__LINE__)             \
+                   ": error: " #msg))                                          \
+  /* abort compilation due to static_assert or syntax error: */                \
+  static_assert(false, #msg);
+#define THRUST_MACRO_CHECK_IMPL0(x) THRUST_MACRO_CHECK_IMPL1(x)
+#define THRUST_MACRO_CHECK_IMPL1(x) #x
+
+#elif defined(__clang__) || defined(__GNUC__)
+
+// GCC/clang are easy:
+#define THRUST_MACRO_CHECK_IMPL(msg) THRUST_MACRO_CHECK_IMPL0(GCC error #msg)
+#define THRUST_MACRO_CHECK_IMPL0(expr) _Pragma(#expr)
+
+#endif
+
+// complex.h conflicts
+#define I THRUST_MACRO_CHECK('I', complex.h)
+
+// windows.h conflicts
+// Disabling for now; we use min/max in many places, but since most
+// projects build with NOMINMAX this doesn't seem to be high priority to fix.
+//#define min(...) THRUST_MACRO_CHECK('min', windows.h)
+//#define max(...) THRUST_MACRO_CHECK('max', windows.h)
+
+#endif // THRUST_IGNORE_MACRO_CHECKS
+
 #include <thrust/${header}>

thrust/iterator/constant_iterator.h

@@ -217,11 +217,11 @@ template<typename Value,
  *
  *  \see constant_iterator
  */
-template<typename V, typename I>
+template<typename ValueT, typename IndexT>
 inline __host__ __device__
-constant_iterator<V,I> make_constant_iterator(V x, I i = int())
+constant_iterator<ValueT, IndexT> make_constant_iterator(ValueT x, IndexT i = int())
 {
-  return constant_iterator<V,I>(x, i);
+  return constant_iterator<ValueT, IndexT>(x, i);
 } // end make_constant_iterator()
 
 

thrust/system/cuda/detail/sort.h

@@ -312,18 +312,18 @@ namespace __merge_sort {
                                 item_type (&items)[ITEMS_PER_THREAD])
       {
 #pragma unroll
-        for (int I = 0; I < ITEMS_PER_THREAD; ++I)
+        for (int i = 0; i < ITEMS_PER_THREAD; ++i)
         {
 #pragma unroll
-          for (int J = 1 & I; J < ITEMS_PER_THREAD - 1; J += 2)
+          for (int j = 1 & i; j < ITEMS_PER_THREAD - 1; j += 2)
           {
-            if (compare_op(keys[J + 1], keys[J]))
+            if (compare_op(keys[j + 1], keys[j]))
             {
               using thrust::swap;
-              swap(keys[J], keys[J + 1]);
+              swap(keys[j], keys[j + 1]);
               if (SORT_ITEMS::value)
               {
-                swap(items[J], items[J + 1]);
+                swap(items[j], items[j + 1]);
               }
             }
           }    // inner loop

thrust/type_traits/integer_sequence.h

@@ -167,11 +167,11 @@ template <typename T, std::size_t N>
 struct make_reversed_integer_sequence_impl;
 
 // Add a new element to the front of an integer_sequence<>.
-template <typename T, T I, typename Sequence> 
+template <typename T, T Value, typename Sequence>
 struct integer_sequence_push_front_impl;
 
 // Add a new element to the back of an integer_sequence<>.
-template <typename T, T I, typename Sequence> 
+template <typename T, T Value, typename Sequence>
 struct integer_sequence_push_back_impl;
 
 }
@@ -189,14 +189,14 @@ using make_reversed_index_sequence =
   make_reversed_integer_sequence<std::size_t, N>;
 
 // Add a new element to the front of an integer_sequence<>.
-template <typename T, T I, typename Sequence> 
+template <typename T, T Value, typename Sequence>
 using integer_sequence_push_front =
-  typename detail::integer_sequence_push_front_impl<T, I, Sequence>::type;
+  typename detail::integer_sequence_push_front_impl<T, Value, Sequence>::type;
 
 // Add a new element to the back of an integer_sequence<>.
-template <typename T, T I, typename Sequence> 
+template <typename T, T Value, typename Sequence>
 using integer_sequence_push_back =
-  typename detail::integer_sequence_push_back_impl<T, I, Sequence>::type;
+  typename detail::integer_sequence_push_back_impl<T, Value, Sequence>::type;
 
 ///////////////////////////////////////////////////////////////////////////////