Merge pull request #11 from TimoMaarse/develop

Fix incorrect inference in `bulk::sum` and `bulk::product`

CHANGELOG.md

@@ -12,6 +12,10 @@ Versioning](https://semver.org/spec/v2.0.0.html).
 
 - `bulk::index` now represents indices as `size_t`
 
+### Fixed
+
+- Prevent `bulk::sum` and `bulk::product` from silently truncating values (@TimoMaarse, #11)
+
 ## [2.0.0] - 2020-03-27
 
 ### Breaking changes

include/bulk/algorithm.hpp

@@ -190,13 +190,13 @@ T min(bulk::world& world, T t) {
 template <typename T>
 T sum(bulk::world& world, T t) {
     auto xs = bulk::gather_all(world, t);
-    return std::accumulate(xs.begin(), xs.end(), 0);
+    return std::accumulate(xs.begin(), xs.end(), T{});
 }
 
 template <typename T>
 T product(bulk::world& world, T t) {
     auto xs = bulk::gather_all(world, t);
-    return std::accumulate(xs.begin(), xs.end(), 1,
+    return std::accumulate(xs.begin(), xs.end(), (T)1,
                            [](auto& lhs, auto& rhs) { return lhs * rhs; });
 }
 

test/algorithm.cpp

@@ -1,4 +1,5 @@
 #include <chrono>
+#include <limits>
 #include <thread>
 
 #include "bulk_test_common.hpp"
@@ -75,6 +76,15 @@ void test_algorithm() {
             BULK_CHECK(bulk::min(xs) == 1, "min of coarray");
             BULK_CHECK(bulk::sum(xs) == 2 * p * (2 * p + 1) / 2,
                        "sum of coarray ");
+
+            BULK_CHECK(bulk::sum(world, (int64_t)std::numeric_limits<int32_t>::max()) ==
+                       (int64_t)p * (int64_t)std::numeric_limits<int32_t>::max(),
+                       "sum of large values");
+            BULK_CHECK(bulk::product(world, s == 0 ?
+                                            (int64_t)std::numeric_limits<int32_t>::max() + 1 :
+                                            1) ==
+                       (int64_t)std::numeric_limits<int32_t>::max() + 1,
+                       "large product");
         }
     });
 }