[libcxx-commits] [PATCH] D142294: [libc++] Allow transforming to a different type in transform_inclusive_scan

[Nikolas Klauser via Phabricator via libcxx-commits]

philnik created this revision.
philnik added reviewers: ldionne, Mordante, var-const.
Herald added a project: All.
philnik requested review of this revision.
Herald added a project: libc++.
Herald added a subscriber: libcxx-commits.
Herald added a reviewer: libc++.

Fixes #60143


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D142294

Files:
  libcxx/include/__numeric/transform_inclusive_scan.h
  libcxx/test/std/numerics/numeric.ops/transform.inclusive.scan/transform_inclusive_scan_bop_uop.pass.cpp


Index: libcxx/test/std/numerics/numeric.ops/transform.inclusive.scan/transform_inclusive_scan_bop_uop.pass.cpp
===================================================================
--- libcxx/test/std/numerics/numeric.ops/transform.inclusive.scan/transform_inclusive_scan_bop_uop.pass.cpp
+++ libcxx/test/std/numerics/numeric.ops/transform.inclusive.scan/transform_inclusive_scan_bop_uop.pass.cpp
@@ -36,6 +36,25 @@
     }
 };
 
+class MyInt {
+  int i_;
+
+public:
+  constexpr MyInt() = default;
+  constexpr MyInt(int i) : i_(i) {}
+
+  constexpr int get() { return i_; }
+
+  constexpr friend bool operator==(MyInt lhs, MyInt rhs) { return lhs.get() == rhs.get(); }
+};
+
+struct transform_to_type {
+  template <class T>
+  constexpr MyInt operator()(T) const {
+    return {};
+  }
+};
+
 template <class Iter1, class BOp, class UOp, class T>
 TEST_CONSTEXPR_CXX20 void
 test(Iter1 first, Iter1 last, BOp bop, UOp uop, const T *rFirst, const T *rLast)
@@ -112,6 +131,18 @@
     std::transform_inclusive_scan(v.begin(), v.end(), res.begin(), std::plus<>(), add_one{});
     assert(res.empty());
     }
+
+  {
+    std::array a{1, 2, 3, 4};
+    std::array<MyInt, 4> b;
+    std::transform_inclusive_scan(
+        begin(a),
+        end(a),
+        begin(b),
+        [](MyInt lhs, MyInt rhs) { return MyInt{lhs.get() + rhs.get()}; },
+        [](int i) { return MyInt{i + 1}; });
+    assert((b == std::array<MyInt, 4>{2, 5, 9, 14}));
+  }
 }
 
 TEST_CONSTEXPR_CXX20 bool
Index: libcxx/include/__numeric/transform_inclusive_scan.h
===================================================================
--- libcxx/include/__numeric/transform_inclusive_scan.h
+++ libcxx/include/__numeric/transform_inclusive_scan.h
@@ -42,7 +42,7 @@
                                _OutputIterator __result, _BinaryOp __b, _UnaryOp __u)
 {
     if (__first != __last) {
-        typename iterator_traits<_InputIterator>::value_type __init = __u(*__first);
+        auto __init = __u(*__first);
         *__result++ = __init;
         if (++__first != __last)
             return _VSTD::transform_inclusive_scan(__first, __last, __result, __b, __u, __init);


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