(arrow) branch main updated: GH-41016: [C++] Fix null count check in BooleanArray.true_count() (#41070)

[apitrou]

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The following commit(s) were added to refs/heads/main by this push:
     new 729dcb8120 GH-41016: [C++] Fix null count check in 
BooleanArray.true_count() (#41070)
729dcb8120 is described below

commit 729dcb8120dca6d35578d70a845ecda6f79efa1a
Author: Joris Van den Bossche <jorisvandenboss...@gmail.com>
AuthorDate: Mon Apr 15 17:30:28 2024 +0200

    GH-41016: [C++] Fix null count check in BooleanArray.true_count() (#41070)
    
    ### Rationale for this change
    
    Loading the `null_count` attribute doesn't take into account the possible 
value of -1, leading to a code path where the validity buffer is accessed, but 
which is not necessarily present in that case.
    
    ### What changes are included in this PR?
    
    Use `data->MayHaveNulls()` instead of `data->null_count.load()`
    
    ### Are these changes tested?
    
    Yes
    
    * GitHub Issue: #41016
    
    Authored-by: Joris Van den Bossche <jorisvandenboss...@gmail.com>
    Signed-off-by: Antoine Pitrou <anto...@python.org>
---
 cpp/src/arrow/array/array_primitive.cc | 2 +-
 cpp/src/arrow/array/array_test.cc      | 7 +++++++
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/cpp/src/arrow/array/array_primitive.cc 
b/cpp/src/arrow/array/array_primitive.cc
index 7c4a14d934..da3810aa39 100644
--- a/cpp/src/arrow/array/array_primitive.cc
+++ b/cpp/src/arrow/array/array_primitive.cc
@@ -56,7 +56,7 @@ int64_t BooleanArray::false_count() const {
 }
 
 int64_t BooleanArray::true_count() const {
-  if (data_->null_count.load() != 0) {
+  if (data_->MayHaveNulls()) {
     DCHECK(data_->buffers[0]);
     return internal::CountAndSetBits(data_->buffers[0]->data(), data_->offset,
                                      data_->buffers[1]->data(), data_->offset,
diff --git a/cpp/src/arrow/array/array_test.cc 
b/cpp/src/arrow/array/array_test.cc
index 21ac1a09f5..60efdb4768 100644
--- a/cpp/src/arrow/array/array_test.cc
+++ b/cpp/src/arrow/array/array_test.cc
@@ -1307,6 +1307,13 @@ TEST(TestBooleanArray, TrueCountFalseCount) {
   CheckArray(checked_cast<const BooleanArray&>(*arr));
   CheckArray(checked_cast<const BooleanArray&>(*arr->Slice(5)));
   CheckArray(checked_cast<const BooleanArray&>(*arr->Slice(0, 0)));
+
+  // GH-41016 true_count() with array without validity buffer with null_count 
of -1
+  auto arr_unknown_null_count = ArrayFromJSON(boolean(), "[true, false, 
true]");
+  arr_unknown_null_count->data()->null_count = kUnknownNullCount;
+  ASSERT_EQ(arr_unknown_null_count->data()->null_count.load(), -1);
+  ASSERT_EQ(arr_unknown_null_count->null_bitmap(), nullptr);
+  
ASSERT_EQ(checked_pointer_cast<BooleanArray>(arr_unknown_null_count)->true_count(),
 2);
 }
 
 TEST(TestPrimitiveAdHoc, TestType) {