(arrow) branch main updated: GH-45700: [C++][Compute] Added nullptr check in Equals method to handle null impl_ pointers (#45701)

[zanmato]

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The following commit(s) were added to refs/heads/main by this push:
     new ac1f05f28e GH-45700: [C++][Compute] Added nullptr check in Equals 
method to handle null impl_ pointers (#45701)
ac1f05f28e is described below

commit ac1f05f28e18e85ee55cf7aaf3c8ae1ffe0e92d7
Author: mroz45 <kamil.toka...@secom.com.pl>
AuthorDate: Fri Mar 14 11:15:20 2025 +0100

    GH-45700: [C++][Compute] Added nullptr check in Equals method to handle 
null impl_ pointers (#45701)
    
    
    ### Rationale for this change
    
    ### What changes are included in this PR?
    This PR adds a check to ensure that the Expression is not nullptr
    ### Are these changes tested?
    Yes.
    ### Are there any user-facing changes?
    No
    
    * GitHub Issue: #45700
    
    Lead-authored-by: mroz45 <kamil.toka...@secom.com.pl>
    Co-authored-by: kamilt <kamil.toka...@secom.com.pl>
    Co-authored-by: Rossi Sun <zanmato1...@gmail.com>
    Signed-off-by: Rossi Sun <zanmato1...@gmail.com>
---
 cpp/src/arrow/compute/expression.cc      | 2 ++
 cpp/src/arrow/compute/expression_test.cc | 9 +++++++++
 2 files changed, 11 insertions(+)

diff --git a/cpp/src/arrow/compute/expression.cc 
b/cpp/src/arrow/compute/expression.cc
index e970cd3175..e065416208 100644
--- a/cpp/src/arrow/compute/expression.cc
+++ b/cpp/src/arrow/compute/expression.cc
@@ -221,6 +221,8 @@ void PrintTo(const Expression& expr, std::ostream* os) {
 bool Expression::Equals(const Expression& other) const {
   if (Identical(*this, other)) return true;
 
+  if (impl_ == nullptr || other.impl_ == nullptr) return false;
+
   if (impl_->index() != other.impl_->index()) {
     return false;
   }
diff --git a/cpp/src/arrow/compute/expression_test.cc 
b/cpp/src/arrow/compute/expression_test.cc
index 0b7e8a9c23..dcc0f2e5c0 100644
--- a/cpp/src/arrow/compute/expression_test.cc
+++ b/cpp/src/arrow/compute/expression_test.cc
@@ -338,6 +338,15 @@ TEST(Expression, Equality) {
               literal(std::numeric_limits<double>::signaling_NaN()));
   }
 
+  // Equality when underlying `impl_` is null.
+  Expression expr1;
+  Expression expr2(literal(1));
+  EXPECT_NE(literal("a"), expr1);
+  EXPECT_NE(expr1, literal("a"));
+
+  EXPECT_FALSE(expr1.Equals(expr2));
+  EXPECT_FALSE(expr2.Equals(expr1));
+
   EXPECT_EQ(field_ref("a"), field_ref("a"));
   EXPECT_NE(field_ref("a"), field_ref("b"));
   EXPECT_NE(field_ref("a"), literal(2));