C++: handle self-assignment correctly (OpenCyphal#292)

edu-rossrobotics · Mar 8, 2023 · 602bfc6 · 602bfc6
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commit 602bfc6
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diff --git a/src/nunavut/_version.py b/src/nunavut/_version.py
@@ -8,7 +8,7 @@
 .. autodata:: __version__
 """
 
-__version__ = "2.0.7"
+__version__ = "2.0.8"
 __license__ = "MIT"
 __author__ = "OpenCyphal"
 __copyright__ = "Copyright 2023 Amazon.com, Inc. or its affiliates. All Rights Reserved. Copyright (c) 2023 OpenCyphal."

diff --git a/src/nunavut/lang/cpp/support/variable_length_array.hpp b/src/nunavut/lang/cpp/support/variable_length_array.hpp
@@ -161,6 +161,10 @@ class VariableLengthArray
             std::declval<allocator_type&>())) && noexcept(VariableLengthArray<T, MaxSize, Allocator>().reserve(1)) &&
         std::is_nothrow_copy_constructible<allocator_type>::value && std::is_nothrow_copy_constructible<T>::value)
     {
+        if (this == &rhs)
+        {
+            return *this;
+        }
         fast_deallocate(data_, size_, capacity_, alloc_);
         data_     = nullptr;
         capacity_ = 0;
@@ -1136,6 +1140,10 @@ class VariableLengthArray<bool, MaxSize, Allocator>
             std::declval<allocator_type&>())) && noexcept(VariableLengthArray<value_type, MaxSize, Allocator>()
                                                               .reserve(1)))
     {
+        if (this == &rhs)
+        {
+            return *this;
+        }
         fast_deallocate(data_, size_, capacity_, alloc_);
         data_     = nullptr;
         capacity_ = 0;

diff --git a/verification/cpp/suite/test_var_len_arr.cpp b/verification/cpp/suite/test_var_len_arr.cpp
@@ -436,6 +436,27 @@ TYPED_TEST(VLATestsNonTrivialCommon, TestForEachConstIterators)
     ASSERT_EQ(MaxSize, i);
 }
 
+#if defined(__clang__)
+#    pragma clang diagnostic push
+#    pragma clang diagnostic ignored "-Wself-assign-overloaded"
+#endif
+
+TYPED_TEST(VLATestsNonTrivialCommon, SelfAssignment)
+{
+    nunavut::support::VariableLengthArray<TypeParam, 20> subject;
+    subject.push_back(0);
+    subject.push_back(1);
+    ASSERT_EQ(2U, subject.size());
+    subject = subject;
+    ASSERT_EQ(2U, subject.size());
+    ASSERT_EQ(0, subject[0]);
+    ASSERT_EQ(1, subject[1]);
+}
+
+#if defined(__clang__)
+#    pragma clang diagnostic pop
+#endif
+
 // +----------------------------------------------------------------------+
 /**
  * Test suite to ensure non-trivial objects are properly handled. This one contains non-generic cases.