45 lines
1.9 KiB
ReStructuredText
45 lines
1.9 KiB
ReStructuredText
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.. title:: clang-tidy - bugprone-multi-level-implicit-pointer-conversion
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bugprone-multi-level-implicit-pointer-conversion
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================================================
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Detects implicit conversions between pointers of different levels of
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indirection.
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Conversions between pointer types of different levels of indirection can be
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dangerous and may lead to undefined behavior, particularly if the converted
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pointer is later cast to a type with a different level of indirection.
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For example, converting a pointer to a pointer to an ``int`` (``int**``) to
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a ``void*`` can result in the loss of information about the original level of
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indirection, which can cause problems when attempting to use the converted
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pointer. If the converted pointer is later cast to a type with a different
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level of indirection and dereferenced, it may lead to access violations,
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memory corruption, or other undefined behavior.
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Consider the following example:
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.. code-block:: c++
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void foo(void* ptr);
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int main() {
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int x = 42;
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int* ptr = &x;
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int** ptr_ptr = &ptr;
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foo(ptr_ptr); // warning will trigger here
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return 0;
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}
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In this example, ``foo()`` is called with ``ptr_ptr`` as its argument. However,
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``ptr_ptr`` is a ``int**`` pointer, while ``foo()`` expects a ``void*`` pointer.
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This results in an implicit pointer level conversion, which could cause issues
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if ``foo()`` dereferences the pointer assuming it's a ``int*`` pointer.
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Using an explicit cast is a recommended solution to prevent issues caused by
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implicit pointer level conversion, as it allows the developer to explicitly
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state their intention and show their reasoning for the type conversion.
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Additionally, it is recommended that developers thoroughly check and verify the
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safety of the conversion before using an explicit cast. This extra level of
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caution can help catch potential issues early on in the development process,
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improving the overall reliability and maintainability of the code.
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