bolt/deps/llvm-18.1.8/clang-tools-extra/docs/clang-tidy/checks/bugprone/casting-through-void.rst
2025-02-14 19:21:04 +01:00

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.. title:: clang-tidy - bugprone-casting-through-void
bugprone-casting-through-void
=============================
Detects unsafe or redundant two-step casting operations involving ``void*``.
Two-step type conversions via ``void*`` are discouraged for several reasons.
- They obscure code and impede its understandability, complicating maintenance.
- These conversions bypass valuable compiler support, erasing warnings related
to pointer alignment. It may violate strict aliasing rule and leading to
undefined behavior.
- In scenarios involving multiple inheritance, ambiguity and unexpected outcomes
can arise due to the loss of type information, posing runtime issues.
In summary, avoiding two-step type conversions through ``void*`` ensures clearer code,
maintains essential compiler warnings, and prevents ambiguity and potential runtime
errors, particularly in complex inheritance scenarios.
Examples:
.. code-block:: c++
using IntegerPointer = int *;
double *ptr;
static_cast<IntegerPointer>(static_cast<void *>(ptr)); // WRONG
reinterpret_cast<IntegerPointer>(reinterpret_cast<void *>(ptr)); // WRONG
(IntegerPointer)(void *)ptr; // WRONG
IntegerPointer(static_cast<void *>(ptr)); // WRONG