================ @@ -0,0 +1,32 @@ +.. title:: clang-tidy - bugprone-casting-through-void + +bugprone-casting-through-void +============================= + +A check detects unsafe or redundant two-step casting operations involving ``void*``. + +Two-step type conversions via void* are discouraged for several reasons. + +1. They obscure code and impede its understandability, complicating maintenance. +2. These conversions bypass valuable compiler support, erasing warnings related + to pointer alignment. It may violate strict aliasing rule and leading to + undefined behavior. +3. 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 + + __bultin_bit_cast(IntegerPointer, static_cast<void *>(ptr)) // GOOD, __builtin_bit_cast is used to implement std::bit_cast ---------------- PiotrZSL wrote:
I don't think we should put __bultin_bit_cast into example. https://github.com/llvm/llvm-project/pull/69465 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
