[clang-tidy] Check request: detect incorrect usage of `std::bit_cast`

[carlosgalvezp]

std::bit_cast is often presented as the correct alternative to type punning in C++. However, we see people use it as a drop-in replacement to reinterpret_cast , which only obfuscates the code and still has UB:

float x{};
-int* y = reinterpret_cast<int*>(&x);
+int* y = std::bit_cast<int*>(&x);

This usage is incorrect. Instead, the code should do:

int y = std::bit_cast<int>(x);

Most likely all usages of std::bit_cast<PointerType> are incorrect.

[llvmbot]

@llvm/issue-subscribers-clang-tidy

Author: Carlos Galvez (carlosgalvezp)

`std::bit_cast` is often presented as the correct alternative to type punning in C++. However, we see people use it as a drop-in replacement to `reinterpret_cast` , which only obfuscates the code and still has UB:

float x{};
-int* y = reinterpret_cast<int*>(&x);
+int* y = std::bit_cast<int*>(&x);

This usage is incorrect. Instead, the code should do:

int y = std::bit_cast<int>(x);

Most likely all usages of std::bit_cast<PointerType> are incorrect.