Does reinterpret_cast with uint8_t break the Strict Aliasing Rule?

Question

Is the following code legal in terms of the Strict Aliasing Rule (and in general)?

const int size = 1024;
uint8_t* buffer = allocateBuffer(size);
float* float_pointer = reinterpret_cast<float*>(buffer);
std::fill(float_pointer, float_pointer + size / sizeof(float), 1.5f);

As far as I understand, generally speaking SAR says we cannot access (either read or write) data through a pointer of a different type - unless we use a pointer of character type.

However, in the above code we use a pointer of a non-character type (float*) to read or write data of (probably) a character type (uint8_t), which I think is illegal.

Am I correct?

Answer 1

However, in the above code we use a pointer of a non-character type (float*) to read or write data of (probably) a character type (uint8_t), which I think is illegal.

Am I correct?

Yes.

Is the following code legal in terms of the Strict Aliasing Rule (and in general)?

No.

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Besides pointer aliasing, another consideration is that alignment requirement of float is stricter than that of uint8_t. There is doubt whether uint8_t* allocateBuffer(arg) returns a pointer that satisfies the alignment of float.