Type punning with char type in C/C++

Is it safe to do type punning on char types?

int *a = new int[3];
for(b = 0;b <= 2;b++){
   a[b] = b;
}
char *ptr = (char*)&a;

I heard someone that type punning is only allowed for char types without undefined behavior. Is this correct?

Casting a pointer to a valid object of any type to a character type and then accessing the pointer is valid in both C and C++. Normal restrictions still apply, so no trying to modify the char referenced by the pointer if the original object was defined as const, etc.

From the C Standard:

An object shall have its stored value accessed only by an lvalue expression that has one of the following types:

...

— a character type.

From the C++ Standard:

If a program attempts to access (3.1) the stored value of an object through a glvalue whose type is not similar (7.3.6) to one of the following types the behavior is undefined:

...

— a char, unsigned char, or std::byte type.