Does a simple cast to perform a raw copy of a variable break strict aliasing?-Collection of common programming errors

I’ve been reading about strict aliasing quite a lot lately. The C/C++ standards say that the following code is invalid (undefined behavior to be correct), since the compiler might have the value of a cached somewhere and would not recognize that it needs to update the value when I update b;

float *a;
...
int *b = reinterpret_cast(a);
*b = 1;

The standard also says that char* can alias anything, so (correct me if I’m wrong) compiler would reload all cached values whenever a write access to a char* variable is made. Thus the following code would be correct:

float *a;
...
char *b = reinterpret_cast(a);
*b = 1;

But what about the cases when pointers are not involved at all? For example, I have the following code, and GCC throws warnings about strict aliasing at me.

float a = 2.4;
int32_t b = reinterpret_cast(a);

What I want to do is just to copy raw value of a, so strict aliasing shouldn’t apply. Is there a possible problem here, or just GCC is overly cautious about that?

EDIT

I know there’s a solution using memcpy, but it results in code that is much less readable, so I would like not to use that solution.

EDIT2

int32_t b = *reinterpret_cast(&a); also does not work.

SOLVED

This seems to be a bug in GCC.

1. If you want to copy some memory, you could just tell the compiler to do that:

   Edit: added a function for more readable code:

   #include 
   using std::cout; using std::endl;
   #include 
   
   template 
   T memcpy(const U& source)
   {
       T temp;
       memcpy(&temp, &source, sizeof(temp));
       return temp;
   }
   
   int main()
   {
       float f = 4.2;
       cout

Originally posted 2013-11-09 23:30:31.