C++ name mangling not tracking extern "C"-ness of function types?

[Stephan Bergmann]

Quoting gcc/cp/mangle.c@34394:

/* Non-terminal <function-type>.  NODE is a FUNCTION_TYPE or
   METHOD_TYPE.  If INCLUDE_RETURN_TYPE is non-zero, the return type
   is mangled before the parameter types.
     <function-type> ::= F [Y] <bare-function-type> E   */

static void
write_function_type (type, include_return_type)
     tree type;
     int include_return_type;
{
  MANGLE_TRACE_TREE ("function-type", type);

  write_char ('F');
  /* We don't track whether or not a type is `extern "C"'.  Note that
     you can have an `extern "C"' function that does not have
     `extern "C"' type, and vice versa:

       extern "C" typedef void function_t();
       function_t f; // f has C++ linkage, but its type is
                     // `extern "C"'

       typedef void function_t();
       extern "C" function_t f; // Vice versa.

     See [dcl.link].  */
  write_bare_function_type (type, include_return_type);
  write_char ('E');
}

Is there any rationale for not tracking extern "C"-ness here (beyond: 
"its just simpler that way")?  I do understand that technically it 
doesn't make much of a difference whether a function's type is extern 
"C" or not, but it took me by surprise to find this deliberate deviation 
from the Itanium ABI.

Stephan