RE: comparing function pointer with int does not produce error

[Andy Chittenden <achittenden@bluearc.com>]

> I'll take another attempt at declaring gcc behaviour to be correct.
> According to 4.10/1, "success" is a null pointer constant:
> 
> # A null pointer constant is an integral constant expression (5.19)
> # rvalue of integer type that evaluates to zero. A null pointer
> # constant can be converted to a pointer type; the result is the null
> # pointer value of that type and is distinguishable from every other
> # value of pointer to object or pointer to function type.
> 
> 5.19/1 defines "integral constant expressions":
> 
> # An integral constant-expression can involve only literals (2.13),
> # enumerators, const variables or static data members of integral or
> # enumeration types initialized with constant expressions (8.5),
> # non-type template parameters of integral or enumeration types, and
> # sizeof expressions.

Then why does the following NOT compile:

void stat ();
enum {success};
void monk ()
{
  if (stat == success);
}

cbool.cpp:6: no match for `void (&)() == <anonymous enum>' operator

As success is an enumerator which is a integral constant-expression by your
definition above; it also has zero value and thus must be a "null pointer
constant" and hence the comparisom should be allowed (however distasteful
that may be).

Andy


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