Re: Problem with use of anonymous types

[Andrew Pinski <pinskia at physics dot uc dot edu>]

On May 6, 2005, at 8:09 PM, Julian Cummings wrote:

> People are reporting trouble compiling blitz with gcc-4.0.0, and the
> compiler errors are resulting from the use of unnamed enums.  A simple 
> code
> illustrates the problem:
>
>   struct nullType {};
>   template <typename T> inline T operator+(const T& a, nullType) { 
> return a;
> }
>   enum named { namedA = 1, namedB = 2 };
>   enum { unnamedA = 2, unnamedB = 4 };
>   struct bar {
>     enum { namedC = namedA + namedB,
>            unnamedC = unnamedA + unnamedB };
>   };
>   int main() {
>   }
>
> The gcc compiler complains about trying to add unnamedA and unnamedB.
> Apparently it gets confused by the presence of the operator+ overload 
> for
> the empty struct nullType.  I don't see why the compiler would think 
> that
> the anonymous enumerators unnamedA or unnamedB would match with type
> nullType.  Enumerators are supposed to default to integers when used in
> arithmetic operations such as operator+.  Everything compiles fine 
> when the
> operator+ overload is not present.  The code compiles as is under 
> gcc-3.4.
> What gives?

This is a bug in your code.  See PR 19404 and PR 20589.

-- Pinski