[Issue 9091] New: Perhaps another forward referencing bug.

[d-bugmail at puremagic.com]

http://d.puremagic.com/issues/show_bug.cgi?id=9091

           Summary: Perhaps another forward referencing bug.
           Product: D
           Version: D2
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: nobody at puremagic.com
        ReportedBy: turkeyman at gmail.com


--- Comment #0 from Manu <turkeyman at gmail.com> 2012-11-28 04:08:31 PST ---
I've created a new bug from this thread:
http://d.puremagic.com/issues/show_bug.cgi?id=9065
That thread has forked into unrelated conversations, and I suspect this is a
separate bug anyway...

Kenji: I boiled this down as much as I could...




class Test
{
    void func()
    {
        void templateFunc( T )( ref const T obj )
        {
            foreach( m; __traits( allMembers, T ) )
            {
                pragma(msg, m);
                static if( isVariable!( __traits(getMember, T, m) ) )
                {
                    //...
                }
            }
        }

        templateFunc( this );
    }

    // some class members
    int x;
}

isVariable throws lots of errors when considering the class members.

Note:
  __traits(allMembers, T) and __traits(getMember, T, m)

These should also work with class instances, not just types, eg:
  __traits(allMembers, obj) and __traits(getMember, obj, m)

And these combinations should also work:
  __traits(allMembers, T) and __traits(getMember, obj, m)
  __traits(allMembers, obj) and __traits(getMember, T, m)

All these configurations throw errors, and the errors are different for each
configuration.


Depends on:

/**
 * Detect whether symbol or type $(D X) is a function.
 */
template isFunction(X...) if (X.length == 1)
{
    static if (is(typeof(&X[0]) U : U*) && is(U == function) ||
               is(typeof(&X[0]) U == delegate))
    {
        // x is a (nested) function symbol.
        enum isFunction = true;
    }
    else static if (is(X[0] T))
    {
        // x is a type.  Take the type of it and examine.
        enum isFunction = is(T == function);
    }
    else
        enum isFunction = false;
}

/**
 * Detect whether symbol $(D X) is a run-time variable.
 */
template isVariable(X...) if (X.length == 1)
{
    static if (!is(X[0]) &&
               !is(typeof(X[0]) == void) &&
               !isFunction!(X[0]))
    {
        enum isVariable =
            is(typeof({ auto ptr = &X[0]; }))
         || is(typeof({ enum off = X[0].offsetof; }));
    }
    else
        enum isVariable = false;
}

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