According to Phobos object docs:

uint flags();
    Get flags for type: 1 means GC should scan for pointers 

This is implemented correctly.

import std.stdio;

void main() {
    writefln(typeid(uint).flags & 1);  //0
    writefln(typeid(uint*).flags & 1); //1
    writefln(typeid(void*).flags & 1); //1
    writefln(typeid(float).flags & 1); //0
}

However, source code to setTypeInfo:

void setTypeInfo(TypeInfo ti, void* p)
{
    if (ti.flags() & 1)
	hasNoPointers(p);
    else
	hasPointers(p);
}

The if statement in this code is clearly backwards.