Bug 6048 – struct methods included in .tupleof

The following code: ---- template canPersist(T) { enum canPersist = canPersist!(T, typeof(T.tupleof)); } template canPersist(T, U...) { enum canPersist = canPersist!(T, U[0]) && canPersist!(T, U[1..$]); } template canPersist(T, U : U*) { static assert(0, "is this a bug in dmd? methods shouldn't be in .tupleof"); } void main() { struct Test { bool opEquals(ref const Test other) const { return true; } } enum foo = canPersist!Test; } ---- Fails to compile with: ---- prog.d(13): Error: static assert "is this a bug in dmd? methods shouldn't be in .tupleof" prog.d(3): instantiated from here: canPersist!(Test,void*) prog.d(25): instantiated from here: canPersist!(Test) ---- Adding additional methods to Test has no effect (they don't show up in .tupleof), same goes for normal fields (providing you add template canPersist(T, U) { enum canPersist = true; }). Iterating over typeof(Test.tupleof) in main() does not give the void* type.

This is expected. An inner struct contains a context pointer to the scope. Use 'static struct' and that 'void*' member will be gone. To illustrate: ----------------------------------- void main() { struct S{ void a(){} } static struct T{ void b(){} } pragma(msg, S.tupleof); pragma(msg, T.tupleof); } ----------------------------------- tuple((S).this) tuple() ----------------------------------- (Although changing that struct to 'static struct' causes a forward-reference error)

Thank you. I'd forgotten that local structs aren't POD.