Bug 8815 – alias modification silently fails on nested fields

@property void modify(alias symb)() { symb = new int; } class Foo { this() { modify!(x); modify!(c.x); assert(x); // ok assert(c.x); // fail, c.x. is null } static struct C { int* x; } C c; int* x; } void main() { auto foo = new Foo; }

But I'm beginning to think using aliases like this isn't the best choice. For one thing it won't work if the alias is a private symbol. It's probably best to use templated functions that take a 'ref' parameter.

I can see why, it seems "c.x" gets converted to "this.x": @property void init(alias symb)() { pragma(msg, symb); // "this.x", should be "s.x" symb = new int; } class C { this() { init!(s.x); } struct S { int* x; } S s; } void main() { auto c = new C; } Additionally I get this in this sample: core.exception.InvalidMemoryOperationError

Can't pass instance fields as alias parameters, this is a known limitation and part of other enhancement requests.