On Tue, Apr 28, 2020 at 02:13:02PM +0200, Jakub Jelinek wrote:
> struct X { };
> struct Y { int : 0; };
> struct Z { int : 0; Y y; };
> struct U : public X { X q; };
> struct A { double a; };
> struct B : public X { double a; };
> struct C : public Y { double a; };
> struct D : public Z { double a; };
> struct E : public U { double a; };
This is only testing the [[no_unique_address]] attribute in the
most-derived class, but I believe the attribute also affects
members in the base class. Is this understanding correct?
Specifically, if we were to add two more tests to the above:
struct X2 { X x; };
struct X3 { [[no_unique_address]] X x; };
struct B2 : public X2 { double a; };
struct B3 : public X3 { double a; };
Then we should see that B2 does *not* count as single-element
struct, but B3 *does*. (That's also what GCC currently does.)
Just trying to get clarity here as I'm about to work on this
for clang ...
Bye,
Ulrich
--
Dr. Ulrich Weigand
GNU/Linux compilers and toolchain
ulrich.weig...@de.ibm.com
