Bug 19134 – [C++] static const y = new Derived(); ->pointer cast from const(Derived) to immutable(void*)** is not supported at compile time

https://forum.dlang.org/post/[email protected] https://run.dlang.io/is/dSVruv Works in DMD 2.080, regressed in DMD 2.081. extern(C++) { class Base { this() {} void consumeAVtblSlot() const {} } class Derived : Base { this() {} } } void main() { static const y = new Y(); } fails with Error: pointer cast from const(Y) to immutable(void*)** is not supported at compile time commenting out the constructor of X makes compilation succeed. Removing extern C++ makes compilation succeed.

I forgot to replace all of the Ys with Derived.

See https://github.com/dlang/dmd/pull/8362#pullrequestreview-142565787.

Commits pushed to master at https://github.com/dlang/dmd https://github.com/dlang/dmd/commit/b952c845f77264d40253e2e144625fdb0c301804 Fix Issue 19134 And revert to D vptr semantics in constructors of extern(C++) classes, i.e., call the most derived override in base constructors. 2.081 introduced a breaking change here, using the most derived override before the super() call and the current class' afterwards. The proper mid-term solution is probably to emit fully C++-compatible constructors for extern(C++) classes, calling the super ctor right at the start and then blitting vptr and class-specific fields from the init symbol. extern(C++) classes (and structs) should get an implicit default ctor (only if there's no other ctor in the class case). extern(C++) classes could then be allocated and properly constructed via C++ `new`; struct declarations in C++ headers for extern(C++) structs wouldn't need to duplicate the field initializers and could simply declare the default ctor (emitted by the D compiler and blitting the init symbol). https://github.com/dlang/dmd/commit/50833f0a98df9ac1f1c78db4dd24743aad300539 Merge pull request #8533 from kinke/fix19134 [stable] Fix Issue 19134 - [C++] static const y = new Derived(); ->pointer cast from const(Derived) to immutable(void*)** is not supported at compile time merged-on-behalf-of: Rainer Schuetze <[email protected]>