[flang-commits] [flang] [flang][runtime] Fix SAME_TYPE_AS()/EXTENDS_TYPE_OF() for CLASS(*) (PR #67727)

[Slava Zakharin via flang-commits]

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@@ -61,13 +61,9 @@ void RTNAME(PointerApplyMold)(
   pointer.set_base_addr(nullptr);
   pointer.raw().attribute = CFI_attribute_pointer;
   pointer.raw().rank = rank;
-  if (pointerAddendum) {
-    if (mold.Addendum()) {
-      // it was copied by operator=() above
-    } else {
-      pointer.raw().f18Addendum = true;
-      pointerAddendum->set_derivedType(nullptr);
-    }
+  if (pointerAddendum && !mold.Addendum()) {
+    pointer.raw().f18Addendum = true;
+    INTERNAL_CHECK(!pointerAddendum->derivedType());
----------------
vzakhari wrote:

Interesting.  I did not think we could do it here, but apparently we can.

Tried this example:
```
module types
  type :: t1
  end type t1
end module types
program main
  use types
  call test()
contains
  subroutine test()
    class(*), pointer :: x
    type(t1) :: y
    allocate(x,mold=y)
    allocate(x,mold=y)
  end subroutine test
end program main
```

The compiler nullifies the pointer before calling `PointerApplyMold`.  This seems to be redundant now, since we started initializing pointers (including the components of the derived types) by default.

Thank you for the additional changes!

https://github.com/llvm/llvm-project/pull/67727